X$2 Heat extricated in Combtiftion. [Book I! , 



fome and complicated apparatus. By this confideration, Mr. de la 

 Place and I have hitherto been prevented frpm making the at- 

 tempt. In the mean time, the place of fuch an experiment may 

 be fupplied by calculations, the refults of which cannot be very far 

 from truth. 



'. Mr. de la Place and I deflagrated a convenient quantity of 

 uitre and charcoal in an ice apparatus, and found that twelve 

 pounds of ice were melted by the deflagration of one pound of 

 i-.itre. We (hall fee, in the fequel, that one pound of nitre is cora- 

 pofed, as under, of 



Pot-alh 7 oz. 6 gros 51. 84 grs. = 



Dry acid 8 i 21.16 == 4700.16. 



The above quantity of dry acid is compofed of 

 Oxygen 6 cz. $ gros 66.34 grs. 3738.34 grs. 

 Azote i 5 25.82 = 961.82. 



* By this we find that, during the above deflagration, 2 gros i \. gr 

 of charcoal have fuffered combuiHon, along with 37.38.34 grs. or 

 6 oz. 3 gros, 66.34 grs. of ozygen. Hence, iince 12 Ibs. of ice 

 were melted during the combuftion, it follows, that one pound of 

 oxygen burnt in the fame manner would have melted 29.58320 Ibs. 

 of ice. To which the quantity of caloric, retained by a pound of 

 oxygen after combining with charcoal to form carbonic acid gas, 

 being added, which was already afcertained to be capable of melt- 

 ing 29.13844^3. of ice, we have for the total quantity of caloric 

 remaining in a pound of oxygen, when combined with nitrous gas 

 in the nitric acid 58.72164; which is the number of pounds of ice 

 the caloric remaining in. the oxygen in that ftate is capable of 

 melting. 



' We have before feen that, in the ftate of oxygen gas, it con- 

 tained at leaft 66.66667 ; wherefore it follows that, in combining 

 with azote to form nitric acid, it only Icfes 7.94502. Farther ex- 

 periments upon this fubjeci are neceflar.y to ascertain how far the 

 refults of this calculation may agree with direft faft. This enor- 

 mous quantity of caloric retained by oxygen in its combination 

 into nitric acid, explains the caufe of the great difengagement of 

 caloric during the deflagrations of nitre; or, more ftriftly fpeaking, 

 upon all occafions of the decompofition of nitric acid. 



' Having examined fcveral cafes of fimple combuftion, I mean 

 now to give a few examples of a more complex nature. One pound 

 of wax-taper being allowed to burn ilowly in an ice apparatus, 

 melted 133 Ibs. 2 oz. 53 grps of ice. According to my experi- 



ments 



