‘ 
352 On the Chemical Constitution of Warwickite. 
phur in any of its compounds. Any substance containing sul- 
phur will yield an alkaline sulphuret if heated with carbonate of 
soda, either with or without the addition of carbonaceous matter 
according as a deoxydizing action is or is not required. The 
magnificent purple which is then produced by the addition of the 
fused mass to a drop of the solution of the nitro-prussid will at 
once prove the presence of sulphur. This reaction is so easily 
‘obtained and is so decisive that the nitro-prussid of soda must 
take its place among the most useful adjuncts to the blowpipe 
tests. By means of it the presence of sulphur in the smallest par- 
ticles of coagulated albumen, horn, nails, feathers, mustard seed, 
&c., which can be conveniently supported on a platinum wire for 
blowpipe experiment, may be most distinctly shown, and I have 
repeatedly obtained the characteristic purple tint in operating upon 
a piece of a single fibre of the human hair less than an inch in 
length. 
rect test for alkaline sulphurets, but as an indirect one for sul- 
ound 
A On the Chemical Constitution of the Mineral, 
of Canada. 
degree the characteristic lustre of the cleavage planes. In Feb- 
rt. XL 
Warwickite; by T. S. Hunt, of the Geological Commission 
d 
ruary, 1846, while a student in the Laboratory of Yale College, — 
I submitted to analysis one of these larger crystals, having a 
hardness a little more than 3, and the specific gravity 3°188. 
The examination showed the presence of titanic and silicic acids, 
r 
% 
proportions as follows. Silica, 18°5, titanic acid, 28°2, protoxyd 
of iron, 10:59, magnesia, 22-2, alumina, 13-84, lime, 1°3, an 
water, 73=101-98. . eee 
_ 'Fhe composition of this mineral differed so much from, that 
_ assigned to Warwickite by Prof. Shepard, that I described it as @. 
t 
bi ad 
bof A Ate ety SPY 
ahh ru 
i -* This Joumal, vol. xxxiv, p. $13, and vol. xxxvi, p. 85. a 
=~ 
