T. S. Hunt on Ophiolites. 221 
with an occasional purplish tinge. Translucent on the edges, 
and resembles, except in color, many common limestones. In 
powder, the rock ie ade with acetic acid, even in the cold, 
and by the aid of heat fifty-seven per cent of the mass were dis- 
solved, consisting of carbonate of lime with a little magnesia 
anda trace of iron, The residue effervesced in the cold with 
dilute nitric acid, whose action, aided by a gentle heat durin 
halfan-hour, dissolved 10-76 per cent of carbonate of lime an 
Magnesia, with a little iron, corresponding to a ferriferous dolo- 
Silica, z 41-20 
Magnesia, ; : : 3 : - 3216 
Protoxyd of iron,  - - - - - 1116 
Lime, - = 3 x = - “65 
Alumina, = - P Z - ‘ - 2°67 
Water, - ‘ : i F - - 12°70 
100°54 
The portion soluble in acetic acid (I) and that dissolved in 
nutri acid (II.) had the following composition for 100 parts:— 
; I I. 
pordeate of lime . . - *. ae 
x “ magnesia, - 8°67 2 
% “son (traces) 6°87 
10000 10000 
It will be scen that the dilute acids attack but slightly the 
aaetine, and that the nitric acid dissolves an intermingled 
dolomite, Which is but little acted upon by the acetic acid. I 
" hay en advantage of this reaction to separate the dolomite 
from the carbonate of lime in a crystalline magnesian limestone, 
Whose analysis is given in my Report for 1854. The proximate 
analysis of the rock in question shows it to be a mixture of car- 
ane of lime, dolomite and serpentine, and we have for 100 
Soluble in acetic acid, .* . : : Be ie 
“nitric acid, - : - - ' etnias 
Insoluble, serpentine, - = “ ™ a 8200 
99°76 
6. Dolomitic Ophiolite-—This granular variety is from the 
. pe Brompton Lake, in the aeventh range of the thirteenth 
of Orf : 
