206 ARCHIL 



To prepare archil, the lichens employed are ground up with water to a uniform 

 pulp, and this is then mixed with as much water as will make the whole fluid; 

 amuioniacal liquors from gas or from ivory-black works, or stale urine, are from time 

 to time added, and the mass frequently stirred so as to promote the action of the air. 

 The orcino or orythrino which exists in the lichen absorbs oxygen and nitrogen, and 

 forms orceine. The roccelline absorbs oxygen and forms crythroleio acid; these being 

 kept in solution by the ammonia, the whole liquid becomes of an intense purple, and 

 constitutes ordinary archil. Kane. 



Archil alone is not used for dyeing silk, unless for lilacs ; but silk is frequently 

 passed 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. It is sufficient 

 here to point out how white silks are passed through the archil bath. The same 

 process is performed with a bath more or loss 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 exactness, 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 ex- 

 ceed the proportions that can add to the beauty without at the samo time injuring, in 

 a dangerous manner, the permanence of the colours. Nevertheless, the colour 

 obtained when solution of tin is employed, is less 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. 



To dye wool with archil, the quantity of this substance deemed necessary 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 stuffis passed 

 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 (Forsettlc tfherbe) a much more durable colour, by putting in the bath some 

 solution of tin. The archil thereby loses its natural colour, and assumes one 

 approaching more or less to scarlet, according to the quantity of solution of tin 

 employed. This process 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, rose- 

 mary-flowers, and other delicate colours, which cannot be obtained so beautiful by 

 other processes. 



The herb archil, just named, called especially orceitte de terre, is found upon the 

 volcanic rocks of the Auvcrgne, on the Alps, and the Pyrenees. 



These lichens are gathered by men whoso whole time is thus occupied ; they scrape 

 them from .the rocks with a peculiarly shaped knife. They prefer collecting the 

 orceille in rainy weather, when they are more easily detached from the rocks. They 

 gather about 2 kilogrammes a day, or about 4^ pounds. When they take their 

 lichens to the makers of archil or litmus for the purpose of selling them, they submit 

 a sample to a test, for the purpose of estimating their quality. To this end they 

 put a little in a glass containing some urine, with a small quantity of lime. As the 

 lichens very rapidly pass into fermentation if kept in a damp state, .and thus lose 

 much of their tinctorial power, great care is taken in drying them ; when dry they 

 may be preserved without injury for some time. 



Archil is perhaps too much used in some cloth factories of England, to the dia- 

 credit of our dyes. It is said, that by its aid |rd 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 cudbear will dye one pound of woollen cloth. A crimson rod is obtained by 



