During the progress of the European conflict the British had developed an explosive they called amatol, which is a mixture of trinitrotoluol—T. N. T.—and ammonium nitrate. As this had proved to be entirely satisfactory in actual service on European battle fields, and as ammonium nitrate could be produced here in large quantities, we adopted it.
The Ordnance Department eventually put into effect a standard policy for the use of high explosives. Every effort was being made to conserve the supply of T. N. T., and consequently this explosive was specified for the shell of smaller calibers only. The standard filling scheme was as follows: T. N. T. for shell between and including the calibers of 75-millimeter and 4.7-inch; amatol for shell of calibers between 4.7-inch and 9.2-inch, including the latter; ammonium picrate, or explosive D, for shell of 10-inch caliber and higher. While these were the standards the scheme was not always followed rigidly. As a matter of fact amatol was loaded into shell of all sizes and so was T. N. T., although explosive D was never used in shell smaller than those for the 10-inch guns. These departures from standard practice were due to the necessity for keeping certain plants in production and to other special causes and exceptional circumstances.
Production of large quantities of T. N. T. and ammonium nitrate was the first big problem to be solved by the high-explosives section of the Ordnance Department. All the work of the explosives section can be subdivided under four group heads—raw materials, propellants, high explosives, and loading.
RAW MATERIALS.
The first steps taken in the endeavor to meet the need for raw materials were to increase greatly the available means for obtaining toluol, phenol, caustic soda, sodium nitrate, sulphuric and nitric acids, ammonia liquor or aqua ammonia, and to attempt to provide a substitute for cellulose in case a shortage of cotton should render its use necessary.
How to increase the supply of toluol, the basic raw material from which T. N. T. is made, was the greatest and most pressing of all the problems in regard to the existing raw materials. Before the war the sole source of this ingredient was from by-product coke ovens. The monthly capacity of these ovens in 1914 was, approximately, 700,000 pounds. By April, 1917, when we stepped into the conflict, this capacity had been increased to 6,000,000 pounds a month.
By the time the armistice was signed our efforts for greater production had been carried on so successfully that the supply had been increased to 12,000,000 pounds a month, and the average cost of this was only 21 cents a pound. This tremendous increase of production not only took care of all demands for commercial purposes and permitted the shipment of about 11,000,000 pounds to the allied Governments, but was more than ample to take care of our own entire explosives program, leaving a stock on hand December 1, 1918, of 17,000,000 pounds.
A few details of how this tremendous increase in production was brought about through the energies of the officials charged with this task and the most efficient and whole-hearted cooperation of patriotic business concerns are interesting.
Three general sources existed from which toluol was obtained: first, from the by-product recovery coke ovens; second, by the stripping or absorbing of toluol from carbureted water and coal gas; and third, by the cracking or breaking down of oils.