A, A. Hayes on Serpentine Rock of Roxbury, Vt. 383 
composition chemically, and of its value in a technical sense es- 
pecially as regards its durability. It receives a high polish and ~ 
its surface then exhibits a beautiful contrast of dark green and 
white colors, in forms of clouds and mottling in a manner pleasing 
to the eye, while the asbestus and other included minerals, have 
a play of lights equalling that of some gems. 
The enduring character of the rock places it in the class of 
granites and syenites and fits it for external use, as we f 
internal decoration and various purposes in the arts. 
Through the kindness of Dr. T. Brewer I added to my col- 
lection of samples of the rock, some nearly pure pieces of the 
La White portions, and the avalytical results which are here detailed 
may be taken as representing in a general manner, the composi- 
tion of the varieties hitherto quarried. Before these analyses 
Were made, the composition of this rock, had been stated to be 
Silica, ; ; : ; : : : 426 
Magnesia, 3 aah Se f : é . 365 
Protoxyd of iron and Chromium, . ; : 8:3 
Carbonate of Lime, : : : ‘ sabi, i 
. ; . . . ' : 13° 
S The proximate method was adopted in this as well as similar 
| cases by myself, and I may here remark, that the success of its 
application has been so great, that little doubt exists of its taking 
the place of other methods, in the study of the more truly simple 
high lustre. In hardness exceeds any variety of cale spar; it 
Scratches the harder dolomites. ‘The powdered mineral loses some 
humidity at 212° F.; at 450° the whole loss is 0-08 per cent. 
100 parts of the dried powder, consist of 
% Carbonic acid, .  .° oat, 80 
: agnesia, . Os : : . - 45-60 
Tale and trace of Silicic acid, .  . + 3°60 
Bilivate protox: ven): ei eos ete rae DOG 
, Proving it to be an anhydrous carbonate © | In dilu- 
ted acids it hardly effervesces until heat is applied, and then 
exhibits an astonishing power of resistance to solution at the 
