Prep. From carrot roots, from which the juice has been pressed out, by boiling them with 1⁄25th part of their weight of carbonate of potassium, and about 6 times their weight of water, until the liquid becomes gelatinous when neutralised with an acid. A pectate of potassium is formed, from which the acid may be obtained by neutralising the alkali with a stronger acid, or by carefully adding a solution of chloride of calcium as long as a gelatinous precipitate (pectate of calcium) falls, and, after washing this with water, decomposing it with dilute hydrochloric acid.
Prop., &c. A colourless jelly, having an acid reaction; scarcely soluble in cold water, more so in hot water; and precipitated by acids, alkalies, alcohol, salts, and even sugar. Its compounds with the bases are called pectates. By long boiling with solution of caustic alkali it is converted into metapectic acid, which does not gelatinise. (See below.)
PEC′TIN. Syn. Vegetable jelly. Obtained by adding alcohol to the juice of ripe currants or other fruit, until a gelatinous precipitate forms, which must be drained, washed with a little weak alcohol, and dried.
Prop., &c. In the moist state it forms a neutral, tasteless, soluble, transparent jelly; when dried, a translucent mass, closely resembling isinglass; boiled with water, or with dilute acids, it is converted into parapectin and metapectin; in the presence of alkalies, these, as well as pectin, are changed into pectic acid, and by continuing the ebullition for some time longer, into metapectic acid, which is not gelatinous. See Pectic acid.
PECTORAL BALSAM. The same as Balsam of Honey, which see. The reference to ‘Pectoral balsam,’ which occurs at the end of the article ‘Balsam of Honey,’ conveys the impression that it is a different medicine. This is an error.
PEC′TORALS. Under this head are popularly included all the various remedies employed in breath or chest diseases.
PEDIC′ULI. See Louse.
PEL′LICLE. See Crystallisation.
PEL′LITORY. Syn. Pellitory of Spain;
(Pellitory root; Pyrethri radix, B. P.); Pyrethrum (Ph. L. & E.), L. The root of Anacyclus Pyrethrum. It is a powerful topical excitant. It is chiefly employed as a masticatory in headache, toothache, palsy of the tongue, and facial neuralgia and rheumatism; and made into a tincture with rectified spirit, it is a common remedy among dentists for the toothache. Internally, it has been given as a gastric stimulant, and in intermittents, &c. Half to 1 dr. may be chewed at a time.