Bulletin No. 334 Series Q, Fuels,

DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY

GEORGE OTIS SMITH, DIRECTOR

THE BURNING OF COAL WITHOUT SMOKE 

IN BOILER PLANTS

A PEELIMINABT KEPOKT

BY

D. T. RANDALL

WASHINGTON

GOVERNMENT PRINTING OFFICE 

1908

CONTENTS.

Page.

Tntroduction ______________________________________ 5

Genera! conditions in the United States__________________ 5

City ordinances for sruoke prevention_______________ 7

The production of smoke___________________r________ 11

The prevention of smoke in boiler plants_________________ 12

Feasibility ________________________________ 12

The principles of smokeless combustion________________ 12

Proper furnace equipment________________________ 14

Difficulty in securing perfect combustion________________ 16

Indirect methods of smoke abatement__________________ 20

Summary ____________________ _ __________________ 21

Bibliography ___________________________________ 22

THE BURNING OF COAL WITHOUT SMOKE 

IF BOILER PLANTS.

By D. T. RANDALL.

INTRODUCTION.

The technologic branch of the United States Geological Survey has 

been conducting investigations to determine the best method of utilizing the coals of the United States. The law under which this work 

has been carried on aims to increase the efficiency and to prevent the 

waste of these fuels, especially such as are used by the United States 

Government. It is a recognized fact that the more nearly perfect the 

combustion of any fuel the greater is its efficiency. With perfect 

combustion there is no smoke. In-view of the need for more complete 

information on the conditions favorable to the burning of coal with 

economy and without objectionable smoke in boiler furnaces, extended 

tests have been made at the fuel-testing plants at St. Louis, Mo., and 

Norfolk, Va. The results of the St. Louis tests are summarized in 

the present paper,1 which has been prepared by the author as engineer 

in charge of smoke-abatement investigations. In addition to this 

Avork a number of commercial plants in the larger cities have been 

inspected to ascertain what are the best methods now in use, and the 

information thus obtained will be published in a later bulletin. ,

GENERAL CONDITIONS IN THE UNITED STATES.

The prevention of objectionable smoke in the manufacturing and 

business centers of large oities is a problem that can not be easily 

solved. At present no city in which a considerable quantity of 

bituminous coal is burned is free from smoke. The cities of the East 

have avoided this problem by a general use of the. smaller sizes of 

anthracite coal. For this reason it is not surprising that the greatest 

improvement in the methods of burning bituminous coal has been 

made in the Central and Western States.
6 THE BUENING OF COAL WITHOUT SMOKE.

Stoves, ranges, house-heating boilers, and hot-air furnaces are as 

a rule intended for the use of anthracite coal or coke. Whenever 

bituminous coal is burned in such furnaces all the principles of combustion are violated and smoke results. The supply of anthracite 

coal is limited, and except for domestic purposes such coal is little 

used outside of the territory adjacent to the mines. The larger cities 

of the Eastern States, which consume practically all the available 

supply of the smaller sizes of anthracite coal for power and heating 

purposes, now find it necessary to supplement this fuel with a considerable tonnage of bituminous coal. Except the power generated 

by waterfalls, nearly all the heat and power used in the United States 

are obtained from the burning of coal. It is evident, then, that for 

the most part this country must depend on its bituminous coal for 

manufacturing, railroad, and power-plant purposes. This means 

that we must improve our usual methods of burning bituminous coal 

or continue to suffer from the loss in economy and smoke resulting 

from imperfect combustion.

There are now three general methods of utilizing coal in steam 

boiler and other furnaces, in gas-producer plants, and in by-product 

coke plants. Of these, the last two methods are readily operated to 

produce heat or power without smoke, but at the present time such 

plants are not numerous and consume only a small portion of the 

coal that is used in this country. It is predicted by persons who are 

enthusiastic regarding the -economy and smokelessness of these 

methods that they will in time be used exclusively for the production 

of heat and power in all our large cities.

It has been demonstrated at the fuel-testing plants of the Geological 

Survey that bituminous coal of all grades can be burned in.a gas 

producer without smoke, generating a gas Avhich when used in a gas 

engine furnishes power with much greater economy than is usual

in steam plants. With good grades of coal mined in the Eastern 

States a horsepower can be generated with about 1 pound of coal. 

One of the most important facts in connection with the gas-producer 

plant is that, besides being smokeless, it will utilize coals so high 

in ash as to be unsuitable for boiler furnaces. The lignite coals of 

the West are also particularly well adapted for use in the producer, 

though they are considered much inferior to bituminous coal for 

boiler furnaces. About fifty producer plants are now in operation 

in the United States, burning bituminous coal. Interest in such 

plants is increasing, and many new ones are being planned, ranging 

in capacity from 500 to 10,000 horsepower each.

That the coal supply is being wasted in many ways is a fact that 

has been frequently brought to the attention of the public. One waste 

results from the ordinary methods of manufacturing coke, in which 

all of the gas from the coal is allowed to escape into the air. This
CITY ORDINANCES FOR SMOKE PREVENTION. 7

loss has led to the installation of a few by-product coke plants in 

which coke is made and the resulting gas is piped to points where 

fuel is needed and there consumed. Other valuable products from 

the distillation of coal are also obtained. These plants, furnishing 

both coke and gas as fuel, constitute a considerable factor in the prevention of smoke in the cities near which they are located, as both 

fuels are burned readily without smoke for domestic purposes and 

for manufacturing industries requiring heat or power. The convenience and cleanliness of these fuels will probably lead to an increase 

of their production and use.

It is reported that there are 30 by-product coke plants in this country, with a total of more than 3,000 ovens, using nearly 20,000 tons 

of coal a day. It is estimated that these plants manufacture daily 

more than 50,000,000 cubic feet of gas, The following are some of 

the cities near which they are loctated: Chicago and Joliet, 111.; Milwaukee, Wis.; Duluth, Minn.; Detroit and Wyandotte, Mich.; Ensley and Tuscaloosa, Ala.; Chester, Dunbar, Everett, Lebanon, Sharon, and Steelton, Pa.; Wheeling, W. Va.; Buffalo, Geneva, and 

Syracuse, N. Y.; Cleveland and Hamilton, Ohio.

In many manufacturing plants furnaces that were formerly fired 

with coal are now using crude oil, natural or manufactured gas, coke, 

or coal burned on automatic stokers. All these methods are giving 

good results in preventing smoke.

CITY ORDINANCES FOR SMOKE PREVENTION.

With the knowledge that it can be prevented, there has come an 

increasing demand from the people of the large cities that smoke 

shall not be allowed to pollute the atmosphere. This is true not only 

of the United States, but also of most European countries. For example, the importance" of burning bituminous coal economically and 

without smoke led the Prussian government some time ago to furnish 

traveling instructors at an expense of about $10,000 a year for the 

training of firemen throughout the State, licenses being given to competent firemen. There are also in Prussia a number of boiler-supervision societies, which employ skilled firemen to direct the work done 

by the regular employees of the plants owned by members of the 

society.

In nearly all cities of the United States efforts are being made to 

abate the smoke given off by manufacturing, steam-boiler, and 

domestic furnaces in which bituminous coal is burned. As a result of 

the demands of the public the ordinances of some of these cities 

require that all new plants be equipped properly and that old ones 

be remodeled, and permits are now necessary for the installation of 

all boilers and furnaces. Most ordinances define the degree of black23540 Bull. 334 08 2
8 THE BURNING OF COAL WITHOUT SMOKE.

ness of smoke which constitutes a violation of the law. In general, it 

may be said that in this country the only excuse recognized for black 

or dense gray smoke is that the fires are being built or cleaned, but 

no such excuse is valid in many of our cities. The conditions in a 

number of the larger cities of the United States are about as 

follows:

The Baltimore ordinance contains a clause which practically excepts the manufacturing plants of the city. Cases brought into court 

were dismissed on account of defects in the ordinance, and an attempt 

is being made by the smoke-abatement league to secure the enactment 

of one that will be more effective. There are on record about 660 

steam plants in Baltimore, not including heating plants. Of this 

number only 12 are equipped with automatic stokers.

The Buffalo ordinance is not effective, as it simply declares the 

emission of large quantities of smoke to be unlawful. In addition to 

the work of the smoke inspector, active efforts to improve the conditions have been made by the Society for Beautifying Buffalo.

The Chicago ordinance makes it unlawful to permit dense smoke to 

escape from any furnace except for six minutes of each hour during 

the time when fires are being started or cleaned. Members of the City 

Club of Chicago have taken an active interest in the suppression of 

smoke. There has recently been a reorganization in the smoke inspector's office and a committee of engineers has been appointed to 

assist and advise with that official. The following is a partial list of 

the equipment installed in Chicago: Plants with chain-grate stokers, 

TO; with overfeed stokers, 40; with underfeed stokers, 12; with special 

hand-fired furnaces, 40. In addition to these there are many small 

plants equipped with steam jets and other appliances.

The Cincinnati ordinance establishes a standard for density of 

smoke permitted and allows a period not exceeding six minutes in any

hour during which the fires are started. During the past year citizens 

of Cincinnati have formed a smoke-abatement league and by public 

subscription raised a fund to pay the salary of a smoke inspector working under the league's direction. The city smoke inspector's office has 

been .reorganized and a number of suits regarding fines for allowing 

stacks to smoke are pending in the courts. Action on other plants 

has been withheld until these cases are settled. The furnace equipment in Cincinnati is as follows: Down-draft furnaces, 90; other furnaces, 5; inclined-grate stokers (a} side feed, 113; (b) front feed, 56; 

(c) underfeed, 89; automatic steam jets, hand fired, 48; steam jets, 

not automatic, hand fired, 24T.

The Cleveland ordinance excepts private residences, but dense gray 

or dense black smoke from other furnaces is declared to be in violation of the law. According to the records of the smoke inspector's 

office there are about 1,800 boilers in the city, equipped as follows:
CITY ORDINANCES FOB SMOKE PREVENTION. 

Furnace equipment in Cleveland.

Boilers.

200

400

170

50

400

125

500

Plants.

40

164

34

131

110

50

The Detroit ordinance makes it unlawful to allow dense gray or 

black smoke to escape from any chimney. The smoke inspector is 

assisted by a committee of the chamber of commerce, and good 

results are being obtained. It is reported that in 1906 the following 

new equipment was, installed: Mechanical stokers, 108; automatic 

smoke-prevention devices, 12; steam jets, 16.

The Indianapolis ordinance makes the production of dense gray 

or black smoke subject to a penalty, private residences being exempt. 

The efforts toward smoke abatement in this city are confined to the 

office of the smoke inspector. According to that official's report for 

the year ending December 31, 1906, the following equipment was

in use:

Furnace equipment in Indianapolis.

Boilers.

43

100

48

5

15

65

.828

Plants.

10

18

10

At present there is no effective ordinance in Louisville and no 

smoke inspector. A movement has been started by a number of citizens to form a smoke-abatement league for the purpose of securing 

the passage of an ordinance and the organization of a smoke-inspection department. Last year there were in- this city, in addition to 

the hand-fired plants, 13 plants with down-draft furnaces, 11 with 

chain-grate stokers, 18 with inclined-grate stokers, and 4 with underfeed stokers.

Milwaukee has an effective ordinance and the smoke-inspection department is doing a considerable amount of educational work among 

the manufacturers. The inspector reports that, during' 1905 the following installations were made: Underfeed stokers, 32; chain-grate 

stokers, 2; inclined-grate stokers, 15; down-draft furnaces, 6; automatic steam jets, 44; total, 99.

The ordinance of New York City makes no exception and provides 

a penalty for the emission of dense black smoke from any furnace. 

The smoke-abatement committee has been active in bringing of-
10 THE BURNING OF COAL WITHOUT SMOKE.

fenders against the law into court, and a number of power plants 

are installing additional equipment to comply with the smoke ordinance. In this city 12,200 stationary boilers are on record, but there 

is no record of the furnaces and equipment. It is reported, however, 

that there are 26 plants equipped with stokers of the overfeed type 

and 2 with stokers of the underfeed type. Many of these stoker 

plants are exceptionally large.

The Philadelphia ordinance declares the emission of smoke of 

greater density that the established standard unlawful, except from 

locomotives or steam craft standing with banked fires, or during a 

period of ten consecutive minutes when fires majr be in process of 

being cleaned or started. Exception is also made of river craft in 

continuous transit through the city. The smoke-inspection department is assisted by the efforts of the citizens' committee, which has 

been active in creating a public sentiment in favor of smoke abatement. The number of boilers in the entire city, as reported by the 

chief inspector, is 8,194, of which 2,132 are using soft coal. The 

number of stokers and appliances for abating smoke is 220.

The Pittsburg ordinance declares that the production of dense 

black or dense gray smoke, except from private residences, is unlawful, but while a new fire is being started or the fires are being 

cleaned such smoke is allowed for a period of eight minutes in any 

hour.

The St. Louis ordinance provides a penalty for allowing dense 

smoke to escape into the air. According to this ordinance it is a 

good defense if the person charged with the violation shall show to 

the satisfaction of the jury or of the court that there is no practicable device, appliance, means, or method by which the emission of 

dense smoke could have been prevented. St. Louis has, in addition 

to its smoke-inspection department, a smoke-abatement committee 

maintained by the Civic League. According to the report of the 

smoke inspector for 1906, there were in the city plants with the 

following furnace equipment: Steam jets. 550 plants; down-draft 

furnaces, 264 plants; fire-brick arches, etc., 50 plants; automatic 

stokers, 19 plants.

An ordinance has recently been passed in Toledo, and the smoke 

inspector is making an effort to cooperate with the .owners of plants 

in the suppression of smoke. The ordinance makes an exception of 

private residences, dense gray or black smoke from all other furnaoes being a violation of the law.

The law governing the abatement of smoke in Washington and the 

District of Columbia makes an exception of private "residences, but 

provides a penalty for dense gray or black smoke from all other 

sources. The law is rigidly enforced and-there is but little smoke 

from bituminous coal.
THE BUBNTNG OP COAL WITHOUT SMOKE. . 11

THE PRODUCTION OF SMOKE.

The term smoke as used in this paper refers to chimney gases that 

.contain small particles of imconsumed carbon, which give the gases 

a dark color. Smoke may be of any degree of blackness, but what 

some persons would call smoke is not considered smoke by others.

Smoke is due to a lack of air at the proper temperature at the point 

where the volatile gases should be burned, the result being that these 

gases are only partly burned and the carbon is set free. The density 

of smoke is measured in many ways, but the most satisfactory at 

present is by means of the Bingelmanu charts. These charts are made 

by drawing black lines at right angles on a white background. The 

lines are so spaced as to give the effect of different percentages of 

blackness when placed at a distance of about 50 feet from the observer. 

The charts are numbered 1, 2, 3, 4, and 5, and represent, respectively, 

20,-40, 60, 80, and 100 per cent of black smoke. As a matter of fact, 

anything but a clean stack will result in a smoky atmosphere. If a 

stack continuously emits a small amount of smoke, it may, during the 

course of the day, have given off as much carbon and have had as bad 

an effect as another stack which has been clear most of the time, but 

which for three or four periods of five minutes each has emitted a 

dense black smoke. In localities where bituminous coal is burned 

exclusively a plant is considered good if the average blackness is 

equivalent to 5 per cent or less.

The following information, taken from the report of the committee 

for testing smoke-preventing appliances, Manchester, England (see 

p. 24), is.of interest:

Observations were made for an entire day on 179 chimneys. The general 

averages of these stacks gave the equivalent of black smoke 102 minutes in 10 

hours. The averages for the individual stack varied from the equivalent of 

black smoke for 423 minutes in the worst to -1 minutes in the best. The relative 

amount of the smoke from different kinds of equipment may be taken as follows :

Average of 36 hand fires with air admission, SI minutes in 10 hours; average 

of 10 hand fires with air admission, good firing, 40 minutes; average of 4 

sprinkling stokers, about 103 minutes in 10 hours; average of 21 coking stokers, 

about 16 minutes in 10 hours; best coking stokers, about 4 minutes in 10 hours.

Coking stokers show best economy as well as prevention of smoke.

Sheffield Association suggest that the permissible limit of smoke emission 

should vary with the number of boilers as follows: For 1 boiler, 2 minutes per 

hour; for 2 boilers, 3 minutes per hour; for 3 or more boilers, 4 minutes per 

hour.

The following are reasons why furnaces sometimes smoke:

1. The furnaces and the grates are not properly designed to burn 

the coal available. There is almost no equipment on the market that 

will handle equally well all the fuels found in the United States.

2. There is a lack of sufficient draft.

3. The firemen are unskilled.
12 THE BURNING OF COAL WITHOUT SMOKE.

4. There is not enough combustion space.

5. Wood, paper, and other refuse are burned.

6. The load is changed quickly.

7. Excessive overloads are maintained.

THE PREVENTION OF SMOKE IN BOILER PLANTS.

FEASIBILITY.

Within the last few years there has been a remarkable development 

in the utilization of coal under the steam boiler. To-day many steam 

power plants in the United States are burning bituminous coal practically without smoke. This has been brought about by improving 

the design of the furnaces and by careful attention on the part of the 

fireman.

It is now possible to design and operate boiler plants burning a 

high-volatile coal which will be practically smokeless under usual 

operating conditions, giving off no black or dense gray smoke except 

when' a fresh fire is being built. Banking the fire, shutting dampers, 

etc., causes smoke of a light or gray shade only. This has been 

demonstrated at the engineering experiment station of the University 

of Illinois, where a boiler has recently been installed, properly 

equipped with a furnace for burning Illinois coal. -Under ordinary 

conditions this plant makes no smoke whatever. This equipment is 

not suitable for burning low-volatile coals such as are largely used 

in the East. In experimenting with this furnace an effort was made 

to produce smoke, but it was found impossible to make black smoke, 

the worst being about 50 per cent black.

A number of large commercial plants having properly designed 

furnaces are now operating daily without smoke in many of our 

larger cities. Reports on some of these plants inspected by engineers 

connected with the technologic branch will be published in a subsequent bulletin.

THE PRINCIPLES OF SMOKELESS COMBUSTION.

Coal can be burned smokelessly, the same as gas, gasoline, or 

kerosene oil, if the equipment is properly designed and adjusted. 

Each of these fuels will give off smoke if conditions are not favorable. All the authorities on the subject of combustion and smoke 

prevention agree upon the following conditions as requirements for 

a smokeless furnace:

1. The coal should be supplied to the furnace in small quantities 

at frequent intervals. The more nearly the feed approaches a continuous and uniform supply the better the results.

2. The air supply should be slightly in excess of the theoretical 

amount required and be admitted principally through the fuel bed, 

with an auxiliary supply admitted at the front or rear of the furnace 

to burn gases from the coal.
THE PREVENTION OF SMOKE TN BOILER PLANTS. 13

3. The temperature in the furnace should be sufficiently high to 

ignite the gases given off from the fuel bed.

4. There should be a fire-brick combustion chamber of sufficient 

dimensions and so designed as to cause the thorough mixture of the 

gases and air, permitting complete combustion before the mixture 

reaches the boiler surfaces.

Much has already been written on the theory and chemistry of 

combustion. " Steam-boiler economy," by William Kent, and " Steam 

boilers," by Peabody and Miller, are both good works on this subject. 

(See p. 23.)

It has been found in this country, as well as in Europe, that when 

smoke is given off, there is also a loss of carbon monoxide (CO) and 

other combustible gases. The loss due to the carbon which. we see 

and call smoke is seldom more than I per cent, but the loss due to the 

escape of the combustible gases may amount to an additional 3 to 10 

per cent.

The steam-engineering section of the technologic branch has found, 

as have other investigators, that, contrary to general opinion, with 

extremely high temperatures more smoke is produced and more unburned gases are lost up the stack. High temperature is of course 

due to a supply of air approaching the theoretical amount, and on 

account of the difficulty of obtaining a complete mixture of the gases 

and air some gas is allowed to escape unburned. (See Table 1.)

The combustible gas most frequently found in the flue gases is carbon monoxide (CO). This gas is nearly always present when the 

stack gives off black smoke, indicating imperfect combustion. Hydrogen and hydrocarbon gases may also be expected in connection 

with the CO, but on account of the difficulty of determining the small 

percentages of these gases they are seldom recorded, though the loss 

due to their escape is considerable. In confirmation of these statements, the accompanying tables are submitted. Table 1 gives a summary of the relation of smoke to unburned gases and combustionchamber temperatures as determined from more than 200 boiler tests 

made at the St. Louis fuel-testing plant.

TAUIYK 1. Relation of smoke to CO and combustion-chamber temperatures.

Average per cent of smoke .... 

Average per cent of CO in flue

Average per cent unaccounted

Average combustion-chamber

Per cent of/black smoke.

0.

3V 

0

0.05 

9.14

26 

2,180

0 to 10.

18 

7.1

0.11 

10.60

1C 

2,215

10 to 20.

56 

15.5

0.11 

9.40

48 

2,357

20 to 30.

51 

24.7

0.14 

10.93

45 

2, 415

30to40.'

30 

34.7

0.21 

11. 41

32 

2, 450

40 to 50.

17 

43.1

0.33 

13.41

17 

2, 465

50 to 60.

4 

52.9

0.35 

13.34

4

2, G17

'Temperatures iu combustion chamber were not determined on all tests.
14 THE BURNING OF COAL WITHOUT SMOKE.

Table 2, from the Manchester report (see p. 24), gives analyses of 

chimney gases, including determinations of hydrogen (H) and 

methane (CH4 ), which occur in small percentages.

TABLE 2. Analyses of chimney

Boiler.

No. ] , hand fired .......

No. 1, with smoke-prevention device

No. 4, fire under caustic 

pot, hand fired ....... 

No. 5, split bridge, hand 

fired .................

No. 6, with smoke-preNo. 7, with smoke-preNo. 8, with smoke-preSmoky.

C02.

fll. 00

no: 65

10.25 

13. 25

10.95

8.75

Oo.

6.90 

6.45

8.60 

3.50

1.30 

7.00

CO.

0.90 

2.1.5

.50 

.05

3.00 

3.25

CH4 .

0 

0. 25

.70 

.40

H2 .

0 

0

3.23 

1.00

No.

81.20

80.76

80.65 

82.95

80.82 

79.60

Clear.

COo.

J7.00 

\9.00

7.25 

7.15 

8.15

02 .

13.50 

9.75

12.00 

12. 15 

11.10

CO.

0 

0

0 

0 

0

CH4.

0 

0 

0

H,.

0 

0 

0

N2 .

79.50 

81.25

80.75 

80.70 

80. 75

Table 3, compiled from results obtained at the fuel-testing plant, 

shows that the losses due to the escape of CO and other combustible 

gases may be considerable and that they are of more importance than 

the gain from a corresponding increase in carbon dioxide (CO,). It 

is evident that the prevention of smoke and the efficiency of the plant 

are very closely related.

Calculations showing the theoretical losses due to the presence of 

combustible gases in the flue gases have been made and the results 

published in "A study of four hundred steaming tests." a

TABLE 3. Relation of CO to efficiency.

Number of tests.

Average per cent of 

C02 in flue gases ...... 

Average per cent of

Average efficiency

(11*)<i. ................

15

7.69 

.63

52.96

11

9.46 

.53

56.73

29

9.29

.27

59.56

25

9.09 

.22

62.08

21

9.48 

.17

63.43

28

9.48 

.19

64.58

42

9.90 

.13

65.55

32

9.60 

.16

66.41

34

9,57 

.12

67.48

49

10.22 

.15

69,10

7

10.94 

.10

71.73

0 For discussion of efficiency 72* see A study of four hundred steaming tests : Bull. 

U. S. Geol. Survey No. 325, 1907.

PROPER FURNACE EQUIPMENT.

Numerous inventions for preventing smoke have been made, based, 

according to the inventors, on the recognized principles discussed in 

the foregoing section. Most of them have not been properly designed 

to meet the severe service to which a boiler furnace is subjected.

Bull. U. S. Geol. Survey No. 325, 1907, pp. 100-101.
THE PREVENTION OF SMOKE IN BOILER PLANTS. 15

The proper design of the furnace and settings, including the breeching and stacks, is a subject of much dispute. All authorities, however, agree that sufficient air must be admitted to allow complete combustion. This means that ample draft must be provided. Stacks 

less than 125 feet high are usually unsatisfactory, but steam or electrically driven fans are now very commonly used to produce either 

forced or induced draft in connection with stacks shorter than would 

otherwise be required.

Provision should be made for the admission of air above the fuel 

bed. It is also now generally conceded that there should be a firebrick chamber of sufficient length to allow time for the gases and air 

to mix and burn. Numerous observations made on power plants show 

that it takes an average of twelve seconds for the gases to pass from 

the furnace to the top of a stack 125 feet high. This allows but one 

second for combustion to take place before the gases leave the combustion chamber. These conditions have been so successfully met in some 

plants as to permit the use of low-grade coal without the production 

of objectionable smoke. These plants are few when compared to the 

total number in operation, but they indicate the possibilities of securing practically perfect combustion.

In general, furnaces designed for burning coal may be divided into 

two general classes, as follower

I. Those into which coal is shoveled at intervals by hand: 

(a) Plain or rocking grates, with no fire-brick arch. 

(6) Same as «, with steam jet under a small combustion 

space.

(c) Plain or rocking grates, with a fire-brick arch, large combustion space, and provision for admitting air over the 

fire either at the front or at the bridge wall.

(d) Plain or rocking grates, with large or small combustion 

chamber and with or without fire-brick arch, equipped 

with steam jets and air-admission dampers which close 

automatically after each firing.

(e) Combinations of any two or more of the above.

(/) Down-draft furnaces, consisting of two grates, the upper 

one of water tubes to prevent its destruction by the heat, 

and the lower one like the common hand-fired grate. 

The fire is built on the upper grate, and coal is fed or 

shoveled on top of the fire. The furnace is so arranged 

that the gases and flame pass down through the upper 

grate and over the lower one, on which a fire of coke, 

supplied from the upper grate is maintained.
16 THE BURNING OF COAL WITHOUT SMOKE.

II. Those to which coal is fed continuously by an automatic device: 

(g) Powdered-coal devices, in which particles of coal are 

thrown or blown into the furnace and burned before 

reaching the bottom of the combustion chamber, which 

must be of fire brick. -

(h) Sprinkling stokers. Devices for automatically feeding 

and distributing small sizes of coal as evenly as possible 

over the entire grate surface. Automatic shaking grates 

are usually installed with this apparatus. 

(i) Coking stokers:

1. Overfeed stokers, in which the coal is fed continuously and coked under a fire-brick arch. Special 

provisions are made to admit air to mix with the 

volatile gases. These may be further subdivided 

into front-feed and side-fe.ed stokers.

2. Traveling chain-grate stokers, in which the coal is 

fed at the front under a fire-brick arch and the 

entire surface of the gate moves toward the bridge 

wall at a rate which allows all the coal to be consumed.

3. Underfeed stokers, in which the coal is automatically 

fed at frequent intervals beneath the bed of hot 

fuel, air is forced through the burning coal by 

means of a fan, and as the volatile gases are given 

off from the fresh coal they mix with the air and 

pass up through the fire. Under favorable conditions combustion is completed within a short distance from the surface of the fuel bed.

DIFFICULTY IN SECURING PERFECT COMBUSTION.

With so great a variety of furnaces to choose from it seems at 

first thought that there should be no difficulty in abating smoke. It 

is, however, difficult to construct a furnace that will be smokeless 

under any and all-conditions of operation. Some furnaces now in 

operation are practically so, conforming to every requirement outlined for smokeless combustion, but there is no type of grate or 

stoker on the market to-day which does not give off offensive black 

smoke in some of the plants in which it is installed. This may or 

may not be due to faults in the furnace. It may be due to lack of 

combustion space or to improper handling.

The efficiency of the furnace and the degree of success attained by 

any equipment in the prevention of smoke depend on the following 

factors: Skill of the fireman, proper design of the furnace and boiler 

setting, character of the coal, capacity of the boilers and furnaces, 

and load carried.
THE PREVENTION OF" SMOKE IN' BOILER PLANTS. 17

The skill of the fireman is the most important element in connection with the ordinary equipment. As a matter of fact, the personal 

element is the greatest hindrance to progress in the abatement of 

smoke. Both the owner and the fireman must be interested to obtain 

the best results. Intelligent supervision in the boiler room to secure 

proper air admission and care in firing will result in the saving of the 

losses due to smoke or unconsumed gases and to heating an excessive 

amount of air. At many plants such supervision has reduced the coal 

bills by 5 to 20 per cent, depending on the coal and the methods formerly in use.

It is a generally conceded fact that intelligent men trained in boilerroom practice could save 10 per cent of the fuel used in 50 per cent 

of the plants of the United States, and that in another 25 per cent of 

the plants' such men could save 5 per cent of the fuel. It is the practice of nearly all large power plants to employ a boiler-room expert, 

and many of them-have chemists who make frequent tests and investigations to determine the conditions favorable to the best economy. 

The saving of only a small percentage of the coal consumed will make 

a handsome return for the cost of the experimental work. There are 

now in a few of our larger cities competent engineers who are making 

a specialty of supervising boiler plants for a number of firms.

A feAv examples of carelessness and indifference on the part of firemen will in a measure explain why many persons are skeptical regarding the value of mechanical stokers and other smoke-preventing 

devices.

At a plant which had a smoke-preventing device, but which was 

smoking, the fireman said a connecting chain had been broken for several days and he " didn't have time to bother with it." It would not 

have required more than ten minutes to join the two ends with wire 

for a temporary repair. In another plant the fireman said: " The 

thing takes too much steam, and I shut it off." Many other cases of 

willful neglect have been observed.

Very few firemen can be induced to fire regularly and frequently, 

because it is easier to put in enough coal to last twenty or thirty 

minutes at one time and have little or nothing to do in the interval 

between firings. In one instance the engineer took occasion to measure the draft between the grates before and after firing oh a downdraft furnace which had a good draft. The draft before firing was 

0.35 inch of water, but after the fireman had thrown on 63 shovelfuls 

of coal the flow of air was so seriously retarded that the draft increased to 0.62 inch. Great volumes of smoke were given off, indicating this lack of air.

Professor Benjamin, in his paper on smoke and its abatement (see 

p. 23), speaking of steam and-air jets, expressed himself as follows:
18 THE BURNING OF COAL WITHOUT SMOKE.

" It is a very effective method of smoke prevention, and is used very 

largely in Cleveland. I have not given it very much weight in my 

paper, because it depends so much upon the individuality of the engineer and fireman. I have found that men who use that means had 

to be watched so continually and reprimanded so much that I got out 

of patience with that sort of prevention."

Difficulties are also encountered with stokers. One of the greatest 

troubles is the tendency of the fireman to poke the fires unnecessarily 

instead of using or adjusting the attachments provided for feeding 

and handling the coal. In many plants where it is possible they will 

shovel green coal into the stokers, instead of feeding it through the 

hopper, and then take a bar and stir up the fresh coal with the coke 

and ashes, causing smoke and wasting the coal.

It is not an uncommon experience that on inspection the boiler 

tubes are found to be covered with scale on one side and soot on the 

other. One plant with nearly 4,000 horsepower had soot hanging 

from the surfaces of the tubes, and on inquiry it developed that these 

tubes had not been cleaned for a period of four months, no cleaning 

having been done since the new master mechanic had taken charge.

The following quotation is from the Manchester report, already 

cited (see p. 24) :

Negligent management of the self-acting damper is responsible for much of 

the smoke from hand firing. * * * No"doubt its use obviates to. some extent 

the necessity for constant attention, but in many cases it has been disconnected 

after attention has been drawn to the smoke.

The foregoing examples emphasize the facts that the management 

of the boiler room is a problem for properly trained men and that 

as the coal burned is a considerable item of expense, averaging about 

50 per cent of the cost of producing power, there is more opportunity to save in the boiler room than in the engine room with any 

given equipment. The average boiler room is a hot, dirty, and otherwise unattractive place. For these reasons but little attention has 

been paid to it by superintendents and operating engineers in moderate-sized plants. The boiler rooms are managed for the most part 

by men hired not so much for what they knoAv as for their ability 

to do hard work, and they get comparatively small wages. There 

are, however, some mechanical appliances, such as the chain grate, 

which leave but little to the skill of the fireman. (See " Suppression 

of industrial smokej" by A. Bement, cited in bibliography, p. 23.)

Many furnaces may be classed as smokeless when attended by 

careful men, but unsatisfactory when fired by ordinary firemen. In 

some power plants it is difficult for even a trained man to secure 

reasonable economy and prevent smoke. This may be due to the 

fact that the plant is poorly designed. It does not follow that a 

plant having a high chimney will have a sufficient draft. The chim-
THE PREVENTION OF SMOKE IF BOILER PLANTS. 19

ney may be too small, or there may be many elbows in the flues leading from the boiler to the stack, or there may be serious leakage of 

air through holes in the flue, boiler setting, and breeching. A poor 

draft is responsible for a great deal of trouble in the boiler room. 

Difficulty in burning coal in some one furnace in a plant has been 

reported where investigation showed that the damper had turned on 

its shaft and instead of being open, as the fireman supposed, was 

nearly closed. Such difficulties can be avoided only by systematic 

supervision.

In many plants the grate surface is not properly proportioned to 

the load carried. This can be remedied in hand-fired furnaces, but 

not without considerable expense in stoker plants. Some plants maintain fires under too many boilers for good economy; on the other 

hand, there are probably more in which the furnaces are overloaded.

The hand-firing of plain furnaces violates all the principles laid 

down for securing good combustion. The coal is usually supplied in 

large quantities at long intervals, and the result is that at the times 

of firing the temperature of the furnace is lowered, the resistance to 

the flow of air through the fuel bed is increased, and consequently 

great quantities of combustible gas are generated which can not be 

burned for lack of air and the necessary amount of heat.

Hand-fired furnaces with steam and air jets may save enough by 

better combustion to make up for the cost of the steam used in the 

jets. They are looked upon as makeshifts by experienced smoke inspectors and others competent to judge of them.

Hand-fired furnaces with ample combustion chambers and adjustable openings for air admission are suitable for some kinds of coal, if 

tended by experienced and careful firemen.

Down-draft furnaces have shown decided economy in many plants 

and have been fairly successful in the prevention of smoke. The principle is a good one, but few installations of these furnaces are properly 

fired. Whether they can be run smokelessly depends on the required 

capacity, the land and size of coal, and the attention. 

. Mechanical apparatus for burning powdered coal in boiler furnaces 

has been tried in many plants and with but few exceptions has been 

found unsatisfactory on account of the cost and difficulty of maintaining the furnace. It has, however, proved a decided success in 

firing cement kilns.

Sprinkling stokers have as yet made little headway in this country. 

Records given in the Manchester (England) smoke-prevention report 

show that these stokers are not as successful in preventing smoke as 

those of the coking type.

Furnaces with mechanical stokers of the overfeed types, including chain grates, which feed the coal gradually and coke it under a 

fire-brick arch, are used more widely than any others except the plain
20 THE BURNING OF COAL WITHOUT SMOKE.

hand-fired furnaces. When these stokers are properly installed in 

connection with ample combustion chambers, and carefully operated, 

they give good results and prevent smoke. Many of these furnaces 

are not properly installed and a still greater number are badly 

operated. The inclined-grate stokers will burn either high-volatile 

coals or coals high in fixed carbon. The chain-grate stokers are successful in burning high-volatile coals such as are found in Indiana 

and Illinois. They require less attention from the fireman than other 

types of stokers, and they can be operated smokelessly when properly 

installed. This stoker has not been adapted to burning low-volatile 

coals such as are largely used in the East.

Underfeed stokers that automatically feed the coal are usually 

successful with either high or low volatile fuels when properly installed and operated at a reasonable rate of combustion.

Many furnaces are burning coal unsuited to them, and under the 

load conditions it is impossible to prevent smoke. A change to another kind, or in some cases to another size of the same kind of coal, 

would prove satisfactory.

INDIRECT METHODS OF SMOKE ABATEMENT..

There is at present a general tendency to centralize power, heating, and gas plants. In the heating of buildings it is customary under 

existing conditions to generate steam in the building. Where this is 

done, it is in general considered more economical to install engines for 

generating current for light and power also. However, many buildings furnish their own heat, but' purchase current. Large power or 

light plants can now be located at any convenient place, say at the coal 

mines, because of the ease and economy with which electric current 

can be transmitted; but heating plants, whether for residence or for

business districts, must be within a comparatively short distance from 

the section to be heated on account of the cost of installation and the 

losses from radiation. There are now more than 150 central heating 

plants in the. United States, furnishing steam or hot water to. residences or business buildings or to both. The greater number of these 

plants are located in the coal-producing States. Some of them have 

been built especially for the purpose of heating; others are additions 

to electric-lighting or industrial plants and utilize the exhaust steam 

from the engines. These central plants can be operated without smoke 

under favorable conditions, and they relieve the smoke situation in a 

measure. The plan of purchasing both heat and light, not only for 

residences, but also for business houses, is popular because it relieves 

the consumer of the details of operating a plant, does away with the 

dust of coal and ashes, and makes available for storage purposes space 

which would otherwise be occupied by the plant.
SUMMARY. "21

It has been suggested that in certain types of furnaces in which perfect combustion can not be maintained, the resulting smoke may be 

washed from the chimney gases in the same way as dust and soot are 

now removed from the air that is used in ventilating large office buildings, schoolhouses, and hospitals.

The increasing use of storage batteries by street railways and other 

interests has aided in the prevention of smoke. These batteries furnish the extra power needed Avhen traffic is heavy during rush hours 

on the street railways and make unnecessary any sudden heavy demands on the power plants. The load on the engines being more 

nearly uniform, there is less change in the rate of combustion in the 

furnaces and less smoke, for change of load and crowding of boilers 

constitute a most prolific source of smoke.

SUMMARY.

The increasing use of gas and coke for domestic, manufacturing, 

and power purposes and the centralization of power and heating 

plants tend to relieve cities of a large percentage of the smoke now 

given off by small and inefficient heating and power plants. Notwithstanding the fact that other ways of utilizing coal are growing 

in favor, it will evidently be necessary to burn coal in small boiler 

plants for some time to come. These coal-burning plants will continue to keep the problem of smoke abatement before* the residents 

of large cities.

It is recommended that in order to improve the conditions in any 

city a record of all equipment and furnaces in the power plants be 

made, and that improvements, methods of operation, and the kinds of 

coal used be made a special study. It is only by such systematic 

methods that the local problem can be solved, as conditions in any 

one city are generally different from those in others, depending on 

the amount and kind of manufacturing and the character of the coal 

available.

The personal element is the most difficult obstacle to overcome in 

the fight against smoke. Study of the requirements and a desire to 

obtain good results on the part of the firemen will do more to clear 

the air in cities than any other one influence.

Being principally the result of an imperfect air supply, smoke 

can be prevented by providing for sufficient air and for its mixture 

with the gases in the furnace.

Well-designed furnaces may smoke to a greater or less degree, 

depending on the methods of the firemen, the kind or size of the coal, 

and the rate at which the coal is burned. They may be expected to 

give smokeless combustion when burning a suitable coal, except under 

the following unfavorable operating conditions:
22 . THE BURNING OF COAL WITHOUT SMOKE.

1. When fires are built. The furnace not being heated to the required temperature, the gases cool below their ignition point and 

escape unburned.

2. When so much coal is burned on the grate that it is impossible 

to supply sufficient air without frequent poking. This condition 

usually results in so large a volume of gas from the coal 'that it can 

not be properly mixed with air and burned in the combustion 

chamber.' On reaching the boiler surfaces it is cooled, combustion 

is arrested, and soot and smoke result..

3. When the rate of combustion is suddenly increased, as when 

more coal is added, and fires are poked to get up pressure in short 

time. .

4. When the fires are checked by closing doors or dampers, thus 

cutting off the air supply. Banked fires are difficult to maintain and 

start up. without smoke. Automatic dampers are frequently the 

cause of smoke when not properly adjusted or designed.

There is need of further study of coals, furnaces, and combustion, 

but enough is now known to enable an engineer to design and operate 

a steam plant without objectionable smoke.

BIBLIOGRAPHY.

SURVEY PUBLICATIONS ON COAL.

The following reports (except Bulletin No. 261) can be obtained 

by application to the Director of the United States Geological Survey, Washington, D. C.:

BULLETIN No. 261. Preliminary report on the operations of the coal-testing 

plant of the United States Geological Survey at the Louisiana Purchase 

Exposition, St. Louis, Mo., 1904. E. W. Parker, J. A. Holmes, M. R. Campbell, committee in charge. 1905. 172 pp. Can be obtained by sending 10 

cents in cash to the Superintendent of Documents, Washington, D'. C.

PROFESSIONAL PAPER No. 48. Report on the operations of the coal-testing plant 

of the United States Geological Survey at the Louisiana Purchase Exposition, St. Louis, Mo., 1904. E. W. Parker, J. A. Holmes, M. R. Campbell, 

committee in charge. 1906. In three parts, 1492 pp., 13 pis.

BULLETIN No. 290. Preliminary report on the operations of the fuel-testing 

plant of the United States Geological Survey at St. Louis, Mo., 1905. J. A. 

Holmes, in charge. 1906. 240 pp.

BULLETIN No. 323. Experimental work conducted in the chemical laboratory of 

the fuel-testing plant, St. Louis, January 1, 1905, to July 31, 1906, by N. 

W. Lord. 1907. 49 pp.

BULLETIN No. 325. A study of four hundred steaming tests, made at the fueltesting plant, St. Louis, Mo., 1904, 1905, and 1906, by L. P. Breckenridge. 

1907. 196 pp. 

BOOKS ON COMBUSTION AND SMOKE PREVENTION.

BARB, WILLIAM M. Combustion of coal and the prevention of smoke. Norman

W. Henley Publishing Company, New York. 

BOOTH, WILLIAM H., and KERSHAW, JOHN B. C. Smoke prevention and fuel

economy. Norman W. Henley Publishing Company, New York, 1905.
BIBLIOGRAPHY. 23

HAYS, JOSEPH WELLER. Combustion and smokeless furnaces. Hill Publishing 

Company, New York, 1906. 104 pp., illustrated.

KENT, WIXLIAM. Steam boiler economy: A treatise on the theory and practice 

of fuel economy in the operation of steam boilers. " Coal can be burned 

without smoke provided (1) the gases are distilled from the coal slowly; 

(2) that the gases when distilled are brought into intimate contact with 

very hot air; (3) that they are burned in a hot fire-brick chamber; (4) 

that while burning they are not allowed to come in contact with comparatively cool surfaces, such as the shell or tubes of a steam boiler. This 

means that the gases shall have sufficient space and time in which to burn 

before they are allowed to come in contact with the boiler surfaces."

PEABODY, C. H., and MILLER, E. P. Steam boilers: A treatise on boilers and 

furnaces. Chapter on combustion.

Poi'PLKWKLL, WILLIAM CHARLES. The prevention of smoke combined with the 

economical combustion of fuel. Scott Greenwood & Co., London, 1901.

NICHOLSON, WILLIAM. Smoke abatement: A manual for the use of manufacturers, inspectors, medical officers 'of health, engineers, and others. C. 

Griffin & Co. (Limited), London, 1905. 09 illustrations.

WILLIAMS, CHARLES WYE. Combustion of coal and the prevention of-smoke, 

chemically and practically considered. London and Liverpool, 1S41; new 

ed., London, 1854.

PROCEEDINGS OF ENGINEERING SOCIETIES.

BEMENT, A. Suppression of industrial smoke, with particular reference to 

steam boilers. A paper presented before the Western Society of Engineers, 

October 17, 1906. 60 pp., 26 illustrations. With discussions by W. L, 

Abbott, Chicago Edison Company; R. H. Kuss, assistant smoke inspector, 

Chicago: Frank Elliott, chief engineer Northwestern Elevated Railroad, 

Chicago; W. L. Goddard, International Harvester Company; A. .T. Saxe, 

supervising engineer, Chicago; Carl Scholz, president Coal Valley Mining 

Company; H. Kreisinger, fuel-testing plant, United States Geological Survey ; E. H. Taylor, Fuel Engineering Company, Chicago; John C. Schubert, 

smoke inspector, Chicago. Communicated by letter: Prof. William Kent, 

Syracuse, N. Y.; F. S. Peabody, Peabody Coal. Company; E. B. Powell, 

New York Edison Company; J. W. Green, Cedar Rapids, Iowa; H. W. 

Woodward, assistant smoke inspector, Cleveland, Ohio; H. E. Horton, 

Chicago; R. S. Moss; Philip McCarty, smoke inspector, Denver; Clinton 

Rogers, Rochester, N. Y.

BENJAMIN, CHARLES H. Smoke and its abatement. Trans. Am. Soc. Mech. 

Eng., vol. 20, New York, 1905, p. 713. Discusses, in a general way, the 

methods employed for preventing smoke in stationary plants and. on locomotives.

HARTMAN, JOHN M. Notes on burning bituminous coal. Proc. Eng. Club, 

Philadelphia, April, 1904.

MABERY, C. F., and BENJAMIN, CHARLES H. Economy in combustion and smoke 

prevention. Jour. Assoc. Eng. Socs., May, 1S96. Doctor Mabery discusses 

the chemical aspect of the combustion of coal; Professor Benjamin discusses smoke prevention from the mechanical standpoint. Good smokepreventing device should have variable feed, variable spacing of grate bars, 

grate bars of the automatic shaking type, some form of air control, sufficiej^t grate area, easy accessibility for cleaning, good firing.
24 THE BURNING OF COAL WITHOUT SMOKE.

ROWAN, F. J. The smoke problem. Traus. Inst. Eng. and Sliipb. Scotland, 

October, 1904. Discusses the production of smoke; the estimation of 

smoke; the prevention of smoke; some considerations affecting municipal 

control.

SHAW, W. N. The treatment of smoke. Jour. San." Inst, October, 1902. Dis-" 

cusses the removal of smoke as a parallel to the removal of sewage.

FRANKLIN INSTITUTE. The smoke nuisance and its regulation, with special 

reference to the condition prevailing in Philadelphia. Jour. Franklin Inst., 

June, 1897. Discussion showing that smoke prevention is possible. R. H. 

Thurston says preventives are legislation, skilful operation of furnaces, and 

special construction of furnaces. " I am inclined to expect highest efficiency, 

ultimately, through the use of the mechanical stoker."

PUBLICATIONS BY STATES, CITIES, AND CITIZENS' COMMITTEES.

BBECKENBIDGE, L. P. The prevention of smoke. Engineering Experiment Station, Urbana, 111.

BUFFALO. The abatement of the smoke nuisance. Committee of manufacturers 

of the chamber of commerce. Contents: To whom smoke prevention is 

beneficial; the present and the proposed ordinance; ordinances of the cities 

of New York, Pittsburg, Cleveland, Detroit, Syracuse, Rochester, Minneapolis, Cincinnati, and Indianapolis.

CLEVELAND. Report of the municipal committee on the smoke nuisance, March. 

1907. Contents: Effect of coal smoke; attempt to enforce ordinance of 

1882; discussion of question " Is there a mechanical device which will 

prevent the emission of smoke?" legal basis requiring its installation; 

responsibility of the owner; review of the present ordinance of the city; 

recommendations.

 Smoke prevention and economy. Department of smoke abatement, 

February, 1905. Contents: Determining factors of smoke abatement; description of smoke-prevention devices; smoke prevention and fuel economy 

synonymous; answers to query "Can smoke be prevented?" from tests and 

letters.

MANCHESTER (England). Report of committee for testing smoke-preventing 

appliances, 1895. Contents: Origin of the movement; scope of the work; 

details regarding tests; deductions from smoke-observations; tables of results of tests. 42 pp., 3 illustrations, and 10 important tables.

MILWAUKEE. Second annual report of Charles Poethke, smoke inspector, 1905. 

Contents: Smoke-preventing devices installed; an indication of fuel economy ; cooperation of manufacturers; gratifying results; imperfections of 

ordinance.

ST. Louis. Report of the smoke abatement department, C. H. Jones, chief inspector, October, 1906. Contents: Smoke-consuming devices (classified) in 

use; difficulties of the department; effect of insufficient boiler capacity.

 The smoke nuisance. Report of the smoke-abatement committee of the 

civic league, November, 1907. Contents: Injurious effects of smoke; damage to plant life; smoke and fuel economy; does smoke come from East 

St. Louis? the problem of the committee; the first ordinances invalid; 

the present ordinance valid; kinds of fuel used in St. Louis; principles 

of proper combustion; smoke devices in use; prolific causes of smoke; comparison of devices in use; smoking locomotives the most reckless offenders; 

brick kilns as smoke makers; does enforcement of ordinance mean persecution; three important factors for the solution of the smoke problem; 

draft of the new ordinance.
BIBLIOGRAPHY. 25

SYRACUSE. Report upon smoke abatement. Chamber of commerce committee, 

1907. Contents: Damage clone by smoke; results in other cities; principle of combustion; causes of smoke; devices for preventing smoke; railroad smoke; economic results from smoke abatement; conclusions.

PAPERS IN TECHNICAL JOURNALS.

BEILBY, GEORGE THOMAS. Smoke abatement. Engineering, June 26, 1903.

Advocates the substitution of gas fuel for coal. 

BENJAMIN, CHARLES H. Smoke and its abatement in large cities. Tech. Quart,

September, 1902.

 The prevention of smoke from bituminous coal. Engineer (U. S.), 

April 1, 1903.

BOOTH, AV. H. Smoke prevention. Am. Machinist, September 29, 1898. Discusses principles of combustion and the requirement of a furnace so. that 

it may not produce smoke.

 - Smoky furnaces and how to avoid them. Elect. Review, London, 1st 

part, July 26, 1901.

 The smokeless combustion of bituminous fuels. Elect. Review, London, September 26, 1902. Discusses principles of combustion.

BKKC.KENRIDGB, L. P. Burning Illinois coal without smoke. Eng. News, June 

11, 1903. The essential features of a smokeless plant are sufficient boiler 

capacity, a good draft, uniform size of coal, some good type of automatic 

stoker, intelligent direction in the boiler room.

CARY, ALBERT A. The suppression of smoke in steam plants using bituminous 

coal. Iron Age, October 2, 1902. " The whole secret of burning coal 

smokelessly is to obtain complete combustion in the furnace or combustion 

chambers before any appreciable amount of the combustible gases meet the 

chilling water surfaces of the boiler. No one furnace setting can be built 

to burn all kinds of fuel with equal efficiency."

 The prevention of smoke. Eng. Record, vol. 53, April 21, 1906, pp. 

514-516. Condensed from an address before the New York section of the 

Society of Chemical Industry. Smoke prevention depends on intelligence 

in the boiler room, proper design of the grate to burn the particular kind 

 of coal used to the best advantage, proper design of the furnace and 

combustion chamber.

DONKIN, BRYAN. On smoke and its diminution. Engineer, London, May 26, 

1S99. Discusses methods in use for diminishing smoke.

HEMPEL, TV. On smokeless combustion and boiler firing. Abstract from " Stall! 

und Eisen." Colliery Guardian, July 24, 1S96. Discusses influence of 

temperature and pressure on gaseous products of combustion.

KERSHAW, JOHN B. C. Industrial smoke and its prevention. Cassier's Magazine, vol. 29, December, 1905, ppT 109-114. Reviews a number of earlier 

works on smoke abatement and concludes that the method of preventing 

smoke is good stoking and scientific control.

 Smoke abatement: A report on the London smoke-abatement conference, December 13-15, 1905. Cassier's Mag., vol. 29, February, 1906, pp. 

335-341.

KING, R. P. The abatement of the smoke nuisance. Municipal Engineering, 

vol. 29, November, 1905, pp. 366-369. Gives municipal aspect of the smoke 

problem. " Of the successful devices there are four classes steam jets, 

furnaces, mechanical stokers, smokeless coal."

LONDON. Conference on smoke abatement; abstract of proceedings. Engineer, 

London, November-December, 1005.
26 THE BURNING OP COAL WITHOUT SMOKE.

MAYNER, WILLIAM. Smokeless combustion and economy of fuel. Sci. Am. 

Suppl., vol. 60, August; 26, 1905, pp. 24788-24789. Discusses the waste 

obtained by burning coal in ordinary furnace. Describes the furnace 

invented by Charles Wegener, of Charlotteuburg.

PABKEB, T. T. Smoke abolition. Am. Machinist, October 16, 1902. Two ways 

of changing horizontal tubular boilers so that they may be made smokeless.

POPPLE WELL, W. C. The' smoke problem and its possibilities. Feilden's Mag., 

December, 1902. Article describes several different stokers.

RAWORTH, JOHN S. The prevention of smoke. Electrician, London, September 

26, 1902. Describes test made with Wilson smokeless process by Electric 

Traction Company at Kidderminster.

SIMMERBACH, O. The suppression of smoke by the use of coke. (From Zeitschrift der Dampfkessel-TJeberwachungs-Vereine.) Progressive Age, February 15, 1S97. Discusses the advantages presented by coke for use under 

boilers as compared with coal.

WILKTNSON, THOMAS L. The smoke problem of Denver. Min. Reporter, December 10,1903. Discusses the general principles of combustion and several 

devices for smoke prevention.

WRIGHT, .T. The possibilities of electrical smoke deposition. Elect. Review, 

London, November 23, 1900. Discusses the possibilities of electrical smoke 

deposition, cites several laboratory experiments to show that it is possible, 

and suggests a plan by which it might be attempted in practice.

An improvement in smoke-consuming furnaces. Sci. Am., March 81, 1900. 

^Describes a smoke-preventing attachment for hand-fired furnaces.

Apparatus for consuming smoke. Sci. Am. Suppl., February 25, 1899. Brief 

review of the report of the commission appointed in Paris for testing smoke-- 

consuming apparatus.

Smoke. Progressive Age, September. 15, 1S9S. Editorial, discussing the probability of avoiding the smoke nuisance by substituting gas for coal.

Smoke abatement. Engineering, August 7, 1S96. Editorial review of smoke 

problem, particularly of the report of the " committee for testing smokepreventing appliances."

.Smoke prevention and smokeless furnaces. Eng. News, January 2, 1896. Discusses briefly conditions of combustion, waste due to smoke, and hygienic 

questions.

The smoke nuisance. Builder, August 12, 1899. General discussion of the

smoke nuisance with particular reference to the waste caused by smoke 

from domestic fires and the damage done to property, etc., by smoke.
CLASSIFICATION OF THE PUBLICATIONS OF THE UNITED STATES GEOLOGICAL

SURVEY.

[Bulletin No. 334.]

The serial publications of the United States Geological Survey consist of (1) 

Annual Reports, (2) Monographs, (3) Professional Papers, (4) Bulletins, 

(5) Mineral Resources, (6) Water-Supply and Irrigation Papers, (7) Topographic Atlas of United States folios and separate sheets thereof, (8) Geologic 

Atlas of the United States folios thereof. The classes numbered 2, 7, and 8 

are sold at cost of publication; the others are distributed free. A circular 

giving complete lists can be had on application.

Most of the above publications can be obtained or consulted in the following 

ways:

1. A limited number are delivered to the Director of the Survey, from whom 

they can be obtained, free of charge (except classes 2, 7, and 8), on application.

2. A certain number are delivered to Senators and Representatives in Congress for distribution.

3. Other copies are deposited with the Superintendent of Documents, Washington, D. C., from whom they can be had at practically cost'.

4. Copies of all Government publications are furnisnecl to the principal public

libraries in the large cities throughout the United States, where they can be 

consulted by those interested.

The Professional Papers, Bulletins, and Water-Supply Papers treat of a 

variety of subjects, and the total number issued is large. They have therefore 

been classified into the following series: A, Economic geology; B, Descriptive 

geology; C,. Systematic geology and paleontology; D, Petrography and mineralogy; E, Chemistry and physics; F, Geography; G, Miscellaneous; H, Foresty; 

1, Irrigation; J, Water storage; K, Pumping water: L, Quality of water; M, 

General hydrographic investigations; N, Water power; 0, Underground waters; 

P, Hydrographic progress reports; Q, Fuels; R, Structural materials. This 

paper is the eighth in Series Q, the complete list of which follows (PP=Professioual Paper; B=Bullet in) :

SERIES Q, FUELS.

B 261. Preliminary report of the operations of the coal-testing plant of the United States

Geological Survey at the Louisiana Purchase Exposition, St. Louis, Mo., 1904;

E. W. Parker, V.T. A. ELolmes, M. R. Campbell, committee in charge. 1905.

172 pp.

PP 48. Report on the operations of the coal-testing plant of the United States Geological 

j Survey nt the Louisiana Purchase Exposition, St. Louis, Mo., 1904; E. W.

Parker, .T. A. Holmes, M. R. Campbell, committee in charge. 1906. 3 parts.

1,492 pp., 13 pis. 

B 290. Preliminary report on the operations of the fuel-testing plant of the United States

Geological Survey at St. Louis, Mo., 1905, by J. A. Holmes. 1906. 240 pp. 

B 323. Experimental work conducted in the chemical laboratory of the United States

fuel-testing plant tit St. Louis, Mo., January 1, 1905, to July 31, 1906, by

N. W. Lord. 1907. 49 pp. 

B 325. A study of four hundred steaming tests made at the fuel-testing plant, St. Louis,

Mo., in 1904, .1905, and 1906, by L. P. Breckenrldge. 1907. 196 pp. 

B 332. Report of the United States fuel-testing plant at St. Louis, Mo., January 1, 1900,

. to July 1, 1907, Joseph A. Holmes in charge. 1908. pp. 

B 333. Coal-mine accidents: their causes and prevention ; a preliminary statistical report,

by Clarence Hall aTTd W. 0. Snelling, with an introduction by J. A. Holmes.

1907. 21 pp. 

B 334. The burning of coal without smoke in boiler plants, a preliminary report, by

D. T. Randall. 1908. 26 pp.

Correspondence should be addressed to

THE DIRECTOR,

UNITED STATES GEOLOGICAL SURVEY,

WASHINGTON, D. C. 

JANUARY, 1908. I

o