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



phosis. In the case of pebble powder, the mechanical condition (size and 

 regularity of grain) of which is perhaps more favourable to uniformity of 

 decomposition, under varied conditions as regards pressure, than that of 

 the smaller powders, the amount of sulphur which remains as potassium 

 polysulphide is very uniform, except in the products obtained at the lowest 

 pressure ; and it is noteworthy that with E. L. G-. powder, under the 

 same conditions, comparatively little sulphur escapes ; while in the case of 

 F. Gr. powder, under corresponding circumstances, there is no free sulphur 

 at all. 



7. But little can be said with regard to those products, gaseous and 

 solid, which, though almost always occurring in small quantities in the 

 products, and though apparently, in some instances, obeying certain rules 

 with respect to the proportion in which they are formed, cannot be 

 regarded as important results of the explosion of powder. It may, how- 

 ever, be remarked that the regular formation of such substances as 

 potassium sulphocyanate and ammonium carbonate, the regular escape 

 of hydrogen and sulphydric acid from oxidation, while oxygen is occa- 

 sionally coexistent, and the frequent occurrence of appreciable proportions 

 of potassium nitrate, indicate a complexity as well as an incompleteness 

 in the metamorphosis. Such complexity and incompleteness are, on the 

 one hand, a natural result of the great abruptness as well as of the com- 

 parative difficulty with which the reactions between the ingredients of 

 the mechanical mixture take place ; on the other hand, they favour the 

 view that, even during the exceedingly brief period within which 

 chemical activity continues, other changes may occur (in addition to the 

 most simple, which follow immediately upon the ignition of the powder) 

 when explosions take place at pressures such as are developed under 

 practical conditions. 



The tendency to incompleteness of metamorphosis, and also to the 

 development of secondary reactions, under favourable conditions, appears 

 to be fairly demonstrated by the results obtained in exploding the different 

 powders in spaces ten times that which the charges occupied (Experi- 

 ments 8, 1, and 16). It appears, however, that, even under conditions 

 apparently the most favourable to uniformity of metamorphosis (namely, 

 in explosions produced under high pressures), accidental circumstances 

 may operate detrimentally to the simplicity and completeness of the 

 reactions. But the fact, indisputably demonstrated in the course of 

 these researches, that such accidental variations in the nature of the 

 changes resulting from the explosion do not, even when very consider- 

 able, affect the force exerted by fired gunpowder, as demonstrated by the 

 recorded pressures, &c., indicates that a minute examination into the 

 nature of the products of explosion of powder does not necessarily con- 

 tribute, directly, to a comprehension of the causes which may operate in 

 modifying the action of fired gunpowder. 



In illustration of the analytical results obtained in these investigations 



