BOOK III. CHAP. Vlir. y-^^. 



makes in favour of the national balance of trade. There is np 

 doubt but the inventor, for a competent reward (of which he i& 

 well deferving), would have publifhed the fecret of his procefs j 

 thoufands of acres now wafte in Jamaica might be cultivated with 

 this plant, with little trouble or expence ; and a qui^ntity obtained 

 anfwerable to the home demand. 



The difappointment this gentleman met with, would intimidate 

 me from proceeding further in the catalogue of productions, if 1 

 had not fome gleam of hope remaining, that the endeavours of in- 

 genious men in thefe remote branches of the empire may hereafter 

 be more regarded, by the patriots of Britain, and the guardians of its 

 commercial interefts. 



The fruit of this plant, eaten when it is ripe, is faid to check 

 fluxes by its mild reftringency ; it is alfo a powerful diuretic, and 

 fometimes imparts a tinge to the urine ; which furniflies a proof 

 that the juice is not always altered with refpedl to the principles of 

 its dye, by the animal falts and fluids with which it has to en- 

 counter in its fecretion through the body. 



Modern difcoveries have fliewn a chemical method of ordering 

 the cochineal dye fo as to retain a very great brilliancy of colour. 



Drcbel, a Dutch chemifl:, firfl: invented the procefs of obtaining 

 from cochineal, by means of a folution of tin in aqua regia, a bright" 

 and folid fcarlet, exceeding in beauty and luftre any before produced. 

 This however anfwered only for woollen flufl^s. Monfieur Macquer 

 difcovercd lately the method of dying filks, and cottons, or linen, in 

 equal perfedion, by a flight variation in the common procefs. He 

 flril dipped a piece of filk into a faturated folution of tin in aqua 

 regia, fomewhat weakened by the addition of a quantity of water, 

 fo imall as to produce no precipitation of the earth or the metaL, 

 Having exprelled the liquor from the iilk, and afterwards wafhed it 

 in water, in order to free it from any fuperfluous part o^the folution, 

 he dipped it into a decoction of cochineal quickened (as is ufual in 

 the dying of woollen cloths) with a fmall quantity of cream of tartar.. 

 The filk immediately took a full bright colour, which refilled all 

 the tells or proof? ufually employed on wool. 



The dyers are therefore, it appears froir^ this narrative,, now pof- 

 fefifed of the art of giving the cochineal dye a brilliancy, perhaps 

 7 fomewhat; 



