QUASS. Syn. Posca venalis, L. Prep. Mix rye-flour and warm water together, and keep the mixture by the fireside until it has turned sour. Used as vinegar in Russia.
QUAS′SIA. Syn. Quassia (Ph. L., E., & D.; Quassia lignum, Quassia wood, B. P.). The “wood of Picræna (Picrasma) excelsa, Lindl.” (B. P., Ph. L.), or Jamaica quassia; and also of the “Quassia amara, Linn.” (Ph. E.), or Surinam quassia. The latter is the original quassia, but it is no longer imported. Quassia is characterised by its intense bitterness. It is reputed tonic and stomachic, assisting digestion, and giving tone and vigour to the system. Its name was given to it by Linnæus, in honour of a negro slave who had long employed it as a remedy for the malignant endemic fevers of Surinam. When sliced,
it forms the ‘quassia chips’ of the shops. It is generally taken in the form of infusion. This last, sweetened with sugar, forms a safe and effective poison for flies.—Dose (in powder), 10 to 20 gr.
Roasted quassia, reduced to powder, is largely employed, instead of hops, to embitter porter; and the unroasted powder is used for the same purpose in the adulteration of the bitter varieties of ale.
QUAS′SIN. Syn. Quassite, Quassina. A peculiar bitter principle, obtained by precipitating decoction of quassia with milk of lime, evaporating the filtrate, dissolving the residue in alcohol, treating with animal charcoal, again evaporating, dissolving in water, and crystallising. 8 lbs. of quassia chips yield 1 drachm.
QUEEN’S BLUE. Thumb blue. See Blue.
QUEEN’S MET′AL. A species of pewter used for teapots, &c., made by fusing under charcoal a mixture of tin, 9 parts, and antimony, bismuth, and lead, of each 1 part; or, tin, 100 parts; antimony, 8 parts; copper, 4 parts; bismuth, 1 part. See Britannia Metal and Pewter.
QUEEN’S YEL′LOW. Subsulphate of mercury.
QUERCITRIN. The bark of the Quercus tinctoria yields a neutral substance, to which the above name has been given. Quercitrin may be prepared as follows by the process of Rochleder:—The bark is boiled with water, the decoction is left to cool, and the impure quercitrin which separates is collected, then rubbed to a pulp with alcohol of 35° B., heated over the water bath, collected on linen, and pressed, whereby the principal impurities are removed. The residue is dissolved in a larger quantity of boiling alcohol, the solution is filtered hot, and water is added to it until it becomes turbid, so that the greater part of the quercitrin separates before the liquid is cold. It is then collected, pressed, and purified by a repetition of the same treatment.
Another process, by Zwenger and Dronke, is this:—The bark, in small pieces, is exhausted with boiling alcohol, the alcohol is distilled off, and the residue, while still warm, is mixed with a little acetic acid, and then with neutral acetate of lead; the filtrate, freed from lead by sulphuric acid, is evaporated, and the quercitrin which crystallises is purified by repeated crystallisation from alcohol.