ON MOLYBD^NA 173 



dissolved in water, brown, and the infusion of galls, dark 

 brown. 



SECTION X. 



I have tried the earth of molybdyena with black flux and 

 charcoal, in order to see if I could reduce it ; as also with 

 glass of borax and charcoal, but in vain. I could not dis- 

 cover the least metallic principle. I conjectured that 

 inflammable bodies might have the same effect upon earth 

 of molybd;nena as the air, viz. to volatilise it (Sec. vi. (&)). I 

 therefore moistened some of this earth with olive oil, put 

 the mixture into a glass retort, and continued the fire till 

 the retort began to melt. But here arose no sublimate ; 

 the residuum in the retort was like a black powder. Some 

 of this powder was put into a crucible, and exposed to a 

 strong fire, when it became red hot, and sublimed in the 

 form of white flowers. I then put the other part into a 

 crucible, and luted on it another inverted crucible, which 

 was likewise exposed to a strong fire. An hour afterwards, 

 when the whole mass was grown cool, I opened the crucibles, 

 but the earth was found with its black colour unchanged, 

 without any sign of fusion. This black powder showed the 

 following phenomena: (1) It did not dissolve in boiling 

 water; (2) nor, when alkali was added, and the boiling 

 heat continued, did it dissolve, notwithstanding alkali on 

 other occasions so readily dissolves it (Sec. vn. (#)). (3) But 

 when mixed with a triple quantity of alkali of tartar, and 

 exposed to fusion into a crucible, there arose a strong 

 effervescence. If the mass be then dissolved in water, and 

 the superfluous alkali saturated with nitrous acid, the product 

 will be a neutral salt, consisting of the earth of molybdoena 

 and alkali, which decomposes all other neutral salts (Sec. 

 VII. (#)). (4) Nitrous acid attacks the phlogisticated earth 



