lU 



Siilphuret of 

 molybdena 

 treated with 



Precipitated 

 vriih muriate 

 ot barytes. 



IDOgrs. sulph 

 of barytes con- 



taioJ.2-5ofucii]; 

 100 of sulph. 



SXP2RIMENTS OX MOLYBDE-NA. 



date of barytes is formed, unless the molybdic salt be neutra- 

 lized ; and not when any free muriatic or nitric acid is pre- 

 sent. 2, that the molybdena contains a large quantity of sul- 

 phur; for the 72 grains of sulphate of barytes, obtained 

 from 25 grains of molybdena in the 2(1 experiment, repre- 

 sent nearly 24 grains of dry sulphuric acid; which indicate 

 the presence of 10*2 grains of sulphur, or 40'8 per cent. 

 Alter these preliminary operations I could proceed to a more 

 accurate analysis. 



Exp. 5. A hundred grains of laminae of molybdena, 

 picked with the greatest care, were put into a retort with 

 six drachms of pure muriatic acid, of the spec. grav. of 

 1*135, and 2| of nitric acid, equally pure, of the gravity of 

 ]'22, and distilled on a sand bath with a gentle heat. After 

 an hour's ebullition almost the whole of the fluid had passed 

 over into the recinver. What remained in the retort was 

 white, some grjiy flocks excepted. The liquor was 

 poured back into the retort, half an ounce of fresh nitric 

 acid was added, and when about a third was distilled over 

 the gray fl icks disappeared. The liquor that had passed over 

 Contained neitl.er sulphuric nor sulphurous acid. The white 

 mass was diluted with six ounces of water and filtered ; and 

 the residuum was repeatedly washed with the greatest care. 

 In order to be well assured, that in precipitating the sulphate 

 of barytes, which .1 was preparing to do, no molybdate of 

 barytes should be thrown down with it, I added two drachms 

 more of pure muriatic acid to the liquor, which held in solu- 

 tion but a small quantity of molybdic acid. This being done, 

 I added a ver}' pure solution of muriate of barytes, and sul- 

 phate of barytes was precipitated. The liquor being passed 

 through a filter previously weighed, the residuum was put 

 into eight ounces of w-ater containing two drachms of muria- 

 tic acid, and well shaken; after which it was filtered again, 

 and WBshed. After being exposed to a red heat it weighed 

 284 grains, to which 6' grains must be added, as the filter, 

 after being thoroughly dried, had gained so much in weight. 



As 100 grains of sulphate of barytes contain 32*5 of sul- 

 phuric acid, this quantity must have contained 94*25 grains: 

 and farther^ as according to my experiments 100 grains of 



sulphuric 



