70 



L. F. Nilson, 



2. c / 7 -Selenite: Hg 14 .0 3 .6SeO + 6H 2 = 6Hg 2 .0 2 .SeO-f-Hg 2 + 6H 2 0. 



The precipitate, that had the same appearance and properties as the 

 former, was extracted with least possible quantity of water, by means of 

 Bunsen's method for filtering- under high pressure, and, after desiccating 

 between folds of bibulous paper, the analysis was performed in the same 

 manner as in the case of the preceding basic salt: 



0.808 gr. salt, treated with hydrochloric acid, gave a precipitate ofO.OGgr. 

 selenium or 0.0843 gr. selenious acid, and from the filtrate from it, by 

 precipitating with hydrosulphuric acid and digesting with cyanide of 

 potassium, 0.7063 gr. mercuric sulphide = 0.087 gr. mercurous oxide 

 and from the filtrate from it, hydrochloric acid precipitated 0.0465 gr. 

 selenium or 0.0653 gr. selenious acid. 



In 100 parts: 



found calculated 



Mercurous oxide . . 79.15 7Hg 2 2912 79.00 



Selenious acid ... 17.24 6Se0 2 666 18.07 



Water (loss) .... 3.61 6H 2 JL08 2.93 



100.00 3686 100^00 



The composition arrived at from the values obtained, is also con- 

 firmed by the relation of the quantity of selenium, immediately precipitated 

 from the salt with hydrochloric acid, to the quantity, afterwards obtained 

 from the solution, the proportion of one to the other being very nearly as 

 7 to 5, and that this must be the case is evident from the following formula 

 tor the decomposition 



2(Hg 14 .0 13 .6SeO) + 56HCl = 28HgCT + 28H 2 4-5Se0 2 4- 7Se. 

 The salt parted at 100° with half its water; 0.445 gr. lost namely 0.073 gr. 

 or 1.04 pr. ct, the calculated loss being for 3 mol. of water 1.47 pr. ct. 



It seems consequently to follow, that no neutral mercurous selenite 

 is to be obtained, by employing really neutral selenite of sodium and a 

 neutral solution of mercurous nitrate. The difference between this result 

 and Kohler's statement might possibly be explained thus, that he had not 

 operated with neutral but with acid solutions; but it will be obvious from 

 the following that we are not entitled to assume this. It is also impossible 

 to judge of the accuracy of the results from his communications regarding 

 the method employed in the analysis of the compound, as he only says: 

 "As for the analytical methods I have only to state that mercury has been 



