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ELEMENTS OF MATERIA MEDICA.

nausea. On account of its volatility it may be applied to produce coldby its evaporation.

Administration. —The usual dose of this liquid in febrile cases isabout half a drachm. When we wish it to act as a diuretic it should begiven in large doses, as two or three tea-spoonfuls.

Antidotes. —In poisoning by the inhalation of the vapour of this com-pound, the treatment will be the same as that described for poisoning bycarbonic acid gas.

Ac’idum Aceficum. — Ace'tic Ac'id.

History. —Vinegar must have been known from the most remoteperiods of antiquity. It is mentioned by Moses ( Numbers , ch. vi. v. 3),1490 years before Christ. Hippocrates {De natura muliebri ) employedoZ,vq \evKov, or white vinegar , medicinally. Both Plutarch and Livy tellus that Hannibal, in his passage over the Alps, softened the rocks by fireand vinegar. Geber ( Investigation of Perfection, ch. iii.) was acquaintedwith the purification of vinegar by distillation. Stahl, in 1723, obtainedconcentrated acetic acid from the acetates by the action of sulphuric acid.

Natural History. —Free or combined with potash, lime, or ammonia,acetic acid is met with in the juices of many plants. Thus, Vauquelinfound the acetates of potash and lime in the sap of the elm; and Morindetected acetate of ammonia in the fruit of the Areca Catechu. Freeacetic acid has been recognized in the gastric juice by Tiedemann andGmelin. The acid found in the perspiration, the urine, milk, and blood,and which some have called acetic, is now generally believed to be adistinct substance, and is termed lactic acid. Gmelin ( Handb. d. Chern.)says acetic acid has been found in some mineral waters. If the observa-tion be correct, the acid is probably to be referred to some decomposingorganic matter accidentally present in the water.

Preparation. —The acetic acid of commerce is obtained from twosources—vinegar and pyroligneous acid: the first is procured by excitingthe acetous fermentation in certain liquors, the other by the distillationof wood.

1. By the Acetous Fermentation, (a.) Manufacture of Vine-gar .—Vinegar may be procured by the fermentation of various sub-stances ; but that met with in English commerce, and which is employedin this country for domestic purposes, is prepared from malt, or a mix-ture of malt and raw barley, which is mashed with hot water, as in theordinary operation of brewing. The cooled wort is then transferred tothe fermenting tun, where it is mixed with yeast, and undergoes thevinous fermentation. The wash is then introduced into barrels, placedclose together in a chamber, and a moderate heat (about 80° F.) is keptup until the acetous fermentation is complete. This process usuallyoccupies several weeks, or even months. The liquor thus procured isnot yet fit for sale. It is introduced into large tuns furnished with falsebottoms, on which is placed rape (the residuary fruit which has servedfor making domestic wines). These rape-tuns are worked by pairs; oneof them is quite filled with the vinegar from the barrels, and the otheronly three-quarters full, so that the fermentation is excited more easily inthe latter than the former, and every day a portion of the vinegar is con-veyed from one to the other, till the whole is completely finished, and fit