•04 Method of crfractlng Mohjldlc Achl, &fc, ■ 



phasnomena exactlv as tliat obtained in expcrimcrit XTV, 

 and was pure molvhdic acid. Numerous occupanons pre- 

 vented me I'rom undertaking new experiments with the so- 

 lution of molybdnte of ammonia until six weeks after. 

 Having evaporated the solution to dryness, 1 put the saline 

 mass into a new Hcsrian crucible in order to expel the am- 

 monia bv incandescence. To my great astonishment I ob- 

 served that the mass deprived of ammonia, which under 

 other circumstances fuses so readily, and which, alter being 

 .<ome time in fusion, penetrates into the substance of the 

 crucible, could not this time be brousrht into fusion even 

 in the stroncjest white heat, and was only softened, emit- 

 tin<i^ vapours of molybdic acid. On examining the cooled 

 mass, I found at its surface several irregular depressions. 

 It had an argentine splendour inclining to grav. On its 

 fracture it exhibited a cupreous blue colour of steel wi{h a 

 metallic tint ; its texture was scalv and very compact} it 

 was difficult to be broken and pulverized. Its specilic gra- 

 vitv was 5050. By pouring over it moderatelv concentrated 

 sulphuric acid the mass acquired a considerable heat, emit- 

 ting nitrous gas in abundance, and transforming itself into 

 white oxide. 



After all these phaenomcna, it can be considered only as 

 metallic molybdena, or oxide of molybdena very near to the 

 metallic state. I can explain this in no other manner than 

 by admitting, that in consequence of the long contact of 

 the ammonia with the molybdic acid the latter was decom- 

 posed, I dare not, ho\\e\er, assert that this v.as actually 

 the case, and that some other cause which 1 did not observe 

 niay not have concurred to produce tlie same cH'ect. • How- 

 Over tliis may be, it is remarkable that under the circum- 

 stances above mentioned the molvhdic acid, the reduction 

 of which is so difficult, should be reduced .so easilv and by 

 so weak a fire; and that the metallic molvbdena, which is 

 so little fusible, should be fused, or at least softened into a 

 lK>mo""eneous n^ass of a scalv texture. The want of mo- 

 lybdena has hitiiei to prevented me i'rom making the experi- 

 ments necessary to ascertain the cause of this singular effiect. 



xxxiir. Of 



