124 Mr. Hatchett’s Analysis of the earthy Substance 
crucible, made strongly red-hot. A feeble detonation took 
place at each projection ; and, after a quarter of an hour had 
elapsed, the crucible was removed. 
When cold, the mass was porous and white, without any ap- 
pearance of the dark grey particles. Boiling water was poured 
on it, and the whole being put into a matrass, one ounce of 
muriatic acid was added, and digested with it in a sand heat. 
By evaporation it became gelatinous : it was then emptied on a 
filter, and, being well washed, dried, and made red-hot, weighed 
75 -5 grains. 
The appearance of this was that of a white earth, arid to 
the touch. When melted with two parts of soda, a colourless 
glass was formed ; and, with four parts of the same, it was so- 
luble in water, and produced liquor silicum ; it was therefore 
pure siliceous earth. 
f . The filtrated liquor was saturated with ammoniac, and, 
upon being heated, a few brownish flocculi were precipitated, 
which, when collected and dried, weighed 0.40 grain. This pre- 
cipitate was dissolved in muriatic acid, and was again precipi- 
tated by prussiate of potash, in the state of Prussian blue. 
The liquor from which the flocculi of iron had been separated 
was then examined, by adding carbonate of potash, and lastly, 
by being evaporated to dryness ; but it no longer afforded any 
earthy or metallic substance : so that, by the process of detona- 
tion with nitre, the $5.50 grains afforded 75.25 grains of pure 
siliceous earth, with 0.40 grain of iron ; and, as the dark grey 
substance was destroyed, excepting the 0.40 grain of iron above- 
mentioned, and as 9.85 grains of the original weight of 85.50 
grains were dissipated, there can be no doubt but that this sub- 
stance, amounting to 10.25 grains, was carburet of iron or 
