DEPARTMENT OF THE INTEEIOE

BULLETIN

OF THK

UNITED STATES

No. 35

WASHINGTON

GOVERNMENT PRINTING OFFICE 

18SG

TJNITED STATES GEOLOGICAL SUEVEY

J. W. POWELL, DIRECTOR

PHYSICAL PROPERTIES

OF

THE, IRON-CARBURETS

THIRD PAPERS

(PRECEDING PAPERS ON Till! IKON-CAItUUKETS IN 11ULLETINS 14 AND 27)

BY

GAEL BAEUS AND VINCENT STEOUHAL

WASHINGTON 

G-OVERNMENT PEINTING OFFICE

1886
CONTENTS.

Page.

Letter of transrnittal........................................................ 10

A. The internal structure of tempered steel......................... ...... 11

Introduction.... ..........................'.......*....................... 11

Apparatus . r ............................................................ 12

Experimental results.......................... ^......................... 16

Discussion.....................I.......*.............................. 31

Conclusion ............................................................. 50

13. The color effect produced by slow oxidation of iron-carburets ............. 51

Data for high temperature .......................................... 52.

Data for low temperature ............................................... 55

Index............................................. ......... ........... 61

(447) 6

ILLUSTRATIONS.

Page. 

FIG. 1. Crucible for heating steel........................................... 13

. 2. Apparatus for quenching steel...................................... 14

3. Holder for galvanic solution........................................ 15

4. Method of suspension............................................... 16

5. Rod No. I after removal of seven shells.............................. 28

6. Holder for resistance measurements .............................. _... 29

7. Chart illustrating density as a function of radius.................... 33

8. Chart illustrating elementary density as a function of radius........ 36

9. Chart showing temperature of the mean " clear blue" film, as a function of time ...................................................... 04

10. Grunow'sshaft in position......................... .... . 59

(449) 7

LETTER OF TRANSMITTAL.

DEPARTMENT OF THE INTERIOR, 

UNITED STATES GEOLOGICAL SURVEY,

DIVISION OF CHEMISTRY AND PHYSICS,

Washington, D. 0., January 18, 1886.

SIR : We have the honor to transmit, through'Prof. F. W. Clarke, chief' 

chemist, the accompanying paper on the physical properties of the iroucarburets for publication as a bulletin of the Survey. The paper is offered in its present fragmentary form, owing to the circumstance that 

certain changes in the location of the laboratory oblige us temporarily 

to suspend the work. The results here presented, however, advance 

the inquiry to well denned stages of research, and we therefore have no 

hesitation about submitting them.

Our earlier work on the iron-carburets will be found in Bulletin 14 

and in Bulletin 27, pp. 30 to Gl.

C. BAKUS. 

V. STROUHAL. 

Hon. J. W. POWELL,

Director United States Geological Survey.

(451) 9

PHYSICAL PROPERTIES OF THE IRON-CARBURETS.

BY CARL BARTJS AND VINCENT STROUHAL.

A. THE INTERNAL STRUCTURE OF TEMPERED STEEL. 

INTRODUCTION,

Theories of magnetization usually premise homogeneity of the material carrying the magnetic quality. If the material is homogeneous, 

such theories still encounter formidable mathematical difficulties, and 

even in the favorable case of soft steel they fail to predict results which 

are in satisfactory accordance with experiments. 1 In proportion as the 

rods become hard and the internal structure becomes more and more 

complex, the phenomena are withdrawn from the scope of theory altogether, and must be grouped and described by a series of empiric laws. 

It is clear, however, that a decided step in advance of mere empiricism 

will have been made when the conditions of internal structure shall be 

fully understood. The present paper is a first endeavor in this direction. 

We may add that what is here said respecting magnetism will apply to 

other properties of steel.

In our magnetic work2 we operated upon very thin steel rods, inferring that where diameter decreases indefinitely structure will more and 

more completely vanish; but to what degree this assumption is warranted for diameters within the reach of experimental methods cannot 

be foreseen. In other words, we do not know to what extent our results fail to express the permanent magnetization of steel, passing 

homogeneously from hard to soft. Even if it be granted that the error 

due to surface decarburatiou is nil, we have still to take into account 

the structural effects originally observed by Fromme.3 We have digested his results in the accompanying table, and from these computed 

a few supplementary data to give the table fullness. The latter are inclosed in parentheses. In the table, M, p: A denote the mass in grammes, 

the radius in centimeters, and the density, respectively, of the given 

glass-hard rod, after the removal of the number of "shells indicated in 

the first column. The mean radius, thickness, mass, and density of

»Of. U. S. Geol. Surv. Bull. 14, pp..113, 114.

3 Bull. 14, chaps. V, VI.

3 C. Frommo : Wied. Ann., VIII, p. 355, 1879.

' (453) - W
12 PHYSICAL PKOPERTIES OF THE IRON-CARBURETS. [BULL. 35.

the consecutive shells are given under R, 3, /«, 3. The second column 

contains the number of days during which the rod was left in dilute 

acid to effect the removal of shells. Froinme determined A once per 

day. We may remark that the rod used was twice glass-hardened, 

and that after losing the three shells mentioned, it showed internal 

fissures. This led Fromme to abandon the experiment.

Table allowing Fromme? s results for structure.

Shell.

0...... .........................

1....... ........................

9

Days.

0

16

20

M

30. 450

OQ rjAR

28. 043

27. 029

P

/A OKO7\

/ft q^OiH

(0. 3396)

(0. 3340)

A

7. 7487

7. 7130

7.7412

7. 7120

R

(0. 3520)

(0. 3450)

(0. 3368)

i>

(0. 0033)

(0. 0108)

(0. 0056)

H

0.704

1.703

1.014

& '

10.5

7 1

(8.6)

It is to us a matter of no little surprise that after having obtained 

these startling results, the significance of which Froinme fully appreciated, he should have given the work no further consideration. The surface densities here encountered are almost incredibly large, especially so 

because the rod, having been twice quenched, must have been superficially decarburized, and because it was internally cracked. And yet, 

in spite of the dangerously small values of 5, the values for A are s.o 

pronounced that the data for # must in their general variations b,e correct. 

Hence these abnormal values, and the probable occurrence of changes of 

strain implied, together with intimations of singular periodic relations, 

give this short series of results unusual physical importance.

Guided by these data, many of our experiments were made chiefly 

with reference to surface effects. Nevertheless, our main object in this 

paper'is to follow the phenomenon of structure throughout comparatively great ranges of depth. Hence our shells are necessarily1 chosen 

thicker (0.01cm to O.lcm ), and for this reason, possibly, we did not detect 

the enormous condensation of Fromme's filmy shells, if, indeed, in the 

steel examined such densities existed. Aside from this difference in 

degree, in the method chosen, and in the material employed our results 

corroborate the data of Fromme in a general way. We also encounter 

harmonic variations of d which appear to be actual occurrences, inasmuch as they cannot satisfactorily be referred to periodic distributions 

of errors.

APPARATUS.

Steel Our steel, as we subsequently found, was not the best for the 

purpose, being a coarse-grained metal, quite brittle in the glass-hard 

state. This steel readily cracks on quenching, easily loses carbon at 

the surface, and is probably incapable of carrying more than small 

values of stress. If the temperature before quenching be too high, the

1 It is impossible to retain perfect cyliiidricity when many shells are removed by 

solution. See p. 49.

' (454)
BARUS AND STROUTIAL.] METHOD OF QUENCHING. 13

superficial layers rarely show hardness at all. All this taken together 

may explain why the values of density in hand vary within an interval 

so much smaller than was the case in Fromme's investigation. Some 

of our experiments, however, were made with other kinds of steel. A 

priori there is no reason why results for the structure of the material 

in question are not just as important as results for the structure of any 

other kind of steel. The objectionable qualities enumerated have indeed 

led to some special results. We show in the sequel that the chemical 

constitution of steel is one of the essential factors determining structure.; 

that in a full investigation it will be necessary to extend the experiments 

to as many kinds of steel as possible.

In all cases, however, the mechanical hardness exhibited by our steel 

in the tempered state was exceptionally great. Moreover, the density 

interval hard-soft is here as large as we have found it in any other kind

of steel. It appears, indeed, that the magnitude of this interval is 

modified chiefly by carburat'ion, and that for moderate thicknesses it 

is almost independent of dimensions a deduction at variance with 

earlier results of Fromme and our own. Cylindrical figures were operated on in all cases.

Crucible. To impart to the thick steel cylinders the desirable uniformity of red heat before quenching, they 

were heated in a cylindrical iron box (height 

8.5cni , diameter 4cm , inside measure) made 

of gas-pipe supplies. The box was heavily 

coated with oxide internally, and the cylinder 

was placed therein on a layer of asbestus, as 

shown in Fig. 1.

This apparatus is introduced into a large 

Fletcher crucible furnace and heated to the degree of redness necessary. The temperature 

of the cylinder must be specially observed from 

time to time bjr momentary removals of the 

lid. The iron box is further useful, inasmuch 

as oxidation, carburatiou, and decarburation 

are very nearly avoided. The surfaces of the 

cylinders remain smooth, showing the colored 

films only.

Apparatus for quenching. This apparatus is also made of gas-pipe 

supplies, as shown in Fig. 2. When in use it is placed vertically in 

the neighborhood of- a hydrant, and a swift current of water is passed 

through it, as indicated by the arrows. Dimensions of'main reservoir: 

Length, 25°'"; diameter, 5cm , inside measure. Diameter of supply-tube, 

2.5cm. Near the lower end of the apparatus is a false bottom of wire 

gauze, a «, held in place by an iron ring. The object of this is to 

hold the steel suspended in the current. The cylinder, having been

(455)

Fie. 1. Crucible for heatingstccl.
14 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [HULL. 35.

heated to the temperature desired, is carried to the quencher in the 

(closed) crucible; after this the lid is quickly taken off, and the cylinder 

is dropped into the water. The advantages and disadvantages of quenching in a current of water have so 

frequently been discussed that comment is unnecessary 

here. It is certainly the best method for the present 

purposes. , Cell for solution. For the purpose of removing consecutive shells from the cylinder, we tried at first to 

use a carbon-pointed master-tool on the lathe. But 

steel is too tenacious and diamond too brittle; so that 

even in the case of stones ground with sharp cutting 

edges the work is rather scraped or ground than cut. 

The progress made is therefore exceedingly slow, and 

the utmost care must bo taken to avoid appreciable 

rise of temperature from friction. This tedious process 

was therefore rejected, and a method in which the shells 

are removed by galvanic solution was used in its stead. 

After solution the cylinders were trued and smoothed 

as far as necessary by the diamond point, scraping under a current of water.

In order to secure uniformity of solution over the 

whole cylindrical surface of the steel, we devised the 

special cell figured in the diagram, Fig. 3 (page 15).

This consists essentially of a steel clamp, c a b d c c, 

the ends of which are sharpened conically, and fit into 

conical depressions, c c, in the end surfaces of the cylinder operated 

upon. A drum, A B D J7, the cylindrical surface of which is of sheet 

copper, with the ends A B and D E closed by plates of suitably per--

forated vulcanite, surrounds the cylinder symmetrically on all sides. 

The steel arm a c passes through the center of the upper plate. The 

lower plate has a much larger perforation, enabling the drum to slide 

easily over the cylinder and fitted to a wooden collar, F F.

Together with the side of clamp e (7, the collar F F serves as a kind 

of foot for the apparatus. When in nse the cell is plunged into a large 

vessel containing the electrolyte, and is submerged at least above the upper face A B of the drum. To prevent corrosion, the clamp c a, I d e c 

is completely enveloped in an insulating coat of rubber hose. For the 

same purpose the ends of the cylinder are painted with, asphaltum. 

Having sprung it into position, the insulation of the-clamp-is made continuous with the insulation on the ends of the cylinder by covering all 

exposed partsxwith a thick layer of paraffine.

The current enters the clamp at +a, passing into the cylinder from 

both ends; thence across the electrolyte to the drum; finally by the 

gutta-percha-covered 'wire B back to the battery. It is well to cover

(456)

1

I 

 isc

Fie

\

\

1. ........... 9'i

1

^

|; ;J

M. 2. Appar

| 1

1

i

^& 

itus for

quenching steel.
1URU8 AND BTftOtJHAL.] GALVANIC SOLUTION. 15

the inner surface of the drum, above the upper and below the lower 

planes of the ends of the cylinder, with asphaltum. In this case the 

axes of the tubes of flow are radial 

lines. In other cases they are 

crowded cither near the ends or near 

the equatorial parts of the cylinder, 

and solution takes place at greater 

rates in those parts.

Two to ten Grove cells, flat pat- ^ 

tern, vulcanite cups, connected either

in series or in multiple arc, supplied 

the amount of current necessary. 

These cells are by no means constant, 

and are practically exhausted for the 

present purposes in two hours. The 

quantity of steel dissolved without 

current being slight, we were able to 

supervise and regulate the rate of 

solution satisfactorily by inserting a 

Siemens' amperirneter. The whole 

process was therefore well under control. Usually the strength of current was so chosen as to dissolve an 

average total amount of 10 g. to 15 

g. during each experiment.

The following little table, selected 

at random from many data, contains 

the statistics of solution and exhibits the mean efficiency of the battery 

(current in amperes) perspicuously: PlG . 3. Boi(ler for galvanic solution.

Time.

h. TO. 

10 10

15

20

25

30

35

40

45

50

Current.

3.0

8.7

11.0

12.2

12.8

13.0

12.8

12.2

11.3

Time.

h. m. 

10. 55

60

11 5-

10'

15

25

45

12 15

Current.

10.5

9.3

8.4

7.4

6.9

5.8

3.G

0.5

During the solution of superficial shells the cylinders frequently 

showed symmetrical furrows and ridges, probably indicative of certain 

varieties of structure of the soft bars. Usually, however, the surfaces 

were merely, rough and pitted, heavily coated with carbon, somewhat

(457)
16 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [HULL. 35.

irregular; so that truing with the diamond is indispensable. In some 

rare instances glossy surfaces appeared, or again rough surfaces partially mottled with glossy patches. All this is probably connected 

with the passivity of iron. Solution is best effected in dilute hydrochloric acid. In the case of dilute sulphuric acid the occurrence of 

passive iron and reduced rates of solution are a frequent annoyance. 

The ferric chlorides attack copper, and are therefore objectionable. Solution in oxalates, though distinctly perceptible, is practically nil. 1

The central depressions or holes in the end surfaces of the steel cylinders have thus far been described only as subserving the purposes of

holding the cylinders in the dissolving cells, 

.and (during truing) in the lathe. But they 

are further useful, in the density work in question, as a means for attaching*thc suspension. 

This is clearly shown in the annexed cut, Fig. 

4. This method of fastening is again employed 

in the resistance measurements.

EXPERIMENTAL RESULTS.

PIG. 4. Method of suspension. Results for density. The results of our measurements are given in the following tables, and 

it has been our endeavor so to arrange them that data referring to cores 

and shells of like order may be easily compared.

Table 1 contains the constants of the cylinders in the soft state, in 

which they reached our hands. Mis the weight in grammes for the 

length I and diameter 2/3 of cylinder. The latter dimension was deter - 

rninable with some accuracy by means of a small spherometer. Using 

this datum and the known density we calculated I. In case of cylinders 

as thick as these, it is not easy to obtain accurate mean values for. I by 

mere measurement. But the difference between.observed and calculated I in the tables is almost wholly due to the differences in the factors of the two centimeter scales (spherometer screw and rule) e°mploycd. 

/4 t is the observed density at t°. From this we computed A, the density 

at 0°, and p, the corresponding value for specific volume (volume of the 

unit of mass), by accepting 0.000036 as the coefficient of cubical expansion of steel. . . TABLE 1. Data for the commercial (soft) siatc.

No.

1 ....

2.....

3.....

4.....

5.....

M

0- i 

332.4745

332. 4955

149. 8985

149. 9675

37. G219 

37. 0217

I observed.

cm. 

5.90

5.98

5.97

5.97

6.00

I calculated.

cm. 

0.013

6.024

6.006

0.024

6.020

2p observed.

cm. 

3. 0000

2. 9953

2.0139

2. 0118

1. OOS5

t

°0. 

24.0

24. 0

24.0

23.8

24.0 

20.8

At

7. 8208

7. 8270

7. 8296

7. 8304

7. 8270 

7. 82S7

A

". 8337

". 8337

". 8303

". 8371

". 8338 

 '. 8302

Mean A

7. 8337

7. 8337

7. 8303

7. 8371

| 7.8350

V

0. 127054

0. 127Gf>4

0. 127012

0.127598

0. 127 033

1 We are indebted to Prof. F. A. Goocli for advico in much of ihis work.

(458)
EXPERIMENTAL DATA. 17

Tables 2 and 3 contain the first series of results. As above, M, p, 

£, J, p are the symbols of mass, radius, temperature, density, specific 

volume, respectively, of the cores. Again, JK, 3-, //w, # are, respectively, 

the symbols of mean radius, thickness, mass, density of the elementary 

shells. If We denote the number of the shell by a subscript, and if the 

first core be the volume of cylinder left after removing the first shell, 

then the relations between the quantities in the tables are succinctly 

these :

=A.-i A, jjn=Mn_} Mn

*»=4,-.4-sr (4.-i 4.K (observed)

 =-= 

i Mnpn

(calculated) v

This distinction between observed and calculated is not quite rigid, 

because both data involve J, but the other quantities are different.

Tables 4 and 5 contain the second series of results, and are constructed 

on the same plan as Tables 2 and 3. Little further explanation is therefore required. When observations of A were made on different days, 

the date of each is usually given. We may remark that in these and 

the preceding tables "diameter observed" is usually the mean of ten 

measurements made with a screw micrometer caliper. In the case of 

rough surfaces, where frequent repetitions are essential, this instrument 

is preferable to the spheroraeter. . Except where otherwise stated, the 

surface has been turned smooth by the diamond.

To facilitate comparison Tables 2 and 3 are printed in parallel form 

(pp. 18-23), as are also Tables 4 and 5 (pp. 24-27).

(459) 

Bull. 35 2
18 PHYSICAL PROPERTIES OF THE IRON-CARBURETS.

TABLK 2. Cyliudum in tlteglass-liard state. Constants ofllic consccutiw cores. First series

of measurements.

 ' [I = 6 cm. approximately.]

MO, po, ^o, PO.

No.

1

3

5

M

832. 1020

149. 7442

87.5913

p observed.

1. 5041

1. 0112

0. 6081

p calculated.

1.5054

1. 0123

t

21.3

94 9

22.7 

24.0

22 4

18.2

At

7. 7680

7 7fi84

7. 7457 

7. 7454

7. 7381

7: 7393

A

7. 7738

7 771ft

7. 7521 

7. 7520

7. 7442

7.7443

Mean A

7. 7744

7. 7520

7.7442

V

0. 128627

0. 12899G

0

1 OO1 on

Remarks.

Ml, Pi, dl, pi.

1

8

821.9377

140.4123

1.4832

0.9996

1. 4823

1.0012

23.1 

26.3

23.9 

25.2

7. 7671 

7.7663

7. 7419 

7. 7417

7. 7735 

7. 7734

7. 7485 

7. 7486

7. 7734

7. 7485

0.128644

0. 129057

MI, Pi,

1

8

307.0620

132.5652

' 1. 4500

0. 0532

1.4477

0. 9528

21.9

21.9

21.8

21.8

7. 7667

7. 7005

7.7411

7. 7403

7. 7728

7. 7726

7. 7472

7 7464

7. 7727

7. 7469

0. 128655

0. 129084

M3, P3,

\

3

1

8

1

8

292. 3284

119. 1982

280.3889

107. 1745

269. 8968

. 91.0238

1.4164

0. 9051

*

1. 3895

0. 8636

..........

1. 4124

0.0036

1. 3833

0. 856G

1.3571

0.7894

21.6 

22.9

22.0 

22.6

21.1

20 9

21.4 

22.0

22.0 

22.1

21.8

22.0

7.7085 

7. 7673

7. 7384 

7.7396

M<, p<,

7. 7077 

7. 7G71

7. 7417 

7. 7421

M6, p6l

7. 7687 

7. 7690

7. 7421

7. 7430

7.7746 

7. 7737

7. 7445 

7. 7460

^4, F<.

7. 7735 

7. 7732

7. 7476 

7. 7482

^5, fe.

7. 7748 

7. 7751

7.7482

7. 7491

7. 7742

7. 7453

7. 7734

7. 7479

7. 7750

7.7486

0. 128631

0. 129111

0. 128644

0. 129067

0. 128017

0. 129056

(460)-
JUUU8 AND BTUOUnAL.1 EXPERIMENTAL DATA. 19

TABLE 3. Cylinders in the glass-hard state. Constan is of the consecutive elementary shellt.

First series of measurements.

[1 = 6 cm. approximately.]

No.

1

3

ft

R ohservedIt calculated.

0 observed.

& calculated. *

£ observed.

4 calculated. Remarks.

C Longitudinal crook ap-

( of the cylinder.

First shell, JR,, $,, fii, <*,.

1

3

1. 4936

1.0004

1. 4930

1. 0068

0. 0200

0. 0116

0.0231

0. 0111

10. 1643

3. 3319

7.809

7.904

7.806

7.914

Shell fllable; removed 

with bard-steel master

tools. 

Do.

Second shell. Ea , #2, n?, &.

1

s

1.4066

0.0764

1. 4650

0.0770

0. 0332

0. 0465

0.0346

0.0484

14. 8757

12. 8471

7.775

7.705

7.702

7.T62

Shell not fllable; dissolved off calvanicallv.

Trued with diamond; 

shell very hard.

Same. Longitudinal and

pear distinctly.

Third shell. E3 , i93, pa, J3.

1

3

1.4332

0.9291

1. 4301

0. 9282

0. 0336

0. 0481

0.0353

0.0492

14. 7336

13. 3670

7.741

7.762

7. 738

7.762 Vertical and transverse 

cracks or crevices visible.

Fourth shell. JR4, tf4, p4 , S4 .

1

8

1. 4030

0. 8858

1. 3978

0. 8801

0.0269

0.0415

0. 0291

0. 0470

11.9395

12.0237

7.795

7.718

7.794

7.723

Surface shows scaly 

fracture.

Do.

Fifth shell. E6, i?6, p6, 66.

1

R

1. 3702

0. 8230

0.027

0.068

0. 0262

0 (\tVT>

10.4921

16.1507

7.733

7.744

(461)
 20 PHYSICAL PROPERTIES OF THE IRON-CARBURETS.

 TABLE 2: Cylinders in -the glass-hard state. Constants of the conseciitivc cores. First series of measurements Continued.

M6, p6, -^6, -PeNo.

1

. 8

M

240. 7900

71.6405

p observed.

1. 3026

» 0.7068

p calculated.

1.2974

0. 7002

t

19.5 

20.8

19.0 

21.4

At

7. 7732

7 7794

7. 7472 

7. 7481

A

7. 7785 

7. 7782

7.7425 

7.7439

Mean A7.7784

7.7532

V

0.128561*

0. 128979

Remarks.

M7, p7, //Tt

1

3

225.8279

56.7829

. 1.2556

0. 6312 .

1. 2408

d. 6232

19.5

20.8

20.0

21.2

7. 7756

7. 7756

7. 7507

7 7>i17

7. 7812

7.7814

. 7.7563

7 7<\RB

7. 7813

7. 7566

0. 128513

0. 128923

M8, PS,

1

3

211. 2518

43.2270

1. 2038

d. 5989

1. 2001

0. 5438

18.8 

19.8

19.2 

22. d

7. 7767 

7. 7758

7. 7478

7 7d7<;

1. 7820 ' 

7.7814

7. 7531 1 

7. 7536 '

7. 7817

7.7538

0. 128507 '

0. 128969

Mg, pg, ^9,

1

3

199. 6350 :

36. 1996 ;

1. 1759

0.5036

1.1664

. 0.4975

21.6;

22.0

22.0 

22.5

7. 7780 

7. 7780

7. 7532 

7. 7536

7.7841 

7. 7841

7. 7593 

7. 7598

' 7.7841

7. 7595

0. 128467

0. 128874

pio,

1

»'

163. 2372

29.7464'

1.1253

0.4603

1. 1175

 0. 4508

21.8 

21.9

.21. 9 ; 

21. 5

. 7. 7805 

7.7811

7. 7561 

7. 7591

7.7866 

7. 7872

7. 7622 

7. 7652'

7. 7869

7. 7637

0. 128421

0. 128804

n, PJI,

V

0

166. 7330 :

!

125.0084

1.0725

0.4182

1. 0656

0. 4134

21.4 

21.3

21.5 

21. d

7. 7834 

7. 7837

7. 7558 

7. 7566

7. 7893 

7. 7895

7. 7618 

7. 7624

7,7894

7. 7621

d. 128380

0. 128831

Pit, PH.

1. 149.7915,

20. 4688 

20 3481

1. 0269

t.8771

1. 0099

d. 3734

19.2

17.4 

l».d

7.7866

7. 7598 

T.7613

7. 7919

7.7640 

7.7666

7. 7919

7.76W

0. 128338

0.228773

,

. _

(462)
BAHUfl AND BTKOUHAL.] EXPERIMENTAL DATA.

TABLE 3. Cylinders in the glass-hard state. Constants of the consecutive elementary shells. 

First series, of measurements Continued.

Sixth shell. J?6, #e> fa, fa

No.

1

8

.Rob- 

 served.

1. 3298

0. 7481

K calculated.

1. 3272

0. 7448

dob- 

, served.

0. 0545

0. 0826

# calcn- 

. lated.

0.0507

0.0892

F

23.1059

19. 3833

Jobserved.

7.734

7.729

5 calculated.

7,741

7.732

Remarks.

»

Seventh shell. R?, &i, fo, 6-t1

8

1. 2791

0. 6690

1.2091

0. CC17

0. 0470

0/075G

0. 05G6

0.0770

20. 9630

14. 8576

7.740

7.739

7.747

7.740

*

Curiously glossy after so.

lution ; crack still percoptiblo.

Eighth shell. R8, \?8, j"s, ^s1

3

1. 2295

0: 5901

1, 2204

0. 5835

0. 0522

0. 0823

0. 0407

0. 0794

14.' 5761

13. 5559

7.777

7.767

7.775

7.765

Ninth shell. Rg, tf9, #9, 69.

1

3

1. 1896

0. 5263

1. 1832

0. 5200

0. 0275

0. 0453

0.0337

0. 04G3

11. 6168

7. 0274

7.730

7.722

7.741

7. 725 4

Tenth shell. -Elo, i?io» fiio> dio-

]

3

1. 1507

0. 4818

1. 1420

0. 4742

0. 0506

0. 0433

0. 0489

0. 0467

16. 3978

6. 4532

7.753

7.737

7.751

7.740

Eleventh shell. Rn, i?n, /in, AH.

1

3

1. 0989

0.4393

1. 0915

0. 4321

0. 0528

0. 0421

0. 0519

0. 0374

16. 5042

4. 7380

7.758

7.772

7.762

7.772

Twelfth shell. Rlz, #12, fin, fla.

1

3

*1. 0497

*0. 3976

tl. 0377

tO. 3934

*0. 0450

*0. 0410

tO. 0557

tO. 0400

16. 9415

4. 5999

7.761

7.746

7.708

7.747

* Rough. t Smooth.
22 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [BULL. 35.

TABLES. Cylinders in the glass-hard state. Constants of the consecutive cores. First 

series of measurements-^- Continued.

MIS, Pl3, As, f7l3.

No.

1

3

M

138. 8822 

138.2C07

p observed.

0.9792

 0.3354

p calculated.

0. 9714

t

18.7 

21.9

At

7.7837 

7. 7872

A

7.7890 

7. 7933

Mean A

7.7911

A

0. 128352

Remarks.

pit,

1

3

127. 5671 

127. 5652

. 0. 9417

0. 2850

0. 9319 21.6 

23.1

7. 7878 

7. 7872

7.7939 

7.7936

7.7937 0. 128308

MIS, Plfi, As, {7j6-

N

1 117.4393 

117.4414

0. 9023 0.8939 22.2 

20.0

7. 7914 

7. 7927

7. 7975 

7. 7983

7. 7979 0. 128239

Mi6t Pl6> As, fTig.

1 106. 8649 

106. 8635

0. 8651 0. 8526 19.8 

21.1

7.7954 

4 7. 7942

7.8010 

. 7.7988'

7.7999 0. 128207

MIT, PIT, AT, PIT

1 07. 9382 

07. 9374

0. 8251 0. 8101 19.8 

21.2

7. 7961 

7. 7952

7.8017 

7. 8010

7. 8017 0. 128177

MIS, PIS, As, fis1 86. 1936 

86. 1931

0. 7767 0.7656 20.5 

22.2

7. 7961 

7.7947

7. 8017 

7.8008

7. 8013 0. 128184 Equatorial parts 

just nlablo.

Mig, pig, Ag, ^19.

1 74. 8681 

74. 8673

0. 7238 0. 7135 21.5 

23.0

7.7973 

7. 7960

7. 8031 

7. 8024

7. 8027 0. 128161 Fileable.

Mjzo, P20, Ao, J720-

1 61. 4094 

61. 4078

0.6515 0.6462 19.4 

22.2

7. 7973 

7.7931

7. 8026 

7. 7992

7.P009 0.128190 Fileable.

(464)
BAKU8 AND BTROUHAL.] EXPERIMENTAL DATA. 23

TABLE 3. Cylinders in the glass-hard state. Constants of the sonsccutive elementary shell*. 

First series of measurements Continued.

Thirteenth shell. E\9, &u, nu, da.

No.

1

3

It ohserved.

*1. 0031

0. 3563

R calculated.

tO. 9907

* observed.

*0. 0477

 «*V

0. 0417

# calculated.

tO. 0385

M

11.2200

6 observed.

7.800

S calculated.

7.800

Remarks.

* Rough. t Smooth.

Fourteenth shell. J?n, t?14. f*u, <5u1

a

0.9605

0.3102

0.9516 0.0375 0.0395 11.0054 7.762 7.758

Fifteenth shell. .K15, i?i6, pi6 (5, 6.

1 0. 9220 0.9129 0.0394 0.0380 10. 1258 7. 746 7.745

Sixteenth shell.

1 0.8837 0. 8733 0.0372 0. 0413 10. 5761 7.775

.........

7.778

Seventeenth shell. En, i?n, fiu, 6^.

I 0.8451 0.8343 0. 0399 0.0365 8.9204 7.781 7.780 v>

Eighteenth shell. JRi8, i^is, /^is. <5is.

1 0. 8009 0.7908 0. 0485 0. 0505 11. 7445 7.805 7.805 Equatorial parts fllable.

Nineteenth sholl. ^19, t?ig, //ig, 6\g.

1 0. 7502 0. 7395 0.0529 0. 0521 11. 3256 7.792 7.793

Twentieth sholl. -Z?8o, #20, Pw, ^so1 0. 6876 0. 6799 0. 0723 0. 0673 13. 4591 7. 811 7.810

(405)
24 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [BULL. 35.

TABLE 4. Cylinders in the glass-hard state. Constants of the consecutive cores. Second

scries of measurements.

[1=6 cm. approximately.!

MO, po, 40, p0.

No.

2

4

6

M

332. 2677

149. 8939

115.3561

..........

p observed.

1.5010

1. 0133

0. 8919

..........

p calculated.

1. 5043

,

.1.0114

0. 8855

..........

t

22.2-

22.2

22.0

17.8

22.2

17.9

At

7. 7841

7. 7837

7. 7678

7. 7690

7. 7975

7. 7992

4 A

7. 7902

7. 7398

7. 7739

7. 7740

7. 8036

7. 8042

Mean A

7. 7900

7. 7740

7.8039.

..........

 V

0. 128370

0. 128634

0. 128141

Remarks.

2

04

aO

321. 1428

320. 6413

144. 7017

144. 7017

.108.1191

108. 1191

1. 4785

0. 9970

..........

0. 8653

1. 4785

0. 9938

..........

0. 8575

23.9

19 4

23.8

19.8

23.6

10 ft

7. 7798

7 7QDQ

7. 7661

7. 7682

7. 7934

7 7Qfifi

7. 7864

7 7QOO

7. 7727

7.' 7738

7. 8000

7 fifl99

7. 7878

7. 7733

..........

7. 8011

0.128406

0. 128645

..........

0. 128187

Rough. Oct. 29,

1885.

1885.

Oct. 29, 1885.

Oct. 31, 1885.

Oct. 29, 1885.

Oct. 31, 1885.

a Difference in A possibly the result of shrinkage. 

Mi, p.2, /VJ72.

2

4

6

310. 9500 

310. 6535

136. 9445 

136. 7036

100.5121

1. 4558

0.9688

0.8314

1. 4549

0. 9663

0.8260

.

20.3 

21.2

19.4 

19.6

20.0

7. 7832

7 7AA1)

7. 7681 

7. 7697

7.7924

7

7OCQ

7. 7888

7 7000

7. 7734

7 77 eo

7.7980

7. 8015

7. 7894

7. 7743

7.7997

0. 128380

0. 128629

0.128210

1

Kough.

Rough.

Rough.

M3, p3,

[73-

2

4

6

297. 6610 

297. 6550

126. 3200 

126. 3191

8a 6386 

89. 6377

1. 4260

0. 9327

0. 7876

' 1. 4237

0. 9284

0. 7809

22.2 

22.3

22.0 

23.4

21.2

23.7

7. 7849 

7. 7853

7 7690 

7. 7685

7. 7929

7 709n

7. 7910 

7. 7914

7. 7751 

7. 7749

7. 7987 

7. 7984

7. 7912

7. 7750

7. 7985

0. 1283T50

0. 128617

0. 128230

p t ,

2

4

6

285. 8320 

285. 8392

110. 3412 

116. 3427

79. 2544 

79. 2530

1. 4001

0. 9024

0. 7436

1. 3950

0. 8908

0. 7342

22.0 

21.1

22.4 

20.4

20.6 

22.6

7. 7805 

7. 7862

7. 7706

7 7791

7. 7940 

7 7919

7. 7926 

7. 7920

7. 7767

7 7770

7. 7998

7 7Q81

7. 7923

7. 7773

7.7990

0. 128332

0. 128579

0. 128222

(466)
BAUU8 AND BTliOUIlAL.] EXPERIMENTAL DATA. 25

TABLE ^. Cylindera in the glass-hard slate. Constants of the consecutive elementary 

slie.ll)i. Second series of measurements.

[1=0 cm. approximately. |

No.

?,

4

fi

R observed.

R calculated.

dob- 

, served.

& calculated. !> 

& observed.

i calculated. Remarks.

First shell. II,, i?i, fr, <V '

2

4

C

1. 4897

1. 0051

0. 8786

1. 49H

1. 0020

0.8615

0.0225

0. 0104

0. 0266

0. 0258

0. 017C

0. 0280

11. 3757

5. 1922

7. 2370

. 7.8C2

7.795

7.849

7.847

7.795

7.847

.

Second shell. -K2 , #a, As, ^2-

2

4

6

1. 4070

0. 9829

0. 8483

1. 4067

0. 9800

0. 8417

0. 0226

0. 0282

0. 0339

0. 0236

0. 0275

0. 0315

10. 0903

7. 8777

15. 0378

7.736

7.756

7.818

7.746

7.756

7.832*

Third shell. £3 , #3, Ma, h2

4

6

1.4410

0. 9508

0. 8095

1. 4393

0. 9473

0. 8035

0. 0298

0. 0362

0. 0437

0. 0312

0. 0379

0. 0451

13. 1437

10. 5044

10. C801

7.740

7.765

7.810

7.748

7.766

7.810

Fourth shell. J?4 , #4 , f.i 4 , <54 .

2

4

6

1.4130

0. 9175

0. 7050

1. 4093

0.909G

0. 7575

0, 0259

0. 0303

0.0440

0. 0287

0. 0376

0. 0467

11. 8224

9. 9770

10. 3845

7.762

7.741

7. 794

7.765

7.748

7.794

(467)
PHYSICAL PROPERTIES OF THE IRON-CARBUKETS. [DULL. 35.

TABLE. 4. Cylinders in the glass-hard state. Constants of the consecutive cores. Second 

series of measurements Continued.

M6, PC,, A5, r«-

No.

2

4

6

M

270. 2447 

270. 2450

105. 6781 

105. 6777

69. 1823 

69. 1831

p observed.

1. 3635

0. 8580 '

0. 6888

p calculated.

1. 3562

0. 8489

0. 0862

t

20.6 

99 n

20.1

91 e.

21.6 

20.3

At

7. 7899 

7. 7888

7. 7749 

7. 7741

7. 7898 

7. 7897

A'

7. 7957 

7. 7949

7. 7805 

7. 7802

7. 7959 

7. 7953

Mean A

7. 7953

7.7803

7: 7956

A

0. 128282

0. 128529

0. 128277

Remarks.

M6, p9, A6,

<>

4 

6

255.7194

255. 7207

96. 7900 

96. 7908 

60. 3109 

60. 3108

t. 3244

...... ....

0. 8205

0.6492

1.3190

0. 8122

0. 6406

22.7

20.8

21.5 

20.0 

 20.4 

21. 7

7.7910

 7. 7915

7. 7761 

7. 7789 

7. 7913 

7. 7897

7. 7974

7. 7973

7. 7822 

7.7842 

7. 7969 

7. 7958

7. 7973

..........

7. 7833

' 7. 7963

0. 128249

0. 128480

0. 128266

'

Mr, p7 , A7 , p-7-

2 

4 

6

244. 6228 

244. 6207 

88. 4153 

68.4148 

52. 0503 

52. 0498

1. 2962

0. 7851

0. 6062

1. 29CO

0. 7762

0. 5953

21.8 

23.2 

21.0 

22.5 

21.4 

22.6

7.7928 

7. 7928 

7. 7790 

7.7783 

7.' 7863 . 

7. 7872

7. 7989 

7. 7992 

7. 7854 

7. 7847 

7.7921 

7. 7936

7. 7990

7. 7850

7. 7928

0. 128221

0. 128452

0. 128323

 

M8, p8, 4 a,

2

4

6

226. 9512

220.9500

76. 7934

76. 7932

42. 5669

42. 5664

1. 2512

..........

0. '269

..........

0. 5186

1. 2422

0. 7241

..........

0. 5383

..........

22.5

21.4

21.7

23.2

22.0

23.4

7. 7958

7. 7956

7. 7830

7. 7812

7. 7882

7. 7862

7. 8022

7. 8022

7. 7891

7. 7876

7. 7943

7. 7926

7. 8022

..........

7. 7883

.... ......

7. 7935

..........

0. 128169

..........

0. 128397

.... ......

0. 128312

..........

-Mg, pg, //9 , (Tg.

2

4

6

205. 7577

one 7<;fvl

63. 6639 

63. 6630

31. 9783 

31. 9793

1. 1946

0. 6635

0. 4729

1. 1825

0. 6584

0. 4607

21.2 

23:0

19.7 

22.5

22.6 

20.0

7. 8009 

7. 7997

7. 7866 

7. 7846

7. 7814 

7. 7816

7. 8067 

7. 8061

7. 7922 

7. 7909

7. 7877 

7. 7872

7. 8064

7. 7915

7. 7875

0. 128100

0. 128345

0. 128411

-

(468)
BARU6 AND STIIOUIIAL.J EXPERIMENTAL DATA. 27

TABLE 5. Cylinders in the glass-hard stale. Constants of the consecutive elementary 

shells. Second series of measurements Continued.

, Fifth shell. I?6, tfu, 08, <k

No.

2

4

6

R observed.

1. 3817

0. 8802

0. 7102

R calculated.

1. 3750

0. 8698

0. 7102

i? observed.

0. 0360

0. 0444

0. 0548

-

i> calculated.

0. 0388

0. 0419

0. 0480

M

15. 5908

10. 0641

10. 0710

Jobserved.

7.737

7.748

7.820

<5 calculated.

7.741

7.748

7.823

Remarks.

Sixth shell. I?fl i #e.

2

4

6

1. 3439

0. 8393

0. 6000

1. 3370

0. 8305

0. 0634

0. 0391

0. 0375

0.0397

0. 0372

0. 0367

0. 0450

14. 5248

18. 88T5

8. 8719

7.701

7.747

7.795

7.700

7.747

. 7.791

Seventh shell. 7??, i?7 , yU 7, J7 .

2

4

6

1. 3103

0. 8028

0.6276

1. 3045

0. 7942 

..........

0.6180

0. 0283

0. 0355

0. 0430

0. 0200

0. 0300

0. 0453

11. 0983

8.3754

8. 2008

7.758

7.705

7.821

7.756

7.766

7.819

Eighth shell. E8, &8, /*8, <J8.

2

4

6

1. 2001

0. 7501

0. 5774

1. 2061

0. 7501

0. 5608

0. 0498

0. 0582

0. 0575

0. 0478

0. 0521

0. 0570

17. 0711

11. 6217

9. 4833

7.759

7.764

7.790

7.760

7. 763

7.790

Ninth shell. J?9, i99, ju g, J9.

2

4

6

1. 2228

0. 6953

0. 5108

1. 2123

0. 6912

0. 5025

0. 0506

0. 0635

0. 0758

0. 0597

0. 0657

0. 0716

21. 1941

13. 1298

10. 5879

7.758

7.772

7. 812

7. 702

7.773

7.812

(469)
28 PHYSICAL PROPERTIES OF THE IRON-CARBURETS.

Resistance data. The present results for specific resistance are merely 

preliminary. They show, however, that even in the case of steel rods 

one centimeter in diameter and of but a few hundred-microhms total 

resistance, the electrical method may be successfully applied to the 

study of structural phenomena and made to yield good results. The 

reasons for this are at hand. The resistance effect due to changes of temper is enormously large as compared with the density effect. The interval hard soft, when referred to the electrical scale, comprehends 300 

per cent, of the/resistance of soft steel; whereas the density effect is 

certainly smaller than 3 per cent, of the density of soft steel. The extreme sensitiveness of the resistance method is to some degree vitiated, 

however, by thefoct that the electrical constants involve the dimensions 

of the rods; and very frequently right sections are not deterininable 

within a few per cent. Moreover, in case of resistances as small as those 

mentioned, the electrical measurement itself must be made with caution, 

and the error will under all circumstances amount to 1 or 2 percent. 

None of these difficulties enter into a determination of the density 

effect; but in spite of the objections specified, the large range of electrical variation renders the resistance method certainly as accurate as 

the density method, It will be invaluable for the investigation of slow 

changes of strain; such, for instance, as would result if the stress in 

the interior parts were essentially conditioned by the stress at the exterior or superficial parts of a tempered steel rod (see Shrinkage, p. 41). 

In this case the necessary results-depend on purely electrical-data only. 

The two methods are admirably complementary, for the resistance 

method begins to yield satisfactorily reliable data at the very stage of 

thickness of rod where the density method shows insufficient sensitiveness, and conversely.

The resistance method has a further advantage: the errors due to

hard ends (see p. 31) may be wholly and conveniently eliminated. For 

if these comparatively thin rods be inserted in the dissolving cell already described, it is only necessary to slide a piece of rubber hose over 

the ends to confine the solution to as small a part of the equatorial regions of the rod as maybe desired. Moreover, thickness may be reduced with some uniformity throughout the chosen lengths, even as far 

as 0. L um of diameter. In the annexed diagram (Fig. 5) one of these rods,

I?IG. 5. Bod No. 11, after removal of seven shells.

from which seven successive layers have been removed, is drawn full 

size. During solution the parts a a are covered with rubber, as has 

been stated. 

To hpld the rods during the resistance measurement, we devised the

(470) ,. ' '
luuua AST* BtuoniAi..] RESISTANCE MEASUREMENT.

special form of clamp shown in the annexed diagram (Fig. 6). A A is a 

block of oiled wood, through the middle of whicb. 'passes an iron bolt cd, 

carrying a steel cross-piece, ef] both 

ends of which are conical. Attached 

to the ends of the block A A are two 

thick strips of hard rubber or of 

nieta 1, ab ab, carrying steel screws, 

mn inn, the point11,, n n of which are 

also conical. The rods ncfn are tested 

in pairs, and secured by aid of conical depressions in their end surfaces, 

between the sharp ends of the screws 

mn mn and the ends of the cross-piece 

.ef, as shown in the figure,. At m m

copper terminals have been soldered 

into the heads of the steel screws, 

through which the line of metal mn 

efnm is inserted with a standard into 

one branch of the bridge, the other 

being thecalibrated wire. From lour 

brass clamps, r r r r, copper wires 

pass tensely around the respective 

steel rods ne fn, find thence (alternately) through galvanometer to sliding contact. The method of measurement is that of Matthiessen-Uockin.

The experimental data obtained in 

the way described are given in Tables 

6 to 8. In Table G (Rod No. 3), column one contains the number of the 

core from which the resistance Wt , at 

t", for the effective length, Z, and the 

radius /> are derived. The column $0 

gives the corresponding specific resistance, at 0°, for the rod in a condition of either rough or smooth 

surface (trued with diamond), as specified.

TABLE 6. Resistance uonvlants (No. '.' ).

Fio. G. Holder for resistance nicnaiirr.monts.

TSTo.

Corol2 ......................................... |

Core 13 ...................... .............. .....^

Core 14 .......I.. .................................

Wt

n«)O

380

340

484

4GI 

074

t

K)

17

17

 20

20 

27

I

4.110

4. J5 

4. 1JJ

4. f)J 

4.C5

P

0.3771.

0. 3354 

0. 2850

So

30. 7

31.3

33.8 

33. 5

34.7 

n^ 1

Rough.

Smooth.

Smooth.

(471)
30 PHYSICAL PROPERTIES OF THE IRON-CARBURETS, fBULL. 35.

The values for S0 being certainly affected with an error of, say, 3 per 

cent., must be regarded as coincident. They merely show that after the 

removal of 14 shells the variations of the hardness of No. 3 occur within 

narrow limits. Moreover, the absolute value of S0 is small, indicating 

either a poor quality of steel, or, more probably, that the strata of large 

resistance have been removed.

Similar results, but more complete," are given in Table 7. The nomenclature is the same as that used above. $ the specific resistance of 

consecutive cores at t°, is reduced to the values for 0°, by aid of the 

temperature coefficient, a. JK, 5, s denote the mean radius, thickness, 

and specific resistancej respectively, of the shells. We have, therefore,

n = Pn-1 Pn

when Q and A are symbols of section and' conductivity, respectively, 

and &=# _, Qn.

TABLE 7. Stubs's bright steel. Resistance constants of the consecutive cores and shells.

Rods tempered glass-hard^

[1 = 6 cin. approximately.].

No.

11

Shell.

0.........

1.........

3.........

4.........

C.........

0. ........

1. ........

9

3........

4.........

5.........

C. ........

7.........

8.........

0. ........

1. ........

2. ........

3........

4.........

5.........

o.........

7.........

TFi

Microhm. 

CCO

820

1,000 

1,200

2, 250

4,130

6,620

( 16,i 110

* 15,970 

680

820

1,020

1,300

2,440

3,390

5,400

t 11,950

{ 9, 520 

22, 640

660

730

800

910

1,310

2,110

3,200

8,330

P

Cm. 

0.318

0 ''94

0.262 

0.227

0. 1.67

0. 130

0.103

0.069

0.070 

0.318

0.296

0.262

0.235

0.182

0.148

0.114

0.089

0.088 

0.059

0.318

0.304

0. 288

0.267

0.223

0.179

0.149

0.092

t

°0. 

19

90

22 

18

?0

9,1

91

24

22 

10

90

99

1R

90

91

9,1

24

22 

93

19

91

90

18

90

91

90

23

St

Microhm. 

42.7

45.4 

44.5

45.1

47.7

48.0

52.5

56.4 

43.1

44.0

44.2

45. 5

47.3

47.0

45.8

67.1

51.6 

52.5

41.8

43.4

43.8

44.2

45.0

45.4

47.0

 48. 5

a

0 (\C\T7

16

16

 17

16

15

ir;

15

14

0. 0017

17

17

16

15

15

16

15

16* 

16

0. 0017

17

17

17

16

16

15

15

-So

Microhm. 

41.4

44.1

' 44.0 

43.2'

43.3

40.3

50.9

54.8 

41.8

42.6

42.7

44.3

46.0

45.7

44.4

64.9

49.9 

50.8

40.4

42.0

42.4

43.0

43.7

44.0

45.8

47.0

It

Cm.

0.306

0.278 

0. 244

0.197

0.149

0. H7

'. 0.086

0.087

0.307

0.279

0.249

0.208

0.165

. 0. 131

0.102

0.101 

0.073

0.311

0.296

0.278

0. 245

0.201

0.164

0.120

&

Cm.

0. 0240

0.0318 

0. 0349

0. 0599

0. 0367

0.0273

0. 0338

0. 0331

0. 0215

0. 0337

0. 0270

0. 0538

0. 0337

Or 0336

0. 0253

0. 0266 

0. 0291

0.0140

0. 0158

0. 0204

0. 0442

0.0444

0. 0297

0. 0574

8

Microhm.

31

46 

45

43

39

44

41

37

43

37

42

47

47

*30

38 

49

30

38

39

41

43

41

45

(472)
AND Sfn6UTIAT..1 OF SfiELLS. 31

TABLE No. 7. Stul>s'i) Iright steel. Resistance constants of the consecutive cores and shells. 

Rods tempered (/lass-hard Continued.

No.

14

Shell.

0.........

1.........

2.........

3.........

4.........

5.........

C. ........

7.........

8.........

W

Microhm. 

C80

740

1,090

900

1,360

1, 990

2,930

5, 710

21, 280

P

Cm.

O Ol Q

0.304

0.289

0.209

6.227

0.189

0.108

0.10C

0.062

t

°C. 

19

 11

 >0'

18

?0

?1

°n

"3

23

S

Michrom. 

42.6

43.4

56.2

44.0

44.8

46. 3

48.4

44.5

55.5

a

0. (.017

17

14

17

16

16

15

17

14

So

Michrom. 

41.4

42.0

54.8

42.7

41.9

44.9

47.0

42.9

53.9

K

Cm.

0.311

(0. 297)

0.287

0.248

0.208

0. 173

0.132

0.084

d

Cm.

0. 0134

(0. 0155)

0. 0350

0.0422

0. 0382

0. 0309

0. 0517

0. 0444

*

Michrom.

36

(a) 

30

45

30

40

51

30

a Bad contact.

Some of the results (see Nos. 11 and 12, shell 7; No. 14, shell 2) 

which it was found necessary to repeat show how exceedingly important 

it is to secure excellence of contact throughout the bridge adjustments. 

In repeating the experiments we should temper rods 20cm long, solder 

the ends to copper terminals, and remove only equatorial parts of shell. 

We may remark that the sectional error is here probably positive and 

relatively large for small values of section. This introduces a very serious element of uncertainty into the results, s is only to be regarded 

as a check on $0 .

Table 8, finally, contains direct tests for shrinkage, p being the radius of the core, Wt denotes the resistance before and after the lapse of 

the number of hours given under h. If shrinkage is an actual occurrence, it must be a phenomenon of viscosity; and hence the observed 

effect would vary gradually through infinite time. The differences of 

Wt , in 'fable 8, however, are mere errors of observation.

TABLE 8. Resistance tests for shrinkage.

No.

r.

B

B

Date.

November 19, 1885 ..................................

November 20, 1885 .................................

November 21, 1885 ...................................

h

0

15

0

21

P

n Qifi

0.30

0.20

Wt

1,030

1,022

1,803

1, 803

Remarks.

DISCUSSION.

True and apparent structure. In Bulletin 14 we defined structure (p. 

113, note) as the law of variation of density encountered on a passage 

along any radius of the rod, from axis to circumference. But a mere 

glance at the above tables shows that we must obtain greater uniformity 

of results if we reverse the order of progress and follow variations of

(473)
32 Pl-iYSiCAL PROPfiRfrfiS 01? TtfE iROtf-CARtttRETS. taOtxaS.

density from the surface normally inward. Let depth, taken positive 

in the direction from surface to axis, be denoted by x. Then the above 

tables enable us to construct

d=F(x}...... .................. ..(I)

where .Fis a symbol of functionality and d the apparent density at a distance x below the surface, d is an approximate expression for the structure of the rod. To pass from this F (x) to the true structure, it is necessary to make allowance for the fact that in any given uniformly tempered cylinder the elementary coaxial shells are not homogeneous in the 

axial direction; that they increase in density as we pass from median 

plane toward the ends of the cylinder. More succinctly : In view of the 

relatively smalt length (210 ) of the cylinders as compared with their 

diameters (2/)0 ), the available method of tempering necessarily imparts 

to them a box-within-box structure. Hence, it follows that

r*

10 F(x] = (I0-X}f(x) + / f(x) cU ............... (2)

L/o

By differentiating, simplifying, and again integrating, this equation 

leads to an elegant expression for true structure,/^), in terms of apparent 

structure, d :

....... ......(3)

o x ,/ to x 

f(x] being the density at a point anywhere within the cylinder at the 

distance x. normally below the surface.

With equation (3) in hand, it is then easy to investigate corresponding expressions for A, the mean density of successive c6res, in terms of 

f(x) and x. These, however, appear under involved forms. They throw 

no new ligljt on the discussion, and therefore are omitted,

Density, A, of successive cores. To digest the data in the above tables 

we shall first examine the relations of z/, the mean density of core; and 

then from these introductory results proceed with the discussion of 

structure proper.

In Figure 7 we have constructed the various results of Tables 1, 2, 4, 

by representing A as a function of radius. The loci for the data of 

cylinders ISTos. 1, 2, 3, 4,' all of which hold for steel of the same kind, 

are similar in their general character. This becomes very clear if 

we pass from the surface in the direction of negative p toward the axis. 

After removing superficial shells, A appreciably falls in all cases to a 

pronounced minimum. It then increases at approximately the same 

rate for each cylinder and in a direction >which if indefinitely prolonged would trend toward the diagrammaticpositiou of" soft" (no.teasily 

introduced into the figure). The chief features of these curvesare therefore the minima, their approximate parallelism, their apparently linear 

contour, their independence of radius. Having obtained these results 

we were inclined to look for similar variations in all other kinds of steel,

(474)
HAHUS AND BTUOUIIAI,.] DENSITY OF CORES. 33

Not a little startled were we, therefore, by the data: for No. C, which 

show an almost complete inversion of the structural character of the 

earlier rods. In the cases of Nos. 1 to 4, A increases from the circumference inward j in the case of No. G, A continually decreases, indeed at

A

A

FIG. 7. Density as a function of radius.

almost the same rate. It is therefore clear that structure must bo radically conditioned by the quality of the steel carrying temper. In other 

words, to discriminate between different kinds of steel by structure 

(/(#)) data, our classification would show immediate relations to tlie 

power for retaining stress heretofore postulated. 1

The superficial minimum or corresponding point in No. G, occurring 

as it does generally, is an observation of some importance. It probably 

marks the depth of layer below which the combined processes of diffusion and oxidation no longer remove carbon from steel. This depth

1 U. S. Geol. Surv. Bull. 14, p. 95.

Pull, 35 3 (475)
34 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [BULL. 35.

will of course depend on the time of exposure to high temperature before quenching. The observation in question is confirmed by this experimental result: if rods be heated very intensely (Nos. 1 and 3, incipient white heat), the superficial layers are frequently so soft as to yield 

readily to steel master tools. Moreover in No. 1, which was twice 

quenched, this shell is comparatively thick. The underlying core is always very hard, and it is thus possible to arrive at the thickness of the 

soft shell with some accuracy. It doe's not extend inward as far as the 

minimum; but this does not tend to invalidate the remarks just made, 

because softness, after quenching, must correspond to an extreme degree of decarburation. There is, however, one point of view from which 

the minimum acquires greater significance than a secondary or incidental result. If the rod subjected to sudden cooling be sufficiently thick, 

it is obvious that the interior will remain soft. Hence the march of A toward smaller values, exhibited by No. 0, cannot keep on indefinitely. A 

must pass through a minimum and then again increase. Hence we infer 

that the position of this minimum, bears some inherent relation to the 

quality of the steel under observation that its depth will increase in 

proportion as the intensity of strain which the rod can carry without 

rupture, increases. Further experiments are necessary to decide this 

question.

It is curious to note that the glass-hard A of longitudinally cracked 

rods (Nos. 3 and 5) is smaller than that of rods of unbroken surface. 

This difference may be an expression for the intensity of stress lost iu 

consequence of rupture. More probably it is an effect of thickness.

In the case of No. 1 structure has been studied throughout an interval 

of almost one centimeter of depth. But it is not until we reach the 

lowest layers for this depth that the curve manifests any tendency 

to change its Character. And even here the evidence is uncertain, both 

because the density measurements of the comparatively thin rod are no 

longer so accurate and because the effect of hard ends, to which we 

adverted in the preceding paragraph, becomes more and more seriously 

appreciable as radius decreases. The singularly simple and suggestive 

curves are therefore in striking contrast with the necessarily complex 

considerations which must enter into their interpretation. If the cylinder be originally given of length 210 and of diameter 2p0 , and if then 

a shell of thickness x be removed, careful inspection of the core will 

enable us to distinguish the following three parts: (1) The central cylinder bounded by mantle (radius pQ x) and two normal planes at a 

distance 70 Pa and (I0 po) from the equator. Within this partial cylinder $ varies from / (p0 ) to / (.*) in the direction of radius, symmetrically with respect to axis. (2) The two end cylinders bounded by mantle and by normal planes, 10 and-/0 a?, /0 , ami (?0 x), respectively, 

from the equator. Here 6 changes from / (x) to/ (o) in the direction of 

axis, symmetrically with respect to equator. (3) The two intermediate

(476)
BARUS AND BTROUIIAL.] DENSITY OF SHELLS. 35

partial cylinders bounded by mantle and normal planes, /0 Po and /0 #, 

 (10 p0 ^ and (?0 x). It is here that the variation of 6 is involved. 

To represent it approximately in the right partial cylinder, let a cone 

be described around a given axis, upon the basal plane ?0 a?, with its 

vertex.-at a distance /0 p0 fr°m the equator. This cone divides the 

said partial cylinder into parts such that in the re-entrant figure, o varies from/(p0 ) to/(a?) in the direction of radius, symmetrically with respect to axis. In the simple conical figure, d varies from / (p0 ) tof(x) 

in the direction of axis, symmetrically with respect to equator. lu 

view of these annoying complications, it is expedient to calculate d from 

successive values of A. This maybe done without any auxiliary hypothesis at all. Having given d we arrive at the true structure as 

shown in the preceding paragraph.

These remarks show that to obtain perspicuous values for A it is advisable to use only the equatorial parts for measurement; that is, to remove the ends completely either by solution or by suitable mechanical 

means before commencing the structure-measurements proper.

Density, d, of successive shells. In our endeavor to construct the relation between tho density d (apparent structure) and the mean radius 

of shell, E, we must necessarily be guided by the following consideration : If the shell be thin and contain no maximum or other singular 

point, then the observed 6 is approximately a point on the locus'sought; 

but if the shell, however thin, contain one or more maxima, then the 

observed # need not be a point on the locus at all, and the discrepancies and the liability to errors of interpretation will increase as the maxima become more and more sharp and crowded. Let the shell be so thin 

that its outer and its inner radius are practically identical with its mean 

radius, i. e., that the right section does not differ appreciably irorn 

2 rr R d Ii=2 Tt'RS, in area. In thiscase 2 nR 5 d is the mean mass per 

unit of length of shell; and hence any elementary contour which, between 

JR B-/2 and JB+5/2 incloses the same area as $ d, may be taken as a> 

boundary of the part of the curve under examination. This shows at 

once the nature of the difficulties encountered in endeavoring to discuss 

the present observations on structure. It opens a field for speculation 

so wide as to be thoroughly unsafe. We will, therefore, in the sequel, 

limit ourselves to right line diagrams, to mere linear combinations of 

the points given by experiment. Wo thus exhibit the results, as far as 

possible, unaffected by any fantasy of our own.

In Fig. 8 the values for d are represented as functions of JK, on a 

scale in correspondence with the smaller accuracy of the present set ol: 

data. The scale is, moreover, such as enables us to insert the interval 

hard-soft for each curve. Bestrictiug our comparison to Nos. 1 to 4= for 

the present, wo find at first sight that the variations are jagged and 

apparently irregular and confused. It is. therefore, well to confine the 

discussion still further; to examine the data holding for No. 1, lor which 

cylinder the observations are most nearly complete ; then to use the

(477)
36 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [uiai»35.

other curves as a means of corroborating aud of further elucidating the 

divers inferences drawn.

1,3

V 

s

fIJVO.

Y

No.4 cjh. \

\ JVa.6

Radius.

o 2*5

Fio. 8. Elementary density aa a f auction of radius.

(478)
BAUUS AXD BTOOUDAL.I HARMONIC DISTRIBUTION OF DENSITY. 37

Inasmuch as the evidence given by No. 1 is fully valid (see discussion 

under Errors, p. 43), as we pass from the circumference inward 6 varies in 

accordance with an obviously harmonic law. We readily discern five 

pronounced periods (all marked in the diagram), which arc crowded 

near the surface, 1 but which lengthen and arc gradually obscured as 

we pass toward the axis. During this oscillatory march, 6 increases 

from values which lie below the glass-hard density almost as far as the 

density of the soft state. In other words, the interval of variation of 

density studied from point to point of a tempered rod is fully twice as 

large as the density interval hard-soft. Indeed, if we take into consideration that 6 is only the apparent structure, that the shells are not 

longitudinally homogeneous, but hard at the ends, it appears altogether 

probable that the density of soft steel will actually be reached. At tlie 

same time, it must be borne in mind, that the density at about 0.7cm 

below the surface does not differ appreciably from the mean density 

of the core. Hence we infer fairly that from here on, inward, largo 

fluctuations .of <5 will no longer occur.

The inquiry next in importance is the relation of density at any point 

within the cylinder to the hardness there mechanically observed. To 

the occurrence of soft strata between the points marked a and b we have 

already adverted. But below this the steel appears exceptionally hard 

so hard that the little ridges and furrows left on the surface by the 

diamond readily grind off the edges of a file or any other hard steel tool. 

This state of hard temper continues until we reach the points in tho 

vicinity of c in the diagram, say 0.7cm below the surface. From here on 

the rod is quite appreciably filable near its equatorial parts, the ends, 

of course, retaining the intensity of hardness of the superficial shell.

After these remarks it is in place to pass in review the corroborative 

evidence obtained from the other cylinders. In no case is the periodicity so sharply pronounced, and were the data for Nos. 2, 3, 4 alone 

available it would escape detection. But the evidence by no means 

conflicts with the inferences adduced for No. 1. No. 2, for instance, 

shows the first and second minima (see diagram) in proper position. 

The inclosed maximum is not so distinctly marked. No. 2, however, 

was quenched from a temperature much below that of No. 1; and since 

the harmonic distribution of density is primarily a mechanical phenomenon, the importance of temperature is at once obvious. For similar 

reasons the periods of No. 4 are more obscure than those of No. 3. In 

all rods (Nos. 1 to 4) the first minimum is unmistakably located near 

0.05cm of depth. The second minimum falls between 0.10cm and 0.15C1» of 

depth; the third minimum in the three observed cases between 0.25CI " 

and 0.30cm ; the fourth minimum between 0.5cm and O.Gcm of depth. This 

accordance is too persistent to suggest mere chance coincidences.

Thoroughly distinct from these curves is the locus of the set of values 

for IJo. C. The variations show almost simple periodicity around the 

glass-hard line as a position of equilibrium. A comparison of the curve

(479)
38 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [HULL. 35.

No. 6 with the curve Nbs. 1 to 4 at once calls to mihd the differences in 

the qualities of the steel used. Similarly to Nos. 2 and 3 we here find 

the density of external shell decidedly above that of the soft state. 

The material is probably poorly carburized; for even in the glass-hard 

state, hardness (mechanical) is not intense.

Having described the principal features of the phenomenon of structure somewhat minutely, it will be our next endeavor to account for the 

remarkable variations observed, at least in some provisional way. The 

methods which suggest themselves to us may be grouped in reference 

to two general heads, periodicity and carburation. But there are two 

ways of explaining periodicity: we may regard it as a real structural 

phenomenon, or we may regard it as a secondary occurrence, bearing no 

inherent relation to temper at all and due to intermittent shrinkage of 

the cylinder while in the hands of the operator. It is expedient to consider these questions in separate paragraphs.

Possibility of harmonic distribution of density. Suppose we ignore the 

occurrence of periodicity for a moment and consider only the mean ascent of the loci for tf. Then in case of steel of a given kind, subjected 

to a given operation of tempering, the hardness or density exhibited by 

any point is essentially dependent on the position of the said point below 

the surface, as our data show. The rate at which the point cools is 

similarly conditioned. Hence it is natural to associate the first phenomenon with the second, and to state that the hardness in a given point is 

a function of the rate at which cooling there takes place. Knowing the 

relative rates of cooling of consecutive shells we would have given us 

therewith a method for expressing hardness (estimated in units either of 

density or of resistance) in terms of rate of cooling. But the adequacy 

.of such a mode of inquiry is incomplete, because the shells in question

are parts of the whole, and not distinct individuals, The consideration

simply suggests the cause for the gradual decrease of hardness from 

surface to axis.

Eeturning from this digression to the consideration of periodicity 

proper, we remark that solids, when subjected to shearing strains, usually exhibit low degrees of elasticity and experience marked changes of 

form. But all substances, whether solid, plastic, viscous, or liquid, 

when subjected to pure isotropic strains in the present instance to a 

strain of compression equally distributed in the three cardinal directions are probably very nearly perfectly elastic. Here, therefore, is a 

principle suggesting the possibility of vibratory movement, even in an 

intensely heated viscous solid. Suppose now there be given a small 

sphere of steel. Let this be heated above redness and then suddenly 

cooled (quenched) uniformly over the whole surface. Then we contend 

that it is not probable that during the initial stages of cooling contraction should manifest itself as a simple, aperiodic, static phenomenon.1

'Attention must hero bo drawn to to the Cumming-Goro phenomenon of sudden contraction at red heat. Cf. U. S. Geol. Surv. Bull. 14, p. 99.

(480)
IUUUB AKD BTROUIIAI..] HARMONIC DISTRIBUTION OF DENSITY. 39

We contend, in other words, that in consequence of sudden and enormous compression, virtually applied at the surface, the whole sphere 

during incipient cooling will be thrown into a state of vibration symmetrical with respect to the center of figure. Under the ideally perfect 

circumstances of quenching, therefore, the sphere must so vibrate that 

all points of any given spherical shell, at a given time are in like phases 

of oscillation. It follows obviously, moreover, that in the case of a long 

cylinder suddenly and uniformly cooled, the phases of the elementary 

coaxial shells will, at a given time, be identical.

The necessary concomitant of the vibration specified is harmonic distribution of density ; and the maxima and minima encountered may 

be made to differ by amounts as large as we please, up to a certain 

limit, by increasing the temperature from which cooling takes place. 

But while vibration is in progress the cylinder itself is cooling rapidly, 

or, in other words, the rigid shell closes inward from surface to center, 

congealing, as it were, and retaining permanently within itself the traces 

of the harmonic distribution of density in question.

More concisely: Let the sphere be of large radius. Then the density 

in a point at a normal distance, x, below the surface, at the time i, during the initial stages of cooling may be expressed by

(1)

where v is the velocity of propagation, A the wave length, A a length

phase.

Let x ~(p(t}] t = ?/;(») ........ (2)

express the depth of the advancing inward boundary of the rigid shell1 

at the time t. Then the mathematical effect of congealing may be said 

to bo equivalent to an elimination of t between equations (1) and (2) so 

that for the rigid sphere,

tf = asiu- A? ?/;(.«) tf + J.^ ...... (3)

a function of x only, applies. Equation (3) shows that the wave actually congealed need be identical in regard to neither phase nor wave 

length with the original wave A; that it will generally be very much 

larger. For instance, under the simplified conditions that x= fp(t}~ 

m -f- nt, if we put

arc ctg n a arc ctg v = ft

the congealed wave will exhibit the new phase A/, and new wave 

length, A,

^^ ..... (4)

respectively. According as a lies anywhere between (3 ^and /?, A 

may have any value between the limits A sin /? and a. But it is es1 Rigidity may Iicro bo tho result of chemical as well as of mechanical action (temperature). See p. 42.

(481)
40 PPIYSICAL PROPERTIES OF THE IRON-CARBURETS. [HULL 3s.

sentially constant, and the periodicity uniform. Here we may remarkin passing, that if shells of like thickness be etched off, the observed 

harmonic law will bear some such relation to the congealed periodicity 

as is expressed in equation (4).

If cp (t) be not linear but represent some more complex function, as it 

must in the case under consideration, A must also vary continuously. 

If, furthermore, n = d cp (t) \ dt, and if n decrease continuously, then A 

will increase with x wherever n > v} it will decrease with increasing x 

wherever n <; v. The former of these criteria seems to be given by the 

diagram, Fig. 8; but it must be borne in mind that the curves there 

given are seriously distorted by other causes. The inference goes LO 

further than to point out that the harmonic distribution of density must 

be of variable period; and that this variation will depend on the relative values of rate of wave propagation and rate of advancing rigidity.

As the process of cooling proceeds, the continually increasing thickness of rigid shell interferes with vibration in a way to obscure the 

periods more and more, as we pass from the surface inward. Within 

the shell the energy of vibration is largely potentialized. We have 

already pointed out that in the case of cylindrical figure true structure 

is related to the apparent structure, tf, by the equation

If F (x) be harmonic, f (x) will also be, with this limitation, however, 

that/ (x) and F(x) cannot, at the same time, both be uniformly so. 

Probably neither will be; and we have a second condition for the variable periodicity observed. The effect of superficial decarburatiou on 

S is a third condition.

Perfect uniformity of sudden cooling or quenching is not practically 

attainable. Pressure is first applied at the parts of the hot cylinder 

which first touch the cold water, and it is not until the mass is fully 

submerged that the temperature, &c., of the surrounding medium is 

fairly uniform. Again, certain parts of the quenched body will always 

be more favorably placed in regard to contact with cold water than 

others. Hence the conditions are such that perfectly symmetrical arrangement of the parts of like given density relatively to the axis and 

center of figure of the steel body must be a very rare occurrence. True 

structure is therefore more or less fully obscured by the divers adventitious circumstances of chilling and by intentional or accidental variations in the operation of tempering itself.

The views here set forth are very well illustrated by the following 

little experiment: Let a ring capable of up and down motion be suspended with its plane always horizontal over a basin of water. If now 

the ring be lowered at regular intervals so as-to dip into the water with 

all its parts at once, and if the period of oscillation of the ring be adjusted synchronously with the oscillation of the circular wave under it,

(482)
BARUS AND 6TROUHAI,] VISCOUS SHRINKAGE. 41

the whole surface of the water bounded by the ring may lie made the 

field of regular and continued wave motion. Suppose now the water 

to congeal from the ring inward at some regular rate, then the congealed 

surface .will show uniform periodicity, which will not, however, be identical, with the period of the liquid surface. It' the rate of advance bo 

variable, the periodicity mus't be variable. Finally the conditions of 

practical quenching may be typified by the interferences resulting it' the' 

ring be dipped obliquely relative to the surface of the water.

Intermittent shrinkage. Whatever the mechanical^ structure of steel 

is, it may be reasonably argued that the conditions of equilibrium at 

every point are in conformity with and influenced by the dimensions of 

the bar. Hence, if parts of the rod be removed, by solution or otherwise, we may look for* an excess of stress in those parts; and if the 

process of removal be, often'repeated, this excess may eventually increase to ail intensity sufficient to effect a permanent and sudden change 

of strain. A series of such changes would constitute the intermit tent 

phenomenon in question.

Glass-hard steel is under a strain of dilatation. The probable effect 

of the removal of superficial coats is, therefore, contraction. We need 

only suppose that the greater part of such contraction takes place uniformly, in proportion as sh.ell is being removed, to obtain the principal 

features of Fig. 7, Nos. 1. to 4; moreover, that sudden contractions of 

higher order, occurring intermittently for the reasons specified, are superimposed upon this main and uniform shrinkage to generate Fig. 8, 

Nos. 1 to 4. For since

J± -£ d ,7,

Mo

and since we may consider /<, Mo, MI, p0 constant in any given experimental case, it is obvious thafeit" f/i vary by small decrements, in consequence of contraction, d will vary by corresponding decrements, and 

conversely. If, therefore, we examine Fig. 8, No. 1, for instance, sudden contraction may have occurred between b and the first minimum, 

between the first maximum and the second minimum, between the second maximum and the third minimum, between the third maximum and 

the fourth minimum, and so on. Between any minimum and the next 

consecutive maximum we have usually a curve of gradual ascent, indicating normal changes of density.

Some evidence of contraction is contained in the above tables, and 

discussed under Errors, p..48; but it is insufficient. On the other 

hand, no contraction could.be discerned by resistance measurements at 

all (p. 31). The occurrence of shrinkage is, therefore, questionable, and 

more searching investigation may show it to be absent. Moreover, it 

would furnish no satisfactory explanation for certain degrees of like-

(483)
42 PHYSICAL PROPERTIES OF THE IRON-CARBURETS, [BULL. 35.

ness in the curves Nos, 1 to 4, to which we have already referred. 

After the removal of nearly lcm of shell, hardness is still retained at 

the ends of No. 1, whereas it gradually vanishes near the middle parts. 

This, again, is adverse to the shrinkage hypothesis.

Carburation. The probability of absence of true shrinkage to which 

we referred in the last paragraph, taken in connection with the great 

molecular stability of the shells in the divers specimens of steel examined, suggests that the intensity of the mechanical strain of glusshard steel may possibly be overestimated. Mere superficial scratch ingis frequently sufficient to explode a Rupert's drop. 1 Glass-hard steel, on 

the other hand, may be reduced in thickness to quite one-third the original diameter, or again, thin rods (0.7cm) reduced to mere filaments 

without showing any thoroughly satisfactory evidence of shrinkage. 

In all the experiments made by the-resistance method, hardness is 

found to increase very perceptibly from surface to core; the (thin) 

rods (radius =0.3cm ) are hardest at the axis. If, therefore, steel has 

once been subjected to an operation capable of evoking the strain of 

dilatation in question, the strain imparted appears to possess a certain permanence of character and to be able to maintain itself independently of the presence or thickness of the surrounding layers. In 

this respect it is peculiar. It yields readily to temperature only ; and 

we infer that it owes its persistency to molecular or chemical agencies.2 

Suppose, therefore, that with the carbon available in steel.it is possible 

under favorable circumstances to produce a variety of iron-carburets; in 

other words, that under favorable variation of circumstances, a certain 

latitude of density is a possible occurrence. Then we argue, .plausibly, 

we think, that during the process of sudden cooling of steel from red heat 

the carbon and iron at any point within the body will unite (for the . given degree of carburation) in correspondence and conformity with the 

intensity of strain there experienced; that, therefore, ill the cold Steel 

the strains are to a large extent permanent and independent of the condition of stress of the surrounding medium of steel.

The remarks just made will have shown how incomplete our knowledge of the phenomenon of structure as yet is, and where further experimentation is essential. The paragraph on periodicity postulates 

certain relations between velocity of wave propagation and rate at 

which rigidity advances inward. The occurrence of shrinkage is hypothetical and lacks satisfactory evidence; nor has direct quantitative 

measurement been brought to bear on the conditions of carburation.

'Our recent experiments show that the respective behaviors of steel and Rupert 

drops here in question are identical. August, 1380. x

2 Conditions favorable to chemical combination (quenching)', so difficult of attainment in case of low degrees of carburation (steel), are given at once in case of greater 

carburation (cast-iron), where mere cooling in air will harden. The mass of available 

carbon is therefore hero an essential factor and the phenomenon in hand is probably 

an instance of mass action.

(484)
HARUS AND BTROUHAL.J EVALUATION OF ERRORS. 43

Nevertheless we believe that cautious blending of the three views 

advanced will reconstruct the actual phenomenon of structure as accurately as the data now in hand describe it.

Resistance. The results in Table 7 show no pronounced periodicity. 

Considered individually, moreover, they would not be of much value. 

Considered as a whole they mutually sustain each other, and indicate a 

decided increase of resistance in passing from surface to core. Hardness increases rapidly inward, and this quality here exists in greatest 

intensity at the axis. These rods therefore show like behavior with !N"o. 

G, and the general structure is that of relatively dense external layers 

surrounding a relatively rare core. But it must be borne in mind that 

these rods are comparatively thin ; that for greater thicknesses tlie loci 

will probably pass through minima of A or maxima of $0 and of hardnesSj thereupon to enter into a second phase of variation, such as is exhibited by the A of rods Nos. 1 to 4. Considered in this light, the minima in Fig. 7, Nos. 1 to 4, are to some extent critical points, inasmuch 

as their position varies in depth with the quality of steel employed, 

and is deepest for steel capable of withstanding a maximum of stress 

of the given kind.

Finally, it is well to remark that the data of the above tables, when 

interpreted in the manner given under carburation, conflict with received physical notions of temper and structure ; for it appears that 

the equilibrium of stress at any point is maintained independently of 

the presence or absence of other layers. Hence, the deduction made in 

Bulletin 14, page 103, from data obtained with malleable cast iron, viz, 

that the electrical variations accompanying temper are evoked by strain, 

and are only to a smaller extent dependent on the conditions of carburation, does not follow in the way in which we there understand it. 1 In 

short, the present results make it questionable whether in the cold rod 

the effects due to strain and to carburation, respectively, can be sharply 

distinguished at all (cf. p. 42). '

Errors. In the present research some of the inferences are dependent on variations of the descriptive function, d, the 'order of which is 

not much above the aggregated effect of errors of observation. Hence 

a full enumeration of the divers sources of discrepancy, together with 

an analysis of the magnitude and distribution of their respective influences, is a matter of cardinal importance.

It seems expedient to commence with the observations proper, since 

it is here feasible to obtain good estimates for the amount of distortion 

probable in each case. If we define tf,,, the density of the nth elementary shell, approximately by

(1)

'Probably in malleable cast iron insnfficient quantities of transmntablo carbon avo 

available, the metal being rich in graphite. The presence of neutral conducting snbetauces obscures the electrical effect of temper.

(485)
44 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [BULL. 35.

we may regard tl.e errors of 6,, essentially conditioned by tbe values 

and variations of J>, 3, An_\ An . The range of variation of these quantities has been

0.5 < R <1.5 ....... (2)

0.01 < 3 < 0.1 ........ (3)

0.0010<4_i An < 0.0050 ...... (4)

Hence, if to prevent confusion of signs we designate errors by prefixing the differential symbol U c7," we easily deduce from (2), (3), (4), and 

partial differentiations of (1),

0.025 d$n < d6n < 37.5 d$n ....... (5)

2.5 d(X-,-4,)< dSn < 75.0 d(An_,-A^ .... (6)

0.005 dRn < ddn < 0.25 dRn ...... (7)

equations to be interpreted numerically. If we consider these cases 

one by one, we obtain as conditions under which (5) is least favorably 

and most favorably applicable : 

6?3n <0.01; 0.375 > ddn > 0.00025 ... (8) 

d&n > 0.001 ; 0.037 > dSn > 0.000025... (9) 

respectively. Again,for the conditions under which (6) is least favora 

bly and most favorably applicable,

d(4_, 4.) < 0.0010; 0.075 > don > 0.0025 . (10) 

d(An_, JB ) > 0.0001; 0.0075 > d&n > 0.00025 . (11) 

respectively. For (7), similarly,

<ZJ5<O.Olj 0.0025 >ddn > 0.00005 . . (12)

dR > 0.001; 0.00025 > ddn > 0.000005 . . (13)

respectively. An inspection of the inequalities (8) to (13) leads to the

result that serious distortion from errors in the measurement of R need

not be apprehended, but that the effect of errors of An_v z/,t , and to

a much greater degree of 5, may, in unfavorable cases, influence Sn to

an alarming extent. It is, therefore, desirable to discuss in detail the 

probable mean errors $3, ^(^n_i 4J> && > and to weigh as nicely as 

possible their influence on d. In order to do this, in a measure at least, 

we made duplicate direct determinations of A after each removal of 

shell; and, similarly again, duplicate measurements of S and R. The 

values for //, 3, and R, as resulting both from direct measurement and 

from indirect gravimetric measurement, are fully given in Tables 2, 3, 

4, and 5. Table 9, however, contains a perspicuous comparison of tho 

special differences betweenot served and calculated, here in question.

(486)'
DAKUB ANW BTnouiiAi,.] EVALUATION OF ERRORS.

TABLIS 9. Exhibit of errors of It and o/i?.

45

Shell.

1.... ........

o

3............

4............

6............

7............

10............

11.........'...

12............

13............

14.'..........

15............

10............

17............

18............

19............

20............

Numerical 

mean ....

No. 1.

dR

-0. 0003

+ 010

+ 031

+ 052

+ 026

+ 000

+ 091

4- 064

H- 087

+ 074

+ 120

+ 124

+ 089

+ 091

+" 104

+ 108

+ 101

+ 107

+ 077

0. 0072

dd

-0. 0022

- 014

- 017

- 022

052

- 096

+ 115

06°

+ 017

+ 009

 101

4- 092

020

+ 014

- 041

4- 034

 020

+ 008

+ 050

0/0042

Shell.

1 ...........

2............

3............

4............

rj

6............

9............

Numerical 

mean ....

No. 2.

dR

-0.0017

4 009

+ 017

4 037

4 061

-1- 063

+ 058

+ 100

4 105

0. 0052

(W

-0.0033

- ' 10

- 14

-- 28

_ no

+ 19

- 07

j- *>n

- 31

0.0020

Shell.

1. ........

3........

4.........

0. ........

7.........

8.........

10.........

11.........

10

Numerical 

mean....

No. 3.

dR

-0. OOC4

- 00

+ O'J

+ ' 57

+ IT

+ *7T

4 CO

+ 07

+ 70

+ 79

+ 42

0. 0050

tW

- 10

CO

- 14

+ ><!

- 10

34

+ 47

-|- 10

0. 0027

No. 4.

Shell.

1. ............................

2.............................

8.............................

4.............................

5.............................

6.............................

7.............................

8.............................

9.............................

dR

+0. 0025

+ 029

4 035

4 079

+ 104

4 088

4 086

4 060

-1. (Ul

0. 0061

(to

0. 0012

4 07

- 17

73

4 25

+ 08

05

+ ci

22

No. 6.

Shell.

1............ ................

2

0

4...........................

5............................

6............................

7...........................

8............................

g

.

dR

+ 0.0171

+ 060

+ ' 060

+ 081

+ 000

+ 050

+ 096

+ 100

+ 08.'!

O.OOfiG

J

d&

-0.0014

-|- 24

14

-|- 08

_ r,g

- 23

05

+ 42

n. oorn

1 111 constructing Table!) it was thought'expedient to facilitate computation by assuming Z = Ccin . The uniform error thus introduced 

(except in case of No. C, about which later) will not exceed a. few tenths 

per cent, of excess. The unbroken character of till is therefore attributable to other causes, principally to the fact that in view of the corroded 

or pitted surface of the cylinder after solution in other words, in view 

of warty .irregularities, which even the diamond does not satisfactorily 

 remove the measured value of R must be too large. To an important 

bearing of this result we have already alluded above (p. 31). In $ this 

uniform error is largely eliminated, because $ is essentially a difference.

(487)
46 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. IBULL.SO.

If we take the numerical mean of the \7 alnes of dR and cfS- for ISos. 

1 to G, respectively, the results must yield us as safe an estimate for 

the mean errors of R and 3 as is conveniently obtainable, even though 

tbis method be not punctiliously rigid. Table 10 shows the value of 

do, corresponding to the numerical mean values under consideration 

(Table 9) for each of the cylinders Nos. 1 to G, and for mean value of 

It, 3, A. The table is readily intelligible, since dd is the influence of the 

error placed on the same horizontal row.

TABLE 10. Calculated (mean numerical) errors of 6.

[R = 1.0; i? = 0.05; AD 1 An = 0.0025.]

So.

1.... ...............

0

3...................

4...................

6...................

dR

0. 0072

0. 0052

0. 0050

0. OOC1

0. 0086

d&

0.0012

0. 0020

 0.0027

0. 0026

0. 0031

<*(A n i An)

0. 0005

0. 0005

0. 0005

6.0005'

0. 0005

dS

0. 0020

0. 0050

0. 0002

0. 0010

0. 0050

0. 0001

0. 0013

0. 0001

0. 0013

0. 0050

0. 0002

0. 0010 

0. 0050

0. 0002

The distortion due to errors of observation enters very fully into the 

third decimal and may affect the second. Its mean value will not be

greater than a few tenths per cent. This is by no means sufficient to 

invalidate the observed harmonic character of Fig. 8. It is indeed only 

just sufficient to permit us to replace the jagged outline of the diagram 

by well-rounded contours.

These data are so important as to. urge further search for corroborative 

evidence. Fortunately, results for this end are in hand. In Tables 3 

and 5 we derive din two ways: first, as depending on mass and density 

alone; secondly, as depending ou dimensions and density alone. The 

two methods of computation both contain J, and are therefore not wholly 

distinct; but they differ from each other by one essential variation at 

least; and although it is again not rigidly precise, it is sufficiently in 

keeping with the present purpose to regard the difference between the 

respective values of. d as a fair estimate for the error of this quantity. 

For the sake of -facilitating expression or of deriving a single final 

result, \ye will go oue step further and regard the differences between 

observed and calculated #, in Tables 3 and 5, as errors of d considered 

for the time being as a constant quantity. With this assumption we

(488)
HAUUS AND 6TKOUHAL.] EVALUATION OF ERRORS. 47

reach a concise/expression for the mean error of one observation. In 

consequence of the transcendental character of the dependence of tf on 

.K, we know of no better method for making this evaluation. The individual and the mean errors thus derived are summarized in Tables 11 

and 12.

TABLE 11. Exl&Mt of errors of <5, first scries.

 No.

1.... .........

Shell.

1

2

3

4

5

C

7

8

9

10

Error. ,

+0. 003

- 17

+- 03

-f- 01

- 07

- 07

+ 02

- 11

+ 02

No.

1...... ......

Shell.

11

12

13

14

1C

17

18

19

£0

Error.

±0.000

- 07

± 00

+ 04

+ 01

- 03

+ 01

+ 00

- 01

4- 01

No. Shell.

1

2

3

4

C

7

8

0

10

11

12

Error.

-0.010

+ 03

± 00

- 05

- 03

- 01

+ 02

- 03

- 03

i 00

- 01

± 0.0041

TABLE 12. Exhibit of errors of J, second series.

No.

2.............

Shell.

1

0

, 3

4

5

C

7

~

9

Error.

+0.015

- 10

- 02

- 03

- 04

 f 01

+ 02

- 0.1

- 04

±0.0009

No.

4............

Shell.

1

2

3

4

5

G

7

8

9

Error.

±0.000

± 00

- 01

- 07

± 00

+ 00

- 01

+ 01

- 01

±0.0026

No.

C.... ........

Shell.

1

o

3

4

5

C

7

8

9

Error.

+0.002

- H

± 00

± 00

- 03

+ 04

+ 02

± 00

± 00

±0. 0054

The magnitude of errors contained in Tables 11 and 12 is in excellent 

accordance with the corresponding data in Table 10. The methods of 

discussion are quite distinct and independent. Wo therefore infer with 

some confidence that, so far as errors of the clpss under consideration 

go, the periodic nature of the dependence of the density at a given 

point within the cylinder on the depth of the same point below the surface cannot be annulled or brought to merge into simpler functions.

Alike in order of importance are such errors as depend on the 

state of the surface of the cylinders. After removal of a shell by solution the surface is rarely glossy, most usually pitted, furrowed, and 

rough. In this case accurate measurement of A is quite difficult, because it is not easy to cleanse the surface thoroughly, either of adhering sheets of invisible air bubbles or of carbon, rust, or even metallic 

precipitate. A obtained from rough surfaces is therefore presumably

(489)
48 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [HULL.3*

too small. The objections here in question are obviated if the surface 

be trued and polished on the lathe with a diamond master tool; but this 

process may introduce a new error, even if proper precaution be taken 

for turning under water. The rise of temperature resulting from friction, or, indeed, the merely mechanical effect of scratching, may change 

the superficial temper very appreciably. In other words, the thermal 

effect of friction may be quite insignificant when distributed over the 

cylinder as a whole; but its effect in changirig the stress under which 

the superficial shell is supposed to exist maj7 nevertheless be marked. 

We take from the above tables a few data to corroborate these remarks. 

Boman indices refer to cylinders by number; Arabic subscripts, to

shells.

TABLE 13. Density effect of friction.

No., <fcc.

Ai".....

Aw"'....

A»n.....

A2".....

A,''.....

Aisi.....

Rough.

1. 78G4

7. 7G4C

7. 7888

7. 7734

7. 7980

7. 7890

Smooth.

7. 7S92

7. 76G6

7. 7900

7. 7753

7. 8015

7. 7933

Difference.

+0. 0028

+0. 0020

+0. 0012

+0. 0019

+0.0035.

+0. 0043

dS.

+0.03

+0.02

+0.01

+0.02

+0.04

+0.04

Density is increased by turning to an amount as large as corresponds 

to the removal of a single shell; and the discrepancy d d resulting may 

be even one-half per cent, of the density of shell sought. The part 

of this increment due to roughness of surface and the part due to 

superficial annealing cannot be distinguished; but it is clear that the 

data will only be sufficiently accurate' for the present comparisons when 

cylinders of like surface, preferably smooth, are examined. If we inspect the equation of errors here4 involved,

wo find ddn alarmingly large when the shells are thin. Such data cannot be regarded as valid until they have been subjected to most careful 

and searching scrutiny.

Curiously enough, even if the rough cylinders be tested from time to 

time, density seems to increase. This may be regarded as an indication of slow shrinkage. Here are a few results, li denoting the interval in hours:

TABLE 14. Efforts possibly due to shrinkage.

No., &c.

A!".....

AiT' .....

7i

0 

50

0

50

A

7. 7727 

7. 7738'

7. 8000 

7. 8022

Difference.

\ +0.0011

| +0.0022

(490)
BARUSAND6TKOUI1AL.J EVALUATION OF ERRORS. 49

The data are again of the same order as the differences of density obtained by removing a single shell. Here, therefore, is a source of error 

the effects of which cannot as yet even be estimated. The few data 

given merely suggest the importance of special inquiry.

A third class of errors results from the fact that it is nearly impossible to preserve perfect cylindricity throughout the course of the experiment. Solution is liable, to take place at greater rates near the ends 

of the pieces of steel, as well as irregularly over the surface. The removal of matter in too great quantity from the ends must bo particularly apprehended. This difficulty may be corrected to some extent by 

painting with asphaltum 5 but it is not thoroughly counteracted. Even 

the diamond polishes the surface without necessarily restoring the cylindrical figure completely. Hence unless great care be taken, the cylinders, after repeated solutions of sheUs, become more and more convex 

and barrel-shaped, and hence if the infinitesimal shells of the- hard 

cylinder be coaxial and symmetrical with respect to its equator, the 

dissolved shell is not in full coincidence with a series of elementary 

shells of the cylinder. Moreover, the discrepancy is greater as the 

harmonic distribution of density is of small period or crowded. In 

such a case the true periodicity may wholly escape detection.

Again the density, d, directly obtained is not the true density for the 

given distance, #, below the surface. This follows readily if it be called 

to mind that the structure of the tempered cylinder must be that of 

box-within-box. Hence if we consider the distribution of density along 

the nth elementary shell we must find, on passing from equator to either 

end, a general.increase to a maximum simply because we approach 

parts near an end surface of the original cylinder. The analysis has 

already been given.

The final source of error is readily detected. We refer to superficial 

oxidation. It is obvious that the rapid descent of the loci of both A and 

6 for points near the surface is partially a secondary phenomenon, a 

simple physical expression for decarburatiou. To this we have already 

adverted (p.33). We may add here that cracks are apparently accompanied by small values of A (p. 34).

It will hardly be necessary to refer to the actual measurements. The 

water in which .steel is frequently immersed soon shows yellowish turbidity, due to suspension of rust. In replacing this by fresh water, we 

invariably weighed the bodies (steel) in both; but the differences between the respective values of density were negligible in all cases.

The results of this discussion may be tersely summarized thus: A first 

approximation reveals structure (#=/(#)), as a simple function of depth 

(x=p 0 p) below surface, nearly independent of radius; more accurate 

approximation suggests an exceedingly complicated, probably harmonic 

function of depth. Final decision as to whether the harmonic relations 

in hand are true expressions for the variations of structure involved, or 

Bull. 35 4 (491)
50 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [BULL. 35.

whether they simply indicate a periodic distribution of errors, can alone 

be given by frequent and laborious repetitions of experiments like those 

here described, with comparisons of all the loci obtained. The experiments must include many types of steel; for it is in this work that the 

quality of the material enters as a factor of exceptionally great importance. We come at once in contact with the power of retaining stress 

postulated in our earlier bulletin.

CONCLUSION.

The general results of the present paper have been so fully summarized in the preceding paragraph that further remarks here are nearly 

superfluous. But there are certain ulterior points at issue which have 

not yet been touched upon. In the first place, it is clear that the investigation of structure, which the present paper merely commences for 

the glass'-hard state, is incomplete : that it must be supplemented by 

the nearly equally important series of data for the other definite states 

of temper between hard and soft. In Bulletin 14 we. studied the phenomenon of annealing in its gross or aggregated effects ; but the minute 

analysis of this phenomenon must, under given circumstances of exposure, necessarily discern differences of harciness at each point of the 

rod annealed. It must distinguish, between the paths, as we may say, 

by which the consecutive individual shells eventually reach the state 

of homogeneous temper, while the rod as a whole passes from hard to 

soft.

An important observation is the dependence of structure on the 

quality or kind of steel carrying the hard strain, so that it may even 

be a sensitive criterion of the character of the material employed. 

Certainly it is difficult to avoid the inference that the lauded theory

of dense shell and rare core, or hard shell and soft core, when regarded as a faithful expression for the structural results of temper, 

is quite incomplete. Under given conditions of quenching and for a 

given kind of steel, the hardness at a point is dependent upon the position of the said point below the surface, and will be harder or softer 

than the superficial layers in proportion as we pass through greater 

values of depth. Hence, so long as crucial evidence for or against viscous shrinkage (i. e., continuous variation of strain due to purely mechanical causes) is not in hand, so long as the strain at any point of a 

tempered-steel bar is persistent and apparently independent of the 

strain of surrounding parts, it will be safest to return to the venerable 

hypothesis of combined carbon, much in the form in which Karsten 

and his stalwart associates left it.1

have since examined the question of structure from a variety of different 

standpoints. It is difficult to give satisfactory excerpts here; aud the reader is 

therefore referred to the American Journal of this year and to forthcoming Bulletins 

of the Survey. August, 188G.

(492)
BAIIUB AND 6TKOunAL.l CAUSE OF OXIDATION. . 51

B. THE COLOR EFFECT PRODUCED BY SLOW OXIDATION OF IRONCARBURETS.

Under this head we desire to continue the investigation on certain color 

phenomena peculiar to iron-carburets commenced in an earlier bulletin. 1

Let there be given an oxide film bounded by two parallel planes, in. 

definite in extent, the anterior plane being continually in contact with 

air, the posterior plane continually in molecular contact with iron. Let 

the degree of oxidation at all points of any parallel plane between them 

be identical. If 0 be the oxidation in an interface at a distance x below the anterior surface, then we regard dO \ dx as an important factor 

of the force in virtue of which oxygen is urged normally through the 

interface, in an inward direction. And, furthermore, since during the 

whole growth of the film the inner and outer coats remain in contact

with iron and air, respectively, we must infer that / x dO, the diftbrcnce between the degrees of oxidation of the two extreme surfaces, is 

constant. Hence the mean value of dO \ dx must decrease in proportion 

as the coat increases in thickness, and hence oxidation ceases completely 

after a certain finite thickness of film has been formed. Experiment 

shows that at each temperature the depth of film below which oxygen 

cannot penetrate is a quantity of definite value, increasing as temperature increases. We find moreover that oxidation advances as far 

as the said maximum depth gradually at a slowly decreasing rate 

through infinite time.

In the case of ordinary diffusion dO \ dx would be a continuous function of x. In the present instance, however, dO \ dx is not necessarily 

continuous. Eegarding the character of dO | dx no further remarkcan here be made than that it must decrease continually from the anterior 

to the posterior face of a film. It is known that the oxide which forms 

on iron duringheating is not of definite chemical composition. According 

to Koscoe and Schorlemmer2 tbe inner layers are not magnetic and approximately G Fc O Fe2 O3 . The outer layers contain more ferric oxide?, 

and are magnetic. This result for thick layers does not, however, bear, 

any immediate relation to the composition -of, extremely., thin fijms, for. 

after the coat has increased to a certain thickness it cracks, and the, 

phenomena, are then repeated in promiscuous and irregular succession. 

The considerations suggested, lead directly to the grained structure of: ; 

matter, and we have remarked. elsewhere that the oxygen molecule docs 

not penetrate deeper than a few thousand times. its own dimensions... 

Nevertheless the convenience of a function like dO [,dx, continuous., 

throughout the great parts of its extent, at least, is obvious. .

!U. S. Geol. Surv. Bull.27, p. 51,.188r>.

2 RQ8cpe and Schorlemmer, Chemistry, 1884, II, 2, p.. 86.,
52 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [uuLL.35.

Our observations arc as yet by no means sufficiently advanced to enable us to express the final (time. o>) thickness of film in its dependence on temperature. The data of the former paper, moreover, are incomplete iu two respects: they contain only isolated values for the 

early stages of oxidation, which stages are important because they exhibit the time effect perspicuously; they furnish no results at all for the 

oxidation effect of low temperatures. To supply these deficiencies is the 

main Object of this paper.

The method of experimentation here adopted is identical with that of. 

the former paper. It ,was found expedient, however, to allow the flame 

of the burner to impinge upon a broad plate of brass; to place the 

shaft with its horizontal asbestus screen properly adjusted, upon the 

plate. This insures greater constancy of temperature throughout the 

area of base. Moreover, no discrepancy due to hot-air currents coming 

directly from the flame is to bo apprehended. To obtain lower temperatures along the given length (25cni) of shaft, we found it fairly expedient to use two brass plates with an interposed sheet of asbestus. 1 By 

this device the range of temperature, 180° to 300°, was reduced as far as 

110° to 160°. Certain objectionable features are to be mentioned below.2 

If care be taken to avoid these, the apparatus will furnish ample facilities for the complete researches on temper value contemplated.

Data for high temperature. The results contained in Tables 15 to 18 

were investigated with a view to corroborating the results of an earlier 

paper.3 The range of temperature here lies within 180° to 200°, and 

the dark bands or zones (colors of higher order) are to be observed 

chiefly during the initial stages of oxidation.

In Table 15 the approximate positions of the color zones are given by 

noting as accurately as possible the consecutive depths (in centimeters) of 

the upper and lower boundaries of the respective zoues below the top of

Shaft as a datum. 7t, here, is the time in hours dated from the moment 

at which the experiment was started. Tho figures under "remarks" 

refer to the observed depth of the center of color of the " clear blue" 

band. The column " dark" contains data for all shades of the variously-tinged blacks which follow the gray. .

lu Table 1C we give results for the successive distributions of temperature on the shaft. "No." refers to the thermo-elernent of platinum 

and platinum-indium (20 percent.) used. c20 is the electromotive force 

of this couple when the hot junction is applied at a depth, cl, and the 

cold junction kept constantly at 20°. From this, £, the temperature 

in degrees centigrade is calculated. The means of the results for temperature and depth are summarized in Table 17.

On the basis of Tables 15, 16,17 we computed the results in Table 18. 

The depths and mean temperatures of the successive color bands are

1 See Fig. 10, p. 59.

2 See p. 58.

* U. S. Geol. Snrv. Bull. No. 27, p. 51.

(494)
COLOR DATA FOR HIGH TEMPERATURE. 53

here given for each time of observation. The results for clear-blue, 

having been specially redetermined, are probably more accurate than 

the others.

TABLE 15. Consecutive positions of the color lands.

Date.

1885. 

Sept. 15..

-

Sept. 16..

Sept. 17..

Sept. 18..

Sept. 19..

Sept. 20.. 

Sept. 21.. 

Sept. 22..

h

0

1.5

2 7

5.5

8.2

0.5

24 

33

48

58

72

00

104 

120 

144 

1C8 

175

Dark.

........

25-24

25-23

25-23 

25-23 

25-23 

25-22

Steelgray.

25- 

25-21

9<»-91

25-21

24-21

23-19

23-20 

23-19 

23-19 

22-18

Lightblue.

-22 

21-20

21-19

21-19

21-19

19-18

20-18 

19-18 . 

19-17 

18-10

Clearblue.

25-24.

25-22

25-22

22-19 

20-19

io_ia

1Q_|Q

19-17

18-16

18-10 

18-15 

17-15 

16-14

Purplo.

94-9")

22-20

22-21

19-18 

- 19-17

18-16

18-10

17-15

16-14

10-10 

15-13 

15-14 

14-12

Brown.

22-

20-

21-

18- 

17-

16-10

16-10

15-9

14-12

10- 

13- 

14-10 

12-

Yellow.

22-

.-19

-10 

-8

1A_<>

10-0

9-0

12-0

-0 

-0 

10-0 

-0

Colorless.

25-0

25-0

-0

-0

-0

19-0

10-0 

8-0

Ml

......

Remarks.

IJottom just visibly darkening.

24.6.

24.0.

23.5.

23.

20. 

19.5.

19.5.

18. (Shaft may

bo considered 

colored throughout its length.)

18.

blue spoil tho 

purity of color.)

16.5. 

16. 

15. 

15.

TABLE 16. Successive distributions of temperature.

Time.

A 

10.......................

10.......................

10.......................

34.......................

34.......................

^1

58.......................

68........... ............

No.

35

35

35

35

35

35

35

35

d

0

12

 24

0

12

24

0

12

em

i<w>n

1470

2053

1284

1533

107";

1243

1455

(

o 

178

191

253

170

197

911?

ICO

190

Time.

A 

58.......................

Ort

96.......................

96.......................

145......................

iii?

145......................

No.

35

35

35

35

35

35

35

d

24

0

12

24

0

19

24

£30

2141

i^in

1439

2009

1277

1506

2113

(

o

2CO

1C4

187

247

170

194

258

(495)
54 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. |"uu,35. 

TABLE 17. Distribution of temperature mean values.-

d .................................................

t .................................................

0

1C9 175

10

ISO

15

202

20

227

23

247

TABLE 18. Anerayc temperatures of ihc successive color land*.

Date.

Sept. 1C, 1885. ......

Sept. 17, 188..........

Sept. 18, 18S5.. ...... 

Sept. 19, 18S5.......

Stpt.21, 1885.......

Sept. 22, 1885.'......

h

0 

~. 7 

5.5

8.2 

9.5

_t

33 

48 

58. 

72 

' 90 

104 

120 

144 

108 

175

Gray.

d

24

*.u

23 

23

21

*,!

21 

21 

20

t

270 

260 

2GO 

260 

250 

240 

240 

210 

240 

230

Lightblue.

d

21 

20 

20 

20 

19 

19 

18 

18 

17

t

240. 

232 

232 

232 

225 

225 

219 

219 

214

Clearbluo.

d

24 

24 

23 

23 

20 

19 

18- 

18 

17 

17 

17 

10 

1C 

15 

15

t

280 

270 

205 

2GO 

232 

229 

225 

220 

210 

214 

214 

. 211 

209 

204 

202

Purple.

d

23 

20 

2i 

19 

18 

17 

17 

17 

15 

13 

14 

14 

13

t

200 

232 

240 

225 

219 

214 

214 

214 

204 

195 

200 

200 

195

Brown.

d

14 

14 

12 

 13

12

t

200 

200 

191 

195

191

Yellow.

d

20

7 

5 

5 

C

5

t

232

177 

172 

172 

173

172

Colorless.

d

19 

10 

8 

5 

0

t

225 

185 

178 

172 

168

In the accompanying figure (Fig. 9) tbe temperature at tbe center 

of figure of tbe clear blue band is grapbically represented in its variation with time. The diagram contains both present and early obser300.

250

20CL

10O. 

PIG. 9. Temperature of thomean " clear blno" film, regarded as a function of time.

vations, the former being distinguished by small circles, tbe latter by 

crosses. Table 18, moreover, would enable us to construct similar loci

(49G)
BARUS AND sTRouHAu] COLOR DATA FOR LOW TEMPERATURE. 55

for the zones gray, light blue, purple, bro. wii; yellow, colorless. But 

the data for these colors arc neither so complete nor so accurate; they 

show like contours with the clear-blue curve, and differ from it chiefly 

in position. They are omitted to avoid confusion in the diagram.

The discrepancy between the present and former loci/ clear blue is 

nowhere larger than 10°. In consideration of the large sources of error 

and uncertainty involved in color measurements, this accordance is 

obviously satisfactory. We obtain a thorough corroboratio i of the 

enrlier result, viz, that the conditions under which any given color is 

reached in normal atmospheric air depend both on the time and on the 

temperature of exposure in such a way that the influence of time more 

and more nearly vanishes in proportion as the exposure is indefinitely 

prolonged. Ultimately, therefore, the color datum is a function of temperature only,

Whenthe(hot) shaftis allowed to cool after the ordinary circumstances 

of exposure, we find that after G hours of cooling it is just warm to the 

touch. We infer, conversely, that the thermal condition must necessarily become stationary within the first 10 hours of heating. Now, 

the upward movement of the color zones on the shaft is still marked 

after 200 hours, and hence cannot be seriously distorted by irregularities of heating at the inception of the experiment.

We may remark that when spread over large areas of planed wrought 

iron the oxide coloration is apparently less brilliant than when comprehended between isothermals lying very closely together. Probably 

streaks of color due to irregularities in the surface (unpolished) interfere 

with the purity of the tints. Hence the use of thinner cylindrical rods 

which the colors, as a whole, would encircle like a narrow girdle may 

be quite as good a method of experiment as the present: for temperature may be interpolated with accuracy for observations made at points 

of the rod on both sides of the girdle. Such rods should be of steel 

and well polished.

Data for low temperature. Tables 19, 20, 21, and 22 are constructed 

on the same plan as Tables 15,1C, 17, and 18, and differ from them only 

in that the results given hold for lower ranges of temperature. The 

tables follow. Depths arc expressed in centimeters, time in hours, 

temperatures in degrees centigrade.

(497)
56 PHYSICAL PROPEETIES OF THE IRON-CARBURETS. [BULL.35 

TABLE 19. Consecutive positions of the color bands.

Date.

Sept. 26, 1885 ....

Sept. 27, 1885....

Sept. '28, 1885....

Sept 30,1885.....

Oct. -2,1885.......

Oct. 3, 1885.......

Oct. 0,1885....... 

Oct. 7,1885. ......

Oct. 8, 18S5.......

Oct. 9, 1885. ......

Oct. 10,1885...... 

Oct. 11,1885...... 

Oct. 13, 1885......

Oct. 14, 1885......

Oct. 1C, 1885......

Oct. 17, 1885......

Oct. 20, 1885...... 

Oct. 22, 1885......

Oct. 23, 1885......

Oct. 25,1885 ..... 

Oct. 26,1885..'....

Oct. 29, 1885......

Nov. 2, 1885 ......

h

, 0

48

87

137

1C1

233 

257

280

305

334 

353 

401

425

478

498

568 

CIO

C44

688 

711

789

887

890

890 

890 

890

Blue.

........

25-24

25-24

25-24

25-24

25-24 

25-24

25-24

25-24 

25-24

25-24

25-24

25-23 

25-24 

25-23

Purple

25-24 

25-23

25 °3

25-22

25-22 

25-22

9<5 99

25 °2

oc; 09

24-21

24-22 

24 22

°4 21

24-22 

24 22

24 22

24-22

23-21 

24-22 

23-20

Brown

25-22

25-23

24-22

9<l 91

22-20 

22-20

29 9()

°°-19

22 19

21-19

22-19 

22-19

21-18

22-18 

22-19

21-19

22-18

21-19 

22-19 

20-18

Strawyellow.

23-19

22-19 

23 19

21 19

' 22 18

20-17 

20-18

9ft 1 7

19 17

19-17

19-17

19-10 

19-16

18-15

18-16 

19-17

19-16

18-15

19-17 

19-18 

18-16

Lightyellow.

25-22

25-21

 25-21

20-14

19-12

19-12 

19-14

19 14

18 14

17-12 

18-14

17 13

17 1Q

17 1Q

17-12

16-12 

16-12

15-12

16-12 

17-12

16-12

15-12

17-14 

18-13 

16-11

Colorless.

22-0

21-0

21 0

14-0

1° 0

12-0 

14 0

14-0

14-0

12-0 

14-0 

13 0

IP n

13-0

12-0

12-0 

12-0

i9_n

12-0 

12-0

12-0

12-0

14-0 

13-0 

11-0

Remarks.

Gas out.

! Remaining faces of the 

cold shaft.a

a The thick asbestus screen surrounding the shaft covers the part between 25.0 and 24.5. This part 

is faintly discolored as .1 consequence.

TABLE 20. Successive distributions of temperature.

Time.

h 

23...... .................

23.......................

48.......................

48.......................

48.......................

87.......................

87.......................

87. ......................

137......................

137......................

m .

185......................

185................ .....

1St\

No.

35

35

35

35

35

e:o

740

849

1142

774

892

1216

764

887

1199

745

867

1166

791

asn

1224

d

0

12

24

0

12

24

0

12

24

0

12

24

0

12

24

t

111

124

114

126

162

113

126

160

110

125

157

115

126

1C?,

Time.

h . 

280.................':...

280.....................

280.....................

385.....................

385.....................

385.....................

Wi

575.....................

W!

715.....................

71 1

715.. ...................

890.....................

890.....................

890.....................

No.

35

35

35

35

35

ew

771

8G7

1197

752

849

1192

740

860

1174

698

843

1118

763

105G

d

0

12

24

0

?4

0

12

24

0

12

24

0

12

24

t

113

125

160

110

124

15!)

109

125

150

105

121

152

100

111

14C,

(498)
BABUS AND STBOUDAL.] COLOR DATA FOE LOW TEMPERATURE. 

TABLE 21. Distribution of temperature mean vilu.es.

57

d 0

110°

5

113°

10

119°

15

129°

20

143°' 154°

TABLE 22. Average temperatures of the successive color lands.

Date.

Sept. 26,1885. ................... 

Sept. 27,1885............ .......

Sept 28, 1885. ..................

Sept. 30, 1885......... ..........

Oct. 2, 1885. ....................

Oct. 3, 1885...- .................

Oct. C, 1885. ....................

Oct. 7,1885. ....................

Oct. 8, 1885. ....................

Oct. 9,1885. ....................

Oct. 10, 1885...... ..............

Oct. 11, 1885....... .............

Oct. 13, 1885...... ..............

Oct. 14, 1885...... ..............

Oct. 1C, 1885...... ..............

Oct. 17,1885...... ..............

Oct. 20, 1885... .................

Oct. 22, 1885.... ................

Oct. 23, 1885...... ......... ....

Oct. 25, 1885.... ................

Oct. 20,1885... .................

Oct. 29, 18£5. ...................

lfov.2,1885 ....................

h.

0

4R

87

161

?33

257

?so

305

334

353

401 

425 

478 

498 

568 

610 

644 

688 

711 

789 

887

Blue.

d.

....

24 

24 

24 

24 

24 

24 

24 

24 

24 

24 

24

t.

300

160 

160 

160 

160 

160 

160 

160 

160 

160 

160 

160

Purple.

d.

24 

24 

24 

24 

24 

24 

23 

23 

23 

22 

23 

23 

23 

23 

23 

23 

23

t.

280

160 

157 

157 

155 

155 

155 

154 

154 

154 

151 

154 

154 

154 

154 

154 

154 

154

Brown.

d.

24 

24 

23

22

21. 

21 

21 

20 

20 

20 

20 

20 

20 

20 

20 

20 

20

t.

260

157 

155 

153

149

146 

140 

146 

144 

144 

143 

144 

144 

143 

143 

144 

143 

143

Strawyellow.

d.

....

21 

21 

21 

21 

20 

20 

19 

19 

19 

18 

18 

18 

18 

17 

10 

17 

18 

17 

17

t.

240

145 

145 

144 

145 

144 

144 

137 

140 

137 

136 

.130 

136 

135 

135 

134 

134 

136 

134 

. 134

Lightyellow.

d.

23 

23

17 

16 

16 

16 

1C 

1C 

15 

16 

15 

15 

15 

14 

14 

14 

13 

14 

14 

14 

14

t.

220

154

154 

134 

130 

134 

134 

134 

132 

128 

132 

129 

129 

129 

127 

126 

126 

126 

126 

127 

126 

120

Colorless.

d.

*.2

21

21 

14 

12 

12 

14 

14 

14 

12 

14 

13 

13 

13 

12 

1L 

12

li*

12 

12 

12 

12

t.

200 

149 

1-15 

. 145 

12G 

123 

12;t 

120 

120 

126 

123 

126

lt**>

125 

125 

123 

123 

123 

123 

123 

123 

123 

123

An inspection of the loci of the data given in Tables 19 to 22, where 

for stated colors mean temperature is expressed in function of time, 

shows this: In most cases only such parts of the respective curves as 

are almost indistinguishable from the asymptotes- have been observed. 

In the earlier Bulletin,1 and in the first parts of the present paper, evidence was adduced to prove that the influence of temperature to produce color bands, the order of which increases contiu uously with time, is 

particularly marked during the first 100 hours of exposure and is very 

nearly complete within 200 hours. In Tables 19 to 22 the blue purple 

bands did not rise observably above the horizontal screen until more than 

200 hours had elapsed after the beginning of the experiment. These 

bands, moreover, extend upward not more than 2cm above the base of 

the shaft. At points so near the bottom the fluctuations in the intensity, 

of flame are not yet either obliterated or rounded. It is therefore pos-

'U. S. Geol. Surv. Bull. 27, p. 51. 

(499)
58 PHYSICAL PROPERTIES OP THE IRON-CARBURETS. tnutL.35.

sible that during the night hours, or at other times when measurements 

were not made, these parts may have temporarily shown temperatures 

^appreciably above the mean values of the sefc of ten series of measurements in hand. Hence the dark bauds may owe their origin to temperatures above the exceptionally low values given in the tables. Finally, 

at points near the base and (hot) screen, oxidation is probably accelerated because the oxidizing air impinges at a temperature necessarily 

higher than is that of the air near the upper parts of the shaft. This, 

therefore, is a second cause for the unusually low temperatures at which 

dark zones have here been obtained.

Eemarks of a similar kind apply in a measure to the dark yellows 

brown and straw-yellow. The colors did not emerge above the screen, 

and hence observation was not feasible until 100 hours after the beginning of the experiment. The lines obtained are practically asymptotes; 

the temperatures are too low.

The present set of measurements is therefore interesting chieCy because of the values obtained for the oxidation of low temperatures. 

The light yellow and colorless parts of the shaft are so high above the 

base that the objections which hold for dark bands are no longer applicable. Moreover, the temperature discrepancy in question can only 

give additional weight to the inferences presently to be drawn. It appears, therefore, that under ordinary atmospheric conditions temperatures,falling below 125° will not perceptibly oxidize iron (color effect), 

however long their action may be continued. It appears, furthermore, 

that the effect of temperatures near this limit is such that the final tint 

or color of highest order is in any given case reached in a comparatively 

short time; or that it is reached at a stage of progress certainly quite 

as early as that observed for dark bauds. Here, then, we observe a 

difference in the temper effect and the color effect of temperature; since

in the former case (of annealing) the influence of time is particularly 

marked for lower temperatures (<100°); whereas for higher temperatures (>200°) it is nearly negligible. The result for color phenomena 

is almost the converse of this, since the time effect here is rather more 

marked, and prolonged through greater intervals, for dark bands than 

for very light bands. Finally we may observe, in a general way, that 

the annealing effect of the action of temperature on hard steel is as 

nearly complete in a few hours as is the color effect in a few hundred 

hours a difference which will probably be crucial.

The color phenomena in question may be made to appear in another 

aspect. We may discuss the rate at which for a given temperature the 

thickness of coat varies when exposure is prolonged indefinitely. A 

method of using monochromatic light of wave length /I and of determining the thickness d of film from d=n j, where n is the order of the

band, is here inapplicable. The bands are too broad and diffused and the 

temperature variation within the first band is of considerable importance.

(500)
I1AIUJB AND STROUHAT,.] GRUNOW'S APPARATUS.

Nevertheless, the colors appearing in white light are available for obtaining the datum sought, and the above results may thus be interpreted. It is, however, best to omit this comparison here. For the 

purpose in question, it is desirable to obtain the colors, in the state 

of extreme purity in which they appear on a polished steel cylinder. 

Mr. William Grunow, of West Point, has been at great pains to furnish 

us with a steel shaft of this land, 25cm long and 6.5cm in diameter. The 

shaft in position, M M M M, is shown in the accompanying diagram, 

Fig. 10, in which a a are plates of metal between which a sheet of

FIG. 10. Grunow's shaft, in position.

asbestus may be interposed. A screen, S S, fully 35cm in diameter, 

protects the shaft from direct flame currents. The essential feature 

of this arrangement is the vertical hole c c, 0.5cm in diameter, arid extending to within a few millimeters of the base. Into this we purpose 

to introduce, momentarily, a properly insulated thermo-couple to determine the thermal distribution throughout the length of the shaft; 

it is generally to be used for the reception of glass-hard steel Avire. Between any given and any known isothermals, therefore, we have on the 

outside of the polished cylindrical surface certain clear color effects. 

Between the same isothermals we have also a definite annealing effect, 

determinable by examining the parts of the steel wires there exposed. 

From a comparison of these data the temper value of the oxide colors 

is deducible in full generality. We may add that under certain circum-

(501)
60 PHYSICAL PROPERTIES OF THE IRON-CARBURETS. [HULL. 35.

stances it may be desirable to invert the cylinder; to introduce the steel 

wires and the elements alternately from below, and to heat the shaft in 

some appropriate way at the top. Indeed it appears to us that rods 

bored on the gun-barrel principle would offer very satisfactory objects 

for accurate measurements of heat conductivity; for the advantages 

of measuring the (constant) temperature at any point in the interior of 

it narrow vertical cylindrical canal, closed above, over measuring the 

corresponding temperature at the mantle of the rod, are obvious at 

once. 

WASHiNGrTON-PRAGUE, January, 1886.

(502)
INDEX,

Pnge.

Annealing, effects of.................. ................J..................... 50

Carburation, effect of stress on .............................................. 42

Coll for solution of steel...............................................'...... 14

Color effect of oxidation .................... ................................ 51

method adopted for studying ............................................ 52

data for high temperature ............................................... 52

data for low temperature ................................................ 55

minimum temperature for ............................................... 58

minimum temperature for perceptible oxidation .......................... 58

Conductivity, device for measuring .......................................... CO

Contraction (see Shrinkage).

Cores, density of successive .............- -.........:........................ 32

theory of rare................................ _.._........................ 50'

Crucible for heating steel ................................................... 13

Cumming-Goro, contraction phenomenon observed by ........................ 38

Dccarburation at surface .................................................... 33

Density, minimum superficial................................................. 33

Density of successive shells.................................................. 35

Errors, evaluation of........................................................ 43

formula) for............................................................. 44,48

moan values of certain .................................................. 46,47

due to state of surface................................................... 47,48

due to imperfect cylindricity ............................................ 48,49

summary of probable effects of........................................... 50

Formula) connecting data observed ........ v.........:....................... 17,30

Fromme, results of, for structure ............................................ 11,12

Galvanic solution, cell for ................................................... 14

Gooch, F. A., aid of................................ A.... ................... 16

Grunow, steel shaft of....................................................... 59

Harmonic distribution of density ............................................ 35,42

difficulties of interpretation of........................................... 35

causes of difficult interpretation of, analyzed ............................ 38,39

Karsten, hypothesis of temper by............................................ 50

'Magnetization, theories of ................................................... 11

Mass action in iron-carburets ................................................ 42

Master tool, use of .......................................;................... 14

Matthiessen-Hockin, use of measurement method of.......................... 29

Oxidation (see Color effect of oxidation).

Oxide films.............. ................................................... 58

Quenching, apparatus for .................................................... 13,14

Resistance, method of measurement and da,ta ................................ 28,29

comparison of, at different depths ........;.............................. 43

deductions from, to indicate structure ................................... 43

61 

(503)
62 INDEX. '

	Page. 

Rupert's drops, mechanical behavior of....;.................................. 42

Shells, density of successive........................... ...................... 35

theory of dense .......................:.................... ............. 50

Shrinkage, tests for ............................................. ............ 31

intermittent ............................................................ 41,^2

uniform viscous......................................v... ................ 41,48

Siemens, use of amperimeter of .............................................. 15

Steel, kind of, used ........................ ................................ 12

Stress, effect of, in modifying carburation...... ............................... 42

Structure, importance of .................................................... 11

true and apparent ...................................................... 31

box-Avitbiu-box .............'............................................ 34

conclusions respecting dependence of, on kind of steel.................... 00

Suspension, method of, in density work ...................................... 10

Table, bhowiug Fromme's results for structure ................................ 12

showing strength of battery (current in amperes) ..._...............-..... 15

No. 1. Density of soft steel ............................................. 10

No. 2. Density of consecutive (glass-hard) cores......................... 18-22

No: 3. Density of consecutive (glass-hard) shells ........................ 19-23

No. 4. Density of consecutive (glass-hard) cores ........ ................ 24-20

No. 5. Density of consecutive (glass-hard) shells ........................ 25-27

No. G. Kesietanco of consecutive (glass-hard) cores... '. .................. 29

No. 7. Resistance of consecutive hard cores and shells ................... 30,31

No. 8. Resistance tests for shrinkage................................... 31

No. 9. Exhibit of errors of II and & .................................. .. 4f>

No. 10. Calculated (mean numerical) errors of d .......................... 40

No. 11. Exhibit of errors of 6", iirst series ................................. 47

No. 12. Exhibit of errora of d, second scries.............................. 47

No. 13. Density effect of friction......................................... 48

No. 14. Effects possibly due to shrinkage................................. 48

No. 15. Consecutive positions of the color bands...... .................... 53

No. 16. Successive distributions of temperature ........................'.. 53

No. 17. Distribution of temperature (moan values) ....................... 54

No. 18. Average temperature of successive color bauds.................... 54

No. 19. Consecutive positions of the color bands.......................... 50

No. 20. Successive distributions of temperature .......................... 50

No. 21. Distribution of temperature (mean values)....................... 57

No. 22. Average temperature of the successive color bands................ 57

(504)
[Bulletin No. 36.]

The publications of the United States Geological Survey are issued in accordance with the statute 

approved March 3,1879, which declares that 

" The publications of the Geological Survey shall consist of the annual report of operations, geological 

and economic maps illustrating the resources and classification of the lands, and reports upon general 

and economic geology and paleontology. The annual report of operations of the Geological Survey 

shall accompany the annual report of the Secretary of the Interior. All special memoirs and reports 

of said Survey shall be issued in uniform quarto series if deemed necessary by the Director, but otherwise in ordinary octavos. Three thousand copies of each shall be published for scientific exchanges 

and for sale at the price of publication; andall literary and cartographic materials received in exchange 

shall be the property of the United States and form a part of the library of the organization: And the 

money resulting from the sale of such publications shall be covered into the Treasury of the United 

States."

On July 7,1882, the following joint resolution, referring to all Government publications, was passed

by Congress:

" That whenever any document or report shall be ordered printed by Congress, there shall be printed, 

in addition to the number in each case stated, the 'usual number' (1,900) of copies for binding and 

distribution among those entitled to receive them."

Except in those cases in which an extra number of any publication has been supplied to the Survey 

by special resolution of Congress or has been ordered by the Secretary of the Interior, this Office has 

no' copies for gratuitous distribution. \

ANNUAL EEPOETS.

Of the Annual Reports there have been already published:

I. First Annual Eeport to the Hon. Carl Schurz, by Clarence King. 1880. 8°. 79 pp. 1 map. A 

preliminary report describing plan of organization and publications.

II. Keportof the Director of the United States Geological Survey for 18SO-'81, by J. W. Powell. 

1882. 8°. Iv, 586 pp. 61 pi. 1 map.

HI. Third Annual Report of the United States Geological Survey, 1881-'82, by J. W. Powell. 1883. 

8°. xviii, 564 pp. 67 pi. and maps.

IV. Fourth Annual Keport of the United States Geological Survey, 1882-'83, by J. "W. Powell. 1884. 

8°. xxxii, 473 pp. 85 pi. and maps.

V. Fifth Annual Keport of the United States Geological Survey, 1883-'84, by J. "W. Powell. 1885. 

8°. xxxvi, 469 pp. 58 pi. and maps. 

The Sixth and Seventh Annual Reports are in press.

MONOGRAPHS.

Of the Monographs, Nos. II, III, IV, V, VI, VH, VIII, IX, X, and XI are now published, viz: 

H. Tertiary History of the Grand Canon District, with atlas, by Clarence E. Dutton, Capt. U. S. A. 

1882. 4°. xiv, 264 pp. 42 pi. and atlas of 24 sheets folio. Price $10.12.

III. Geology of the Comstock Lode and the Washoe District, with.atlas, by George F. Becker. 

1882. 4°. xv, 422pp. 7 pi. and atlas of 21 sheets folio. Price $11.

IV. Comstock Mining and Miners, by Eliot Lord. 1883. 4°. xiv, 451 pp. 3 pi. Priee$1.50.

V. Copper-bearing Rocks of Lake Superior, by Roland D. Irving. 1883. 4°. xvi, 464 pp. 151. 

29 pi. Price $1.85.

VI. Contributions to the Knowledge of the Older Mesozoio Flora of Virginia, by "Wm. M. Fontaine. 

1883. 40. xi, 144 pp. 54 1. 54 pi. Price $1.05.

VII. Silver-Lead Deposits of Eureka, Nevada, by Joseph S. Curtis. 1884. 4°. xiii, 200 pp. 16 pi. 

Price $1.20.

Vm. Paleontology of the Eureka District, by Charles D. "Walcott. 1884. 4°. xiii, 298 pp. 241. 

24 pi. Price $1.10.

IX. Brachiopoda and Lamellibranchiata of the Raritan Clays and Greensand Marls of New Jersey, 

by Robert P. Whitfield. 1885. 4°. xx, 338 pp. 35 pi. Price $1.15.

X. Dinocerata. A Monograph of an Extinct Order of Gigantic Mammals, by Othniel Charles Marsh. 

1885. 4°. xviii, 243 pp. 56 1. 56 pi. Price $2.70.

XI. Geological History of Lake Lahontan, a Qusiternary Lake of Northwestern Nevada, by Israel 

Cook Russell. 1885. 4°. xiv, 288 pp. 46 pi. Price $1.75.
ADVERTISEMENT.

The following is in press, viz:

XII. Geology and Mining Industry of Leadville, with atlas, by S. F. Emmons. 1880. 4°. 

770 pp. 45 pi. and atlas of 35 sheets folio. " 

The following are in preparation, viz: 

I. The Precious Metals, by Clarence King.

 Gasteropoda of the New Jersey Cretaceous and Eocene Marls, by R. P. "Whitfield.

 Geology of the Eureka Mining District, Nevada, with atlas, by Arnold Hague.

 Lake Bonneville, by G. K. Gilbert.

 Sauropoda, by Prof. 0: C. Marsh.

 Stegosauria, by Prof. 0. C. Marsh.

 Brontotheridae, by Prof. 0. C. Marsh.

 Geology of the Quicksilver Deposits of the Pacific Slope, with atlas, by George F. Becker.

 The Penokee-Gogebic Iron-Bearing Series of North "Wisconsin and Michigan,, by Eoland D. living.

 Younger Mesozoic Flora of Virginia, by William M. Fontaine.

 Description of New Fossil Plants from the Dakota Group, by Leo Lesquerenx.

 Report on the Denver Coal Basin, by S. F.' Emmons.

 Report on Ten-Mile Mining District, Colorado, by S. F. Emrnons.

 Report on Silver Cliff Mining District, by S. F. Emmons.

 Flora of the Dakota Group, by J. S. Newberry.

BULLETINS.

The Bulletins of the Survey will contain such papers relating to the general purpose of its work as 

do not properly come underthe heads of Annual Reports or Monographs.

Each of these Bulletins contains but one paper and is complete in itself. They are, however, numbered in a continuous series, and may be united into volumes of convenient size. To facilitate this, 

each Bulletin has two paginations, one proper to itself and another which belongs to it as part of the 

volume.

Of this series of Bulletins Nos. 1 to 36 are already published, viz:

1. On Hypersthene-Andesite and on Triclinic Pyroxene in Augitic Rocks, by "Whitman Cross, with 

a Geological Sketch of Buffalo Peaks, Colorado, by S.F. Emmons. 1883. 8°. 42pp. 2 pi. Price 10 cents.

2. Gold and Silver Conversion Tables, giving the coining values of troy ounces of fine metal, etc., by 

Albert Williams, jr. 1883. 8°, 8 pp. Price 5 cents.

3. On the Fossil Faunas of the Upper Devonian, along the meridian of 76° 30', from Tompkins County, 

New York, to Bradford County, Pennsylvania, by Henry S. "Williams. 1884. 8°. 36pp. Price 5 cents.

4. On Mesozoic Fossils, by Charles A. "White. 1884. 8°. 36 pp. 9 pi. Price 5 cents.

5. A Dictionary of Altitudes in the United States, compiled by Henry Gannett. 1884. 8°. 325 pp. 

Price 20 cents. . .

6. Elevations in the Dominion of Canada, by J. "W. Spencer. 1884. 8°. 43 pp. Price 5 cents.

7. Mapoteca Geologica Americana. A catalogue of geological maps of America (North and South), 

1752-1881, by Jules Marcou and John Belknap Marcou. 1884. 8°. 184 pp. Price 10 cents.

8. On Secondary Enlargements of Mineral Fragments in Certain Rocks, by R. D. Irvingand C. R.

VanHise. 1884. 8°. 56pp. 6 pi. Price 10 cents.

9. Report of work done in the Washington Laboratory during the fiscal year 1883-'84. F. "W. Clarke, 

chief chemist; T. M. Chatard, assistant. 1884. 8°. 40 pp. Price 5 cents.

10. On the Cambrian Faunas of North America. Preliminary studies, by Charles D. "Walcott. 1884. 

8°. 74 pp. 10 pi. Price 5 cents.

11. On the Quaternary and Recent Mollusca of the Great Basin; with Descriptions of New Forms, by 

R. Ellsworth Call; introduced by a sketch of the Quaternary Lakes of the Great Basin, by G. K. Gilbert. 1884. 8°. 66pp. 6 pi. Price 5 cents.

12. A Crystallographic Study of the Thlnolite of Lake Lahontan, by Edward S. Dana. 1884. 8°. 

34 pp. 3 pi. Price 5 cents.

13. Boundaries of the United States and of the several States and Territories, by Henry Gannett, 

1885. 8°. 135pp. Price 10 cents.

14. The Electrical and Magnetic Properties of the Iron-Carburets, by Carl Barus and Vincent 

Strouhal. 1885. 8°. 238pp. Price 15 cents.

15. On the Mesozoic and Cenozoic Paleontology of California, by Charles A. White. 1885. 8°. 

33 pp. Price 5 cents.

16. On the higher Devonian Faunas of Ontario County, New York, by John M. Clarke. 1885. 8°. 

86 pp. 3 pi. Price 5 cents.

17. On the Development of Crystallization in the Igneous Rocks of "Washoe, Nevada, by Arnold 

Hague and Joseph P. Iddings. 1885. 8°. 44 pp. Price 5 cents.

18. On Marine Eocene, Fresh-water Miocene, and other Fossil Mollusca of "Western North America, 

by Charles A. "White. 1885. 8°. 26 pp. 3 pi. Price 5 cents.

19. Notes on the Stratigraphy of California, by George F. Becker. 1885. 8°. 28 pp. Price 5 cents.

20. Contributions to the Mineralogy of the Rocky Mountains, by "Whitman Cross and "W. F. Hillebrand. 1885. 8°. 114 pp. 1 pi. Price 10 cents.
ADVERTISEMENT.

21. The Lignites of the Great Sioux Keservation, by Bailey "Willis. 1885. 8°. 10 pp. 5 pi. Price 

5 cents.

22. On New Cretaceous Fossils from California, by Charles A. White. 1885. 8°. 25 pp. 5 pi. Price 

5 cents.

23. Observati6ns on the Junction between the Eastern Sandstone and the Keweenaw Series on 

Keweenaw Point, Lake Superior, by R. D. Irving and T. C. Chamberlin. 1885. 8°. 124 pp. 17 pi. 

Price 15 cents.

24. List of Marine Mollusca, comprising the Quaternary fossils and recent forms from American 

localities between Cape Hatteras and Cape Koque, including the Bermudas, by "William H. Ball. 1885. 

8°. 336pp. Price 25 cents.

25. The Present Technical Condition of the Steel Industry of the United States, by Phincas Barnes. 

1885. 8°. 85 pp. Price 10 cents.

26. Copper Smelting, by Henry M. Howe. 1885. 8°. 107 pp. Price 10 cents.

27. Report of work done in the division of Chemistry and Physics, mainly during the fiscal year 

1884-'8o. 1886. 8°. 80pp. Price 10 cents.

28. The Gabbros and Associated Horn blende Rocks occurring in the neighborhood of Baltimore, Md., 

by George H. Williams. 1886. 8°. 78 pp. 4 pi. Price 10 cents.

29. On the Fresh-water Invertebrates of the North American Jurassic, by Charles A. White. 1886. 

83 . 41 pp. 4 pi. Price 5 cents.

30. Second contribution to the studies on the Cambrian Fannas of North America, by Charles D. 

Walcott. 1886. 8°. 369pp. 33 pi. Price 25 cents.

31. A systematic review of our present knowledge of Fossil Insects, including Myriapods and Arachnids, by Samuel H. Scudder. 1886. 8°. 128 pp. Price 15 cents.

32. Lists and Analyses of the Mineral Springs of the United States; a preliminary study, by Albert 

C. Peale. 1886. 8°. 235 pp. Price 20 cents.

33. Notes on the Geology of Northern California, by Joseph S. Diller. 1886. 8°. 23 pp. Price 5 

cents.

34. On the relation of the Laramie Molluscan Fanna to that of the succeeding Fresh-water Eocene 

and other groups, by Charles A. White. 1886. 8°. 54 pp. 5 pi. Price 10 cents.

35. The Physical Properties of the Iron-Carburets, by Carl Barns and Vincent Strouhal. 1886. 8°. 

62 pp. Price 10 cents.

36. Subsidence of flue Solid particles in Liquids, by Carl Barus. 1887. 8°. 58 pp. Price 10 cents.

Numbers 1 to 6 of the Bulletins form Volume I j Numbers 7 to 14, Volume II; Numbers 15 to 23, 

Volume III; Numbers 24 to 30, Volume IV; Numbers 31 to 36, Volume V; Volume VI is not yet complete.

The following are in press, viz:

37. Types of the Laramie Flora, by Lester F. Ward.

38. Peridotite of Elliott County, Kentucky, by Joseph S. Diller.

39. The Upper Beaches and Deltas of the Glacial Lake Agassiz, by Warren Upham. 

In preparation:

40. Changes in River Courses in Washington Territory due to Glaciatiou, by Bailey Willis.

41. Fossil Faunas of the Upper Devonian the Genesee Section, by Henry S. Williams.

42. Report of work done in the division of Chemistry and Physics, mainly during the fiscal year 

1885-'86. F. W. Clarko, chief chemist.

43. On the Tertiary and Cretaceous Strata of the Tuscaloosa, Tombigbee, and Alabama Eivers, by 

Eugene A. Smith and Lawrence C. Johnson.

44. Historic statement respecting geologic work in Texas, by R. T. Hill.

45. The Nature and Origin of Deposits of Phosphates of Lime, by R. A. F. Penrose, jr.

46. Bibliography of North American Crustacea, by A. W. Vogdes.

STATISTICAL PAPERS.

A fourth series of publications, having special reference to the mineral resources of the United 

States, has been undertaken.

Of that series the following have been published, viz:

Mineral Resources of the United States [1882], by Albert Williams, jr. 1883. 8°. xvii, 813pp. Price 

50 cents.

Mineral Resources of the United States, 1883 and 1884, by Albert Williams, jr. 1885. 8°. xiv, 1010 

pp. Price 60 cents.

Mineral Resources of the United States, 1885. Division of Mining Statistics and Technology. 1886. 

8°. vii, 576 pp. Price 40 cents.

Correspondence relating to the publications of the Survey, and all remittances, which must be by 

POSTAL NOTE or MONEY ORDER (not stamps), should be addressed

To THE DIRECTOR OF THE

UNITED STATES GEOLOGICAL SURVEY,

WASHINGTON, D. C. WASHINGTON, D. C., March 1, 1887.