ARCHIL

A violet red paste used in dyeing, of which the substance called cudbear in Scotland (from Cuthbert , its first preparer in that form), is a modification. Two kinds of archil are distinguished in commerce, the archil plant of the Canaries, and that of Auvergne. The first is most esteemed: it is prepared from the lichen rocellus , which grows on rocks adjoining the sea in the Canary and Cape de Verde Islands, in Sardinia, Minorca, ., as well as on the rocks of Sweden. The second species is prepared from the lichen parellus , which grows on the basaltic rocks of Auvergne. There are several other species of lichen which might be employed in producing an analogous dye, were they prepared, like the preceding, into the substance called archil . Hellot gives the following method for discovering if they po e this property. A little of the plant is to be put into a gla ve el; it is to be moistened with ammonia and lime-water in equal parts; a little muriate of ammonia (sal ammoniac) is added; and the small ve el is corked. If the plant be of a nature to afford a red dye, after three or four days, the small portion of liquid, which will run off on inclining the ve el, now opened, will be tinged of a crimson red, and the plant itself will have a umed this colour. If the liquor or the plant does not take this colour, nothing need be hoped for; and it is usele to attempt its preparation on the great scale. Lewis says, however, that he has tested in this way a great many mo es, and that most of them afforded him a yellow or reddish brown colour; but that he obtained from only a small number a liquor of a deep red, which communicated to cloth merely a yellowish-red colour. Prepared archil gives out its colour very readily to water, ammonia, and alcohol. Its solution in alcohol is used for filling spirit-of-wine thermometers; and when these thermometers are well freed from air, the liquor loses its colour in some years, as Abbé Nollet observed. The contact of air restores the colour, which is destroyed anew, in vacuo, in proce of time. The watery infusion loses its colour, by the privation of air, in a few days; a singular phenomenon, which merits new researches. The infusion of archil is of a crimson bordering on violet. As it contains ammonia, which has already modified its natural colour, the fixed alkalies can produce little change on it, only deepening the colour a little, and making it more violet. Alum forms in it a precipitate of a brown red; and the supernatant liquid retains a yellowish-red colour. The solution of tin affords a reddish precipitate, which falls down slowly; the supernatant liquid retains a feeble red colour. The other metallic salts produce precipitates which offer nothing remarkable. The watery solution of archil applied to cold marble, penetrates it, communicating a beautiful violet colour, or a blue bordering on purple, which resists the air much longer than the archil colours applied to other substances. Dufay says, that he has seen marble tinged with this colour preserve it without alteration at the end of two years. To dye with archil, the quantity of this substance deemed nece ary, according to the quantity of wool or stuff to be dyed, and according to the shade to which they are to be brought, is to be diffused in a bath of water as soon as it begins to grow warm. The bath is then heated till it be ready to boil, and the wool or stuff is pa ed through it without any other preparation, except keeping that longest in, which is to have the deepest shade. A fine gridelin, bordering upon violet, is thereby obtained; but this colour has no permanence. Hence archil is rarely employed with any other view than to modify, heighten, and give lustre to the other colours. Hellot says, that having employed archil on wool boiled with tartar and alum, the colour resisted the air no more than what had received no preparation. But he obtained from herb archil ( l’orseille d’her be ) a much more durable colour, by putting in the bath some solution of tin. The archil thereby loses its natural colour, and a umes one approaching more or le to scarlet, according to the quantity of solution of tin employed. This proce must be executed in nearly the same manner as that of scarlet, except that the dyeing may be performed in a single bath. Archil is frequently had recourse to for varying the different shades and giving them lustre; hence it is used for violets, lilacs, mallows, and rosemary flowers. To obtain a deeper tone, as for the deep soupes au vin , sometimes a little alkali or milk of lime is mixed with it. The suites of this browning may also afford agates, rosemary flowers, and other delicate colours, which cannot be obtained so beautiful by other proce es. Alum cannot be substituted for this purpose; it not only does not give this lustre, but it degrades the deep colours. The herb-archil is preferable to the archil of Auvergne, from the greater bloom which it communicates to the colours, and from the larger quantity of colouring matter. It has, besides, the advantage of bearing ebullition. The latter, moreover, does not answer with alum, which destroys the colour; but the herb archil has the inconvenience of dyeing in an irregular manner, unle attention be given to pa the cloth through hot water as soon as it comes out of the dye. Archil alone is not used for dyeing silk, unle for lilacs; but silk is frequently pa ed through a bath of archil, either before dyeing it in other baths or after it has been dyed, in order to modify different colours, or to give them lustre. Examples of this will be given in treating of the compound colours. It is sufficient here to point out how white silks are pa ed through the archil bath. The same proce is performed with a bath more or le charged with this colour, for silks already dyed. Archil, in a quantity proportioned to the colour desired, is to be boiled in a copper. The clear liquid is to be run off quite hot from the archil bath, leaving the sediment at the bottom, into a tub of proper size, in which the silks, newly scoured with soap, are to be turned round on the skein-sticks with much exactne , till they have attained the wished-for shade. After this they must receive one beetling at the river. Archil is in general a very useful ingredient in dyeing; but as it is rich in colour, and communicates an alluring bloom, dyers are often tempted to abuse it, and to exceed the proportions that can add to the beauty without at the same time injuring in a dangerous manner the permanence of the colours. Neverthele , the colour obtained when solution of tin is employed, is le fugitive than without this addition: it is red, approaching to scarlet. Tin appears to be the only ingredient which can increase its durability. The solution of tin may be employed, not only in the dyeing bath, but for the preparation of the silk. In this case, by mixing the archil with other colouring substances, dyes may be obtained which have lustre with sufficient durability. We have spoken of the colour of the archil as if it were natural to it; but it is, really, due to an alkaline combination. The acids make it pa to red, either by saturating the alkali, or by substituting themselves for the alkali. The lichen which produces archil is subjected to another preparation, to make turnsole (litmus). This article is made in Holland. The lichen comes from the Canary Islands, and also from Sweden. It is reduced to a fine powder by means of a mill, and a certain proportion of potash is mixed with it. The mixture is watered with urine, and allowed to suffer a species of fermentation. When this has arrived at a certain degree, carbonate of lime in powder is added, to give consistence and weight to the paste, which is afterwards reduced into small parallelopipeds that are carefully dried. The latest researches on the lichens, as objects of manufacture, are those of We string of Stockholm. He examined 150 species, among which he found several which might be rendered useful. He recommends that the colouring matter should be extracted in the places where they grow, which would save a vast expense in curing, package, carriage, and waste. He styles the colouring substance itself cutbear, persio, or turnsole; and distributes the lichens as follows:—1st. Those which left to themselves, exposed to moderate heat and moisture, may be fixed without a mordant upon wool or silk; such are the L. cinereus , æmatonta , ventosus , cor all in us , we string i i , saxatilis , cons pa us , barbatus , plicatus , vulpinus , . 2. Those which develop a colouring matter fixable likewise without mordant, but which require boiling and a complicated preparation; such are the lichens subcarneus , dillenii , far in ace us , jubatus , furfur ace us , pul mon are us , corni gat us , cocci fer us , digit at us , an cialis , adunc us , . Saltpetre or sea-salt are requisite to improve the lustre and fastne of the dye given by this group to silk. 3. Those which require a peculiar proce to develop their colour; such as those which become purple through the agency of stale urine or ammonia. We string employed the following mode of testing:—He put three or four drachms of the dried and powdered lichen into a flask; moistened it with three or four measures of cold spring water; put the stuff to be dyed into the mixture, and left the flask in a cool place. Sometimes he added a little salt, saltpetre, quicklime, or sulphate of copper. If no colour appeared, he then moistened the lichen with water containing one twentieth of sal ammoniac, and one tenth of quicklime, and set the mixture aside in a cool place from eight to fourteen days. There appeared in most cases a reddish or violet coloured tint. Thus the lichen cinereus dyed silk a deep carmelite, and wool a light carmelite; the l. physodes gave a yellowish-gray; the pustulatus , a rose red; sanguinarius , gray; tartare us , found on the rocks of Norway, Scotland, and England, dyes a crimson-red. In Jutland, cutbear is made from it, by grinding the dry lichen, sifting it, then setting it to ferment in a close ve el with ammonia. The lichen must be of the third year’s growth to yield an abundant dye; and that which grows near the sea is the best. It loses half its weight by drying. A single person may gather from twenty to thirty pounds a day in situations where it abounds. No le than 2,239,685 pounds were manufactured at Christians and, Flekkefiort, and Fakrsund, in Norway, in the course of the six years prior to 1812. Since more solid dyes of the same shade have been invented, the archil has gone much into disuse. Federigo, of Florence, who revived its use at the beginning of the fourteenth century, made such an immense fortune by its preparation, that his family became one of the grandees of that city, under the name of Or i cellar i i, or Rucellarii. For more than a century Italy po e ed the exclusive art of making archil, obtaining the lichens from the islands of the Mediterranean. According to an official report of 1831, Teneriffe furnished annually 500 quintals (cwts.) of lichen; the Canary Isles, 400; Fuerta Santur a, 300; Lancerot, 300; Gomera, 300; isle of Ferro, 800. This busine belonged to the crown, and brought it a revenue of 1500 piastres. The farmers paid from 15 to 20 reals for the right to gather each quintal. At that time the quintal fetched in the London market 4 l. sterling. Archil is perhaps too much used in some cloth factories of England, to the discredit of our dyes. It is said, that by its aid one third of the indigo may be saved in the blue vat; but the colour is so much the more perishable. The fine soft tint induced upon much of the black cloth by means of archil is also deceptive. One half-pound of cutbear will dye one pound of woollen cloth. A crimson red is obtained by adding to the decoction of archil a little salt of tin (muriate), and pa ing the cloth through the bath, after it has been prepared by a mordant of tin and tartar. It must be afterwards pa ed through hot water.