EXPERIMENTS ON MOLYBDENA. O^S 



formed a brownish yellow solution, which on dilution with 

 water assumed at first a blueish yree'n colour, and after- 

 ward became completely green. A similar quantity having 

 been previously shaken in water, and afterward put into mu- 

 riatic acid, gave rise to a pretty considerable evolution of 

 sulphuretted hidrogen, and produced a blue solution, which 

 goon assumed a tiui^e of green, and let fall a blue precipi- 

 tate insoluble in water. This I had an opportunity of ob- 

 tjerving in several experiments. Its external appearance 

 greatly reseinbles that of the blue oxide of molybdena, 

 from which it differs however, since it is not soluble like it 

 in water. It requires farther examination therefore, to de- 

 termine its nature. 3. Five grains of the dried residuum 

 were put into half an ounce of cold water, and shaken ; but 

 no effect was produced. Being boiled for a quarter of an 

 hour, part was dissolved, leaving two grains of a fine red- 

 dish yellow colour. The solution had the same colour as 

 the preceding: it emitted a strong smell of sulphuretted 

 hidrogen : the sulpi'uvic acid increased this smell, and 

 changed the solution at first blue, afterward green. 



From all these circumstances it appears, that the residuum A compound 

 is a triple compound of hidrotliian acid, ammonia, and mo- t^d'hid, >Un" 

 lybdena. With respect to the acids it comports itself like ammonia; and 

 the precipitates obtained in the experiments 38, 41, and 43. "^° ^ ^"^* 

 After being roasled to redness it approaches the native sul- 

 phuret of mplybdena, from which however it appears to dif- 

 fer still by retaining a small portion of sulphuretted hidro- 

 gen. It is much more quickly converted into acid by the 

 action of fire than the sulphiiret of molybdena. 



Erp. 45. Ten grains of very pure moiybdic acid, first Sulphuretted 



fused, then powdered, and afterward boiled in ten ounces of hidroyn gas 



' "^ . passed into wa- 



water, which dissolved but a very small part, were put into ter in which 



the same apparatus as that of the preceding experiment, ""^'[''JjJ^^/^.ij 

 and subjected to the same treatment. As soon as the sul- was diffused. 

 phuretted hidrogen gas began to pass over, the liquid be- 

 came brown: the colour i>rew deeper and deeper, and the 

 greater part of the raolyijdic acid, 'vhich swam in" the solu- 

 tion, was dissolven : nothing rema.. t-( an the botC(;i!! but 

 some brownish black flocks. At thi conclnsion the liquor 

 assumed tlie same colour as in the preceding- experiments, 



and 



