78 | On the Tellurie Bismuth oy Ving 
To ascertain the purity of the silica it was fused with carbon- © 
ate of soda and was found to contain 1:31 per cent of alumina. A 
second attack by acids would doubtless effectually decompose - 
this mingral. Correcting the silica and alumina and adding the _ 
water determined on the first portion, the composition of thes se- 
lection made will be thus :— oe, 
Silica, . ‘ : ; 49:96 ee 
Alamina, : ‘ : ‘ 24-41 Soa 
“ea of iron, j é ‘ 1-48 : 
Magnes ; ; ‘ 5-18 ; 
Cicbowas of lame ; ; : A421 
sh, ‘ ‘ i 9:97 
Water, ; ; ‘ ; 5:06 
The amount of carbonic acid directly estimated agreeing so 
nearly with that in the carbonate of lime obtained, evidently 
shews that the lime is not a constituent of the mine eral. Deduct- 
ing, therefore, the carbonate of lime and reducing the renee 
members to per-centage PeaPereons they will stand th US 3 
Silica, : ; 52-00 27-01 7 
Alumina, . . 25°42 11°88 7 
Peroxyd of iron, 1:54 “AT ‘ 
Magnesia, . 5:3 2-08 _ 
Potashi-*. 10°38 1-75 : 
Water, °° ey 4-68 1 or 1 
100-00 
‘The above composition is very well represented by the formula, 
; (Mg, K)3 Si+3 Si2+3 
Boston, April 18, 1850. 
sonoma 
Arr. XL—On the Telluric — oe Virginia; by Dr. 
C. T. Jac 
I piscoverep this ore in May, 1848, among some specimens of — 
native gold given me by Mr. Knowles ‘Taylor. At that time f 
had not a sufficient quantity of the mineral to enable me to make 
a complete analysis of it, but having made a blowpipe assay and 
satisfied myself that it was an ore of Tellurium, I communicated 
my results to the American Journal of Science o Arts, and my 
note was published in vol. vi, No. 17, 1848, 
My only object then was to announce the Seo of Tellu- | 
rium, and I intended at the earliest moment in my power to pro- 
cure a larger supply of the ore and to complete my analysis. 
Subsequently, Mr. Fisher* of Philadelphia made an anplyemt 
* This Journal, [2] vii, 282. 
