EXPERIMENTS ON MOLYBDENA. J^J 



times molybdic acid, sometimes moiybdena in the metallic 

 -State, or at least approaching to it, is obtained, according to 

 circumstances. 



I employed the latler method, that with ammonia, as being The latter m&- 

 the most advantageous. Previous trials had taught me, that ]^^^ ^"^^ ^'^^' 

 three parts of pure liquid ammonia, of the specific gravity of 3 p^^ts of am- 

 0-97, dissolve one of molybdic acid reduced to fine powder, monia dissolve 

 and separate it from any impurity, that may be present. In add, ^ 

 consequence I powdered the produce of the preceding roast- 

 ing ; put it into a bottle with ammonia closely stopped ; and 

 Jcft it to digest for twelve hours, shaking it from time to time. 

 The acid disappeared, and two ounces of heterogeneous mat- 

 ter remained, containing still a little moiybdena not decom- 

 posed. This residuum was boiled w4th two ounces of common 

 nitric acid, and the moiybdena was readily converted into 

 acid, which was obtained perfectly pure by means of ammo- 

 nia. 



The ammoniacal liquor, in which the roasted mass had ^ ^'^^'^ ^'^''^^ 



Till T 1 ,-1 1 • • of iron precipi- 



been dissolved, became a little turbid at the expiration of tated from the 



five hours, and assumed a yellow ochre colour. Five days '"°^y^''^^^°^ 



/■ ^ 1 • 1 1 • , • 1 1 , . ammonia. 



alter, the matter ttiat occasioned this turbidness had sub- 

 sided, and comported iiseli like oxide of iron. Part of the 

 limpid solution was evaporated to dryness, and part of the 

 residuum was heated red hoc, to obtain from it the pure mo- 

 lybdic acid, as I had formerly done with a smaller quantity, 

 but my expectation was frustrated. At the beginning the Effect of heat 

 molybdate of ammonia turned blue; and it ended in assura- daieof ammu^ 

 ing a metallic aspect throughout, even interiorly; the blue '^^^• 

 colour changed to a coppery red, and it had a similar appear- 

 ance to products I had formerly obtained, which every thing 

 indicated to be moiybdena in the metallic state, or nearly 

 metallic. The mass became oxided anew on the surface: 

 but it was more agglutinated in those places, where the heat 

 had acted most strongly. 



III. Experiments to ascertain the most advantageous method 

 of reducing moiybdena to the metallic state. 



Exps. 7 fl"^ 8. By the process just mentioned having ob- Attempts to 

 ^ . , 1-1 ^L- 1 J i • reduce molyb- 



tamcd a mass, which every thing led me to suppose was in ^^^^^ 



the 



