ROSE ON THE ANHYDROUS SULPHATE OF AMMONIA. 561 



is precipitated from the salt when cold, if mixed with hydro- 

 chloric acid, than when this is not the case. The quantities 

 of sulphate of barytes, added together, indicate 65*54 of sul- 

 phuric acid in the 100 of salt ; the slight excess is unquestion- 

 ably derived from the parasulphat-ammon which the salt con- 

 tained, because it had been prepared from but a small quantity 

 of the sulphat-ammon. 



When I first prepared the crystals of the parasulphat-ammon, 

 having obtained but a small portion of it, I resolved not to employ 

 them for analysis, but to examine the irregularly crystalline 

 masses obtained by evaporation to dryness, w^hich must consist 

 of a mixture of the deliquescent salt, and the parasulphat- 

 ammon*; analyses confirmed this by finding only 67'47 per 

 cent of sulphuric acid in this mixed substance. The hydi'ous 

 sulphat-ammon is perfectly analogous to a salt which I ob- 

 tained during my investigation of the compounds of carbonic acid 

 and ammonia t, and which consists of carbonate of ammonia and 

 half an atom of water, requisite to convert the ammonia [am- 

 monium ?] into the oxide of ammonium. The same is also the 

 case with the hydrous sulphat-ammon. With respect to the car- 

 bonic salt, I have advanced the opinion that it might be regarded 

 as carbonat-ammon with the carbonate of oxide of ammonium. 

 The same view may also be adopted with respect to the hy- 

 drous sulphat-ammon, by regarding it as a compound of sul- 

 phat-ammon with the sulphate of oxide of ammonium S N H^ 

 + S N H"* ; the salt may perhaps also be formed by saturating 

 the first hydrate of sulphuric acid 2 S -|- H, contained in Nord- 

 hausen sulphuric acid, with dry ammoniacal gas. 



The deliquescent salt unquestionably originates from the 

 parasulphat-ammonia when dissolved in water, and remaining 

 for some time in contact with it. Very pure crystals of the 

 parasulphat-ammon, quite free from the deliquescent salt, when 

 dissolved in water, and evaporated over sulphuric acid in vacuo, 

 always yield a considerable quantity of the deUquescent salt, 

 along with the crystals of parasulphat-ammon. As crystals 

 of the parasulphat-ammon become acid, when exposed to moist 

 air for some time, it seemed to me interesting to inquire into 

 the nature of the alteration which they undergo. Some ex- 



* I'oggindorff 's Annalen, Bd. xlvii. S. 174, 

 f PoggcndorfPs Annalen, Bd. xlvi. S. 373. 



