300 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1908. 



dinaiy ones, just as in the case of the old Wack powder. In the 

 author's opinion, and his view is shared by very eminent colleagues, 

 there can be no doubt that nitrocotton (and for the matter of that 

 any other nitrocellulose) is not a suitable ingredient for a service 

 powder. Having built or reconstructed a number of works and seen 

 quite half of all those in Europe, he ventures to speak with some 

 authority. Let us again recapitulate its defects. Made from a 

 material which is most complex and liable to form unstable com- 

 pounds, we elect to use it in a form which can neither be clean, nor of 

 uniform growth, nor even of constant composition. The conditions 

 of manufacture are such that in the absence of very special precau- 

 tions the nitrocotton retains unstable compounds and is liable to 

 decompose. Under the influence of heat, of certain additions or in- 

 gredients, of unsuitable treatment or friction, the nitrocotton may 

 decompose and react in a progressive manner upon the other ingre- 

 dients. It requires a solvent in order to be brought into a physical 

 state which will permit the rate of burning of the powder to be regu- 

 lated. Such solvent, if volatile, requires prolonged heating to drive 

 it off as completely as possible. This heating helps to shorten the life 

 of the powder, and any solvent remaining behind affects its ballistic 

 properties. Nitrocellulose is not a uniform compound by any means, 

 and it is almost impossible to make sure that every batch shall have 

 the same composition and effect. The latter by no means depends on 

 the percentage of nitrogen being the same, though this condition may 

 be fulfilled by suitable blending. For instance, a mixture of soluble 

 and insoluble nitrocellulose would not have the same effect as a 

 nitrocellulose prepared direct, although each may contain the same 

 percentage of nitrogen. 



The question will naturally be asked, What will be the powder of 

 the future? If we may venture a prophecy, the future belongs to a 

 stable nitrocompound of the aromatic series, perhaps in conjunction 

 with nitroglycerin. Such nitrocompounds have already been pro- 

 posed, and sooner or later one will be found that meets all require- 

 ments. Although every service will be reluctant to make a change, 

 yet having learned to appreciate the value of scientific research, some 

 government will be sure to make a bold plunge, when all others will 

 soon follow suit. 



