b. (Patent yeast.) Take of hops, 6 oz.; water, 3 galls.; simmer for 3 hours, strain, and in 10 minutes stir in of ground malt, 1⁄2 peck; next reboil the hops in water, as before, and let the strained liquor run into the first mash, which must then be well stirred up, covered over, and left for 4 hours; after that time drain off the wort, and, when the temperature has fallen to 90° Fahr., set it to work with yeast (preferably patent), 1 pint; after standing for 20 to 24 hours in a warm place, take off the scum, strain it through a coarse hair sieve, and it will be fit for use. 1 pint is said to be enough for 1 bushel of bread.
Obs. The preparation of artificial yeast, and substitutes for yeast, has long engaged the attention of both the scientific chemist and the practical tradesman. The subject is, undoubtedly, of great importance to emigrants and voyagers. The above processes, by good management, yield products which are all that can be desired.
YEL′LOW DYES. The following substances impart a yellow to goods, either at once or after they have been mordanted with alumina or tin:—annotta, barberry root, dyer’s broom, French berries, fustic, fustet, quercitron bark, and turmeric. Goods mordanted with acetate of lead, and afterwards passed through a bath of chromate of potash, acquire a brilliant chrome-yellow colour;—solution of sulphate or acetate of iron, followed by immersion in potash or lime water, gives a buff or orange;—orpiment, dissolved in ammonia water, imparts a golden yellow. (See the above-named substances, in their alphabetical places.) An aniline yellow (chrysaniline) has recently been obtained by Mr Nicholson, which is said to be a most valuable dye-stuff, comparable, indeed, with the aniline reds and purples.
YELLOW FE′′VER. The bilious remittent fever of hot climates. It is very common in the West Indies and the Southern States of America. New Orleans has been several times nearly depopulated by it.
YELLOW PIG′MENTS. Of these the principal are—
Brown Pink. Prep. Take of French berries and pearlash, of each 1 lb.; fustic chips, 1⁄2 lb.; water, 2 galls.; boil in a tin or pewter vessel, and strain the decoction through flannel whilst hot; then dissolve alum, 11⁄2 lb. in hot water, 21⁄2 galls.; add the solution to the strained decoction as long as a precipitate falls, which must afterwards be washed, drained, and dried. Some manufacturers omit the fustic. A good glazing colour, when ground in linseed, and used with drying oil.
Yellow, Chrome. Syn. Chromate of lead, Yellow c. of l.; Plumbi chromas, Plumbi chromas flavum, L. The preparation of the pure salt is noticed under Chromium and Lead; that of the commercial pigment is as follows:
1. Add a filtered solution of nitrate or acetate of lead to a like solution of neutral chromate
of potash as long as a precipitate falls; then collect this, wash it well with clean soft water, and dry it out of the reach of sulphuretted vapours.
2. To the lye of chromate of potash, prepared by roasting the chrome ore with nitre, and lixiviation with water, add a solution of acetate of lead, and otherwise proceed as before.