OoroBEB 23, 1908] 



SCIENCE 



543 



taken out and so become absolute waste. 

 In most coal mines there are several layers 

 of the coal separated by shale formation. 

 Some of these are narrow and can not he 

 mined to advantage; others are so broken 

 up and dislocated by the mining of adja- 

 cent seams that it is impossible to take them 

 out. AU of these causes and perhaps some 

 others make up a loss of from forty to 

 seventy per cent, of the coal in the average 

 coal mine of the country. As we obtain 

 only thirty to sixty per cent, of the coal, it 

 is evident that we are exhausting our coal 

 fields twice as fast as the actual amount of 

 fuel used would indicate. 



This immense drain upon the coal sup- 

 ply must very soon have an effect. It has 

 been estimated that our anthracite coal 

 can not last more than seventy-five years. 

 The bituminous coal will last much longer, 

 but it wiU become exhausted in those places 

 where it is now used to the greatest extent. 

 The most important coal vein in the United 

 States is in the Pittsburg belt and is being 

 more rapidly mined than any other. Each 

 acre of land has supplied about eight thou- 

 sand tons of coal, and at this rate the state 

 geologist of West Virginia estimates that 

 at the beginning of the next century there 

 will be no coal within one hundred miles 

 of Pittsburg. No one can fail to perceive 

 that this will be a terrible blow to the 

 manufacturing industries of that great 

 industrial center. In many sections of the 

 country where neither anthracite nor bitu- 

 minous coal is found large deposits of 

 lignite exist. This lignite can be used for 

 heating purposes in houses, but is worthless 

 for manufacturing purposes because the 

 amount of ash is so great that it will not 

 produce steam. In sections of country 

 where this is the only fuel supply it is 

 necessary to bring coal from long distances, 

 which makes it very expensive and puts a 

 great tax upon manufacturing industries. 



Our coal measures cover such an exten- 



sive area and the supply has seemed so 

 great that the conservation of our fuels has 

 received very little attention until within 

 the past few years. In 1903 the Tech- 

 nologic Branch of the United States Geo- 

 logical Survey was established in St. Louis 

 in connection with the exposition, and since 

 then a very extensive study of the fuel sup- 

 plies of the country has been carried on. 

 Dr. Holmes, the director of this branch; 

 Professor Lord, of the Ohio State Univer- 

 sity, in charge of the chemical work; Pro- 

 fessor Breckenridge, of the University of 

 Illinois, in charge of the boiler tests, and 

 Professor Fernald, of Case School of Ap- 

 plied Science, in charge of the gas pro- 

 ducer and gas engine tests ; are all members 

 of this society. The results obtained by 

 these men, all of them engineers, have been 

 of an astonishing character. It has been 

 found that the fine coal, the refuse of mines 

 and breakers, hitherto regarded as of little 

 value and sold at an extremely low price, 

 can be made into briquettes at a compara- 

 tively low cost and it is then as valuable 

 as the finest coal that can be obtained. It 

 has also been found that many non-coking 

 coals can, by proper methods, be coked as 

 readily as the best coking coals of Pennsyl- 

 vania. These two results alone are worth 

 many times as much as this bureau has 

 cost the government, for certain manufac- 

 turiag industries must have coke for fuel 

 and ia some sections it has been necessary 

 to bring the coke from long distances be- 

 cause no coking coal was at hand, although 

 large supplies of other coal were easily 

 obtainable. 



But perhaps the most wonderful resxdts 

 from these experiments have come through 

 the investigations in regard to the use of 

 coal in the gas producer and the gas engine. 

 With the old processes we do not obtain on 

 the average more than five per cent, of the 

 heat value of our coals. The steam engine 

 utilizes from four to ten per cent., but the 



