ACIDUM LACTICUM, U. S.-Lactic Acid.-An organic acid, usually obtained by subjecting milk sugar or grape sugar to lactic fermentation; composed of 75 per cent., by weight, of absolute lactic acid (HCH.O; 89.79), and 25 per cent. of water.

Lactic acid is made from sour milk, cheese, meat juice, lactin, and from many vegetable products. Cane sugar is treated with sulphuric acid, so as to convert it into invert sugar, solution of caustic soda added, and the mixture heated until it ceases to precipitate Fehling's solution, showing the absence of sugar. Sulphuric acid is added, and the sodium sulphate formed is crystallized out, an addition of alcohol causing the precipitation of the remainder. The alcoholic liquid contains impure lactic acid; onehalf of it is heated and zinc carbonate added until effervescence ceases; the other half of the alcoholic liquid is now added, and the whole allowed to cool. Zinc lactate crystallizes out; this, by treatment with hydrosulphuric acid, yields zinc sulphide, lactic acid remaining in solution. Acidum lacticum is a colorless syrupy liquid, absorbing moisture on exposure to damp air; sp. gr. 1.213; odorless; very acid taste; acid reaction; freely miscible with ether, but insoluble in chloroform, benzin, or carbon disulphide.

SACCHARUM LACTIS, U. S.-Sugar of Milk. C12H22O11HO; 359.16.-A peculiar, crystalline sugar obtained from the whey of cow's milk by evaporation and purified by recrystallization. It occurs in the form of white, hard, crystalline masses, yielding a white powder feeling gritty on the tongue, permanent in the air; odorless; faintly sweet taste; neutral reaction.

FEL BOVIS, U. S.-Ox Gall.-The fresh gall of Bos taurus (Class, Mammalia; Order, Ruminantia) contains glycocholic acid, C6H4NO6; taurocholic acid, C26N45NSO,; hyoglycocholic acid, CH4NO; hyotaurocholic acid, CH4NSO, and chenotaurocholic acid, OHNSO. A brownish-green or dark-green, somewhat viscid liquid, having a peculiar odor; a disagreeable, bitter taste, and a neutral or faintly alkaline reaction; sp. gr. 1.018-1.028.

FEL BOVIS PURIFICATUM, U. S.- Purified Ox Gall.Fresh Ox Gall, 300 C.c.; Alcohol, 100 C.c. Evaporate the ox gall in a porcelain capsule, on a water-bath, to one part, then add to it the alcohol, agitate the mixture thoroughly, and let it stand, well covered, for twentyfour hours. Decant the clear solution, filter the remainder, and, having mixed the liquids and distilled off the alcohol, evaporate to a pilular consistence.

CETACEUM, U. S.-Spermaceti.—A peculiar, concrete, fatty substance, obtained from Physeter macrocephalus (Class, Mammalia; Order, Cetacea) contains cetin, cetin elain, which, when saponified, yield cetinelaic acid, an acid resembling, but distinct from, oleic acid. The cetin is essentially etyl palmitate, CH3(C16H1O2). There are small amounts of fats containing stearic acid, C18H3O2; myristic acid, CH2O; and lauro-stearic acid, C12H2O2, and the alcohol radicals corresponding to

these acids.

33

36

Official Preparation.-Ceratum Cetacei.

WHITE WAX.

Official Products of the Class Pisces.

173

ICHTHYOCOLLA, U. S.-Isinglass.-The swimming bladder of Acipenser huso, and of other species of Acipenser (Class, Pisces; Order, Sturiones).

Official Preparation.-Emplastrum Ichthyocollæ.

OLEUM MORRHUÆ, U. S.-Cod-liver Oil. (Oleum Jecoris Aselli.)-A fixed oil obtained from the fresh livers of Gadus morrhua, or of other species of Gadus (Class, Pisces; Order, Teleostia, Family, Gadida).

Preparation.-Heat the livers in a wooden tank by means of low-pressure steam, and drain off the oil. In the case of the finest varieties, the oil, which is made only in the winter months, is drawn off by taps from the bottom of the cooking tank, and then put into a cooling house to freeze. The solid frozen mass is put into canvas bags, and submitted, while at a low temperature, to severe pressure, whereby the pure oil is expressed. This constitutes the light oil of commerce. Cod-liver oil consists chiefly of olein, some palmitin, and stearin, with minute traces of iodine, chlorine, bromine, phosphorus, and sulphur. Oleum Morrhuæ is a colorless or pale-yellow, thin, oily liquid; sp. gr. 0.920-0.925; peculiar, slightly fishy, but not rancid odor; bland, slightly fishy taste; faintly acid reaction.

Official Products of the Class Aves.

VITELLUS, U. S.-Yolk of Egg.-The yolk of the egg of Gallus Bankiva, var. domesticus (Class, Aves; Order, Gallina), contains vitellin, a protein compound resembling casein, albumen, fat, cholesterin, inorganic salts, coloring matter, etc.; water 50 per cent. White of egg consists principally of albumen, with 80 per cent. of water. The inorganic salt present in largest proportion is potassium chloride. Official Preparation.-Glyceritum Vitelli.

Official Products of the Class Insecta.

CANTHARIS, U. S.-Cantharides. (Spanish Flies.) Cantharis vesicatoria (Class, Insecta; Order, Coleoptera.)-Cantharides should be thoroughly dried at a temperature not exceeding 40° C. (104° F.), and kept in well-closed vessels. Cantharides owe their blistering properties to cantharidin, C10H12O4, a white substance, in the form of crystalline scales, of a shining micaceous appearance; inodorous; tasteless.

Official Preparations.-Ceratum Cantharidis, Collodium Cantharide,

Tinctura Cantharidis.

COCCUS, U. S.-Cochineal.-The dried female of Coccus cacti (Class, Insecta; Order, Hemiptera) owes its red color to carminic acid, CH18O10 It contains mucilage, fat, inorganic salts, etc.

CERA FLAVA, U. S.-Yellow Wax.-A peculiar, concrete substance, prepared by Apis mellifica (Class, Insecta; Order, Hymenoptera). CERA ALBA, U. S.-White Wax.-Yellow wax bleached. A yellowish or brownish-yellow solid. It is brittle when cold, and when broken presents a dull, granular, not crystalline fracture, but becomes

plastic by the heat of the hand. It melts at 63°-64° C. (145.4°-147.2° F.); sp. gr. 0.955-0.967; agreeable, honey-like odor; faint, balsamic taste. Beeswax is a mixture of three different substances, which may be separated from one another by alcohol, viz.: I, myricin, insoluble in boiling alcohol, and consisting chiefly of myricil palmitate, C30H61(CH3O2), which is a compound of palmitic acid, CH3O2, and myricyl alcohol, CH62O; 2, cerotic acid, CHO, (formerly called cerin when obtained only in an impure state), which is dissolved by boiling alcohol, but crystallizes out on cooling; 3, cerolein, which remains dissolved in the cold alcoholic liquid. This latter is probably a mixture of fatty acids, as indicated by its acid reaction to litmus paper. (Remington.)

By permission of T. C. MEN

TABLES FOR CONVERTING U. S. WEIGHTS

The only authorized material standard of customary length is the Troughton standard. The yard in use in the United States is therefore equal to the British The only authorized material standard of customary weight is the Troy pound standard of mass. It was derived from the British standard Troy pound of 1758 latter, and contains 7000 grains Troy.

The grain Troy is therefore the same as the grain Avoirdupois, and the pound The British gallon: 4.54346 litres.

The British bushel = 36.3477 litres.