364 



Dr. EL Debus. 



[Feb. 23, 



same harrel, the one from the upper, the other from the lower parts. 

 These two samples showed a difference of no less than 1*54 per cent, 

 of the weight of the powder in the amount of carbon they contain, or 

 the weight of carbon is by one-seventh greater in the second 

 than in the first sample. Mr. Wills found 1*31 per cent, of sulphur 

 less than Noble and Abel in the same description of powder. Such 

 differences in the composition of samples of powder of the same 

 nature, together with the usual errors attaching to complicated and 

 difficult analytical operations, are almost sufficient to explain the 

 variations in the proportions of the products of the combustion of 

 gunpowder, as found by Messrs. Noble and Abel, without requiring 

 a theory like the one proposed by M. Berthelot for that purpose. 



6. Noble and Abel analysed the products of explosion by means of 

 Bunsen and Schischkoff's method. The author has proved that by 

 the treatment of the solid powder residue according to this method 

 a portion of the potassic sulphide is converted into potassic hypo- 

 sulphite, and under certain conditions into potassic sulphate. The 

 quantities of the two salts so produced vary in different experi- 

 ments. Hence, the fluctuations observed by Noble and Abel in the 

 relative quantities of potassic sulphide, potassic sulphate, and potassic 

 hyposulphite are partly, if not entirely, due to the method of analysis. 

 Potassic hyposulphite is decomposed at temperatures above 225° ; from 

 this fact, as well as from a comparison of the oxygen in the original 

 powder with that of the products of explosion, it follows that the 

 potassic hyposulphite found in powder residues must be regarded as 

 the product of the analytical method. 



7. It is well known that the higher sulphides of potassium attack 

 metals with great energy at a white heat. Noble and Abel exploded 

 their powders in a hermetically closed steel cylinder at high pressures, 

 and the products remained after explosion from one to two minutes in 

 a fluid condition at a white heat in contact with the iron of the 

 apparatus. These products contain potassic disulphide. The descrip- 

 tion given by Noble and Abel of their solid powder residues indicates 

 that they contain ferrous sulphide. The absorption of a portion of 

 the sulphur by the iron will increase the amount of potassic carbonate 

 and diminish the quantities of potassic sulphate and disulphide. The 

 quantity of sulphur so uniting with iron depends on pressure, time of 

 cooling, and other conditions, and will vary in different experiments. 

 We have then in the formation of ferrous sulphide another cause of 

 the fluctuation in the quantities of the products of explosion observed 

 by Messrs. Noble and Abel. 



8. It follows from the statements given under Nos. 5, 6, and 7, that 

 there is no reason to assume that the chemical metamorphosis of gun- 

 powder cannot be represented by an equation. 



9. Noble and Abel calculate the total weight of the solid residue, 



