332 
Dr. Pearson's Experiments 
disappeared. When about three-fourths of the matter were 
dissolved, a white sediment like the siderite of Bergman be- 
gan to appear, and increased as the dissolution went on. 
By standing, still more of this white sediment fell down, 
and green crystals, apparently those of sulfate of iron, formed 
a stratum which lay over the white matter. The black matter 
adhered to the sides of the retort, it appeared also upon the 
surface of the liquid, and some of it was deposited under the 
white sediment. 
This experiment was made with steel wire, and the toughest 
iron wire. 
The phenomena during the dissolution of steel were the 
same as those last related ; except such as obviously arose 
from mechanical differences in the substances to be dissolved. 
In particular the quantity of insoluble black matter, of white 
sediment, and of green crystals, was apparently the same. But 
with respect to the phenomena of the dissolution of iron, there 
was one material difference between it and the dissolution of 
wootz and steel, namely, that the liquor was not turbid and 
black, but clear, with a very small quantity of black matter 
upon its surface. It is however proper to state, that seem- 
ingly the same kind and quantity of white sediment and green 
crystals were produced as from the dissolution of wootz and steel. 
I think it of consequence also to notice, that the black mat- 
ter appears in the greatest quantity when about half, or three- 
fourths of the matter is dissolved ; but after this period, al- 
though gaz be separated in as great quantity as before, the 
Hack matter seems to diminish. Hence I was at first inclined 
to conclude with Mr. Berthollet, that part of this black or 
carbonaceous matter was dissolved by the gaz, but I think I 
