gjg Experiments on molybdena. 



oxide obtained by the decomposition of molybdate of am- 

 monia» for this oxide appears to be insoluble in water: and 

 besides, the precipitate does not furnish blue oxide with 

 mblybdic acid, but only with molybdena in the metallic 

 State, which indicates a higher degree of oxigenation than 

 that of the blue oxide. 

 With muriatic Exp. 32. Ten grains of powdered molybdena were put 

 * ■ into a drachm of muriatic acid of the specific gravity of 



1*135, and left for twenty-four hours. The acid exerted no 

 action on the metal, it remained in the same state : and 

 even after it had been boiled to dryness, a second drachni 

 of acid ddded, and this boiled on it a few minutes, no 

 effect was produced. 



This fact appearing to me inconsistent with the property! 

 had observed in metallic molybdena of being converted into 

 blue oxide after having been simply wetted, I tried muriatic 

 acid diluted with water. The metal however was not at- 

 tacked, whether I employed one, two, or three parts of wa- 

 ter to one of acid, and digested the metal in it for a long* 

 time, or boiled it. 

 Waned mo- Thus it appears, that, when powdered molybdena is sira-^ 

 Sed by'Ihe ply Wetted, the oxidation is not produced by the water, but by 

 water,'butby ^j^g oxigen of the atmosphere; the water serving only to 

 ^*^ *"^' conduct the oxigen, and dissolve the oxide formed, so that 



the metal continually presents a fresh surface to the action 

 of the air. 

 Oxlgsni^ed Exp. 33. Ten grains of metallic molybdena were put 



jBuriatic acid, '^^^q three ounces of water saturated with vapour of oxigen- 

 ized muriatic acid : the mixture was shaken a little, and a 

 blue solution void of smell was produced. But the greater 

 part of the metal was not dissolved : nor was it by the ad^ 

 dition of six ounces of acid. The liquor when filtered was 

 of a fine blue colour; but on adding liquid oxigenizfed mu- 

 riatic acid, the solution became as clear as water; and when 

 more molybdena in the metallic state was put into it, the 

 blue colour reappeared. 



•1 Fsn 34. Ten grains of molybdena were put into a 



Arsenic acici- Ji^^'y ^-^ o ^^ i i*. •. • \.i. t 



4raehm of liquid arsenic acid contaming halt its weight ot 



dry acid, and left to stand twenty-four hours in a closely 



stopped bottle. At the expiration of this time a thin stra^ 



'^ tura 



