254 Dr Davy on the Combinations of 



ducdon of a little carbonate, as well as the separation of some 

 ammonia ; and the spiritus ammoniae, and the spiritus ammo- 

 nise aromaticus of the London Pharmacopoeia, appear to be ex- 

 amples of this kind of solution ; they effervesce distinctly with 

 an acid, but less powerfully than a solution of the same strength 

 of the carbonate of ammonia. * 



3. On the Bicarbonate of Ammonia, 

 Of this salt I have examined various specimens, procured by 

 four different methods : J st, By the exposure of the sesquicar- 

 bonate to the atmosphere ; ScZ/e/, By passing carbonic acid gas, 

 by means of Nooth's apparatus, into a strong solution of the ses- 

 quicarbonate ; Sdli/, By the action of alcohol on the sesquicar- 

 bonate, either in powder or in solution ; and, 4}thli/, By heating 

 sesquicarbonate in a saturated solution of this salt under pres- 

 sure, and cooling the concentrated solution thus produced, also 

 under pressure. The salt procured by the first and third me- 

 thod is in the state of powder ; that obtained by the two other 

 processes is crystallized, in one instance in rhomboidal plates ; 

 in the other, (by the second method), as is well known, in 

 prisms, commonly four-sided, with pyramidal terminations. 



The following table shows the results I have obtained, in sub- 

 jecting specimens of this salt to the same process of analysis as 

 that which was applied to the sesquicarbonate, and in the same 

 quantities : — 



The salt No. 1, 2, 3, was in rhomboidal crystals, formed in 

 the manner described, and dried by exposure to the atmosphere, 



• From one experiment that I have made, alcohol of Sp. gr. .829, ap- 

 peared to disolve about 50 times its volume of ammojaiacal gas. The an- 

 hydrous carbonate of ammonia is also soluble in alcohol of this strength ; 

 but its degree of solubility I have not ascertained. 



