126 Dr. E. Divers on the Diammonic Carbonate, 



carbonate with a solution of ammonia. Some of this substance 

 dissolves in the ammonia-water; the rest remains, as a skeleton 

 of the original solid, in the condition of a soft mealy semicrys- 

 talline mass. This is the normal carbonate. If it be digested 

 for some days in a closed vessel with the ammoniacal liquor 

 after this has had its free ammonia renewed in it by the passage 

 of some ammonia gas through it while kept cool by external 

 means, a remarkable phenomenon is observed. Even when the 

 solid is at first in such quantity as to leave the mixture only 

 semifluid, the whole will gradually, particularly when occasion- 

 ally agitated, become a solution. Warming the vessel in the 

 early period of the digestion seems to have little effect in has- 

 tening this peculiar solution; while cooling it in ice has little 

 effect (if any) in increasing the solidification of the mixture. 

 This interesting occurrence of the slow disappearance of the solid 

 carbonate I shall not in the present paper attempt to explain 

 (though 1 am quite satisfied that I am able to do so) ; for my 

 experiments in this direction are, as yet, incomplete. If now 

 to the clear liquid more of the commercial carbonate be added, 

 further solution of it occurs; and now a gentle heat seems 

 favourable to this process. Either on cooling after warming, or 

 by the action of applied cold, fine spicula fill the liquid, almost 

 solidifying it from the commencement of their formation, though, 

 somewhat like the potassic silicofluoride, they do not much 

 diminish the transparency of the whole. These minute crystals, 

 which are identical in composition with the mass left when 

 the commercial carbonate is treated with ammonia, rapidly in- 

 crease in quantity, but not materially in individual size. They 

 are not grouped in stars or bundles, but diffused uniformly 

 through the liquid. By jolting the vessel, the crystals, if not 

 too numerous, may be shaken together so as to form a shrunken 

 mould, as it were, of the inside of the vessel. Removed from their 

 mother-liquor, or, more correctly, drained from and squeezed 

 free of their mother-liquor, they begin to decompose. But with 

 proper precautions to prevent this decomposition, they can be 

 exhibited in soft masses of minute crystals of brilliant silky lustre. 

 They smell most intensely of ammonia. They dissolve very 

 freely in water, but require about seventy measured parts of or- 

 dinary rectified spirit to dissolve them. In strong ammonia 

 solution they dissolve at first very sparingly ; but solution con- 

 tinues to go on slowly, as I have above described it doing 

 in the case of the carbonate in the mealy condition. Exposed 

 freely to the air, the salt entirely loses its lustre in a few mo- 

 ments, evolving torrents of ammonia, and becoming at the same 

 time damp from the liberation of water. After a while (very 

 rapidly if disturbed and repeatedly pressed between fresh bibu- 



