/ 
200 
1 
Quantity taken in milligr’'ms, 485 
Silica, 45°06 
Alumin 5 
Sesquio f iron, 38°85 
Protoxyd of iron, ees 
“of manganese, trace. 
Lime, trace, 
Magnesia, 455 
Potash and Soda, trace, 
Water, ay 
The mean of these analyses gives :— 
Si 45°29 
xl 3°62 
Fe 20:47 
Fe 16°47 
Mn trace. 
Oa 0-28 
Mg 4-56 
Na, K trace, 
9-22 
99°91 
This ratio gives a formula which may be expressed by 
ok Si+ 8 Si+3H. 
gives the amount existing as sesquioxyd. 
Oxygen. 
23° 
G. J. Brush on Chalcodite. 
protoxyd first obtained 
3. 4. 
338 217 
20-92 20:02 
16:04 1691 
‘aE aa gs 
23°53 et 
783 1 
5:56 t 
8-18 I 
ares tee) | ees 2) = 
