ee 
J. L. Smith on Warwickite. 433 
When pure warwickite was examined, it’ was found that 
One of its most important constituents had been overloo 
But so little of the pure mineral was then at our disposal, 
and so difficult was it to separate it from the associated min- 
érals, that all that could be arrived at, at that time, was the 
spinel. When the mineral is powdered in the mortar the 
small particles of spinel will be felt, and with a magnifyin 
ass can be discovered. Notwithstanding these simmalien 
am satisfied that I have made out its composition. Its physical 
characters have been pretty well described in works on Miner- 
alogy. Its specific gravity as made out by me is 3362; by 
Brush, 3-351 small crystals, 3-423 large crystals; and by 
Damour, 3°355. The luster of the cleavage surface is very 
bright and characteristic, being of a dark hair-brown or chocolate 
color. It is very readily cleaved in the direction of the prism. 
The results of my analysis are as follows: 
Ratio. 
Boracic acid 27°80 19°06 9 
Titanic acid 23°82 10°37 5 
ia 36°80 14°46 6 
Oxide of roe Se: 10 1 
