PLANTAIN. The plantain, which belongs to the nat. ord. Musaceæ, and is a native of the East Indies, is cultivated in all tropical and subtropical regions of the world, in many of which it constitutes the principal food of the inhabitants. There are a great many varieties of the plantain, in some of which the stem is 15 or 20 feet high, whilst in others it does not exceed 6 feet. It is one of the largest of the herbaceous plants.
The fruit is sometimes eaten raw, but is more generally boiled or roasted. It contains both starch and sugar. Boiled and beaten in a mortar, it forms the common food of the negroes in the West Indies. It also constitutes the chief food of the Indians of North and South America.
Humboldt has calculated that the food produce of the plantain is 44 times greater than that of the potato and 133 times that of wheat.
The banana is a species of plantain. See Banana.
PLASMA. The liquor sanguinis. A tenacious plastic liquid, forming the coagulating portion of the blood, and that in which the corpuscles float.
PLAS′TER. (In boiling, &c.) See Mortar.
Plaster of Paris. Calcined sulphate of lime. See Alabaster, Gypsum, Lime, &c.
PLASTER. (In pharmacy.) Syn. Emplastrum, L. Plasters (emplastra) are external applications that possess sufficient consistence not to adhere to the fingers when cold, but which become soft and adhesive at the temperature of the human body.
Plasters are chiefly composed of unctuous substances united to metallic oxides, or to powders, wax, or resin. They are usually formed, whilst warm, into 1⁄2-lb. rolls, about 8 or 9 inches long, and wrapped in paper. When required for use, a little is melted off the roll by means of a heated iron spatula, and spread upon leather, linen, or silk. The less adhesive plasters, when spread, are usually surrounded with a margin of resin plaster, to cause them to adhere.
In the preparation of plasters the heat of a water bath, or of steam, should alone be employed. On the large scale, well-cleaned and polished copper or tinned copper pans, surrounded with iron jackets, supplied with high-pressure steam, are used for this purpose. The resins and gum resins that enter into their composition are previously purified by straining. After the ingredients are mixed, and the mass has acquired sufficient consistence by cooling, portions of it are taken into the hands, anointed with a little olive oil, and well