DIRECT BENEFITS DERIVED FROM INSECTS. 273 



sand it forms grindstones ; and added to lamp or ivory black, 

 being first dissolved in water with the addition of a little 

 borax, it composes an ink not easily acted upon when dry by 

 damp or water. In this country, where it is distinguished by 

 the names stick-lac, when in its native state, unseparated from 

 the twigs to which it adheres ; seed-lac, when separated, 

 pounded, and the greater part of the colouring matter ex- 

 tracted by water; lump-lac, when melted and made into 

 cakes; and shell-lac, when strained and formed into trans- 

 parent laminae ; it has hitherto been chiefly employed in the 

 composition of varnishes, japanned ware, and sealing-wax : 

 but for several years past it has been applied to a still more 

 important purpose, originally suggested by Dr. Roxburgh — 

 that of a substitute for cochineal in dyeing scarlet. The first 

 preparations from it with this view were made in consequence 

 of a hint from Dr. Bancroft, and large quantities of a sub- 

 stance termed lac-lake, consisting of the colouring matter of 

 stick-lac precipitated from an alkaline lixivium by alum, were 

 manufactured at Calcutta and sent to this country, where at 

 first the consumption was so considerable, that in the three 

 years previous to 1810, Dr. Bancroft states that the sales of 

 it at the India House equalled in point of colouring matter 

 half a million of pounds weight of cochineal. More recently, 

 however, a new preparation of lac colour, under the name of 

 lac-dye, has been imported from India, which has been sub- 

 stituted for the lac-lake, and with such advantage, that the 

 East India Company are said to have saved in a few months 

 14,000Z. in the purchase of scarlet cloths dyed with this 

 colour and cochineal conjointly, and without any inferiority 

 in the colour obtained.^ 



Some other insects besides the Cocci afford dyes. Reaumur 

 tells us, that in the Levant, Persia, and China, they use the 

 galls of a particular species of Aphis for dyeing silk crimson, 

 which he thinks might lead us to try experiments with those 

 of our own country.^ That dyes might be thus obtained 

 seems probable from an observation of Linne's, in his Lap- 

 land Tour, upon the galls produced by Aphis pini on the ex- 



1 Bancroft on Permanent Colours, ii. 20. 49. 



2 Reaum. iii. Preface, xxxi. 



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