MOLYBDENUM. 85 



oxide in platinum, and at a low temperature, and the small 

 portion of the acid volatilized during this operation was 

 caught and determined. The reduction was completed in 

 a porcelain tube at a white heat. Debray gives his results 

 at 48.03; 48.04; and 47.84. [The analytical data, recalcu- 

 lated, give 95.30; 95.55; 95.73; perhaps on account of 

 misprints. Reduction to vacuum would still further reduce 

 the numbers.] The acid was purified by sublimation in 

 platinum, conversion into ammonium salt, and regeneration 

 by heat. In two experiments ammoniacal solution of molyb- 

 dic acid was evaporated in the dark with excess of argentic 

 nitrate, the argentic molybdate dissolved out and the excess 

 of silver determined. Debray found 5.510 acid = 7.657 

 silver, and 7.236 acid = 10.847 silver. Hence he calculates 

 M = 48 and 47.98. [A little calculation shows that the 

 first data are misprinted. They should read 5.11 acid = 

 7.657 silver. The corrected data give for Ag = 107.93 ; M 

 = 96.06 and 95.99. The mean of the recalculated analyses 

 is 95.73.] {Paris Comptes Rend., 66, 1868, 732.) 



L. Meyer : 96.10 (O = 16). 



Calculated from three analyses of the dichloride, two 

 analyses of the tetrachloride, and two analyses of the pen- 

 tachloride, made by Leichte and Kempe in Meyer's labora- 

 tory. The dichloride was analyzed by heating in a current 

 of hydrogen sulphide, and subsequently in a current of 

 hydrogen. Molybdenum disulphide is the residue. The 

 HCl formed was caught in ammonium hydrate and precipi- 

 tated by argentic nitrate, after the hydrogen sulphide had 

 been driven oflT by boiling in a flask provided with a con- 

 densing drip-tube. The tetra and pentachloride were 

 decomposed with nitric acid, excess of ammonium hydrate 

 was added, and molybdenum trisulphide precipitated with 

 ammonium sulphide. A weighed portion of the dry pre- 

 cipitate was converted into disulphide by heating in a cur- 

 rent of hydrogen. The chlorine of the higher chlorides 

 was determined in the filtrate after precipitation of the 

 trisulphide. By comparing the amount of chloride analyzed 

 with the amount of argentic chloride obtained, Meyer finds 

 in mean M = 95.92 ; extreme diflTerence, 1.87 for O = 15.96. 

 By comparing the amount of disulphide with that of argen- 

 tic chloride, M = 95.75 ; extreme difference, 1.35. By com- 

 paring the amount of chloride analyzed with the amount of 

 disulphide obtained for one analysis of tetrachloride and 

 two analyses of pentachloride, begets M = 95.94; extreme 

 difierence, 2.15. The general mean is M = 95.86; extreme 



