Brazil-wood Lake.—1. Take of ground Brazil wood 1 lb., water 4 gallons; digest for 24 hours, then boil for 30 or 40 minutes, and add of alum 1½ lb., dissolved in a little water; mix, decant, strain, and add of solution of tin ½ lb.; again mix well and filter; to the clear liquid add, cautiously, a solution of salt of tartar or carbonate of soda, as long as a deep-coloured precipitate forms, carefully avoiding excess. 2. Add washed and recently precipitated alumina to a strong and filtered decoction of Brazil wood. Inferior to the last.
Cochineal Lake.—1. Cochineal (in coarse powder) 1 oz.; water and rectified spirit, of each, 2½ ozs.; digest for a week; filter and precipitate the tincture with a few drops of solution of tin, added every 2 hours, until the whole of the colouring matter is thrown down; lastly, wash the precipitate in distilled water and dry it; very fine. 2. Digest powdered cochineal in ammonia water for a week, dilute the solution with a little water, and add the liquid to a solution of alum, as long as a precipitate falls, which is the lake. Equal to the last. 3. Coarsely powdered cochineal 1 lb., water 2 gallons; boil 1 hour, decant, strain, add a solution of salt of tartar, 1 lb., and precipitate with a solution of alum. By adding the alum first, and precipitating the lake with the alkali, the colour will be slightly varied. All the above are sold as carminated or Florence lake, to which they are often superior.
Lac Lake.—Boil fresh stick-lac in a solution of carbonate of soda, filter the solution, precipitate with a solution of alum, and proceed as before. A fine red.
Madder Lake.—1. Take of Dutch grappe or crop madder 2 oz., tie it in a cloth, beat it well in a pint of water in a stone mortar, and repeat the process with fresh water (about 5 pints) until it ceases to yield colour; next boil the mixed liquor in an earthen vessel, pour it into a large basin, and add of alum 1 oz., previously dissolved in boiling water, 1 pint; stir well, and while stirring, pour in gradually of a strong solution of carbonate of potassa (salt of tartar) 1½ oz.: let the whole stand until cold, then pour off the supernatant liquor, drain, agitate the residue with boiling water, 1 quart (in separate portions), decant, drain, and dry. Product, ½ oz. The Society of Arts voted their gold medal to the author of the above formula. 2. Add a little solution of acetate of lead to a decoction of madder, to throw down the brown colouring matter, filter, add a solution of tin or alum, precipitate with a solution of carbonate of soda or of potassa, and otherwise proceed as before. 3. Ground madder, 2 lbs.; water, 1 gallon; macerate with agitation for 10 minutes, strain off the water, and press the remainder quite dry; repeat the process a second and a third time; then add to the mixed liquors, alum, ½ lb., dissolved in water, 3 quarts; and heat in a water-bath for 3 or 4 hours, adding water as it evaporates: next filter, first through flannel, and when sufficiently cold, through paper; then add a solution of carbonate of potassa as long as a precipitate falls, which must be washed until the water comes off colourless, and lastly, dry. If the alkali be added in 3 successive doses, 3 different lakes will be obtained, successively diminishing in beauty.
Orange Lake.—Take of the best Spanish annotta 4 ozs.; pearlash, ¾ lb.; water, 1 gallon; boil it for half an hour, strain, precipitate with alum, 1 lb., dissolved in water, 1 gallon, observing not to add the latter solution when it ceases to produce an effervescence or a precipitate. The addition of some solution of tin turns this lake a lemon yellow; acids redden it.
Yellow Lake.—1. Boil French berries, quercitron bark, or turmeric, 1 lb., and salt of tartar, 1 oz., in water, 1 gallon, until reduced to one half; then strain the decoction and precipitate with a solution of alum. 2. Boil 1 lb. of the dye-stuff with alum, ½ lb.; water, 1 gallon, as before, and precipitate the decoction with a solution of carbonate of potash.
Artificial Ultramarine.—This is obtained by several processes, of which the following are examples:—1. Take kaolin, 37 parts; sulphate of soda, 15; carbonate of soda, 22; sulphur, 18; and charcoal, 8 parts; mix these intimately, and heat in large covered crucibles for twenty-four to thirty hours. The resulting product is then to be again heated in cast-iron boxes at a moderate temperature, until the required tint is obtained; it is finally pulverised, washed in a large quantity of water, and the floating particles allowed to subside in a separate vessel; the deposited colour is now collected and dried. 2. Expose to a low red heat, in a covered crucible as long as fumes are given off, a mixture composed of: kaolin, 2 parts; anhydrous carbonate of soda and sulphur, of each 3 parts. Some persons use one-third less carbonate of soda.
Twaddell's Hydrometer, which is much employed for ascertaining the strength of soda and chloride of lime solutions, etc., is so graduated and weighted that the 0 or zero mark is equal to 1,000, or the specific gravity of distilled water at the temperature of 60° F., and each degree on the scale is equal to ·005; so that by multiplying this number by the number of degrees marked on the scale, and adding 1·, the real specific gravity is obtained. Thus 10° Twaddell indicates a specific gravity of 1050, or 1·05, and so on.