Paraffinum Durum. Hard Paraffin. A mixture of several of the harder paraffins. Colourless, semi-transparent, crystalline, inodourous and tasteless. Melting-point 130° - 135° F. (54.4° - 57.2° C). Insoluble in water, slightly soluble in alcohol, readily soluble in ether. 1Unguentum Paraffini. - 30; Soft Paraffin, 70.

Paraffinum Liquidum. Liquid Paraffin. A clear, colourless, odourless, tasteless liquid, obtained from petroleum.

Paraffinum Molle. Soft Paraffin. (Vaseline). A white or yellow, translucent, soft, unctuous, mixture of the softer members of the paraffin series. Melts at 96° - 102° F. (35.5° - 38.9° C). Insoluble in water, slightly soluble in absolute alcohol, readily soluble in ether, chloroform and benzol.

Paraldehydum. Paraldehyde. Dose, 1/2 - 2 fl. dr.; 2 - 8 c.c. A clear colourless liquid, with a characteristic odour and an ethereal, acrid and afterwards cool, taste. Soluble 1 in 10 of water, miscible in alcohol and ether.

Pareirae Radix. Pareira. Root. The dried root of Chondrodendron tomentosum. In long nearly cylindrical and somewhat twisted pieces. from 3/4-2 inches or more in diameter; covered with a thin black bark with numerous furrows, ridges and fissures; internally greyish: no odour, taste bitter.

Extractum Pareiræ Liquidum. Dose, 1/2 - 2 fl. dr.; 2 - 8 c.c. Aqueous and alcoholic.

Pepsinum. Pepsin. Dose, 5 - 10 gr.; 3 - 6 dgms. The enzyme obtained from the stomach of the pig, sheep or calf. It should be capable of dissolving 2,500 times its weight of hard-boiled white of egg.

1Glycerini Pepsini. Dose, 1 - 2 fl. dr.; 4 - 8 c.c. - 9.15; Hydrochloric Acid, 1.15; Glycerin, 60; Water, to 100.

Phenacetinum. Phenacetin. Dose, 5 - 10 grs. 3 - 6 dgms. Paraacet-phenetidin. C2H5O.C6H4.NHCOCH3. White tasteless, inordor-ous, crystals, neutral to litmus. Soluble, 1 in 1,700 of water, 1 in 21 of alcohol.

Phenazonum. Phenazone. (Antipyrine.) Dose, 5 - 20 grs.; 3 - 12 dgms.

Phenyldimethyl-iso-pyrazolone. Colourless, inodorous, scaly crystals, with a bitter taste. Soluble, 1 in 1 of water, 1 in a little more than 1 of alcohol. Incompatibles, ferric chloride (gives a red colour), syrup of ferrous iodide, calomel, mercuric chloride, solution of arsenic and mercuric iodides, iodine, potassium permanganate, tannic acid, spirits of nitrous ether and other solutions containing nitrites (a green colour being produced), chloral (in strong solutions); triturated with sodium salicylate a mass or liquid is formed; with thymol, acetananilid, and resorcin a liquid is formed.

Phosphorus. Phosphorus. Dose, in pill or solution, 1/100 - 1 /20 gr.; 1/2 - 3 mgms.

A semi-transparent, wax-like solid. Insoluble in water, but soluble 1 in 350 of alcohol absolute, 1 in 80 of ether, 1 in 25 of chloroform, 1 in 1/2 of carbon bisulphide, 1 in 80 of olive oil.

Incompatibles oxidising agents, explodes if triturated with them. 2Oleum Phosphoratum. Dose, 1 - 5 min. 0.06 - 0.3 c.c. - 1; dissolved at 180° F. in 99 of Almond Oil.

1Pilula Phosphori. Dose, 1 - 2 grs.; 6 - 12 cgms. - 2; White Beeswax, 25; Lard, 25; Kaolin, 23; Carbon Bisulphide, q.s.; Gum Acacia, q.s. To this mass is to be added 1/3 of its weight of Gum Acacia before dispensing. The pills should be varnished.

Physostigmatis Semina. Calabar Bean. The ripe seeds of Physostigma venenosum. Large brownish reniform seeds, usually an inch long by 3/4 of an inch wide and 1/2 inch thick. The active principle is the alkaloid physostigmine.

3Extractum Physostigmatis. Dose, 1/4 - 1 gr.; 15 - 60 mgms. An evaporated alcoholic extract to which three times its weight of Milk-sugar has been added.

Physostigminæ Sulphas. (Eserine Sulphate.) Dose, 1/60 - 1/20 gr.; 1 - 3 mgms.

Yellowish-white, minute crystals, which turn red on exposure to air and light. Soluble 1 in 4 of water; 2 1/2 in 1 of alcohol.

1Lamellæ Physostigminæ. 1/1,000 in gelatin discs.