BY COMPKESSION. 'J^)^ 



have no tendency to rulh out j the heat employed to open the 

 barrel being barely fiifficient to foften the metal. Since, then, 

 the opening of the barrel was accompanied by the difchargeof 

 elaftic matter in great abundance, it is evident, that this mqft 

 have proceeded from fomething fuperadded to the air originally 

 included, which could be nothing but the carbonic acid of 

 the carbonate. It follows, that the calcination had been, in 

 part at ieaft, internal; the feparation of the acid from the 

 earthy matter being complete where the heat was flrongefl, 

 ard only partial where the intenfity was lefs. 



The chemical principles ftated in a former part of this Part of the in- 

 paper, authorffed us to expecl a refult of this kind. As eluded carbonate 



, ' . . was calcined, 



heat, by increafing the volatility of the acid, tended to another part re- 

 feparate it from the earth, we had reafon to exped, that, !f'"''"S.'ts acid. 



11/- -^ 1 ■ i-/y Real.ining on 



under the lame comprelhon, but m different temperatures, this fad, 

 one portion of the carbonale might be calcined, and another 

 not : And that the leaft heated of the two, would be the leaft 

 ^xpofed to a change not only from want of heat, but like- 

 wife in confequence of the calcination of the other mafs ; 

 for the carl)onic acid difengaged by the calcination of the 

 hottefl: of the two, muft have added to the elaflicity of the 

 confined elaftic fluid, fo as to produce an increafe of com- 

 prefiion. By this means, the calcination of the coldeft of the 

 two might be altogether prevented, and that of the hotteft 

 might be hindered from making any further advancement. 

 This reafoning feemed to explain the partial calcinations 

 which had frequently occurred where there was no proof of 

 leakage ; and it opened fome new pra6iical views in thefe 

 experiments, of which I availed myfelf without lofs of time. 

 If tlie internal calcination of one part of an inclofed mafs, 

 promotes the compreflion of other raafies included along with 

 it, I conceived that we might forward our views very much by 

 placing a fmall quantity of carbonate, carefully weighed, in 

 the fame barrel with a large quantity of that fubftance ; and 

 by arranging matters fo that the fmall fiducial part fliould 

 undergo a moderate heat, while a ftronger heat, capable of 

 producing internal calcination, fliould be applied to the reft 

 of the carbonate. In this manner, I made many experiments, 

 and obtained refults which feemed to confirm this reafoning, 

 and which were often very fatisfaftory, though the heat did 

 not always exert its greateft force where I intended it to 

 do fo. 



On 



