556 ROSE ON THE ANHYDROUS SULPHATE OF AMMONIA. 



manner, 204 '49 parts of sulphate of barytas, equivalent to 70*29 

 of sulphuric acid. If we were to regard the crystals prepared 

 by me, on account of their similarity to the combinations formed 

 by M. Regnault, as a sulfamide, it must be considered as hy- 



drated, S N H^ + H. 



Since, however, the existence of hydrous amides is not suffi- 

 ciently proved, and even appears in some respects to be impro- 

 bable, I have denominated these crystals parasulphat-ammoriy 

 or parasulphammon, on account of their similar per centage 

 composition with sulphat-ammon. 



In the solution of the parasulphat-ammon the ammonia is 

 still more imperfectly separated by reagents than in a solution 

 of the sulphat-ammon. In solutions of equal strength, one part 

 of each salt to nine parts of water, a concentrated solution of 

 tartaric acid does not effect the formation of supertartrate of am- 

 monia, even after several days in the parasulphat-ammon, while 

 a precipitate, though not an abundant one, is produced in the 

 sulphat-ammon. A concentrated solution of racemic acid occa- 

 sions, after some time, a very small quantity of crystalline pre- 

 cipitate in the solution of parasulphat-ammon, and much smaller 

 than in the solution of sulphat-ammon ; solutions of chloride of 

 platina, carbazotic acid and sulpliate of alumina, react in the 

 same manner with the solution of sulphat-ammon. 



As the presence of sulphuric acid is not indicated in the solu- 

 tion of parasulphat-ammon by the salts of barytes and lead, this 

 is also the case, as might be anticipated, with the salts of strontia 

 and of lime. 



I have long hesitated whether the crystals of parasulphat- 

 ammon should be regarded as distinct from the sulphat-ammon, 

 merely on account of their different crystalline forms. It is 

 well known how difficult it is to obtain perfectly anhydrous sul- 

 phuric acid ; and, if it contain only a trace of water, a corre- 

 sponding quantity of sulphate of ammonia is formed on satura- 

 tion with dry ammoniacal gas ; and the solution of barytes, 

 being an extremely sensible reagent for sulphuric acid, it might 

 easily happen that the solution of sulphat would be slightly pre- 

 cipitated, even in the cold by barytes, owing to its being impure, 

 on account of the presence of sulphate of ammonia. It is, 

 indeed, true, that the solution of parasulphat-ammon acts some- 

 wnai differently from that of sulphat-ammon, with solutions of 



