320° Seybert’s Analysis of Molybdenum ° 
Art. XIb.—Analysis of a Sulphuret of Molybdenum 3 by 
Henry Srvsert, of Philadelphia. 
(Communicated for this Journal.) 
Tuts mineral was found near Chester, Delaware county, 
Pennsylvania, and. in its external character so much resem- 
bles that of Saxony, as to make a description of it unnecessa- 
ry. It occurs in a gangue of quartz, and is often accompa- 
nied by the sulphuret of iron. 
The specific. gravity of apurcpicca was 4. 444, 
Analysis. 
A. 5 Grammes reduced to minute lamine were treated 
by pure concentrated nitric acid ; soon after the addition of 
the acid, the mineral assumed a beautiful blue colour. When 
heat was applied, effervescence commenced, nitrous acid 
was abundantly disengaged, and the liquor became turbid, 
owing to the precipitation of the molybdic acid. The total 
decomposition was effected with difficulty, and took place 
twenty-four hours after the acid was added. The liquor 
was then filtered, and the residue was washed to separate 
the sulphuric Agu, that was formed during the decomposi- 
tion of the mineral. The filtered liquor was eollte bey 
slight excess of muriate of barytes, a precipitate of ni iti 
of barytes. was formed, which after being washed and calci- 
ned, weighed 14.39 grammes, equivalent to 4.945 grammes 
of sulphuric acid, or to. 1.984 grammes of sulphur on 5 
grammes, or pr 100 — 39.68. 
B. The liquor (.4,) containing a portion of the molybdic 
cid, was evaporated to dryness, to expel the nitric acid. 
The dry mass was treated by water; a portion of the mo- 
lybdic acid remained insoluble, the liquor was then filtered ; 
the molybdic acid, remaining on the filter, after being wash- 
ed and moderately calcined, weighed 0.44 grammes. The 
liquor was then treated by ammonia, it became turbid, owing 
to.a precipitation of molybdate of barytes ; another portion 
of muriate of barytes was added to it, and it was then filter- 
ed, the molybdate of barytes remaining on the filter, when 
washed-and calcined, weighed 0.90 grammes, which corres- 
ponds to 0.415 grammes of molybdic acid. 
