GEOLOGICAL SURVEY CIRCULAR 63

December 1949

THE CHROMOGRAPH, A NEW ANALYTICAL TOOL 

FOR LABORATORY AND FIELD USE.

By

Rollin E. Stevens and Hubert W. Lakin
UNITED STATES DEPARTMENT OF THE INTERIOR 

J. A. Krug, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

WASHINGTON, D. C.

Free on application to the Director, Geological Survey, Washington 26, D. C.
THE CHROMOGRAPH, A NEW ANALYTICAL TOOL 

FOR LABORATORY AND FIELD USE

CONTENTS

 Page

Abstract................................ 1

Introduction............................. 2

Acknowledgments.......................... 2

Types of chromographic determinations.... 3

Properties used to compare spots......... 3

Detailed description of a chromograph.... 3

Effect of speed of flow.................. 6

Page 

Modifier ions........................... 7

Examples of the use of the apparatus 

for determination of copper and nickel 

in soils.............................. 8

Experimental results.................... 9

Field trials of the chromograph......... 10

References.............................. 10

ILLUSTRATIONS

Figure 1. The ohromograph assembled................................................

2. Parts of filter base and filter head of ohrbmograph......................

3. Copper teats on soils near a small copper deposit........................

4. Correlation of magnetic dip-needle observations and nickel tests on soil 

on traverse across serpentine..........................................

Page

TABL'ES

Page 

Table 1. Effect of speed of flow of solution on chromographic tests for nickel.......... 6

2. Effect of speed of flow of solution on chromographic tests for copper.......... 7

3. Results of comparing nickel dimethylglyoxime test spots with standard

spots made with and without modifier ions present............................ 7

4. Results of comparing copper rubeanate test spots with standard spots

made with and without modifier ions present.................................. 8

5. Analyses for nickel and copper by the shrornographic method..................... 9

ABSTRACT

The chromograph, a new device for making confined spot tests: on .reagent papers, is described. 

The device is used to confine areas of definite size on a strip of reagent paper fed through the 

apparatus, and to control automatically the rate of flow of test so.lution through the confined 

spot. After a spot test is completed, the sample number may be wri'tten on the paper, and the 

paper.pulled through the apparatus to bring into position a spot oft an unused portion of the reagent paper for the next teat. The strips of paper containing the spots serve as semipermanent 

records of tests performed. The rate of flow of test solution through the reagent paper is controlled by the pull of a column of water and/or the filtrate from previous testa, and by a capillary tip which decreases the rate to less than that permitted by. the. reagent paper alone.

Procedures for chromographic determination of nickel with djUot.etnylglyoxime reagent paper and 

of copper with rubeanic acid reagent paper are described. The chrfofciiDgraph has been used sucessfully in locating nickel- and copper-bearing formations by testing samples of the overlying soils 
INTRODUCTION

The use of spot tests for detecting ions 

in solution has long been known as a technique 

capable of high sensitivity and specificity. 

Yagoda (1937) cites the use of such a method 

by Pliny, as early as 23 to 79 A. D., whereby 

ferrous sulfate in verdigris was detected by 

use of papyrus saturated with extract of gallnuts. In modern qualitative analysis, test 

papers treated with reagents are extensively 

used. Peigl's (1942) "Qualitative Analysis 

by Spot Tests" is perhaps the best-known compilation of such methods.

The spot-test technique consists essentially of bringing reagent and test solution 

together on paper or other porous medium. The 

reaction products, concentrated in a small 

area at the contact of reagent and test solution, are easily detected, and the excess 

liquid flows away in the surrounding fibers. 

The spqt test may be made by placing a drop 

of test solution on the paper followed by a 

drop of reagent solution, the reagent may be 

put on the paper first followed by the test 

solution, or reagent solution and test solution 

may be placed side by side with the reaction 

products forming at the junction of the two 

drops. Papers previously coated with reagents 

also are used extensively. (Feigl, 1942)

As a qualitative technique, spot tests 

have several advantages over teats made in the 

usual way in solutions. Colored reaction products concentrate in a small area and are thus 

easily seen against the white background of 

the paper. As the solution spreads by capillarity through the paper, reaction products 

may form in the paper at different distances 

from the point where the drop was placed, in 

accordance with differences in solubility. 

This makes possible the detection of a number 

of ions in one spot test, as well as making 

the test for a given ion more specific. Another advantage of the spot test is the speed 

and ease with which the test may be. made with 

simple and cheap apparatus. Whether the ion 

is present In large or small amounts also can 

be seen.

The sensitivity of the spot test is increased by any modification that prevents 

spreading of the reaction products through the 

pores of the paper. Hahn (1931) accomplished 

this by applying the test solution to the reagent paper through the fine tip of a capillary tube, the reaction products concentrating 

at the point of entry of test solution into the 

paper. Clarke and Hermance (1937) used this 

technique to control the speed of flow of test 

solution onto the reagent paper by the inclination of a capillary burette in a special assembly.

These spot-test techniques serve well the 

needs of qualitative testing, as they are highly sensitive, specific, and easy to perform. 

Their" application in determining the quantity of 

an ion present, however, is limited by the fact 

that the reaction products form in an area of 

indefinite extent. This exact area is not 

reproduced in successive tests. In colorimetric determinations the quantity of an ion 

is found by the intensity of color in a fixed 

volume of solution of fixed thickness. Similarly, in spot testing the area containing the 

colored reaction product, the intensity of the

color, and the volume of test solution used 

must be known in order to determine the quantity of an ion present.

Yagoda (1937) first proposed the use of 

a confined spot in quantitative spot testing. 

The spot test was confined within an area of 

definite size by means of a barrier containing 

water-repellent material, such as paraffin 

wax. Yagoda describes equipment needed to 

impregnate the paper with paraffin and leave 

spots of definite size for making the spot 

test. The test was made by placing a measured drop on the confined area containing 

reagent and drawing the solution through the 

paper by suction below. The estimate may be 

made by comparing the color of the confined 

spot with standards, or, as recommended by 

Yagoda, by diluting the solution to the point 

where the color produced in the confined spot 

is barely visible and matches that of a standard.

In making quantitative spot tests with 

large volumes of solution, Clark and Hermance 

(1938) confined the reaction by pressure 

around apertures above and below the paper. 

The reagent paper was in the form of a disc 

placed between apertures and held In a special 

clamping assembly. They recognized the Importance of speed of flow of solution through 

the confined spot and were able to control 

this with the large volumes used (650 to 1000 

ml) simply by adjusting a stopcock. The present study shows that control of speed of flow 

is necessary for reproducible results also In 

small volumes of test solution.

The chromograph (patent applied for) was 

designed to control the speed of flow and to 

confine new areas for successive tests quickly 

and easily. The device confines areas of definite size on a strip of reagent paper fed 

through the apparatus, and automatically controls the rate of flow of test solution 

through the confined spot. As each spot test 

is completed, the sample number, location, 

or other distinguishing data are written on 

the paper, and the paper is pulled through 

the apparatus to bring into position for the 

next test a spot on an unused portion of the 

reagent paper. . The strips of paper containing the spots serve as semipermanent records 

of tests performed. The rate of flow of test 

solution through the confined spot is automatically controlled by the pull of a column 

of water and/or the filtrate from previous 

tests, together with a capillary tip to retard 

the rate of flow. The capillary tip makes the 

rate of flow essentially independent of the 

porosity of the filter paper and of the quantity of precipitate on the confined spot.

ACKNOWLEDGMENTS

Details of design of the chromograph 

were made by Joseph F. Mullins, instrument 

maker at the Bureau of Plant Industry, U. 3. 

Department of Agriculture. His help and that 

of Frederick CJ. Settle, who constructed the 

chromographs, made this study possible.

Soil samples for the field trial were 

collected by Charles Milton and H. E. Hawkes. 

George E. Blandford, Jr., assisted in the 

analytical work during the field trial.
Laboratory determinations of copper in soils, 

used in establishing the accuracy and dependability of the field test, were made by Laura 

Reiohen, Frederick Ward, and Hy Almond.

TYPES OP CHHDMOOHAPHIC DETERMINATIONS

1. Precipitation reactions.

la. With reagent papers. The paper is 

Impregnated with a slightly soluble reagent 

which slowly dissolves, causing the ion sought 

to be precipitated. The solubility of the reagent must be such as to act as an efficient 

precipitant without being completely removed 

during the passage of the solution. The determinations of copper and nickel in soils, to 

be described, are examples.

Ib. With reagent added to the solution. 

A test for nickel may be made by adding a 

water solution of sodium dimethylglyoxime to 

the solution in the chromograph and catching 

the precipitate on a confined area of un^ 

treated'filter paper.

lo. .Group separations followed by specific tests on the spot.Numerous reagents 

serve as preoipitants for several ions,, thus 

indicating the {presence or absence of groups 

of ions. The'resulting spots can then be altered to indicate the quantity of each ion 

present. For example, rubeanlc acid precipitates cobalt, nickel, and copper from ammoniacal solution, and such a spot would serve to 

indicate the presence or absence of all three 

of these ions. Spots made in this way remove 

all three ions from solution, and the spots 

may then be tested for each of these three 

ions.

2. Alteration of materials on the paper.

The paper contains reagents whose composition and properties are changed by the passage of specific ions. Bleaching of a reagent 

paper containing zirconium allzarlnate by fluaride ion offers possibility of chromographic 

application as a test for fluorlde.

3. Ion-adsorption technique.

The reagent paper is coated with a 

material capable of adsorbing certain ions; . 

these ions are fixed on the surface of a confined spot, which then may be tested for a 

specific ion. Amberlite resin and activated 

alumina are examples of such materials. Lead 

ion may be adsorbed in a confined spot on reagent paper containing amberlite resin; the 

presence of lead in the spot is indicated by 

the appearance of a red color with potassium 

rhodizonate solution.

PROPERTIES USED TO COMPARE CONFINED SPOTS

Color is the most obvious property for 

comparing confined spots in quantitative determinations. Any measurable property of the 

deposits on the confined spots may be us-ed as 

means of comparison. As examples, fluorescence., radioactivity, or weight may be the 

means of measurement or comparison. In addition the confined spot may be used as a means 

of collecting the ion to be measured, after 

which the material may be removed from the 

spot prior to determining the ion by whatever 

.means available.

DETAILED DESCRIPTION OF A CHRONOGRAPH

An assembled chromograph is shown in 

figure 1 and details of the filter base and 

filter head are shown in figure 2. The filter base and filter head are Lucite plastic. 

Filter base and stopcock may be made in one 

piece if desired.

Dimensions.

In order to make comparable results with 

different ohromographs, certain dimensions 

were tentatively adopted. The bottom opening 

of the funnel insert and the hole in the beveled washer were made a quarter of an inch in 

diameter, thus producing a confined spot of 

that size. The drain tube through the filterbase body also was made a quarter of an inch 

in diameter, and, for purposes of timing and 

adjusting, marks a quarter of an inch apart 

were placed on the outside of the filter-base 

body, as shown in figure 1, the upper mark 

being a half inch below the top of the beveled 

washer when placed in the washer seat. The 

drain tubes leading to the capillary tip are 

sufficiently large to allow the free flow of 

liquid. The outlet of the capillary tip was 

placed 9 inches below the upper timing mark.

Assembling the apparatus.

Screw the filter-base adaptor into the

* filter-base body to make a liquid-tight connection (see figure 2). Insert the beveled 

washer in the washer seat of the filter-base 

body, beveled edge up. Assemble the funnel 

head by inserting the funnel insert (screw 

section up) into the pressure flange (screw 

section down), and screw the funnel insert 

screw cap tightly onto the top of the funnel 

insert. The parts of the funnel head are 

constructed with sufficient clearance so that 

the funnel insert turns freely in the pressure 

flange when the filter head is assembled. 

Next screw the filter head into the top of the 

filter-base body.

Connect the 3-way stopcock to the filterbase adaptor and the standard capillary tip 

to the outlet tube with rubber tubing. 

Connect the adjuster bulb to the adjuster-bulb 

tube, as shown in figure 1.

Selection or adjustment of papillary.

The time of drainage tentatively adopted 

was 200 i 10 seconds for the top of a column 

of solutTon to fall from the upper timing 

mark to the lower with a 9-inch head of solution, and without paper in the reagent paper 

slot. In order to attain this it was necessary to select .or adjust the capillary. A 

2-inoh capillary of 0.15 mm internal diameter 

was found to meet these requirements for 

drainage time. Capillaries of larger bore 

could be used by drawing the tube out in the 

flame, and pinching off the tapered end bit 

by bit until the proper drainage time was 

attained. Capillaries that were of slightly 

smaller bore could be adjusted to the proper 

drainage time by shortening in a like manner.

Filling the apparatus.

Before use, the outlet tube, capillary,

- adjustor-bulb tube, and adjuster bulb are 

filled with water.
Filter head

Filter base

Capillary protector 

plug

Capillary

Clean-out 

plug

Connector tube

I 3 way stopcock

Adjuster bulb tube

Adjuster 

bulb

Figure 1. The ohromograph aaaeoibled
Funnel Insert 

Screw Cap

Pressure Flange

Filter Base Body

Funnel Insert

Angle Edge

Reagent Paper 

'Slot

Washer Seat

Adaptor

Figure 2. Parts of filter base and filter head of chromograph
EFFECT OF SPEED OF FLOW

The intensity of color on the confined 

spot has been shown by Clarke and Hermanoe 

(1938) to be affected by the speed of flow of 

the test solution through the reagent paper. 

A simple automatic device for keeping the 

speed of flow of the solution fairly constant 

was therefore embodied in the chromograph.

The effect of speed of flow in chromographlc tests for nickel with dimethylglyoxime 

reagent paper is shown in table 1. In these 

tests, the capillary tip was removed from the 

chromograph and the speed of flow was varied 

by increasing or decreasing the column of 

water in the tube below the reagent paper. 

The results in table 1 were obtained by comparing the test spots with standard spots prepared 

as described later, under the procedure for 

nickel. A decrease of yield of nickel can be 

seen with increasing speed of flow, corresponding to increase in the length of water column 

used. 'Results in table 1 are all low because 

the rate of flow was excessively fast and also 

because of the absence of modifier ions, discussed in the following section; the decrease 

in yield with increased rate of flow is clearly indicated.

The effect of the stiction provided by 

2-inch and 8-inch columns of water, without 

capillary, for the copper test is shown in 

table 2. The spots are compared with standard 

spots prepared or described later under the 

procedure for copper. The time required for 

the solutions to pass through the paper is 

given in the second column.

With a 2-inch water column fairly satisfactory spots were obtained for very low 

concentrations. "However, at a concentration 

of 3.16 micrograms of copper per milliliter, 

the paper became clogged with precipitate 

and more than twelve minutes was required for 

passage of 0.2 ml of the solution through the 

test paper.

The 8-inch water column was much too 

fast for solutions of low concentrations, 

and adequately fast for solutions of high 

concentration.

An Inspection of these data leads to the 

following conclusions: (1) The rate of flow 

must be slow enough to permit essentially 

complete precipitation of the test Ion; (2) 

the effective suction must be great enough to 

pull all of the test solution through the 

paper in a reasonable period of time; (3) the 

reaction of the test ion with the reagent in 

the paper forms a precipitate which decreases 

the effective porosity of the paper. From 

these considerations it becomes evident that 

the rate of flow must be reasonably independent of changes in the porosity of the teat 

paper. This, we believe, is attained by use 

of a 9-inch column of water below the test 

paper to give an adequate suction capacity; 

the rate of application of the suction is 

controlled by a capillary of sufficiently 

small bore to allow 0.2 ml of solution to 

flow through the capillary in 200 seconds. 

With this system, solutions very low (0.26 

miorogram per millillter) in copper require 

250 seconds for passage through the test 

paper, whereas solutions of the maximum concentration used (42.0 micrograma per milliliter) require only 360 seconds for passage.

Table 1. Effect of speed of flow of solution on ohromographic tests for nickel 

£0.2 ml of solution was used in test. Capillary tip was omitted. 

Modifier ions were present in standard spots but not in test spots.)

10 gammas of Nl per ml taken

Head of

Water 

(inches)

2

2

2

2

3

3

3

3

6

6

6

6

12

12

12

12

Time to Flow

through Paper 

(seconds)

90

80

110

92

50

47

26

19

26

28

8

8

8

8

NI Found'

( gammas/ml )

2.4

2.0

2.4

2.0

1.7-

1.0

1.5

1.2

.8

.7

.8

1.0

.2

.2

.2

.2

Percent

of Error

-76

-80

-76

-80

-83

-90

-85

-88

-92

-93

-92

-90

-98

^98

-98

-98

75 gammas of Ni per ml taken

Head of

Water 

( inches )

2

2

2

2

3

3

3

3

6

6

6

6

12

12

12

12

Time to Flow

through Paper 

(seconds)

202

203

174

158

129

170

148

188

43

34

38

37

15

12

15

Ni Found

( gammas/ml )

35

35

30

30

30

30

30

30

20

20

20

20

15

15

15

15

Percent

of Error

-53

-53

-60

-60

-60

-60

-60

-60

-73

-73

-73

-73

-80

-80

-80

-80
Table 2. Effect of speed of flow of solution on ehromographie tests for copper 

(0.2 ml of solution was used in test. Capillary tip was' omitted. 

Modifier ions were present in standard spots but not in test spots.)

Head of Water 

(inches)

2

2

2

2

2

2

2

8

8

8

8

8

8

8

8 

8

8

8

8

8

8

8

8

Time to Flow 

through Paper 

( seconds)

186

210

150

181

151

231

744

75

54

54

45

47

42

54

51

51

105

248

248

270

270

276

264

Gu Content of 

Solution 

(gammas /ml)

0.56

.75

1.00

1.33

1.78

2.37

3.16

.56

.75

1.00

1.33

1.75

2.37

3.16

4.22

5.62

7.50

10.00

13.30

17.80

23.70

31.60

42.20

Cu Found 

( gammas /ml )

0.4

1.2

1.2

1.4

1.6

3.0

6.0

.4

.4

.4

.8

1.2

1.3

2.4

3.2

3.6

6.0

12.0

18.0

24.0

24.0

44.0

44.0

Percent of 

Error

-29

+60

+20

+ 5

-10

+27

+90

-29

-47

-60

-40

-31

-45

-24

-24

-36

-20

+20

+35

+35

+ 1

+39

+ 4

MODIFIER IONS

Preliminary results with the chromograph 

were disappointing because the effect of other 

ions on the intensity of colors was not fully 

considered. Other ions which are not themselves precipitated by the reagent have marked 

effects on the colloidal dispersion and, therefore, the filterability of the precipitates 

formed. Ions that increase or decrease the 

color obtained on the spot are those with high 

valences such as ferric iron, aluminum, and 

titanium. Even the small quantity of silicon 

derived from the test tube in which the bisulfate fusion was made was sufficient to increase 

the precipitation of nickel dimethyIglyoxime.

Results obtained by comparing the test 

spots for nickel with a standard spots made 

in the absence of modifier ions and with those 

made in the presence of modifier ions obtained

from soil are shown in table 3. The tests 

were made on standard mixtures of nickelbearing laterite and garnierite diluted with 

quartz, orthoclase, and oaloite. The results 

in table 3 show that test on solutions containing these ions should be compared only 

to standards prepared from solutions of similar composition, not solutions containing 

nickel alone.

The effect of modifier ions on the test 

for copper with nibeanic acid reagent paper 

is shown in table 4. These ions had an inhibiting action on the precipitation of copper rubeanate, and when they were present a 

less intense color was obtained. For this 

reason, when the standard comparison spots 

were made in the absence of these modifier 

ions, results of tests on soil samples were 

low, frequently by more than 50 percent of 

the copper present, as shown in table 4.

Table 3. Results of comparing nickel dimethylglyoxime test spots with 

standard spots made with and without modifier ions present

Nickel Present 

(parts per million)

77

85

92

160

170

170

180

390

4OO

480

500

680

680

880.

920

2500

2700

3300

3400

Nickel Found (parts per million)

Compared with Standard Spots 

Made with Modifier Ions Present

75

70

70

150

220

200

220

400

450

600

450

900

700

1000

900

1700

2000

.2500

2500

Compared with Standard Spots 

Made from Pure Nickel Solution

160

200

200

400

400

400

500

800

1200

1200

1100

1600

1600

2200

2200

2800

3000

3000

3800
Table 4. Results of comparing copper rubeanate test spots with standard 

spots made with and without modifier ions present

Copper Present

(parts per million)

60

120

120

120

200

200

200

380

410

650

1000

Copper Pound (parts per million)

Compared with Standard Spots

Made with Modifier Ions Present

80

100

80

150

180

250

150

400

350

550

1000

Compared with

Made from Pure

30

80

30

60

60

90

80

360

280

200

600

Standard Spots

Copper Solution

EXAMPLES OP THB USE OP THB APPARATUS FOR 

DETERMINATION; OP COPPER AND NICKEL IN SOILS

Preparation of reagent papers. Large 

quantities of the reagent papers may be prepared and stored for future use.

1. Dimethylglyoxime reagent paper. With 

an atomizer spray a one-percent solution of 

dimethylglyoxime in alcohol onto Whatman No. 

50 filter paper, applying just enough of the 

solution to fill the pores of the paper. Avoid 

localized excesses of the solution, as uneven 

distribution of the reagent results when the 

solution spreads by capillarity through the 

paper. Make three applications of the solution, allowing the paper to dry after each 

application. Dry the paper and cut into strips 

7/16 inch in width.

2. Rubeanic acid reagent paper. Prepare 

in the same way as the dimethylglyoxime paper, 

using a one-percent solution of rubeanic acid 

in alcohol.

Preparation of standard spots. The colors obtained on the confined spots are affected 

by the presence of modifier ions in' the solution, such as iron and aluminum, as previously 

explained. It is therefore necessary to prepare the standard spots used for comparison, 

not from solutions that contain copper or nickel alone, but from solutions that contain the 

ions that will be present in the unknown solutions to be analyzed.

Soil solution: Fuse in Pyrex beaker 7 g. 

of soil, selected for exceedingly low copper 

and nickel content, with 35 g. of potassium 

blsulfate. Cool, add 27 g. of sodium citrate 

and 100.ml. of distilled water, and digest on 

the steam bath until the cake is disintegrated. 

Cool, dilute to 200 ml., and filter through 

Whatman No. 50 filter paper.

Standard nickel and coppetf'test solutions: 

Prepare a series of standard 'nickel and copper 

test solutions by adding appropriate volumes 

of standard solutions of these metals from a 

mlcroburette to 3 ml. of the soil solution. 

Add NH40H until a piece of red litmus paper in 

the solution turns blue. Dilute to 5 ml. The 

series of nickel test solutions should vary 

from 40 gamma Ni/ml. (corresponding to 2000 

p.p.m. Ni in 0.1 g. of soil sample) to 0.30 

gamma Nl/ml. (corresponding to 15 p.p.m. Nl 

in 0.1 g. of soil sample) and the series of 

copper test solutions should vary from 30 gamma 

Cu/ml. to 0.20 gamma Cu/ml. Dilute the copper 

test solutions by adding 1 ml. of 1-to-l acetic 

acid so that they contain from 26.7 gamma Cu/ml

(corresponding to 1500 p.p.m. Cu in 0.1 g. of 

soil sample) to 0.167 gamma Cu/ml. (corresponding to 10 p.p.m. Cu in 0.1 g. of soil 

sample). The nickel and copper contents of 

the standards in the series should be made so 

that successive standards differ by about 30 

percent.

Make confined spot tests with 0.2 mL of 

each of the standard test solutions, using 

dimethylglyoxime reagent paper for the nickel 

test solutions, and rubeanic acid reagent 

paper for the copper test solutions. Mount 

the series of spots on the edge of a cardboard chart and cover with cellophane tape. 

Label each spot with the figure of parts per 

million of Nl or Cu to which It corresponds.

Preparation of sample solution. Fuse 

0.1 g. of soil with 0.5 g. of KHS04 in a 

test tube until a dull-red quiescent melt is 

obtained. As the tube cools, revolve it to 

allow the molten material to crystallize In 

a thin layer on the walls of the tube. To 

the cooled tube add 3 ml. of 13.3 percent 

sodium citrate solution and boll until the 

lumps of KH304 disintegrate. Cool, add concentrated NH40H until a piece of red litmus 

paper turns blue, and dilute to 5 ml. with 

water. Divide the solution in half ( one half 

for determining nickel and the other half for 

determining copper). Filter one portion for 

nickel.

Determination of nickel. Place a strip 

of dimethylglyoxime reagent paper in the reagent-paper slot of a chromograph. With the 

stopcock turned to connect the adjuster bulb 

with the connector tube, press the rubber 

adjuster bulb to force the water up the tube 

to the upper timing mark, then close the stopcock. Turn the pressure flange to press the 

reagent paper tightly between the funnel insert and the beveled washer. Place 0.2 ml. 

of the filtered solution for the nickel test 

in the bottom of the funnel insert. Turn the 

stopcock to Join the connector tube with the 

outlet tube. When all of the solution has 

drained through the reagent paper, turn the 

stopcock to join the adjuster bulb to the 

connector tube. Raise the filter head by 

turning the pressure flange and allow the 

liquid column together with the test solution 

(from which the nickel has been removed) to 

be drawn down into the adjuster bulb. Raise 

the filter head sufficiently high so that the 

bottom of the funnel head is well clear of 

the reagent paper. Draw the reagent-paper 

strip through the reagent-paper slot until 

the spot is clear of the filter head, and 

write the sample numb.er on the reagent paper 

below the spot. Readjust the liquid column
to the level of the upper timing mark and 

proceed as before with the next solution to 

be tested for nickel. When the spots containing the red nickel dimethylglyoxime are dry, 

compare them with the chart containing spots 

made with known quantities of nickel.

Determination of copper. To the 2.5 ml. 

of solution set aside for copper, add 0.5 ml. 

of 1-to-l acetic acid. Filter. Make a confined-spot test with ,0.2 ml. of this solution 

in another chromograph containing rubeanic 

acid reagent paper in the manner described 

for the nickel determination, and compare the 

spots when dry with the chart of standard copper rubeanate spots.

Storage of test spots. When dry, place 

the strip of reagent paper containing the test 

spots on a slightly longer piece of cellophane 

tape, with -spots face down against the adhesive, 

and mount the strip on a page of the notebook. 

Spots stored in this way have undergone no 

apparent changes in six months, other than a 

slight browning of the paper.

EXPERIMENTAL RESULTS

Results obtained, in the chromographic 

determination of niqkel and copper are given 

in table 5. For nickel three samples were 

studied which had been analyzed by D. Smith 

and R. Nordgren, reported by Sandell and 

Goldich (1943) together with a large number 

of standard mineral mixtures of known nickel 

content containing garnierite and laterite. 

Ghromographic tests were made for copper on 

soils previously analyzed for copper by the 

dithizone method of Holmes (1945).

Most of theae results are accurate to 

within 30 percent of the element determined 

(26 out of 38 for nickel, and 27 out of 38 

for copper fall within this limit), showing 

that the device is capable of yielding useful 

information in the field. This fact is further 

illustrated by results in the next section.

The confined spot obtained with a chromograph measures only the amount of the element 

dissolved in the attack of the sample. The 

method as outlined did not give good results 

for nickel on lavas from Hawaii, apparently 

because of failure of the blsulfate fusion to 

dissolve all of the nickel.

Table 5. Analyses for nickel and copper by the chromographic method

Type 

of 

Material

Basalt

Basalt .

Laterite + calcite

Garnierite + orthoclase + quartz

Garnierite + quartz + calcite

Laterite + orthoclase

Laterite + orthoclase

Basalt

Basalt

Baaalt

Garnierite + orthoolase + quartz

Laterite + orthoclase

Garnierite + quartz + calcite

Laterite + calcite

Basalt

Basalt

Basalt

Garnierite + orthoclase + quartz

Garnierite + quartz + calcite

Laterite + orthoclase

Laterite + orthoclase

Laterite + calcite

Garnierite + quartz + calcite

Garnierite + orthoclase + quartz

Laterite + orthoclase

Laterite + calcite

Garnierite + orthoclase + quartz

Laterite -f orthoclase

Laterite + calcite

Laterite + orthoclase

Laterite + calcite

Laterite + calcite

Laterite + orthoclase

Garnierite + orthoclase + quartz

Garnierite + quartz + calcite

Garnierite + orthoclase + quartz

Garnierite + orthoclase + quartz

Garnierite + calcite + quartz

Nickel 

(parts per 

million)

Taken

70a/

70a/

77

85

92

110

110

120a/

120a/

120a/

180

170

170

180

290a/

290a/

290a/

390

400

480

480

500

680

680

880

920

970

2500-

2700

2900

2900

2900

2900

3300

3400

3600

3600

3600

Found

30

30

75

70

70

150

220

100

100

90

150

200

220

220

220

240

240

400

450

900

600

450

700

900

1000

900

1500

1700

2000

3000

4000

4000

3500

2500

2500

3000

2200

4000

Percent 

of 

Error

- 57(

- 57

- 3

- 18

- 24

+ 36

+100

- 17

- 17

- 25

- 6

+ 18

+ 29

+ 22

- 24

- 17

- 17

 f 3

+ 13

+ 88

 f 46

- 10

+ 3

+ 32

+ 14

- 2

+ 55

- 32

- 26

+ 3

+ 38

+ 38

+ 21

- 24

- 26

- 17

- 39

+ 11

Type 

of 

Material

Soil

Copper 

(parts per 

million)

Takenk/

11

14

18

20

20

35

45

80

80

80

78

120

120

120

120

120

120

120

160

200

200

200

310

310

380

380

410

410

410

410

590

600

650

650

800

880

1000

1000

Found

10

50

20

10

10

80

45

60

80

80

140

120

90

130

130

80

150

90

130

150

250

250

300

200

600

400

300

350

300

320

650

850

550

500

600

1000

1000

1200

Percent 

of 

Error

- 9

+260

 f 11

- 50

- 50

+ 71

0

0

+ 33

 f 33

 f 80

0

- 25

 f 8

 f 8

- 53

+ 25

- 25

- 28

- 25

+ 25

+ 25

- 3

- 36

+ 58

+ 5

- 27

- 15

- 27

- 22

+ 10

+ 42

- 15

- 23

- 25

+ 25

0

+ 20

a/ Colorimetric results by D. Smith and R. Nordgren, reported by Sandell and Goldich (1943). 

b/ Laboratory results of Laura Reichen, Hy Almond, and Frederick Ward by dithizone method of 

Holmes (1945). _
FIELD TRIALS OP THE GHROMOGRAPH

To discover unforeseen difficulties in 

the field use of the chromograph and to illustrate its use in locating hidden geological 

features, one day was spent in a field trial 

of the apparatus. No operational difficulties 

were encountered.

Samples of residual soil over a serpentine 

body high in nickel and' a small copper deposit 

in Fairfax County, Va., were collected and 

tested for both copper and nickel. Wherever 

possible the subsoil was sampled at a. depth 

df 1 to 2 feet by means of a light soil auger. 

Samples were brought to the field station for 

testing, and the resulting spots mounted in a 

notebook for later study.

Figure 3 shows the data on the copper 

content of soil as related to copper-stained 

Triassic sandstone cropping out about 20 feet 

north of the zero point on the traverse line. 

The copper apparently follows a fault striking 

approximately north. Background values were

about 10 parts per million, whereas near the 

copper-bearing outcrop, values were as high as 

1000 parts per million.

Figure 4 shows results of tests for 

nickel on soil collected along a line normal 

to a serpentine dike. Inasmuch as the dike 

rock was strongly magnetic, its exact location could be established by magnetic dipneedle observations. The correspondence in 

location of the serpentine between soil tests 

and magnetic observations is seen to be good 

except for station 800E, presumably where 

limits of the nickel-rich soil have been 

displaced slightly to the west as a result 

of soil creep. Nickel in the soil east of 

the serpentine dike averaged 160 parts per 

million (six trials showed a low of 150 parts 

per million and a high of 170 parts per million); nickel in the soil west of the dike 

averaged 62 parts per million (three results 

were 35, 50, and 100 parts per million). Soil 

over or immediately adjacent to the serpentine 

dike contained from 500 to 5000 parts per 

million of nickel.

BXfEBBBQBS

Olarke, Beverly L., and Hermanoe, H. V., 1937, Paper 

as a Bedim for analytical reactions. X. iBprorenents in the spot tost technics Ind. and lag* 

Chemistry, A&al. >* . *ol. 9, pp. 893-4.

1988, Paper an a aedlua for analytical reactions* 

A Bethod of applying reagent papers to largo TO!UMS 

of solution! Ind. and tog. Oheaistry, Anal. Id., 

TOl. 10, pp. 691-600.

feigl, friti, 1943, QualitatlYO analysis oy spot tostsi

How York, llserier Publishing Co., Zno.

Bahn, P. L., 1931, Die heutigen Orensen Bikroeheniiehen 

Irkonnoi und MS sons t Hikreehoaio, rol. 10, pp. 

318-31.

Eolnes, 1. 8., 194S, Determination of total oopper, 

 ino, cobalt, and lead in tails and toil solutions! 

Soil Soiaaoa, rol. 69, pp. 77-84.

Sandell, 1. B., and Qoldieh, 8. 8., 1943, Th« rarer 

Mtalllo constituents of SOM Amor loan rooks t Jour. 

Oeelogy, rol. 61, p. 100.

Yagoda, Bsrnan, 1937, Application of confined spot 

tests in analytical chemistry i lad. and Ing. 

Chemistry, Anal. Id., rcl. 9, pp. 79-63.

10
1200

1000

600

600

400

200

60 40 Weit

40 60 

East

DISTANCE IN FEET FROM OUTCROP OF COPPER DEPOSIT

Figure 3. Copper teati on soils near a small copper deposit 

0.8 Bile east of Ohantllly, Fairfax County, Va., on U. S. Highway 50

SSOOr

TRAVERSE EAST-WEST MAGNETIC)

Figure 4. Correlation of magnetic dip-needle observations 

and nickel tests on soil on traverse across serpentine (Jenkins farm, 

1.5 miles southeast of Dranesville, Va., on U. 3. Highway 7. Dip-needle 

readings were made by Charles Milton.

11