562 ROSE ON THE ANHYDROUS SULPHATE OF AMMONIA. 



ceedingly pure crystals of the salt were reduced to powder 

 and moistened during several hours, by which the salt acquired 

 an acid reaction, and it was then perfectly dried in a water- 

 bath ; 100 parts of the dry residue were dissolved in cold 

 water ; the solution reddened litmus paper, but not strongly, 

 and it precipitated solution of chloride of barium. By the 

 method frequently mentioned, I obtained 198* 19 parts of sul- 

 phate of barytes equivalent to 68*13 of sulphuric acid ; it fol- 

 lows from this result that the parasulphat-ammon, by moisten- 

 ing with water, is partially converted into the deliquescent salt. 

 The acid reaction arises from the pr.isence of free hydrate of 

 sulphuric acid. 



It results from these investigations, that, although the sulphat- 

 ammon seems to dissolve in water without decomposition ; yet, 

 when the solution crystallizes, the crystals obtained, notwith- 

 standing they are similar in composition to the sulphat-ammon, 

 possess m.any properties which differ from it. In the solution 

 of the sulphat-ammon the constituents of water are more readily 

 combined with it by the action of certain reagents, and the 

 compound therefore changes more readily. This is the case 

 with the crystallized sulphat-ammon, or the parasulphat-am- 

 mon, which resists more powerfully the action of such reagents. 

 The conditions of the sulphat-ammonand parasulphat-ammon, 

 may be compared with the vitreous and crystalline state of 

 certain bodies, in which they exhibit different properties. 



The combinations of anhydrous sulphuric acid with am- 

 monia may be regarded, according to Dr. Kane, as perfectly 

 analogous to the hydrate of sulphuric acid. By supposing 

 that ammonia is an amide of hydrogen, and that the amide 

 combines in a similar manner with other bodies, as oxygen and 

 chlorine, the amide of hydrogen becomes a body analogous to 

 the oxide and chloride of hydrogen. But when sulphuric acid 

 is combined with water or other oxibases, it may possess pro- 

 perties very different fi'om those which belong to it when com- 

 bined with the amide of hydrogen. We have, in fact, of late, 

 become acquainted with a great number of cases, in which the 

 sulphuric acid, when combined with certain substances, as for 

 example, with the oxide of ethule, and other bodies of organic 

 origin, loses some of the peculiarities by which we were pre- 

 viously accustomed to characterize it, especially that of giving 

 an insoluble precipitate with barytic salts. But [hypothetical] 



