5. Alum, 3 parts; wheat flour, 1 part; as No. 2.
6. (Lead pyrophorus—Göbel.) Heat tartrate of lead to redness in a glass tube, and then hermetically seal it. See Tartrate of Lead.
Obs. When the above are properly prepared, a little of the powder rapidly becomes very hot, and inflames on exposure to the air. The accession of the combustion is promoted by moisture, as a damp atmosphere or the breath. With the exception of the first and sixth, “they owe their combustibility to the presence of sulphide of potassium.” (Gay Lussac.)
PYROPHOSPHOR′IC ACID. See Dibasic Phosphoric acid (Phosphorus).
PYRO′SIS. Syn. Black water, Water brash, Water qualm. An affection of the stomach, attended by a sensation of heat and the eructation of a thin, sour liquid, often in considerable quantity, especially in the morning.
The following pill will be found of service in this affection:—Powdered opium, 1⁄8th gr.; subnitrate of bismuth, 5 gr.; extract of gentian, sufficient to make into 2 pills. To be taken two or three times a day, before meals.
The solution of bismuth and citrate of ammonia (Liquor Bismuthi et Ammoniæ Citratis, B. P.), in doses of 1⁄2 dr. to 1 dr., taken as above, is another medicine which may be had recourse to, should the above fail to give relief.
PYBOTARTAR′IC ACID. H2C5H6O4. Obtained by the destructive distillation of tartaric acid. See Tartaric acid.
PYROTECH′NY. The art of making fireworks.
The three principal materials employed in this art are charcoal, nitre, and sulphur, along with filings of iron, steel, copper, or zinc, or with resin, camphor, lycopodium, or other substances, to impart colour, or to modify the effect or the duration of the combustion. Gunpowder is used “either in grain, half crushed, or finely ground, for different purposes. The longer the iron filings are, the brighter red and white spots they give; those being preferred which are made with a coarse file, and quite free from rust. Steel filings and cast-iron borings contain carbon, and afford a more brilliant fire, with wavy radiations. Copper filings give a greenish tint to flame; those of zinc, a fine blue colour; the sulphide of antimony gives a less greenish blue than zinc, but with much smoke; amber affords a yellow fire, as well as colophony (resin) and common salt; but the last must be very dry. Lampblack produces a very red colour with gunpowder, and a pink one with nitre in excess; it serves for making golden showers.” When this substance is lightly mixed with gunpowder and put into cases, it throws out small stars resembling the rowel of a spur; this composition has hence been called ‘spur fire.’ “The yellow sand, or glistening mica, communicates to fire-works golden radiations. Verdigris imparts a pale green; sulphate of copper and sal ammoniac gives a palm-tree green. Camphor yields a very white flame and aromatic fumes, which masks the bad smell of other substances. Benzoin and storax are also used, on account of their agreeable odour. Lycopodium burns with a rose colour and a magnificent flame; but it is principally employed in theatres to represent lightning, or to charge the torch of a Fury.” (Ure.) See Fires (Coloured), Flame Colours, Gunpowder, Stars, Rockets, &c.