Fermenting Ingredient in Grape-Juice. 29

have guided legislators and moral and religious teachers, may be the better appreciated; and the weight to be given to these convictions of men of other ages, in their bearing on modern questions as to the law of wines, may perhaps become more apparent.

ELEMENTS IN GRAPE-JUICE WHICH GIVE ORIGIN TO FERMENT.

In grape-juice are found two of the leading ingredients which furnish nutrition to plant and animal organism: sugar, composed of the three chemical elements, carbon, hydrogen, and oxy. gen; and gluten or albumen, composed of the four elements, carbon, hydrogen, oxygen and nitrogen, to which is also added a small amount of sulphur and phosphorus. The watery, sweet juice, flowing between the skin and the central seed-envelope, is chiefly sugar dissolved in water; while the gluten is gathered in the pulp that lines the skin and in the seed-envelope at the center of the grape. Nitrogen, in all its compounds, is an unstable element; ready to release itself from one union and to seek another. Hence it has a double office: to hasten the decay and decomposition of worn-out vegetable and animal organisms; and this, that it may fulfill its main mission of acting as the propelling agent in the composition and promotion of new organisms.

It is at once the destroyer of old and the organizer of new compounds.

When the two classes of nutritious ingredients found in the grape-juice, namely, sugar and albumen, are in contact, the nitrogen of the albumen is disposed to act on the sugar, and change it into new ingredients. In order to this action, two intermediate agents must be present: water and the oxygen of the air. The impenetrable skin of the grape excludes the oxygen of the air, and by the process of drying the water may be evaporated through the skin, so that the action of the albumen on the sugar will be permanently prevented. The dried raisin may be kept for years unchanged. If, however, the skin be ruptured, and the approach of the oxygen of the air be secured, a chemical change immediately commences, which in a few hours will become apparent; and which, if unarrested, will cause a series of transformations in the compounds successively developed. If, however, when the skin is thus ruptured, the watery, sweet juice be gently pressed out, so as to leave the glutinous albumen in the skin, the sugar will be so separated from the albumen that the change produced will be very slight. On the contrary, if a heavy pressure be exerted on the grape, which shall expel the albumen as well as the sugar, and leave them mingled together in the open air, the

Nature of Ferment and its Products. 31 chemical changes will be both rapid and radical. The changes thus wrought are called " ferments;" changes whose laws have been practically known to mankind in all ages the records of whose history are preserved.

THE NATURE OF FERMENT AND ITS PRODUCTS.

The word "ferment," from the Latin fervere, to boil, whence also the word "effervesce," calls attention to the rise and escape of bubbles, which soon appears when expressed grape-juice is exposed to the air. It is likewise observed in the action of yeast on rising bread, and in the effervescence of soda-water, beer, cider, and corked wines. This ebullition is but the visible. indication of connected changes, by which the elements composing grape-sugar are converted into compounds including eight subdivisions; two of which are alcohol, two water, and four carbonic acid gas, whose escape causes the observed effervescence. The following table indicates, first, the chemical elements in the grapesugar; second, their redistribution after the first ferment.

Grape-sugar contains, and its three results, alcohol, water, and carbonic acid, receive, the following elements in the proportions indicated by their numbers:

The presence of a large proportion of water, mixed with the sugar in grape-juice, causes the proportion of alcohol in wines to be small; although, as indicated, 24 parts out of 40 equivalents found in the grape-sugar itself have been converted into alcohol. It is the alcohol which forms the intoxicating element in wines. This ferment, however, called the "vinous or alcoholic ferment," is but the first stage tending to an ultimate result; which, if Nature be not interfered with in her law of action, will soon appear.

In the vinous ferment, the change of grapesugar into alcohol, water, and carbonic acid gas will go on till all the sugar is transformed; while the exhaustion of the nitrogen in the albumen is but partial. The remaining albumen now hegins to act upon the alcohol, diluted as it is in water. In this action, the alcohol is first decomposed by the union of two atoms of its hydrogen with two portions of oxygen from the air; fu.nishing thus the two compounds, aldehyde and water.

Nature of Ferment and its Products. 33

The ferment proper here ceases; but by oxida tion two more atoms of oxygen are absorbed by the new compound aldehyde, thus converting it into acetic acid or vinegar; the nutritive compound, which, as its name, derived from the French, indicates, is simply "sour wine." And yet Nature's end is not complete.

The universally recognized chemical changes thus wrought in Nature by ferment may be traced in any one of the ordinary text-books, as those of Silliman, Wells, Youmans, Rolfe and Gillet; they may be historically reviewed in the exhaustive articles found in the best English, French, and American encyclopedias; or they may be analyzed in their scientific principles. as they touch on philosophic theories, in such works as those of Liebig and Helmholtz. The important truth to hold in mind in all this examination is, that we are not entitled to infer authoritatively what is the design of the Creator until we have reached the last of the series of the changes wrought by ferment. The three upon which attention is to be fixed are, first, the formation of alcohol; second, of vinegar; third, of food for new plants and animals.

Liebig, of Germany, says, that "while the vinous ferment is going on, the acetous ferment can not begin;" thus indicating that the forming of alcohol is but the first in successive