192 Mr. Hatchett’s analytical Experiments 
being then mixed with ivory-black, or lamp-black, is employed 
by them as an ink, which, when dry, is not easily acted upon 
by damp or water. Upon trial, I found the fact to be exactly as 
Mr. Wilkins had stated, and therefore made other experiments ; 
but the results of these I shall at present omit, as they will 
occur with more propriety and perspicuity in the latter part of 
this Paper. 
In respect to the natural history of lac, we are much in- 
debted to Mr. Kerr,* Mr. Saunders,^ and Dr. Roxburgh ; £ 
from whose valuable communications to this Society, we learn 
many curious particulars concerning the formation of this sub- 
stance, which, from their accounts, and from inspection, evi- 
dently appears to be the nidus or comb of the insect called 
coccus or chermes lacca, deposited on branches of certain species 
of mimosa and other plants. 
Lac is distinguished into four kinds ; of which, however, only 
three are commonly known in commerce, viz. stick lac, seed 
lac, and shell lac ; the difference of these, with that of the fourth, 
called lutnp lac, is as follows. 
1. Stick lac, is the substance or comb in its natural state, 
incrusting small branches or twigs. 
2. Seed lac, is said to be only the above, which has been se- 
parated from the twigs, and reduced into small fragments ; but I 
suspect it to have undergone some other process, as I have 
* Natural History of the Insect which produces the Gum Lacca. By Mr. Jambs 
Kerr, of Patna. Phil. Trans, for 1781, p. 374. 
f Some Account of the vegetable and mineral Productions of Boutan and Thibet. 
By Mr. Robert Saunders. Phil. Trans, for 1789, p. 107. 
J Cbermes Lacca. By William Roxburgh, M. D. Phil. Trans, for 1791* 
p. 228. 
