BARWOOD.

34i

According to Prof. Girardin, the alcoholic tindure of santal wood exhibitsthe following reactions:—Addition of water causes a yellow turbidity; withalkalies the colour turns carmine; lime-water produces a reddish-brownochreous precipitate ; protochloride of tin a blood-red precipitate ; bichlorideof tin a brick-red precipitate; per-salts of iron a red-brown precipitate; saltsof lead a violet precipitate ; corrosive sublimate a scarlet precipitate ; salts ofsilver a red-brown precipitate.

Santal wood is used for some peculiar red shades upon wool and cottonafter having been mordanted with alumina or oxide of tin, and also as a bottomfor the so-called Nemours or “national blue” upon wool. Mixed with otherdyes, it is used for the produdion of brown, bronze, and olive colours. Santalwood dyes wool permanently, even without the aid of any mordant.

The following woods met with in commerce belong, as far as is known, tothe same category as santal wood :—

Caliatur or Cariatur Wood is imported from India in blocks of from 2 to3 metres in length ; it is a hard, compad, and imperishable wood, internallybright red, and is superior to santal wood as a dye-stuff, but is rather expensive,and is rarely used.

Madagascar Wood is of a wine-red colour.

Barwood may be considered as the type of the insoluble class of redwoods. It is obtained from the west coast of Africa, especially from SierraLeone and Angola. The botanical name of the tree is Baphia nltida , which,singularly enough, is also said to yield camwood. In the log barwood iscompad, and has an orange colour when polished. When rasped—the statein which it is generally met with in trade—it is a rough, harsh, red powder,without smell. Cold water, after maceration for five days with the groundwood, acquires merely a pale fawn-colour, about 0*85 per cent only of colourbeing taken up. Boiling water takes up about 7 per cent of colour, which oncooling is almost entirely re-deposited as a reddish powder. Hence allattempts to prepare from it a liquor or extrad fit for use in dyeing and printinghave failed. In alcohol the tindorial principle is more soluble, but it is onlyby repeated treatment with boiling spirit that the wood is entirely exhausted.The amount of colouring matter is high, averaging 23 percent. In causticsoda and ammonia it dissolves with a violet-red hue, and is re-deposited onneutralising the liquor with an acid. An attempt has been made to utilisethe solvent power of alkalies in order to obtain an extrad, but the brightnessand permanence of the colour are so much impaired that the process is of nopradical value. Acetic acid extrads the colour, and becomes of a dark brownhue, but if this extrad is mixed with water it dyes very flat and meagreshades.

The alcoholic solution gives the following precipitates :—With proto-saltsof iron, a violet; with salts of copper, a brownish-violet; acetate of lead, adeep violet; chloride of tin, a light red ; sulphate of zinc, a bright red ; tartaremetic, a cherry-red ; nitrate of bismuth, brilliant crimson ; corrosive subli-mate, a brick-red.

Barwood is very extensively used in producing upon cotton-yarn the well-known “ barwood red.” This is a shade much more permanent than anyobtained from the soluble red woods, and is used as a cheap substitute forlurkey-red.. The cotton is first well mordanted with an astringent,—generally