394 Afr. Hatchett’s Observations on the Change 
D. The 122 grains were mixed with 240 of pure potash; 
and, as some particles of charcoal remained, 50 grains of nitre 
were added, and the whole was strongly heated, during half 
an hour, in a silver crucible. The mass was then dissolved 
in distilled water, and, muriatic acid being added to excess, the 
liquor was evaporated to dryness, and was again digested with 
muriatic acid much diluted ; a quantity of pure silica then re- 
mained, which, after having been exposed to a red heat, weighed 
98 grains. 
E. The liquor from which the silica had been separated, was 
evaporated nearly to dryness, and added to boiling lixivium of 
potash; after the boiling had been continued for about one 
hour, the liquor was filtrated, and a quantity of oxide of iron 
was collected, which amounted to 6 grains. 
F. Solution of muriate of ammonia was added to the preceding 
filtrated liquor; and, the whole being then heated, a copious 
precipitate of alumina was obtained, which, after having been 
made red-hot, weighed 15 grains. 
Carbonate of soda caused the preceding liquor (after the 
separation of alumina) to become slightly turbid, but not any 
precipitate could be collected. 
By this analysis, 250 grains of the schistus afforded. 
Grains. 
Water - 
A. 
42 50 
Thick brown oily bitumen 
1 B 
jR - 
f 7-50 
Mixed gas (by computation) 
1 23.75 
Charcoal (by computation) 
C. - 
54-25 
Silica - 
D. - 
98 
Oxide of iron - 
E. - 
6 
Alumina - 
F. - 
15 
247. 
