$2 F. A. Genth—American Vanadian Minerals. 
of the substance to the Microscopical Society and at the Acad- 
emy of Sciences of California in September, I made the gene- 
ral statement that it was a potash-mica, containing 23 per cent — 
chromic oxide and traces of lithia. It was not until I had sent 
a specimen of the mineral to Dr. Genth to analyze that the pres- 
ence in it of vanadium was discovered, and to him is due the 
entire credit of having first detected the true character of this 
interesting mineral. I have availed myself of the action of — 
nitrohydrochloric acid on the mineral to prepare a considerable 
quantity of vanadic compounds for physiological experiment, — 
as this affords about the easiest method of obtaining vanadic 
acid, although it is impossible thus to extract all the vanadium ~ 
m the mica. 
aii 
Art. V.—On some American Vanadium Minerals; by F. A. 
GENTH. 
1. Roscoelite. 
I am indebted to Dr. James Blake of San Francisco, Cali- 
fornia, for a small quantity of the very interesting mineral, 
which he called “ Roscoelite,” in honor of Professor Roscoe, 
whose important investigations have put vanadium in its proper 
place among the elements. 
scoelite occurs in small seams, varying in thickness from 
a3 to ;; of an inch in a decomposed yellowish, brownish or 
greenish rock. These seams are made up of small micaceous 
es, sometimes } of an inch in length, mostly smaller and 
frequently arranged in stellate or fan-shaped groups. They 
show an eminent basal cleavage. Soft. The specific gravity 
een. 
_ Before the blowpipe it fuses easily to a black glass, color- 
ing the flame slightly pink. With salt of phosphorus gives 
a skeleton of silicic acid, a dark yellow ne in the oxidizing 
O 
slightly acted i a by acids, even by boiling concentrated 
ut readily decomposed by dilute sulphuric 
: nS tani te mass. The roscoelite, which I 
received for Investigation was so much mixed with other sub- 
