ARCH′IL

(artsh′-ĭl). Syn. Arch′el *, Or′chil ; Archil′la , Orchil′la (ch as k), L.; Orseille , Fr., Ger.; Or i cello , It. A violet-red, purple or blue colouring matter or dye-stuff, obtained from several species of lichens, but of the finest quality from roccella tinct or i a (DC.), and next from r. fuci form is (DC.). The archil of commerce is met with as a liquid paste, or as a thin liquid dye or stain of more or le intensity. The ordinary archil or orchil of the shops ( ORCHIL-LIQUOR ) is under the last form; and is known as either BLUE OR RED ARCHIL —distinctions which arise as follows:— Prep. 1. Blue archil :—The bruised or coarsely ground lichen is steeped for some time in a mixture of stale urine, or bone-spirit, and lime or milk of lime, or in any similar ammoniacal solution, contained in covered wooden ve els in the cold; the proce being repeated until all the colour is extracted. 2. Red or crimson archil :—The materials are the same as for the last variety, but rather le milk of lime is used, and the ‘steep’ is generally made in earthen jars placed in a room heated by steam, technically called a stove. The two kinds merely differ in the degree of their red or violet tint—the addition of a small quantity of lime or alkali to the one, or of an acid to the other, immediately bringing them both to the same shade of colour. Prop. Archil has a disagreeable putrid ammoniacal odour. Its colouring matter is soluble in water, alcohol, urine, ammoniacal and alkaline lyes, and weak acid liquors; alkalies turn it blue, acids red; alum gives with it a brownish-red precipitate, and solution of tin a red one; the alcoholic solution gradually loses its colour when excluded from the air. Its colouring matter consists chiefly of orcein. Pur. Archil is frequently adulterated with extract of logwood, or of Lima or Sapan-wood. It may be tested as follows:—1. A solution of 50 or 60 drops of pure archil in about 3 fl. oz. of water slightly acidulated with acetic acid, almost entirely loses its colour, or presents only a yellowish tinge, when heated to ebullition in a flask along with 50 drops of a fresh solution of pro to chloride of tin made with 1 part of the salt to 2 parts of water:—2. A drop of fluid extract of logwood treated in the same way, gives a distinct violet tint, which resists several hours’ boiling; but when only 3 or 4 per cent. of logwood is present, the boiled liquid has a permanent grey tint:—3. If the boiled liquid retains its red hue, extract of Sapan-wood is present:—4. The boiled liquor, when the archil is pure, re-acquires its colour by exposure to the air, and the logwood is destroyed only by an alkaline solution of tin, and is restored by acids. Uses, . It is employed to tinge the spirit used to fill the tubes of thermometers, and to stain paper, wood, . The aqueous solution stains MARBLE , in the cold, of a beautiful violet colour, of considerable permanence when not exposed to a vivid light. “Marble thus tinged preserves its colour unchanged at the end of two years.” (Dufay.) Its principal use is, however, in dyeing. By proper management it may be made to produce every shade of pink and crimson to blue and purple. Unfortunately, although the hues it imparts to silk and wool po e an exquisite bloom or lustre, they are far from permanent, and unle well managed, soon decay. It is hence generally employed in combination with other dye-stuffs, or as a finishing bath to impart a bloom to silk or woollens already dyed of permanent colours. In using it as a dye it is added to hot water in the required quantity, and the bath being raised to nearly the boiling-point, the materials are put in and pa ed through it, until the desired shade is produced. A mordant of alum and tartar is sometimes used, but does not add to the permanence of the colour. Solution of tin added to the bath increases the durability, but turns the colour more on the scarlet. (Hellot.) Milk of lime or salt of tartar is added to darken it; acids or solution of tin to redden it. A beautiful crimson-red is obtained by first pa ing the stuff through a mordant of tin and tartar, and then through a bath of archil mixed with a very little solution of tin. By the proper management of this dye, lilacs, violets, mallows, rosemary flower, soupes au vin, agates, and many other shades may be produced on silk or cloth, either alone or in conjunction with other dyes to modify it. 1 ⁄ 2 lb. of solid archil, or its equivalent in a liquid form, will dye 1 to 2 lb. of cloth. Herb-archil , it is a erted, will bear boiling, and gives a more durable tint than the other lichens, especially with solution of tin. (Hellot.) Recently Mr Light foot has patented a proce for dyeing with archil with the aid of oil, after the manner followed for producing Turkey-red on cottons. Archil, Facti′′tious:—1. From a mixture of onions (in a state of incipient putrefaction) with about 1-10th to 1-12th their weight of carbonate of potash and some ammonia, fermented together; and adding, after some days, 1-7th to 1-8th of the weight of the potash used in a salt of lead. The details of the proce e ential to succe are, however, now unknown, the secret having died with a relative of the writer of this article. 2. Extract of logwood di olved in juice of elderberries and putrid urine, with the addition of a little pearlash for the BLUE , and a very little oxalic acid or oil of vitriol for the RED variety. Used to stain wood.