EXPERIMENTS OW MOLYBDENA, 3^5 



Sulphuric acid contain 425 of sulphur, it follows, tliat 100 ^^'■<^' 42 5 of 

 grains of sulphuret of molybflena contain 40'56 of sulphur, lOO of sulphu- 

 uhich differs very little from the result of experiment 2. ret of mo!ybd. 

 rr.i • .. I ^ I •. r ^ Contain 40'55 



Ihis agreement seemed to render it unnecessary tor me to re- ©f sulphur 



peat the analysis: yet certain circumstances, which will ap- 

 pear farther on, induced me to commence a new one, thai no 



doubt mi"ht lemain. I took a hundred grains of powdered Experiment 



. . f. . repealed, 



molybdena, put them into a mixture of three ounces of nitric 



acid and one of muriatic, and treated them as the preceding; 

 with this difference only, that, by employing a larger quantity 

 of acid in the first instance, it was not necessary to return 

 into the retort the liquor that passed over into the receiver. 

 The sulphtite of barytes obtained in this instance weighed 2S8 

 grains, which, according to the preceding computations, con- 

 tained 93 6 grains of sulphuric acid, and 3978 of sulphur. ThisgaTe39-7S 

 Taking a mean between this result and the preceding, we may ^^ 

 conclude, that, 100 parts of sulphuret of molybdena contain 



Sulphur - 40 Medium. 



Metallic molybdena*'' 60 



Exp. 6. A hundred grains of sulphuret of molybdena, Sulphuret of 

 dissolved as the preceding, and distilled to dryness, were put treated as Ije- 

 jnto two ounces of pure liquid ammonia, diluted with an fore, and am- 

 equal quantity of water. Tiie mixture being shaken, in the ™^"'^ ^ ^ » 

 course of a quarter of an hour the whole was dissolved, ex- 

 cept a few yeiiowish flocks, which, collected on a filter, 



scarcely weighed a grain after being heated red hot. On about 1 gr. of 



,■,•".,• ••^*- •.• -j'^ 1 I silex and oxide 



boiling this precipitate m ny^riatic acid it was decomposed, ^^.^.^^^ ^g^^^_ 



and yielded 0'75 of a grain of silex, with | of a grain of ted, 



oxide of iron, 'i'he smallness of the quantity seems to show, 



that these two substances were accidentally present in the 



♦ Scheele supposed, that molybdena existed in the acid state in its 

 ore: it was the doctrine of the French chemists, says Fourcroy, that 

 corrected this m'stake, by showing Guyton, Pelletier, and all the authors 

 or par'.izans of the pneumatic theory, that Scheele produced the a,cid hy 

 burning the molybdena, and loading it with as much oxigenjas it could 

 take up. Foarcroy's Chemis:ry, Sect. VI, art. IV", § 2. 



In the subbcqufciii part of this paper of Mr Bucholz it is shown in the 

 mcft evident iuunueij that liie molybdena is in the metallic state in its 

 pre. 



molybdena, 



