TTieort/ of Gunpowder. 507 



regularly decreasing temperatures are to be observed. Through- 

 out the entire duration of the experiment the liquid is kept in 

 motion by the stirrer. 



An experiment executed in this manner with great care, gave 

 the following values for w : — 



Observed Observed 



Time t. Temperature. 



(y 19-86 



5' 19-83 



6' 19-83 



Explosion 67' 



Maximum temperature 16' 21*10 



26' 20-98 



56' 20-60 



The weights of the separate parts of the apparatus were, — 



Weight of the Glass 79- 14 grms. 



„ „ Brass 13211 „ 



„ „ Platinum .... 3-50 „ 



„ ,, Gunpowder . . . 0-7152 „ 



„ Water 376-40 



The value in water of all these weights is 4047 grms. These 

 404-7 grms. water were raised 1°-14 C. by the heat produced 

 in the combustion of 0-7125 grm. gunpowder. 



Hence the heat of combustion of the powder used in our ex- 

 periments, that is, the quantity by which one part by weight of 

 water is heated by the combustion of one part by weight of 

 powder, is 643°-9 C. 



A small correction is necessary in this number ; for the 

 combustion of the 0-7125 grm. powder took place in the her- 

 metically sealed tube which was full of air. Hence the com- 

 bustible gaseous products of decomposition would burn, and 

 thereby produce a small quantity of heat which does not really 

 belong to the true decomposition. According to the scheme D, 

 the 0-7125 grm. of powder taken for the experiment gave, — 

 000669 grm. Carbonic oxide. 

 000014 „ Hydrogen. 

 0-00128 „ Sulphuretted hydrogen. 

 Assuming with Favre and Silbermann that the heat of combus- 

 tion of these three constituents are respectively 2403, 34462, 

 and 2741, the heat produced by their combustion, compared 

 with a gramme of water, would amount to 24°-4 C. And 

 the above number would accordingly have to be reduced by that 

 quantity, which would place the real heat of combustion at 



619°-5 C. 



The heat, on the other hand, produced by tho increased press- 



2 L 2 



