of the Laisos of Elastic Fluids.^ 1 3 7 



quantity of caloric ; and, generally, the whole caloric of any 

 gas is reciprocally as the square root of its density. These 

 are consequences which may be experimentally examined. 

 We have unfortunately, however, no good experiments on this 

 part of the subject, and therefore cannot come to a numerical 

 comparison. But as far as experiments go, I conceive they 

 make against the general consequences of M. Laplace's 

 theory; namely, that the same compression however made 

 develops the same quantity of heat. I have always under- 

 stood that rapidity of compression is essential to the eleva- 

 tion of temperature, and that in very slow compressions no 

 rise of temperature has been observed. This M. Laplace 

 would account for on the supposition of insensible abstraction 

 by the surrounding bodies ; but was such the case, the tem- 

 perature evolved would always be sensible by immersing the 

 apparatus in water, and properly insulating it; for it would be 

 absurd to suppose it to become latent, unless the water change 

 its state. 



I shall presently show that a very easy consequence of 

 M. Laplace's theory is, that the elasticities being the same, 

 the absolute quantities of caloric are equal in equal volumes 

 of all gases. By his equation 2, therefore, equal and si- 

 milar compressions of equal volumes of any two gases must 

 evolve equal portions of caloric, provided the temperatures 

 were at first equal. Now it is well known that the specific 

 heats or capacities of different gases for caloric are different. 

 Applying consequently M. Laplace's theorem, that the caloric 

 expressed is as the difference of the square roots of the pres- 

 sure, it follows that equal and like compressions of equal 

 volumes of different gases, the primitive temperatures and 

 pressures being also equal, develop the same part of the whole 

 caloric of each, and therefore unequal^ not equal quantities of 

 caloric. Hence the results of the theory alone on compres- 

 sion are contrary to those of the theory on the same subject, 

 applied to established facts, which would not be the case if 

 the theory were correct. 



It appears by the theory I have expounded, that the masses 

 of the particles of the moving sides by which the compressions 

 are effected, have an influence on the' elevation of temperature. 

 AH other things being alike, the greater the masses of the par- 

 ticles ill the compressing sides, the greater the rise of tempera- 

 ture by e(jual celerities of compression, even in the same gas. 

 When therefore equal compressions are equally and similarly 

 made on equal volumes of the same gas at the same tempera- 

 ture and elasticity, the elevations ot temperature are as the 

 masses of a particle of each compressing side directly. This 

 Vol. G2. No. 301. ////:/. 1823. S is 



