Brass Colour, as employed by the colourmen to imitate brass, is of two tints, the red or bronze, and the yellow like gilt brass. Copper filings mixed with red ochre or bole, constitute the former; a powdered brass imported from Germany is used for the latter. Both must be worked up with varnish after being dried with heat, and then spread with a flat camel-hair brush evenly upon the surface of the object. The best varnish is composed of 20 ounces of spirits of wine, 2 ounces of shellac, and 2 ounces of sandarach, properly dissolved. See [Varnish]. Only so much of the brass powder and varnish should be mixed at a time as is wanted for immediate use.
Brass Foil. Dutch leaf, called Knitter or Rauschgold in Germany, is made from a very thin sheet brass, beat out under a hammer worked by water power, which gives 300 or 400 strokes per minute; from 40 to 80 leaves being laid over each other. By this treatment it acquires its characteristic solidity and lustre. See above, the process for converting the copper superficially into brass by the fumes of zinc.
BRAZING. (Braser, Fr.; Messing-lothung, Germ.) The soldering together of edges of iron, copper, brass, &c., with an alloy consisting of brass and zinc, sometimes with a little tin or silver. The surfaces to be thus united must be filed perfectly bright, and not be soiled with the fingers or in any other way. The granular or nearly pulverulent alloy is usually wetted with a paste of ground borax and water, applied in this state, dried, and then exposed carefully to bright ignition at a clear forge fire. Some workmen enclose the part to be soldered in a clay lute, but others prefer leaving it uncovered, that they may see when the solder has flowed freely, and entered into all the seams.
BRAZIL-WOOD. (Bois de Fernambouc, Fr.; Brasilienholz, Germ.) This dye-wood derives its name from the part of America whence it was first imported. It has also the names Fernambuca, wood of Saint Martha, and of Sapan, according to the places which produce it. Linnæus distinguishes the tree which furnishes the Brazil wood by the name of Cæsalpinia crista. It commonly grows in dry places among rocks. Its trunk is very large, crooked, and full of knots. It is very hard, susceptible of a fine polish, and sinks in water. It is pale when newly cleft, but becomes red on exposure to the air.
It has different shades of red and orange. Its goodness is determined particularly by its density. When chewed, a saccharine taste is perceived. It may be distinguished from red saunders wood, as the latter does not yield its colour to water.
Boiling water extracts the whole colouring matter of Brazil-wood. If the ebullition be long enough continued, it assumes a fine red colour. The residuum appears black. In this case, an alkali may still extract much colouring matter. The solution in alcohol or ammonia is still deeper than the preceding.
The decoction of Brazil-wood, called juice of Brazil, is observed to be less fit for dyeing when recent, than when old or even fermented. By age it takes a yellowish-red colour. For making this decoction, Hellot recommends to use the hardest water; but it should be remarked, that this water deepens the colour in proportion to the earthy salts which it contains. After boiling this wood reduced to chips, or, what is preferable, to powder, for three hours, this first decoction is poured into a cask. Fresh water is poured on the wood, which is then made to boil for three hours, and mixed with the former. When Brazil-wood is employed in a dyeing bath, it is proper to enclose it in a thin linen bag, as well as all the dye woods in general.
Wool immersed in the juice of Brazil takes but a feeble tint, which is speedily destroyed. It must receive some preparations.
The wool is to be boiled in a solution of alum, to which a fourth or even less of tartar is added, for a larger proportion of tartar would make the colour yellowish. The wool is kept impregnated with it for at least eight days, in a cool place. After this, it is dyed in the Brazil juice with a slight boiling. But the first colouring particles that are deposited, afford a less beautiful colour; hence it is proper to pass a coarser stuff previously through the bath. In this manner a lively red is procured, which resists pretty well the action of the air.
Brazil-wood is made use of for dyeing silk what is called false crimson, to distinguish it from the crimson made by means of cochineal, which is much more permanent.