Description and Analysis of the Sillimantte. 21% 
Per 100 Parts. 
A. Water, . 00.510 containing oxygen, 
B. oe 43.000 tt + 21.629 
C. e, 54.210 « a“ 25.315 
D. Pontnid cat Tron, 02.000 
99.720 
100.000 
.280 Loss. 
In order to verify the above results this analysis was va- 
ried as follows, viz. After having ascertained the loss by cal- 
cination, and Separ ated the silex 7 “in the usual wae the 
healu- 
mine and iron then precipitated by hydro-sulphuret of hori 
These two substances were afterwards separated by the ac- 
tion of caustic potash. The solution to which the hydro- 
sulphuret had been added, was then tested, and was thus 
ound to contain neither lime nor magnesia. Three analy- 
ses which were made of this mineral, coincide almost ex- 
actly in their results, and give, as a mean, its composition 
as follows. 
Per 100 Parts. 
Water, 00.510 containing oxygen, 
Silica, 42.666 21.460 
Alumine, 54.111 “ “f 25.270 
Oxide of Iron, 01.999 <« ¢ 
99.286 
100.000 
714 Loss. 
It is therefore a silicate of alumine, with an accidental 
portion of oxide of Sse: and its mineralogical formula will 
be CS, 
he mineral wh sembles 
in selena! bleh te is the eadeiy tie: “There is how- 
