EXPERIMENTS ON MOLYBDENA. J 35 



• Jiijiety grains. The pieces of glass having been weighed, they 

 were carefully washed, and weighed again ; \yhen they were 

 found to have lost a gra^n. Thus the hundred grains of sul- 

 phuret of molybdena had yielded ninety-one grains of ma- 

 Jybdic acid : and, if we admit as above sixty parts of metal 

 in the sulphuret, the proportion of metal to oxigen will be as 

 sixty to thirty-one, or as 100 to 51'67 ; consequently 100 

 parts of acid contain 34'06' of oxigen. 



Exp./IQ. Desirous of making a counter trial, I took some Another exf<^ 

 of ihe substance obtained in decomposing moiybdate of am- 

 monia by heat, which at that time I considered as molyb- 

 dena in the metallic state, and endeavoured to oxigenize it. 

 Having poured on it nitric acid of the spec. gray, of 1'22, a 

 brisli efli'rvescence immediately took place, which continued 

 for some time, without requiring the aid of heat ; but as I 

 was drying the oxigenized mass, it was suddenly thrown out 

 of the vessel, occasioning a loss, that prevented me fronj gq- 

 ing on with the trial. 



J then repeated the operation, employing a very tall glass This repeated^ 

 to contain the oxigenized mass, while I dried and melted it. 

 A hundred grains, treated with ten drachms of nitric acid^ 

 produced a radiated mass, that weighed exactly a hundred 

 and nine grains ; and, if we add one grain for what may have 

 remained adhering to the vessels employed, we shall have 110 

 grains of acid from 100 of the metallic substance. 



This result differed so widely from the preceding as to con- The substance 



vince me, either that the substance I had taken for molvb- 9t»tained by ex- 



•' pelhngtheam- 

 dena in the metallic slate was not actually so, or that I had m on ia from the 



made some mistake in determining the quantity of sulphur "^'y*^^^^®^** 



. "^ an oxide, 



contained, and the quantity of oxigen absorbed, by the na- 

 tive sulphuret of molybdena. I resolved therefore to repeat 

 my experiments. 



I have already given the result of the second experiment I Experiment 

 made to find the quantity of sulphur contained in the native ^''^ ^^® ^"^" 

 sulphuret. What 1 did to verify the proportion of oxigen to lybdena. 

 metal in the formation of the acid consisted in taking a hun- 

 dred grains of native sulphuret of molybdena, which I put 

 into a mixture of one ounce of muriatic acid and three 

 punces of nitric acid; and, in order to prevent loss frqip pqy 



being 



