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not be detailed. They all confid in exciting afrefh fermentation in wine and keeping it up ina moderate degree till acetification is compleat.Many refufe parts of the vine are of ufe forthis purpofe, fuch as the hulks, the four fuccu-lent twigs, the marc or cake left in the wineprefs, and the like and after they have onceferved, they are dill more valuable, as the acidwhich they naturally contain, or which is evol-ved by them, is more readily produced.

Wine may alfo be converted to good vinegarwithout thele additions, Amply by adding wine,efpecially when on the fret, to vinegar alreadymade, and expofing it to a proper heat. In thisway many manufacturers proceed, keeping theircalks always full by taking out of them at in-tervals about a third or fourth part, replenilhingthem with wine, and again bringing the con-tents to the flate of vinegar.

In this country vinegar is chiefly made frommalt. The following is the ufual pvocefs inLondon . A main of malt and hot water ismade, which after infu'ion tor an hour and ahalf is conveyed into a cooler a few inchesdeep, and thence, when fuiliciently cooled, intolarge and deep fermenting tuns, where it ismixed with yeaft and kept in fermentation forfour or five days. The liquor (which is now aftrong ale without hops) is then diftributedinto fmaller barrels fet clofe together in a ftevedchamber and a model ate heat is kept up for aboutfix weeks, during which the fermentation goeson equally and uniformly tiil the whole isfoured. This is thfen empt ed into commonbarrels, which are fet in rows (often of manyhundreds) in a field in the open air, the bung-hole being juft covered with a tile to keep offthe wet but to allow a free admilfion of air. Herethe liquor remains for four or five months,according to the heat of the weather, a gentlefermentation being kept up, till it becomes per-fect vinegar. This is finilhed in the followingway. Large tuns are employed, with a falfebottom, on which is put a quantity of the refufeef faifins or other fruit left by the makers ofraifin and other home-made wines, called tech-nically rape. Thefe rape tuns are worked bypairs; one of them is quite filled with thevinegar from the barrels, and the other onlythree-quarters full, fo that the fermentation isexcited more eafily in the latter than the for-mer, and every day a portion of the vinegar isladed from one to the other till the whole iscompletely finilhed and fit ror fale.

Vinegar, as well as fruit-wines, is often made

in fmall quantity for dorr.eftic ufes, and theprocefs is by no means difficult. The materialsmay be either brown fugar and water alone, orfugar with railins, currants, and efpecially ripegoole'berries. Thefe fiiould be mixed in theproportions which would give a drong wine,put into a final; barrel, which it Ihould fillabout three-fourths, and the bung-hole veryloolely Hopped. Some yeaft, or, what is better,a toalt lopped in yeaft fhould be put in, and thebarrel fet m the lun in fummer, or a little wayfrom a fire in winter, and the fermentation willfoon begin. This Ihould be kept up Cendantbut very moderate, tiil the tade and fined in-dicate that ihe vinegar is compleat. It fhouidbe poured off clear and bottled carefully, andit will keep much better if it is boiled for aminute, cooled and drained before bottling.

Vinegar contains a confiderable quantity ofcolouring extractive matter, from which it canonly be freed by didiliation, the procefs ofwhich, together with the chemical properties ofthis acid, have been mentioned under the articleAcetous Acid.

When vinegar is long kept, efpecially expofedto the air, it becomes muddy, acquires a mouldyunpleafant fmell, lofes its clear red colour andail its properties, and finally is changed to aflimy mucilage and water.

VITAL AIR. See Oxygen.

VITRIFICATION. See Glass.

VITRIOL, native. Naturlicher VitriolWern.

Its colour is greyilh or yellowifh-white, appleor verdigris-green, or lky-blue ; when decoinpo-fing it is covered with an ochery crud. It occursin mafs, diffeminated, daladritical and capillary.Externally it is rough and dull, internally it ismore or lefs fhining, with a vitreous or lilkyludre. Its fraddure is generally fine and draitfibrous, fometimes alfo lamellar or concheidal.It is foft, brittle, tranflucent, and has an acerbmetallic flavour. It is more or lefs foluble inwater, and is a mixture in various proportionsof the fulphats of iron, copper, and zinc.

It not unfrequently occurs in caverns andfhafts, in argillaceous fchiitus, and in old mines,efpecially fuch as abound in blende and pyrites.

VITRIOL blue. See Copper , Sulphat of.

VITRIOL green. See Ikon, Sulphat of.

VITRIOL white. See Zinc , Sulphat of.

VITRIOLATED TARTAR. See Sul-phat of Potafli.

VITRIOLIC ACID. See Sulphuric Acid .VOLATILE ALKALI. See Amalonxa, .