Indian Science and Technology in the Eighteenth Century: Some Contemporary European Accounts c25.6

c25.6

I have for several years past been attentive to the methods used by the natives of this country for dyeing their cotton cloths and I think I have discovered the singular circumstance by which they are enabled to give that permanency to the colour which is so much admired. I am unable to give any theory of the operation of the chief substance they use and without which they can do nothing. It seems to all cases when a cloth is wetted with an infusion of it and a solution of alum, and then put into a vegetable colour to deposit something which has a strong attraction at the same time for the cloth and the colouring principle and which renders them ever afterwards inseparable. It seems to have the same effect on animal dyes, if I be not mistaken on some trials that I have had made with cochineal. The natives have many methods of altering the colour of vegetables or heightening their splendour simply by the addition of acids or of alum or of water in which...( Indecipherable in original.—Editor.) of iron had been infused or the recent excrement of some animal while it still retains much of the volatile alkali & c. But I know that to render these colours durable on the cloth (after separating a number of circumstances that only in appearance conduce to that end) they have no other method than the one I have mentioned. If this appears to you a matter of consequence as the cotton manufacturers are now in so flourishing a condition in England I shall at some future period communicate more particularly their method to you.