Experiments and 01 nervations on Lac. 351 



clry, is not easily acted upon by damp or water. Upon 

 trial, I found the fact to be exactly as Mr. Wiikins had 

 stated, and therefore made other experiments; but the re- 

 sults 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- 

 tlcbtcd to Mr. Kerr*, Mr. Saunders f, and Dr. Roxburgh J; 

 from whose valuable communicatious to this Society, we 

 learn many curious particulars concerning the formation of 

 this substani^e, whicli, from their accounts, and IVom in- 

 spection, evidentlv^ appears to be the nidus or comb of the 

 insect called coccus or chermcs lacca, deposited on branches 

 of certain species of mimosa and other pUnts. 



Lac is distinguished into four kinds; of which, how- 

 ever, 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 lump 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 separated from llic twigs, and reduced into small frag- 

 .jnents ; but I suspect it to have undergone some other pro- 

 cess, as I have found the best specimens to be veVy con- 

 siderably deprived of the colouring matter §. 



3. Lump lac, is formed from seed lac, liquefied by fire, 

 and formed into cakes. And, 



4. Shell lac, according to Mr. Kerr and Mr. Saunders, 

 is prepared from the cells, liquefied, strained, and formed 

 into thin transparent lamin?e, in the following manner. 



"Separate the shells from the branches; break them 

 into small pieces ; tlu'ow them into a tub of water, for 

 one day; wash off the red water; dry the cells, and 

 with ihem fill a cylindrical tube of cotton cloth, two feet 

 long, and one or two inches in diameter ; tie both ends, 

 and turn the bag above a charcoal fire; as the lac liquc- 



• Natviral history of tlx iii'^cct wliich prr duces the Gum Lacca. By 

 Ml. Jainei Kerr, of i'<itna. Phil. Trans, for i7.;i, p. 374. 



t Some account of the ve^ct.ible and miner-il productions of Boutan 

 and Thilict. By Mr. Robert SannHers. Phil. Trans, for 1789, p. 107. 



I Ciicrnies Lacca. By William Rox'jurgh, M. D. Phil. Trans, for 

 f79i. p. 2zS. 



§ Mr. VVill'.ins informs mc that the crude lac, as it is tiken from the 

 branche<i and twigs of th; trees, ij usually deprived of its colouring mat- 

 ter tjy bi.iling, haviiiy; been [>reviously reduced, by pounding, inro small 

 fr.'i; nei.t'.. In Bcnijal, the silk-dyers arc the people who thus produce 

 what vvc call the ited lac, which tli-.y do for thi; sake of the colour. 



3 fjC3, 



