i 
. 
": 
: 
G. J. Brush on crystallized Diopside as a furnace product.. 133 
with the reflecting goniometer, 86° 50’, 86° 52’, 87°, and 87° 12’. 
The prism was truncated at each of its obtuse angles by a plane 
of nearly the same width as the planes of the rhombic prism, 
The terminal planes were observed on only a few of the smaller 
crystals, and as they were microscopic were not measured, 
There is a tendency to cleave apparently in the direction of the 
rhombic prism, but no reflected image could be obtained from 
the more or less conchoidal surfaces thus produced. 
The hardness of the crystals was about 5°, and the specific 
gravity was found to ‘16 (determined on 138 milligrams of 
substance). Lustre, vitreous and brilliant. Before the blowpipe 
in the forceps the substance fuses easily with intumescence to a 
colorless glass, giving at the same time an intense soda flame, 
It is partially attacked by chlorhydric acid, emitting the odor 
of sulphuretted hydrogen; and entirely decomposed by fusion 
with carbonate of soda. Analyses made by Mr. Peter Collier, 
assistant in this Laboratory, gave the following results :. 
I IL IIL Mean. Oxygen. 
Silica, 49°95 49°86 49°91 26°61 | og.95 
Alumina, 08 5-00 501 234 5 
7 + SPil 23°55 4 a 08} 
agnesia, - 7°25 17°42 14°57 
Ferrous oxyd,- 0°39 41 0-4 09 
Potash, eee : 1:42 1-4 2 
22a rice eee eis 2716 216 56 
Calcium, = - 0:30) 0°88 031 
Sulphur, : 024f 0.26 ; 0°25 
Manganous oxyd, tr. tr. tr. 
100-42 
acid. The alkalies (III) were determined m thod 
The small amount of sulphur was calculated as sulphid of cal- 
she xygen ratio of the mean shows the relation of the 
side, and corresponds very nearly with that described by Hunt 
from Bathurst, in Canada.' The erystalline form, as determined 
¥ the observations and measurements of Mr. Blake, shows 
further its relation to yroxene, and, taken with the chemical 
composition, leaves no doubt as to the identity of the crystals 
With the diopside variety of that mineral. Diopside has been 
wy observed as a furnace product by Vv. Kobell,’ and 
usmann,® from iron farnaces at Jenbach, near Schwatz, in 
the Tyrol, and at Gammelbo in Sweden. 
z Rept. of Geol. Canada, 1863, p. 467. 2 Miinchener gelebrte Anzeigen, xix, 97 
: ~ Liebig & Kopp, Jabresbericht. 1851, 767. : 
Am. Jour. Sc1.—Seconp SERIES, Vou. XXXIX, No. 116.—Marcu, 1865. 
18 
