from Xat'we JMoli/lJena. I97 



molybdate, adding an excels of nitric acid. A large portion 

 of the precipitate was rtdissolved. After some hours di- 

 gestion I tried the nature of the precipitate, after having 

 collected and washed it on a filter. On putting a little 

 of the precipitate, still moist, into a Hessian crucible, and 

 exposing it to heat, it resolved itself into a transparent li- 

 •]uor. When the whole moisture was dissipated, and the 

 crucible had begun to be red, the matter entered into fu- 

 sion ; but onlva very weak volatilization was observed by an 

 increase of heat. The fused mass \\ as of a yellowish gray 

 colour. A great part of it had passed through the crucible. 

 It resulted from these phqenomena, compared with those 

 which the free acid exhibited with \\ater and in the fire, 

 that the precipitate obtained in this experiment was a mix- 

 ture of free molybdic acid and acidulous molybdate of pot- 

 ash. 



After this imperfect success I resolved to try the muri- 

 atic acid to decompose acidulous molybdate of potash. 



Kxperiment Y. 



I decomposed the above-mentioned solution by means 

 of muriatic acid. An abundant precipitate was formed. I 

 added a strong excess of acid, which dissolved a remarkable 

 quantity of the precipitate. I digested the mixture for some 

 hours in a v/arm place, which completed the solution of al- 

 most the whole it. After cooling, there w as formed in the 

 liquor a considerable number of very small crystals. I tried 

 these crystals, and found that they were almost entirely so- 

 luble in three or four parts of warm water; that they rea- 

 dily fused in an ignited crucible without emitting much va-' 

 pour; that they penetrated the matter of the crucible; and 

 that after cooling they had a grayish yellow colour. I 

 thence concluded that the precipitate obtained by the mu- 

 riatic acid ccuiaincd scarcely anv free acid, but was almost 

 entirely composed of acidulous molybdate. I then evapo- 

 rated to one-half, in a moderate heat, the solution which 

 still contained molybdic acid. During the evaporation, but 

 in particular after cooling, there was separated a quantity 

 of small ycllov.ish white crystals : there, however, remained 

 in the solul'on a still greater quantity of molybdic acid, as 

 V. as indicaled by its acid taste and the trials to which it was 

 iiiibjected. 'I'he crystals obtained exhibited the same i^haMio- 

 Hiena with water, and in the fire, as pure molybdic acid, 



These experiments did not furnish a method of preparing, 



with safety and advantage, pure molybdic acid, and of ob- 



Uiuing the whole (juaulity contained in the sulphurated 



>.' 3 molyhdenaj 



