appropriate temperature, in a remarkable degree, promotes fermentation. These different points of heat should be accurately noted and settled by the thermometer, or other certain methods; though, for common, or all economical purposes, they may be limited to what is in general termed a tepid and a fervid heat: the former is the bane of all vinous fermentation; the latter, or imperceptible warmth, is the great promoter of it. And if, notwithstanding a due attention to a proper temperature and all other circumstances, the liquor will not work of itself, it should then be assisted by such substances as are called ferments, and of which we baye already given some account.
In the Memoirs of the Philosophical Society at Manchester, Mr. Henry states the result of some experiments, in which he produced a fermentation both in bread and wort, and even in punch and whey. Conjecturing, therefore, yeast to be simply a quantity of fixed air detained among the mucilaginous parts of the fermenting liquor, he boiled some wheaten flour and water to the consistence of a thin jelly, which he put in the middle of Dr. Nooth's machine for communicating fixed air to water. A considerable portion of gas was absorbed; and the next day the mass was in a state of fermentation.—The third day it bore so great a resemblance to yeast, that an experiment was made on some paste for bread; for which purpose it answered tolerably well, after being baked four or five hours.
Mr. Henry made another experiment with some wort only; part of which was impregnated with air in the same manner as the flour aud water, and when poured into the remainder, a brisk fermentation ensued in 24 hours; a strong head of yeast began to collect on the surface, which on the third day was fit for tunning. In the course of the experiment, good bread was made with the yeast taken off the surface.
The dispute which has arisen concerning Mr. Henry's mode of producing fermentation, may be easily decided by a comparative trial. Let two gallons of wort be put into a separate vessel, and kept in a moderate heat for a certain time: let also two other gallons be impregnated, either wholly or in part, according to Mr. Henry's method, be put into a similar vessel, and deposited in the same place. If the fermentation commence in the liquor impregnated with fixed air sooner than in the other, the air may be rationally conjectured to induce such fermentation. At all events, Mr. Henry's experiments, with respect to bread, are certainly decisive, and those relative to liquors may thus be easily ascertained; an object of the utmost importance to the public.
FERMENTED LIQUORS, are those obtained by the process described in the preceding article. See also Beer, Brewing, Cyder, Wine, &c.
All liquors which have undergone the vinous fermentation, are considered as great antidotes to putrefaction: hence the total abstinence from them is assigned as one of the chief causes why the Turks are more liable to the plague, and other contagious diseases, than those nations among whom beer or wine is the common beverage. It has farther been remarked, and perhaps with justice, that since the custom
