of the Terrestrial Globe. 245 



degree (.07) more. Thus, instead of a reduction of the tempera- 

 ture, we should have found a slight increase. But we should 

 require to wait some additional three or four years, before we can 

 affirm with certainty that this slight difference is not owing to 

 some irregular and accidental oscillation. 



SOME EXPERIMENTS AND OBSERVATIONS ON THE COMBINA- 

 TIONS OF CARBONIC ACID AND AMMONIA. By JOHN DAVY, 



M, D., F,R. S. Communicated by the Author. 



In referring to the note-books of my brother the late Sir 

 Humphry Davy, for the purpose of drawing up a memoir of his 

 life, I have found an account of some experiments, which he 

 made in 1799 at Bristol, on the salts of ammonia, and more es- 

 pecially on the carbonates. He then ascertained that the common 

 subcarbonate (the sesquicarbonate) is partially decomposed by 

 heat, and that a portion of its carbonic acid is disengaged ; and 

 he believed, that when it is sublimed a new salt is formed, more 

 volatile than any known carbonate, containing a larger propor- 

 tion of ammonia, of most pungent ammoniacal odour, and deli- 

 quescent. The only published notice of these experiments, oc- 

 curs in his researches on the nitrous oxide, introduced inciden- 

 tally in connection with the analysis of the nitrate of ammonia. 

 'He says, " In making the analysis of the carbonate of ammonia, 

 I discovered that there existed many varieties of this salt, con- 

 taining very different proportions of carbonic acid, alkali, and 

 water ; the carbonic acid being superabundant in it, in propor- 

 tion as the temperature of its formation was low, and the alkali 

 in proportion as it was high ; and not only that a different salt 

 was formed at every different temperature, but, likewise, that 

 the difference was so great that the carbonate of ammonia 

 formed at 300°, contained more than 50 per cent, alkali, whilst 

 that produced at 60° contained only 20 *."" 



It appears from a note to this paragraph, that it was his in- 

 tention to have given a particular account of these experiments, 



• " Researches, chemical and philosophical, chiefly concerning nitrous 

 oxide, &c." p. 76. 



