70 



Since the quantities of caloric which bodies contain are as their 

 temperatures and capacities conjointly, tiie caloric proceeding froni 

 the combustion of c of charcoal is represented by C x c x (^ + <) 

 (where C = capacity of charcoal, c its quantity, 6 its temperature 

 before combustion, and t the number of degrees of Fahrenheit 

 which the combustion of a portion of charcoal would heat an 

 equal portion ;) and supposing all this to be found in the gases, 

 their temperature (— x) x A a = C c {6 + t), where A and a 

 are the capacity and quantity of them, therefore x = '' ^ i^ "^ ''' • 



but a, as is well known, consists of 4 volumes of nitrogen and I 

 of carbonic acid, or, by weight, of 9.3 nitrogen + 3.6 carbonic 

 acid, and from this we can compute A.{d) As the limit is when 

 X = 0, dy.Aa-cCx (i' + O and 6 (^A a -^ C c) = c C h 



c Ct , , . 9.3 N + i . 6 . P , . _ 



or0 = T;^—M^ A = Q.s + s Te and ^ - 



ct cCt 



\ 9.3+3.6 J ^ I 



or = 



rZTc') No^ 



w 9. 3 + 3 . 6 / I 



we know C t by experiment, Lavoisier, Crawford and Dalton have 

 all given values of it which differ from each other considerably. 

 I prefer Lavoisier's, which was made in the calorimetei- described 

 by him, and is, that 1 pound of charcoal gives as much heat as is 

 equivalent to the fusion of 96 pounds of ice, 100 may be taken as 



(d) Let two bodies whose capacities are N and P, be mixed in the quantities n and;?, 

 to hnd the mixtures, capacity A. The quantities of caloric contained in tliem before and 

 aftermixture ar- the same, as there is no chemical action, but these are as the products 



. . N n + Pp, 

 of their weights and capacities, therefore Nn+ P p = (« + p) A, and A = „ ^ p 



but here n the quantity of nitrogen = (9. 3) c and p that of carbonic acid = (3. 6) c. 



