54 Experiments on Dje'mg Cotton. 



durability of this dye. But I (liall fpeak only of thofe cloths 

 which were premacerated in an aftringeut folution of alum. 

 The cloth which had imbibed oil, and that which had not 

 imbibed it, both flood alkaline falls; for thefe falls rendered 

 the colour of both darker, without any other change. Nitric 

 acid not diluted with water rendered the colour of both firft 

 brighter, then yellow, and at laft deftroyed it altogether. 

 But ftill there was a great difference : for the cloth which 

 had been prepared with oil retained its colour much longer, 

 and when walhed in water, at the end of fcvcn or eight mi- 

 nutes the colour returned, but of a violet hue ; whereas cloth 

 prepared without oil loft its whole colour fooner. The fame 

 arid diluted injured the latter, but not the former. Even 

 the Turkev dye, prepared with madder, which is more con- 

 llaut, will not long withRand the nitric acid ; nor is it ne- 

 ceffary that all our cloths lliould be of fuch a nature as to 

 bear all acids. If a few drops of mineral acid fall by chance 

 upon a piece of cloth dyed in this manner, a yellow fpot is 

 produced ; but it entirely vanilbes from both kinds, if the acid 

 be immediately well waflied out with water. It is needlefs 

 to remark, that acid vegetable juices do this dye no hurt. It 

 fuftains no injury from human urine, even if the cloth be 

 left in it for fevcral day?. When expofed to the rays of the 

 fun for fome days, thefe cloths fuffered no injury, though 

 that dyed without oil fecmcd to have loft more of its colour. 

 But cloth which has even been prepared with oil, will not 

 bear to be boiled with foap; its colour firft becomes violet, 

 and then totally difappears. 



Thefe few experiments fo fully demon ftrate the great ad- 

 vantage of oil in dyeing cotton, that no doubt can be enter- 

 tained of its utility. I muft ftrongly recommend it, there- 

 fore, iK)t only to thofe who dye cotton, but to thofe alfo who 

 dye linen. For, as the great power of the oil on the too 

 fading dye of the carthamus is, that the colouring matter is 

 fooner abforbed, and in greater abundance, by the cloth, and 

 alfo retained longer bv it, its power would doubtlefs be much 

 greater upon dvcs which, hv their natural qualities, bear, 

 without any afft,(tance, foap, the rays of the fun, and falls, 

 by which the dye of the delicate carthamus is injured. 1 do 

 not, however, imagine that I have found out the beft me- 

 thod of employing oil ; but I entertain a hope, that thofe 

 who may profecute thefe experiments will difcover a better. 

 Thofe, in my opinion, will be more fuccefsful who can ufe 

 iifh oil, which, in many places, may eafiiy be procured by 

 dyers. Nor is it impofliblc that whale oil, called commonly 

 train oil, may be ib prepared as to be fit for the purpofes of 

 4 dyeing. 



