coal: the resource and its full utilization. 
11 
or wholly recovered according to the details of the practice. Where 
the by-products are wholly recovered, no part of the coal is wasted. 
In round numbers, 1 ton of bituminous coal yields 1,440 pounds of 
coke, 10,000 cubic feet of gas, 22 pounds of ammonium sulphate, 1 
2J gallons of crude benzol, and 9 gallons of tar. 2 Half of the gas is 
available for use as fuel or in lighting; the ammonium sulphate is a 
valuable fertilizer; benzol is an excellent motor fuel, a substitute for 
gasoline ; tar is a waterproofing material used for making roofing and 
for dressing roads. 
These four first-products have an unlimited field of usefulness as 
such. In addition, three of them represent raw materials upon which 
important fields of present industry are dependent and upon which, if 
bountifully supplied, new industrial activities of far-reaching conse- 
quences can be reared. The ammonia, recovered as such, instead of in 
the form of ammonium sulphate, forms the basis of modern refrigera- 
tion and is used for making explosives and chemicals. Benzol is a 
mixture of substances, including the deadly toluol, which can be made 
to yield explosives, dyes, drugs, medicines, solvents, photographic 
developers, and other chemicals. Tar, likewise, yields a 10 per cent 
fraction which may be turned into explosives, disinfectants, dyes, 
drugs, and other products. Benzol and tar, in short, are the basis of 
the coal-tar industry, inadequately developed as yet in America — an 
industry which Germany has intensively cultivated to an advantage 
now well known. 
The by-product oven is complicated and costly to install 3 and to 
operate. Like the beehive oven, its prime purpose is to deliver coke, 
but it can compete with the beehive only when the by-products can 
be disposed of with sufficient advantage to cover the greater expense 
of the by-product practice and contribute a margin of incentive. 
The development of by-product coking in the United States has been 
slow, considering the social and national importance of the possi- 
bilities inherent in this activity. At the beginning of 1918, the 
beehive oven still turned out over half of the coke produced, although 
war conditions and war demands have given a strong impetus to 
by-product coke development. 
The reasons for the lagging growth of by-product coking in America 
are clear and specific. There has not been a sufficient demand for 
all five of the products, due to inadequate industrial utilization of gas 
and the practical lack of a coal-tar industry. 4 Our economic ad- 
justment gave a stable demand for only two of the products, coke and 
1 The solid form in which much of the ammonia is recovered. 
2 These figures are approximate. They vary with practice and grade of coal. 
3 The cost of constructing a modem by-product coke oven plant of minimum commercial size in normal 
times would be nearly a million dollars; under present conditions, more than twice that amount. 
« Also the apparent abundance of gasoline put no demand upon benzol as a motor fuel , contrary to the 
experience of European countries. 
