ROSE ON THE ANHYDROUS SULPHATE OF AMMONIA. 553 



A solution of carbazotic acid acted in the same way ; it im- 

 mediately produced a considerable precipitate with the sulphate 

 of oxide of ammonium, and to a less extent, and after a longer 

 time with the sulphat-ammon. 



The sulphat-ammon is a homogeneous powder; when exa- 

 mined by the microscope it does not exhibit any appearance of 

 crystallization ; like other powders it attracts moisture from the 

 air, but this is got rid of without any change of properties, by 

 drying in a water-bath, and by fresh exposure it gains as much 

 water as before. 



Although I have already stated an analysis of sulphat-ammon, 

 yet ha\ing, by a method which I shall hereafter describe, ob- 

 tained it in larger quantity and of great purity, I have considered 

 it necessary to repeat the examination. The proofs of the purity 

 of this salt are not only that it scarcely reddens htmus paper, 

 but on the contrary renders it blue (after it has been reddened), 

 but only to a slight degree, and this effect it continues to pro- 

 duce only when kept in a bottle containing ammoniacal gas. 

 When litmus paper, which has been dipped in a solution of 

 sulphat-ammon, sulphate of oxide of ammonium, or most 

 other soluble ammoniacal salts, is dried in the air, it is red- 

 dened. 



One hundred parts of sulphat-ammon were treated with a so- 

 lution of chloride of barium ; the whole was evaporated to dry- 

 ness, heated to low redness, treated with hydrochloric acid and 

 water, and there were obtained 203-79 parts of sulphate of 

 barytes. This is the only method by which the whole of the 

 sulphuric acid can be converted into sulphate of baiytes ; but 

 this substance, when so procured, passes through filters, and 

 requires frequent filtration. The sulphate of barytes obtained 

 indicates 70'04 of sulphuric acid, which agrees as nearly as pos- 

 sible ^\■ith the amount of this acid calculated from the formula 



S + NH^, or 70*03 per cent. The results of several analyses, 

 confirming this composition, will be subsequently stated. 



II. Parasulphat-ammon. 



I have thus denominated a remarkable salt, which crystallizes 

 in large well-formed crystals from the concentrated aqueous 

 solution of sulphat-ammon ; they may likewise be obtained by 

 combining sulphat-ammon with anhydrous sulphm-ic acid by a 

 method already mentioned. These are the crystals Avhich 



