D Y tevenl detached parts: by conti- nuing the heal on the foui i!i cat more coherent ; and the froth, occasioned by Btir- r.ing the liquor, appears blur, w bile iU :r is . i a deep gr e e n. > .:i it assumes this app arance, the vat should l>e idled ; tor hich porpo b liquor must be pre- pared, by putting 5 gallons of .wa- . no a copper, i . I ier with a pound of pot-ash, and half an oz. "i madder. When these ingre- dients have boiled halt' an hour, the decoction is poured into the , the 11 stirred, and, if it produce much troth, it will be in a proper state for working the next day. This may likewise be ascertained by the brassy or scaly crust, which floats on the surface of the liquor: and, farther, if on blowing, or stirring, the latter with the hand, it assume a deep green colour, while the surface appears of a brownish blue. After the vats have been thus prepared, the dyeing of woollen or silken stuffs is very easy ; no other process being required, than im- mersing them in warm water, wringing, and then steeping them in the vat for a longer or shorter time, according to the deepness of the colour intended to be imparted. The stuffs should be occasionally opened, that is, taken out of the vat, wrung over it, and exp to the air ror a minute or two, till it become blue : for it must be ob- served, that, in all the solutions of indigo, or either dyeing materials above described, the blue colour is produced only by exposure to the air, and the stuff, en being first drawn out of the liquor, always appears green, and will retain that iinge, unless it be exposed to the sir. In dyeing blue, therefore, it J DYE? [203 1 essary to U t the colour ihus ••ond im- m rsion, th it the shade may be the better distinguished, as dark • require 1 dip- ped, — The method of dyeing 1 ton or tin !S so little from that ah is to render any farther directions uflrie- iry. 2. The next of the primitive co- lours to be considered is red, of which .here are many shades and varieties; but the principal are rim son, and madder-red. The process to be adopted for ob- taining these colours, essentially differs from that of blues; as the former require a peculiar prepara- tion of the stuffs to be dyed, on the exactness of which, the good- ness of the colour in a great mea- sure depends. These preparatory ingredients consist of alum, tartar, aqua-fbrtis, ox a solution of tin in this aeirf. Gaits and alkaline salts are also sometimes added, though they do not materially con- tribute to the colour. There are three kinds of scarlet, namel-e, that dyed with kermes, with cochineal, and with gum-lac. The first of these, called Fene- tia/i scarlet, is the most permanent, but the least bright : it is also apt to be less spotted than the others : but, on account of the difficulty of procuring the insects which afford the colour, it is very seldom, if ever, used in this country. The second kind of scarlet, namely, t'.at dyed with cochineal, is less permanent than the "Vene- tian scarlet, though the drug is procured at a more reasonable price. It is, however, very diffi- cult to dye the true cochineal scar- let: the success of this operation equally depends upon the choice of
