ALC OHOL. —Alcoholometry.
or raw grain, may perhaps be found equally usefulfor various manufacturing purposes.
The process of the fabrication is exceedingly simple:mere washing of the madder supersedes the mashingof the grain or malt in common distilleries. Theroot being dried and ground, as already stated, ismixed in a series of vats with the requisite proportionof cold water, or water at the ordinary temperature.These vats are 3 feet deep by 5 or C in diameter.The mixture is effectually rummaged by the work-men with instruments resembling large hoes, themadder being kept in a state of diffusion in the liquiduntil it is conceived that the saccharine matter isentirely extracted. The liquor is then drawn off bysluices, and the vats being lined with coarse cloth,it percolates through that medium as a filter, leavingthe madder behind, to be again carefully collected,dried, and finally ground for the use of the dyer.
When the madder liquor, or worts, is drawn off, itis let into a kind of under-back, from which it isimmediately pumped up into a large fermenting tun:2 tons of madder are found in practice to yield 2500gallons of liquor, or madder worts, of a densityequivalent to 30° by Allan’s saecharometer.
The fermenting tun being filled by the produce ofseveral washings, has usually begun to ferment beforeit receives the liquor from the last washings. It isnot a little remarkable, that this fermentation of themadder liquorcommences and proceeds spontaneously,without the addition of yeast or the application ofheat. No ferment of any description is added, andthe water used throughout the entire process, up tothe point of distillation, is at the ordinary tempera-ture. The addition of yeast has been tried, butwithout any sensible advantage, either in promotingthe fermentation or increasing the ultimate yield ofspirits. In consequence, however, of the spontane-ous character of the process, the fermentation isslower than usual, averaging from six to eight days toa proper attenuation. This is conceived to be accom-plished when the gravity of the worts is reducedfrom 24° to 12°.
From the fermenting tun the wash is immediatelyrun into the still, and the rest of the operation pro-ceeds as in the distillation of malt or raw grain whisky.The still used is STElN’spatent, and is somewhat similarto Coffey’s, but rather more complex in its arrange-ments, and possessing the undoubted advantage thatit may be applied, with equal efficiency, either to thedistillation of malt or raw grain whisky. From thisstill the madder spirit is drawn off at one operation ;it may be run weaker or stronger, but is generallytaken from the still about 60° to 64° over proof bySikes’ hydrometer.
The produce from 2 tons of madder, yielding, ashas been stated, 2500 gallons of liquor at 30°, is about60 gallons of spirit.
' The berries of the Sorbus Aucuparia have been usedin the North of France for the production of spirit,and the result is said to be equal to the purest distilla-tion from grapes for brandy. The berries, whenperfectly ripe, are first exposed to the action of coldin the open air, then put into a wooden vessel, bruised,
125
and boiling water poured on, the menstruum beingstirred until it has sunk in temperature to 82° Fahr.(27°-7 C.). A proper quantity of yeast is then added,the whole covered and left to ferment. When theaction has terminated, the liquor is put into the still,and drawn over in the usual way. The first runningis weak and disagreeable in flavour, but being distilledfrom very fresh finely-powdered charcoal, in the pro-portion of 8 or 9 lbs. to 40 gallons of weak spirit, afine product is obtained. The charcoal should remainin the liquid two or three days before the seconddistillation.
Alcoholometry. —This is the process of ascertain-ing the centesimal quantity of anhydrous alcohol ina spirituous liquid. It is generally accomplished bydetermining the specific gravity of the liquid, but itis in this case absolutely necessary that only alcoholand water should be present. The quantity of alcoholin spirit containing much volatile oil or saccharinematter, &c., cannot be at once found by its specificgravity.
It happens sometimes that only small quantitiesof the alcoholic fluid is at command. In such a caseit is impossible to obtain a correct result by determin-ing the specific gravity of the few drops of alcoholobtained by distillation. It is then safer to subjectthe alcohol to organic analysis by combustion withoxide of copper, and to calculate the quantity ofabsolute alcohol from the resulting carbonic acid andwater. This is of course only applicable when thealcohol does not contain other volatile hydrocarbons.
With the view of being able to calculate the absolutealcohol included in a spirituous liquid from its specificgravity, it was deemed advisable to mix anhydrousalcohol and water in the different proportions, and byexperiments, to establish with certainty the specificgravity of these mixtures. Such experiments havebeen gone through at distinct periods; the mostaccurate and complete were those performed byGilpin. They were undertaken by Sir CharlesBlagden at the instance of the British government,it being of course a matter of great importance to theexcise that extreme accuracy should be attained inall determinations, and that their decisions should beabove dispute. These determinations were made byGilpin under Sir Charles Blagden ’s direction, andwere first given to the world in 1790. In order toinsure their correctness they were subsequentlytwice repeated, and were ultimately published in thePhilosophical Transactions of the Royal Society in 1794.
The method adopted was to weigh the mixture ofalcohol and water in a long-nccked flask, which wasfilled up to a mark showing the bulk of a knownweight of water. The specific gravity of forty mix-tures was thus determined, eacli one at fifteen differ-ent degrees of temperature. Alcohol of specificgravity 0-82514 was used, which was taken as being0-825, the requisite allowance bcingmade in the tables.From Gilpin’s conclusions, aided by results of hisown, Tralles constructed the tables appended.
The percentage of absolute alcohol may be statedby one of two methods; namely, by weight or volume.