412 Capt. Noble and Mr. F. A. Abel [June 18, 



in the development of gas, of fairly uniform composition (and very uni- 

 form as regards the proportions which it bears to the solid), from powders 

 not differing widely in constitution from each other, are susceptible of 

 very considerable variations, regarding the causes of which it appears only 

 possible to form conjectures. Any attempt to express, even in a com- 

 paratively complicated chemical equation, the nature of the metamor- 

 phosis which a gunpowder of average composition may be considered to 

 undergo when exploded in a confined space would therefore only be 

 calculated to convey an erroneous impression as to the simplicity, or the 

 definite nature, of the chemical results and their uniformity under dif- 

 ferent conditions, while it would, in reality, possess no important bearing 

 upon the elucidation of the theory of explosion of gunpowder. 



The extensive experiments which the Committee on Explosive Sub- 

 stances has instituted, with English and foreign gunpowders of very various 

 composition, have conclusively demonstrated that the influence exerted 

 upon the action of fired gunpow r der by comparatively very considerable 

 variations in the constitution of the powder (except in the case of small 

 charges applied in firearms) is often very small as compared with (or 

 even more than counterbalanced by) the modifying effects of variations in 

 the mechanical and physical* properties of the powder (i. e. in its density, 

 hardness, the size and form of the grains or individual masses, &c.). 

 Hence it is not surprising to find that a fine-grain gunpowder, which 

 differs much more in mechanical than in chemical points from the larger 

 powder (R. L. Gr.) used in these experiments, should present decided dif- 

 ferences, not only in regard to the pressures which it develops under 

 similar conditions, but also as regards the proportions and uniformity of 

 the products which its explosion furnishes. On the other hand, the dif- 

 ferences in regard to size o individual masses, and other mechanical pe- 

 culiarities, between the R. L. G-. and pebble powdars are, comparatively, 

 nob so considerable, and are in directions much less likely to affect the 

 results obtained by explosions in perfectly closed spaces. 



Again, the analysis of solid residues furnished by various kinds of gun- 

 powder, which presented marked dissimilarity in composition, did not esta- 

 blish points of difference which could be traced to any influence exerted 

 by such variations ; indeed the proportions of the several products com- 

 posing residues which were furnished by one and the same powder, in 



* The desirability of applying these means to effecting modifications in the action of 

 fired gunpowder was pointed out by Colonel (now General) Boxer in a memorandum 

 submitted to the~War Office in 1859; and the first Government Committee on Gunpowder, 

 soon afterwards appointed (of which General Bo>>er and Mr. Abel were members , ob- 

 tained successful results, which were reported officially in 1864, by limiting the altera- 

 tions in the manufacture of gunpowder intended for use in heavy guns to modifications 

 in the form, size, density, and hardness of the individual grains or masses, the composition 

 of the powder remaining unaltered. The Committee on Explosive Substances Lave 

 adhered to this system in producing gunpowder suitable for the largest Ordnance of the 

 present day. 



