1836.] Analysis of the residuum of fired gunpowder. 7 



is, with what was this potassa combined ? It is very clear 

 that it was not, and from the course followed, could not be 

 introduced during the analysis, because no potassa was used 

 under any of its combinations. And as it is evidently a 

 surplus beyond the quantity in combination with the sulphur, 

 and. the sulphuric and carbonic acids, the most reasonable 

 supposition seems to be that it existed in combination with 

 nitric acid, and was simply saltpetre that had escaped de- 

 composition. I shall therefore so account for it, and the 

 quantity of saltpetre which it is equivalent to is grains 12*39. 



40. — The ultimate analysis of the 50 grains of matter ex- 

 perimented on will then stand thus : — 



Sulphate of potassa , . .17.22 (36) 



Carbonate do 14.35 (36) 



Nitrate do 12.39 (39) 



Sulphuret of potassium 3.78 (36) 



Sulphuretted hydrogen 0.87. (36) 



Un consumed charcoal , . . . 0.25. . , . , .(21) 



Earthy matter..,. 0.65, (21) 



Experimental error 0.49 



Total grains. .50.00 



41. — It is not to be inferred from the foregoing quantity of 

 saltpetre that nearly 25 per cent, of what is originally in the 

 gunpowder is undecomposed, or unnecessary— for this quan- 

 tity has reference only to the solid matter remaining after 

 gunpowder has been fired. And I am inclined to think that 

 this quantity is accidental, and is to be attributed to the im- 

 perfect mixture of the substance (3) before the experiment 

 was commenced. I have made two other analyses of 100 

 grains each, after the original matter was better mixed, and 

 the quantity of saltpetre in those experiments is exhibited at 

 only 14 or 15 per cent. As these experiments were conduct- 

 ed precisely in the same manner as the 50 grain experiment, 

 which has been fully explained, I shall here insert them as a 

 part of the original investigation. 



