IQ^ ON THE EFFECTS OF HEAT. 



think, tl)at Mr. H^tchett has clearly proved, that coagu- 

 lated albumen is possessed of chemical properties essentially 

 different from those which albumen possesses iu a fluid 

 state. 



Mr. Dalton's " I perceive from a note in Dr, Thompson's System of 

 *''"^' Chemistry, that Mr. Dalton supposes the particles of 



gasses, to be surrounded with atmospheres of heat ; but, as 

 1 have never seen Mr. Dalton's work, I cannot pretend to 

 say how far he may have anticipated any thing which I 

 have said. Dr. Higgins is undoubtedlv the author of the 

 theory, and I have endeavoured to extend it to all the che- 

 mical phenomena, which recurred to my recollection. 



Mr. Gough on From the same excellent work, (Dr. Thompson's Che- 



the elasticity njig|-,.yj J j^^ve become acquainted with Mr. Gough's expe- 

 « caoutchouc. •' ' _ ^ or 



riments on the elasticity of caoutchouc. When I wrote the 



paper above I was reading this work, but had not read so 

 far as the part which gives an account of these experi- 

 ments* : I was therefore very agreeably surprised, to find 

 the same conclusion drawn from experiment, which I had 

 previously deduced from theory, viz: that caloric is the 

 cause of elasticity. 

 ffFectof Many substances (^. g. carbon) will not combine with 



" ' oxigen, until ignited ; it is perhaps needless to observe, 



that the addition of caloric equalizes the density of the at- 

 mospheres, which surround the particles of these bodies, 

 and that this is the cause of their combination. 

 locrfase of It has been objected, by the French chemists, to the theory 



{jravuy of ^^f jy^. jj^y^, respecting the metallic bases of the fixed 

 whenoxideJ alkalis, &c. : that, if potash (for example) were an oxide of 

 accounted for. potassium, its specific gravity, like that of all other metallic 

 oxides, should be less than that of the metal, from which it 

 is formed. Not to insist upon the circumstance, that pot- 

 ash is a hydrate of the oxide of potassium, I think it may 

 be clearly conceived, according to the principles stated 

 above, that oxigen may be so far condensed by theabstrac-. 

 tion of caloric, as to increase the density of potassiunr, 

 (or perhaps even of any other metal,) considerably. Ac- 

 cordingly we find, from the experiments of Gay-Lussac and 



* This postscript was sent some w^eks after the letter to which it is 

 annexed: C 



Thenard 



