195 
The next specimens, submitted to investigation, was a bottle used 
by Professor Black for chemical purposes. 
The specific gravity was 2*75. 
Water was found to dissolve from it *22 of a grain per cent., con- 
sisting of lime, oxide of iron, silica, and magnesia. 
Hydrochloric acid dissolved substances to the amount 2-82 per 
cent., and potash, *56 of a grain per cent. 
The glass had the following composition : — 
Silica, 
56*90 1 
Protoxide of Iron, . 
3*61 
Ratio of 
oxygen 
in 
Alumina, 
10*22 
bases 
to that 
of 
Lime, 
25*80 
silicic 
acid as 
1 
Potash, 
1*90 
to 2. 
Soda, 
1*55 J 
99-98 
The last sample made the subject of analysis was the so called 
basalt glass of Messrs Chance and Co. 
It is produced by the mere fusion of basalt, is very hard, and of a 
black colour. 
The specific gravity was ascertained to be 2*709. 
Water dissolved *34 of a grain per cent., consisting of silica, pro- 
toxide iron, lime, and magnesia. 
Hydrochloric acid dissolved 3*4 per cent., and potash 1*44 per 
cent. 
The composition of the basalt glass may be thus represented : — - 
Silica, . 
Protoxide Iron, 
Alumina, 
Lime, . 
Potash, 
Soda, 
54*88 
17*83 | 
Ratio of 
oxygen 
in 
11*54 | 
bases 
to that 
of 
9*26 t 
silicic 
acid as 
1 
1*05 I 
to 2. 
5*34 ' 
99*90 
