558 ROSE ON THE ANHYDROnS SULPHATE OF AMMONIA. 



The results of two additional experiments are still more deci- 

 sive of the difference between sulphat-and parasulphat-ammon ; 

 100 parts of the same sulphat-ammon, as alread}' employed, 

 corresponding to 91-42 when dried in the water-bath, dissolved, 

 cold and mixed with a solution of chloride of barium, gave 

 63-84 of sulphate of barytes, which was separated by the filter 

 half an hour after precipitation, and are equivalent to 2 2 '41 of 

 sulphuric acid ; in another experiment the sulphate of barytes 

 separated an hour after precipitation, the sulphate obtained in- 

 dicated 23-49 of sulphuric acid; the quantity of sulphate of 

 barytes, obtainable by evaporation, was not determined in either 

 experiment. 



It is CAddent, from these experiments, that the quantities of 

 sulphuric acid, precipitated in the cold by chloride of barium, 

 may differ greatly ; the three portions employed were weighed 

 at the same time from the same quantity of the preparation ; 

 the greater or less quantity of the sulphate of barytes obtained 

 in the cold, by a solution of the chloride of barium, undoubtedly 

 depends not only upon how soon it is filtered, but upon the 

 quantity of water in which the sulphat-ammon is dissolved, and 

 the concentration of the solution of chloride of barium. 



Were we to suppose, that in the last-described experiments, 

 the sulphuric acid precipitated in the cold is derived from the 

 sulphate of oxide of ammonium, there would arise greater con- 

 tradictions than would attend the results of the first-mentioned 

 analysis ; for 22-41 parts of sulphuric acid would correspond to 

 37-03 parts of sulphate of oxide of ammonium. The different 

 analyses of the sulphat-ammon having constantly given 'JO-OS 

 per cent., or very nearly, of sulphuric acid, there would be ob- 

 tained by further treatment 47-62 per cent, of the same acid, 

 which corresponds to 68 parts of the sulphat-ammon. But in 

 this case the quantities of sulphate of oxide of ammonium and 

 the sulphat-ammon would amount to 105-03 per cent., and there- 

 fore the analyses would indicate an excess of 5-03 per cent. 



In the last-mentioned examination of the sulphat-ammon 

 23-49 per ceuL. of sulphuric acid were obtained in the cold; if 

 these indicated 38-81 parts of sulphate of oxide of ammonium, 

 and if 46-54 parts of sulphuric acid, obtained by evaporating, 

 correspond to 66-46 parts of the sulphat-ammon, the analyses 

 Avould have given an excess of 5-27 per cent. 



