realgar and orpiment, they have long been familiar. Among 
the salts of the metals, we find the sulphates of copper, of 
zinc, and of iron, and of the latter, the red distinguished 
from the green : the diacetate of copper, and the carbonates 
of lead and of iron, are not only mentioned in their works, 
but used medicinally. If we had time, we might shew 
that some of the names by which these articles are indicated 
are of Hindoo origin ; as Tutia, which occurs in Geber, but 
is not explained by Dr. Thomson; and Misy, which is 
mentioned by both Greek and Arabian authors. 
That the substances indicated in these ancient works, 
were actually such as what we now understand by the 
English names we have assigned, is proved, as well by 
the names under which we can, and I have procured 
them in the bazars of India, as by the processes which 
are given for making them. So that it was not merely 
because some were found within the limits of their terri- 
tory, that the Hindoos became acquainted with these 
substances ; which, though a strong argument to show that 
they must have been acquainted with a substance, before it 
could have been exported to foreign countries; yet 
would have proved little towards their originating, or 
at least cultivating, chemistry prior to the Arabs, if we had 
not had some chemical processes to which we could confi- 
dently point. Thus, as in the case of the acids and 
alkalies, we here see the formation of oxides, in the 
directions for making the oxide of zinc; of a sulphuret, 
in those of mercury or factitious cinnabar; and still more 
interesting are the processes for making a kind of calomel, 
as well as of corrosive sublimate. In these a sulphuret is 
first formed by mixing quicksilver with fused sulphur; 
a layer of the black powder, which is thus obtained, is 
then placed over another of common salt, in a vessel half 
filled with small bricks ; over this another vessel is directed 
