248 Dr Davy on the Combinations of 



These trials were made at the ordinary temperature of the at- 

 mosphere, which at the time was pretty constant at 60°. 



Though the salt formed by the direct union of carbonic acid 

 and ammonia possesses singularly alkaHne properties, and is as far 

 as possible from being neutralised, yet it has very properly been 

 called carbonate of ammonia, and been considered as composed 

 of one proportion of each of its elements ; and, I may remark, 

 that, in accordance with this, it is decomposed by a solution of 

 the neutral muriate of lime without effervescence, producing a 

 neutral mixture. 



2. On the Sesquicarbonate of Ammonia* 



I apply the term Sesquicarbonate, after Mr Richard Phillips, 

 to that salt of ammonia commonly called the subcarbonate, 

 which is obtained by the mutual decomposition, by means of 

 heat, of carbonate of lime and salammoniac. 



The results of my experiments on the analysis of this salt, 

 agree, as nearly as might be expected, with those of Dr Ure * 

 and of Mr Richard Phillips -f, according to which the sesquicar- 

 bonate may be considered as composed of one proportion of am- 

 monia, of one and a half of carbonic acid, and of one of water. 



The method of analysis which I have applied to this salt, 

 and also to the neutral or bicarbonate, is different from those 

 employed by these gentlemen. It is briefly as follows. The 

 proportion of carbonic acid has been ascertained by decomposing 

 the salt J over mercury in a graduated tube, by means of dilute 

 muriatic acid in excess, making due allowance for the gas ab- 

 sorbed by the liquid §. The proportion of ammonia has been 

 learned indirectly, by decomposing the salt by means of dilute 

 muriatic acid in excess, driving off the excess of acid by expo- 

 sure of the muriate, in the capsule in which it has been formed, 

 to the temperature of boiling water ; dissolving this salt in dis- 



• Annals of Philosophy, voL x. p. 203. 



•|- Quarterly Journal of Science, vii. 294. 



$ The salt is conveniently introduced wrapped in fine bibulous paper. 



§ Strong muriatic acid is capable of absorbing about half its volume of car- 

 bonic acid gas at ordinary temperatures; when moderately diluted with 

 water, its power of absorption is much the same ; and it is not sensibly altered 

 by the addition of a little muriate of ammonia. 



