ALCOHOL.

195

substances are slowly converted into gases and a substance called vege-table mould (humus), constituting the process called the putrefactivefermentation.

To produce a vinous liquid it is necessary that there be present sugar(or some substance capable of forming sugar, as starch), a certain quan-tity of water, and a ferment (usually yeast). Moreover a certain tempera-ture (the best is between 70° and 80° F.) is necessary. The precisefunctions which each of these essentials performs are not known. AsBerzelius has remarked, the changes may depend on the developementof forces of no common nature. The products of this process are carbonicacid, alcohol, and yeast. To account for the two first of these we takethe data furnished us by Thenard.

SUBSTANCES FERMENTED AT 59°.

Yeast

PRODUCTS OF FERMENTATION.

Alcohol of 0-822 . 171-5

Carbonic Acid. 94-6

Nauseous residue. 12-0

Residual yeast. 40'0

318-1

Loss.41'9

360 0

Now the nauseous residue and residual yeast nearly make up the quan-tity of yeast employed ; and supposing the loss to be proportionallydivided between the alcohol and the acid, it follows that, by the vinousfermentation, sugar is resolved into carbonic acid and alcohol.

The explanation of the changes which occur in the conversion ofsaccharine solutions into alcoholic liquors, depends, of course, on the viewtaken of the composition of sugar. If we adopt, with Mr. Brande ( Manualof Chemistry ), 162 as the equivalent for sugar, the following are thechanges :—One equivalent or 162 parts of sugar, with two equivalents or18 parts of water, are converted into four equivalents or 88 parts ofcarbonic acid, and four equivalents or 92 parts of alcohol.

EDIENTS USED.

Sugar .

Water.

4 eq. Carbon . . 24

1 .

4 eq. maroon . .

8 eq. Carbon . . 48162^ 8 eq. Oxygen . . 64-2 eq. Oxygen . . 1610 eq. Hydrogen.eq. Oxygen . .

18

S 2

RESULTS.

* 4 eq. Carb c . Acid . . 88

4 eq. Alcohol .

92

The liquid obtained by the vinous fermentation has received differentnames, according to the substance from which it is obtained. Whenprocured from the expressed juices of fruits, as grapes, cun-ants, goose-berries, &c., it is denominated wine (vinum); from a decoction of maltand hops, ale or beer (cerevisia); and from honey and water, mead(.hydromeli ). Fermented infusions of barley (raw grain and malt) pre-pared by the distillers of this country for the production of ardent spirit,are technically denominated washes.

The liquid obtained by the vinous fermentation consists of water,alcohol, colouring and extractive matters, volatile oil, various acids andsalts.

Stage 2. Production of Ardent Spirit. —By the distillationof a vinous liquid we obtain ardent spirit (spiritus ardens ). Whenwine is employed, the spirit is called brandy (spiritus vini gallici ) ; when