6o On Djeing'Collon ivhh thd 



•wailicd out and deftroyed. Let us try, then, if a method 

 cannot be difcovcred to render the nature of cotton more 

 like to th.it of wool. This, indeed, will be the cafe, if we 

 inflil into it an oily fubRance fo as to become a component 

 part of it, which can neither be waftied out with cold water 

 nor foap, nor in any other manner. 



But as the TurkKh red polfelfes all thofe qualities which 

 are requifite in Ituffn that have been dyed, this affords a fiiffi- 

 cient proof that cotton mav be fo prepared bv art as to re- 

 ceive a conftant and fixed colour. That Turkiili dvc, there- 

 fore, nuift be the pattern to which all our experiments are 

 directed : for it itands the rays of the fun, as alfo the aftion 

 of foap and common ley ; though when often waflicd, and 

 expofed to the fun, it undergoes fome variation : but the 

 colour is fo far from beconiine worfe, that it is rather im- 

 proved, and rendered brighter. If the cotton yarn, however, 

 be digefted long in a cauitic lev, or rubbed in ii too much, 

 the colour is injured. Re(iliiied»fpirit of wine (alcohol) does 

 not hurt the colour of the ya'rn digefted in it, nor does the 

 fpirit acquire anv tinfturc from it. Spirit of fal-ammoniac, 

 prepared by means of lime (cauftic annnoniac,) is no lefs in- 

 effeilual. The colour is not injured by urine when under- 

 going decompofition ; nor does microcofmic fait hurt, but 

 rather makes the colour more agreeable, as is faid ; though 

 that experiment I never tried. Mineral acids corrode the 

 threads, but the colour itfclf remains. If digel^ed for fome 

 days in nitric acid, or in aqua-rcgia, the colour becorrtes 

 yellowifli, and at length difappears. 



Thefe experiments, which I myfclf and many chemifts 

 have tried, feemed to preclude all hope of diflblving and dif- 

 covering the nature of that dye ufed by the Turks, till J. C. 

 Oettinger, formerly profcflbr at Tubingen, who has deferved 

 fo well of chemillrv, threw out fome hints likely to lead to 

 a knowledge of it. He, as far as I know, was the firft perfon 

 \\\\o had an opportunity of obfcrving the great efl'eft which 

 oil of olives has upon that Turkey dye. He found, that if 

 cotton yarns dvcd with it were dipped in this oil, and then rub- 

 bed a little, they lolt; their colour, and that the whole colour- 

 ing matter became fo thoroughly diflblved, that other threads 

 cotdd be dved in that. oily Iblution ; fo thai, by the help of 

 oil, the dye on Turkilh yarn could be transferred to other 

 undvcd cotton. 



Thefe obfervations afiord grounds for various conjeftures. 

 The colouring matter which the Turks uie, is perhaps of 

 fuch a nature as to be foluble in oil in the fame manner as 

 ^:efins; and pcihaps the colouring matter adheres to vege- 

 table 



