no
and stirred with the rake, which is a semi-circular wooden instru-ment, having a long handle. The mixture is occasionally agi-tated, till the vat has received all the hot liquor; and, as soon asthe vessel is nearly half full, it should be covered with a lid, some-what larger than its own circumference. A cloth should he like-wise thrown over it, in order to confine the heat; after which thewhole should be suffered to subside for four hours; when it oughtto be uncovered, in order to give it air, and to mix it thoroughly.No fine, as is generally though falsely directed by dyers, shouldbe put into the vat, but a small air-hole left on the top: the stirr-ing and agitation may once more be repeated, at the expiration ofthree or four hours. If the ingredients, after these operations, benot yet ready and come to, that is, if the blue does not rise to thesurlace, but continues to foam, it will then be necessary, afterworking tl'.e mixture well, to let it stand an hour and a half longer ;care being taken during that time to observe it minutely, in caseit should cast blue. The vat is then to he tilled up with water,and a sunicie.it quantity of indigo, dissolved in a ley of pot-ash,pure water, bran and madder. The vat being again covered, atthe end of three hours a pattern is to be immersed in the liquorfor a similar space of time, when it is to be taken out, to inspectihe state of the vat. This pattern, when lirst taken out, shouldbe of a green colour, but instantly turn blue; if the green bebright and good, the vat is to be stirred again, and then coveredup, with the addition of a tew handfuls of bran. Three hours af-ter, the same operation is to be repeated, with, the addition of morebran, if necessary, when it is to be covered up for ail hour and ahalf longer ; and, as soon as it subsides, another specimen is to beimmersed in it for an hour, when it must be examined, to ascer-tain the state ol the pastel. It the lonner be of a good green,when taken out, and turn suddenly to a deep blue, on being ex-posed to the air, another pattern is to he pul in, to discover theeffect of the vat; which, if the. colour be sufficiently high, is to betilled with hot water, or (which is preferable, if it can be procured)with the liquor of an old madder-vat, and then stirred again. Nowthe vat is to be once more covered for an hour ; after which thestuds to be died should be immersed.
Woah is the next article in the making of a blue colour: themode of preparing it (lifters in no respect from the preceding one,just described, excepting that iL is weaker, and yields less co-lour.
Ixdigo is the last ingredient in dyeing bines. The vat is about5 feet high, 2 feet in diameter, and somewhat narrower towardsthe bottom, being surrounded by a wall, and having a vacancyfor the embers. A vat of this size requires from 2 to 5, or even(ilbs. of indigo ; and this operation is conducted us follows: 1.About la gallons of river water are put into a copper to boil forabout half an hour, together with 2lbs. 0 f pot-ash, 2 oz. of madder,and a handful of bran. 2 . Immerse 2lbs. of indigo in a pail ofcoid water, in order to separate the solid from the volatile parti-cles, which will immediately rise to the surface. The wateryliquor is then poured off, and the indigo, settled at the bottom ofthe pail, should he triturated in an iron mortar, with the additionof a small quantity of hot water, that ought to be shaken from sideto side ; and the lloating particles of indigo, which are those mostfinely pounded, must be poured into another vessel. In thismanner, the indigo remaining in the mortar is continually reduc-ed, fresh water being repeatedly added, till the whole is pulver-ized so finely as to rise to the surface. The liquor which had,during the above stated preparation, been boiling in the copper,is now poured into the vat, together with the indigo, when thewhole is well stirred with a rake, the vat closely covered, andsurrounded with embers. If this operation commence in the af-ternoon, the embers must be relieved in the evening, and also inthe morning and evening of the following dav, in the course ofwhich it should be twice gently stirred. Similar measures oughtto be pursued on the third day, in order to preserve an uniformheat, and intimately mix the ingredients. A brassy scum willthen be perceived to rise to the surface, in several detached parts :by continuing the heat on the fourth day, the scum becomes morecoherent; and the froth, occasioned by "stirring the liquor, appearsblue, while the latter is of a deep green. As soon as it assumesthis appearance, the vat should be filled, for which purpose a freshliquor must be prepared, by putting^ gallons of water into a cop-per, together with a pound of pot-ash, and half an oz. of madder.
When these ingredients have boiled half an hour, the decoctionis poured into the vat, the whole well stirred, and if it producemuch froth, it will be in a proper state for working the next day.This may likewise he ascertained by the brassy or scaly crust,which boats on the surface of the liquor; and, farther, if on blow-ing, or stirring, the latter with the hand, it assume a deep greencolour, while the surface appears of a brownish blue. After thevats have been thus prepared, the dyeing of woollen or sijkenstuffs is very easy ; no other process being required, than immers-ing them in warm water, wringing, and then steeping them in thevat for a longer or shorter time, according to the deepness of thecolour intended to be imparted. The stuffs should be occasion-ally opened, that is, taken out of the vat, wrung over it, and expos-ed to the air for a minute or two, till it become blue: for it mustbe observed, that, in all the solutions of indigo, or other dyeingmaterials above described, the blue colour is produced only byexposure to the air, and the stuff, on being first drawn out of theliquor, always appears green, and will retain that tinge, unless itbe exposed to the air. In dyeing blue, therefore, it is necessaryto let the colour thus change previously to a second immersion,that (he shade may be the better distinguished, as dark blues re-quire to be repeatedly dipped. The method of dyeing cotton orlinen blue, varies so little from that already described, as to renderany farther directions unnecessary. When silk isto be dyed blue,there is generally a greater portion of indigo added.
For the Turkey Bi.ue, which is the deepest, a very strongarchil hath is lirst given; and for the Koval Blue, one of the samekind, but weaker. Other blues are dyed without any ground be-ing previously given. There * s however a blue made as deep asthe royal blue, for the ground of which cochineal is used insteadof archil, in order to render it more permanent, whence the titlebleu lin has been given it. A blue of little durability may begiven to silk by means of verdegris and logwood ; but it might bemade more lasting, by first giving it a lighter shade than is intend-ed in a bath of this kind, afterwards dipping it in an archil bath,and in the vat after that.
When Kaw Silk is to be dyed blue, that should he chosenwhich is naturally white. It should be thoroughly soaked in wa-ter, and afterwards put into the vat in separate hanks, in the samemanner as the scoured silk. In general, raw silk takes the dyemore readily, and, if possible, the scoured silk is put into the vatbefore it. If raw silk require archil, or the other ingredientsabovementioned, it is to be treated in the same manner alreadydescribed.
2 . The next of the primitive colours to be considered is Red,of which there are manv shades and varieties ; but the principalare scarlet, crimson, and madder-red. The process to be adoptedfor obtaining these colours, essentially differs from that of blues;as the former require a peculiar preparation of the stuffs to bedyed, on the exactness of which, the goodness of the colour in agreat measure depends. These preparatory ingredients consist ofalum, tartar, aqua-fortis, or a solution of tin in this acid. Callsand alkaline salts are also sometimes added, though they do not ma-terially contribute to the colour. There are three kinds of scarlet,namely, those dyed with kermes, with cochineal, and with gum-lac. The first of these, called Venetian scarlet, is the most perma-nent, but the least bright; it is aiso apt to be less spotted than theothers; but on account of the difficulty of procuring (lie insectswhich afford the colour, it is very seldom, if ever, used in thiscountry. The second kind of scvrlet, namely, that dyed .vithcochineal, is less permanent than the Venetian scarlet, though thedrug is procured at a more reasonable price, it is, however,very difficult to dye the true cochineal scarlet: the success oi thi-,operation equally depends upon the choice of tiie material, thewater employed," and the method of preparing a solution of tin,which is theonlv ingredient by which that delicate colour can beproduced. To" eight ounces of spirit of nitre an equal quantity ofriver-water is to be added ; in this mixture are to he graduallydissolved half an ounce of the purest and white.-t sal-ammoniac,and two drams of purified salt-petre. An ounce of tin, reduced tograins, by being dropped into cold water while melting, is nextto be added drop by drop to the liquor thus prepared ; the firstbeing perfectly dissolved before a second''..; introduced. The so-lution resembles that of gold, and, if fine lin be employed, willlie perfectly transparent, without any dust or sediment. W ith