LICHENS.

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D. Yellow and Orange Lakes.

1. Annatto Lakes.—A yellow lake maybe obtained by mixing the aqueousdecodtion of annatto with carbonate of soda, bringing the liquid to a boil, andthen precipitating it with a solution of alum in excess.

An orange lake may be prepared from the same dye-ware by boiling it incarbonate of soda, and then precipitating with alum or salt of tin, A redderorange is produced by boiling the ware first in water, and rejecting the solution ;boiling again* in solution of carbonate of soda, and precipitating this latterextra# with alum or salt of tin.

2. Fustic Lake.—Extra# of fustic, which has been allowed to stand for afew days, is mixed with basic acetate of lead, stirring constantly.

Yellow lakes can be obtained from other dye-wares by processes similar tothe above.

Aniline Lakes.

Dissolve in $ kilo, of alcohol, at 95 per cent, 10 grms. copal and 1 grm.magenta. Filter, and add dry starch to form a uniform mass, dry, and powder.Other aniline colours may replace the magenta, giving a variety of colours.

Aurine yields a variety of beautiful precipitates if mixed with metallic andearthy solutions and thrown down by the cautious addition of an alkali.These, however, are not true lakes, but merely hydrated oxides, or sub-saltswith which the aurine is mechanically incorporated. On washing with dis-tilled water they lose their colour.

COLOURING MATTERS DERIVED FROM LICHENS.

Several kinds of lichens acquire a fine violet colour under the joint influenceof ammonia and atmospheric oxygen. This fa#, which depends on thepresence of one or more peculiar principles, has been empirically known andapplied industrially a long time before its theoretical explanation was dis-covered.

About the year 1300 a Florentine nobleman, named Federigo, discoveredaccidentally, while on a journey in the Levant, the colour-yielding propertiesof lichens; and Italy, especially Florence, supplied for more than a centurythe orchil manufa#ured with lichens from the Mediterranean. Afterwardsthe lichens were obtained from the Canary and Cape Verd Islands, and in ourdays they are imported from Madagascar, Zanzibar, Lima, Guayaquil, Angola,Madeira, Corsica, the Greek Islands, and Sardinia. The weeds belong to thegenus known as Roccella , viz., tinctoria and fuciformis, and are distinguishedas sea or marine orchil, because the plant thrives on rocks in the sea and alongthe sea-beach. These plants have a very short, circular base of implantation,from which issue several cylindrically-formed stems, ramifying like thebranches of a tree, and terminating in fine points. Their specific chara#ersv ary, and so do their colours when dried, ranging from greyish-white to abrown. The richness in tin#orial matter, or rather in the principles capablebecoming pigments, varies even for one and the same kind, but certain testsenable the manufa#urer to judge of the quality and purchase accordingly.The land lichens are met with on the naked rocks of the Pyrenees, Cevennes,Alps, and even the Scandinavian mountains, and belong to the genus Vario-