Cir> Examination of the received DoBrines 



The rcfults obtained by the preceding experiment, though 

 onlv a fmall part of the effect could be appreciated, are fuffi- 

 eienl to afcertain the facl it was meant to eftablifh — that the 

 doctrine which afferts heat to exitt in a latent ftate in the 

 almol'phere, and confequently to be not feparable from it 

 without a chemical decomposition of the air, cannot be true, 

 otherwife mechanical preffure and chemical dccompofilion 

 mean the fame thing, which the advocates for the exiftence 

 of heat in two diftin£t ftates will hardly maintain. 



But the effect would be much more (biking, and the 

 quantity of heat could even be comparatively eftimated by 

 employing in the experiment fuch an apparatus as would 

 enable us, in fome meafure, to intercept the heat as it paffes 

 off from the whole furface of the air-holder, and accumulate 

 it in fome liquid. 



After thinking on various contrivances, with this view, a 

 method of conitructing fuch an apparatus occurred to me, a 

 defcription of which, though I have not yet had time to carry- 

 it into execution, I beg leave to lay before the Society. 



Defcription of a Gafo-Calorimcter. 



The gas-holder A, fig. 2. of any capacity, fay a quart, con- 

 ftructed of tinned copper or any other metal, well foldcred 

 and riveted at the joinings, thould be made double, or, in 

 other words, the veficl, properly called the gas-holder, lhould 

 be covered with another of the fame fhape made of thin metal, 

 (as tinned iron) in fuch a manner that the two may not 

 touch each other except at the lower part, where they are 

 fitted on, and foldered fait to one common collar. By this 

 means a fpace is left between the exterior furface of the gas- 

 holder and the interior of the cover, to be- filled with a fluid 

 for the purpofe which fliall immediately be liated. The in- 

 terior vefl'el, which is to receive the gas, is open at the collar, 

 and into this collar is fitted the cock B, made of glafs, be- 

 caufe of the mercury to be employed in the experiments, and 



the purpofe of e jualifing the Waft. In thefe the increafe of temperature 

 is more fe- fi)!e .han in the blowing cylinder. It takes place at a cbn- 

 fidc'rable ditlance from any mechanical friction, and i- therefore evidently 

 Di'oducal by heat extricated from the air. 



v for 





