greater power are, in fact, known, but the increase of power is almost invariably accompanied by chemical instability and mechanical sensitiveness to shock and friction, which make it difficult to apply such explosives in a practical way. Advances have been made in the discovery and application of useful in- termediary explosives of the tetryl type, and there is room for further advances in this direction, but these are limited in scope. In the sphere of propellants, it appears likely that advances may be made in the direction of improvements on the present methods of gelatinizing by volatile solvents, the introduction of compounds of greater stability, and the attainment of greater power without the erosion which has hitherto limited it.
All investigations must naturally be subservient to a great extent to economic considerations. In the World War the availa- bility of raw materials was a factor of decisive importance, and this limited the choice of compounds which could be made in large quantities. The necessity of importing the materials
necessary for the manufacture of explosives is bound to direct attention to materials which can be obtained from home sources. This lends a special significance to the fixation of atmospheric nitrogen in the form of ammonia and nitric acid. It points also to the further development of perchlorates, which can be manu- factured electrolytically from materials obtainable in most coun- tries; and further investigations may overcome the present difficul- ties in the use of liquid oxygen.
In the future, as in the past, the advances will probably lie mainly in the direction of improvements in the methods of appli- cation of explosives, unless some method should be discovered whereby the enormous energy of disintegration of the atoms could be released at will; this cannot however be said to be within sight, and it is perhaps well that such stupendous forces should be withheld from human control until a greater sense of interna- tional responsibility is developed in mankind.
(C.D.C.;R.C.F.)
