AMMONIA WITH CARBONIC ACID, 125 



portion employed did not consist of pure crystals, but also in 

 part of the solid sublimate). At times it is a mixture of both 

 salts; for, from 0-189 gnu. of the salt of another preparation I 

 obtained 0-273 grm. of metallic platina, or 25-12 per cent, of 

 ammonia. 



The quicker the sublimation of the sesquicarbonate takes place, 

 the less do the various products of the operation separate, and the 

 more they are cooled the more they approach in their composi- 

 tion to the common sesquicarbonate. Under the conditions 

 specified not so much carbonic acid is evolved in the form of gas 

 as during the slow distillation, and it is again partly absorbed by 

 the distilled salt, especially if kept well cooled. When I subjected 

 common sesquicarbonate at a high temperature to a rapid subh- 

 mation, and cooled the product well, I obtained a moist salt, from 

 which 1-246 grm. gave 1-903 grm. of metallic platina, which cor- 

 responds to 26-56 per cent, ammonia. Had the salt been dry, the 

 quantity of ammonia would have corresponded still more nearly 

 to that of the sesquicarbonate. 



VI. The five-four Carbonate of Ammonia, with a greater 

 proportion of Water. 



If the -l-carbonate of ammonia be subjected to a sublimation 

 as slow as that of the sesquicarbonate ; and if the operation be 

 discontinued when the contents of the retort have changed into 

 a clear hquid, and all the solid salt has disappeared, carbonic 

 acid gas is again disengaged during the subUmation, and a soHd 

 salt is subhmed : the hquid in the retort, when perfectly cool, 

 consohdates to an apparently solid salt, which, however, when 

 laid between blotting paper, gives out much water. The dis- 

 engagement of carbonic gas proves that simple carbonate has 

 been again formed from one portion of the bicarbonate supposed 

 to exist in the i carbonate, which, as the most volatile product 

 of subUmation, is deposited in the part of the tube furthest from 

 the retort. On account of the insignificant quantities of the salt, 

 however, -which were employed on sublimation, it could not be 

 obtained perfectly pure ; and the solution of it, mixed with a so- 

 lution of chloride of barium and filtered, was rendered somewhat 

 opalescent by ammonia. 



The salt sublimed in the neck of the retort, and in the re- 

 ceiver, have the same composition. It is the undecomposed 



