408
DISTILLATION.
while the middle portion, constituting in a well-managed distillery, trom three fourths tofour fifths of the whole, are received into the spirit-back. The faints are mixed with a largequantity of water, and redistilled, in order to free them from the fetid oil derived fromthe husks of the grain. The interception of this noxious oil may be best effected by aself-regulating bath, between the capital of the still and the refrigeratory, as will beexplained in treating of Stills. The capitals of the common Scotch stills are made from15 to 20 feet high, in order to prevent the chance of the wash boiling over into theworm; and they are, towards the beginning of the process, struck from time to timewith a rod, and by the sound emitted it is known whether they be empty, partiallyfilled, or in danger of an overflow ; in which case the fire is damped, by a spoutnear the furnace door, connected by a leather pipe with an elevated reservoir of water.When very pure spirits are wished for, a third or even a fourth distillation is had recourseto ; there being a quantity of water mixed each time with the spirit in the still, to pre-vent its acquiring a harsh alcoholic flavor.
According,40 some experienced distillers from raw grain, the mashing temperature ofthe first liquor should not exceed 140° F.; whereas with malt it may be safely andbeneficially 165° or 170°. When rye is used instead of malt, 90 bushels of it are mixedwith 190 bushels of raw grain, constituting 280 bushels in whole, for the mashing ofwhich 5200 gallons of water are required. An hour and a half more time is necessaryfor settling the mashing of the above mixture, than of grain alone. Gin is made in thisway. .
The distiller of malt whiskey calculates on obtaining two gallons of proof spirits fromone bushel of malt, in average years. The highest yield is 20 gallons per quarter of 8bushels ; and the lowest is 16, when the malt and fermentation are indifferent. The besttemperature to set the fermenting tnn with malt wash is about 70° or 72° F.
When malt is 5s. the bushel, 6 bushels at 30s. will yield 12 gallons of proof spirits.These cost therefore 2s. 6 d. per gallon for the malt; to which must be added 3d. perbushel for the amount of malt duty not returned, or 1| d. on the gallon ; this added to theScotch duty of 3s. id. the gallon, makes the price altogether 5s. lljd.; besides the ex-penses in fuel, yeast, labor, and rent, which may be estimated at 8jd.. per gallon. But 3d.may be deducted for what is paid by the dairymen for the spent wash and grains. Thetotal cost, therefore, exclusive of use of capital, is 6s. 5 d. per gallon in Scotland .
The following is the work of a Scotch distillery, where good malt whiskey wasmade.
One bushel of the malt weighed 35 lbs., or the boll, = 6 bushels, 210 lbs. In mashingeach boll of malt, 110 gallons of water were run on it at 160° F. As soon as the fer-menting tun of 3000 gallons capacity was charged with the wash at from 64° to 74° F., 2gallons per cent, of barm were added. When the wash had become attenuated fro®1-060 to 1-040, another gallon of barm was introduced.
The temperature of the fermenting wash sometimes rises to 96°, which is, however,an extreme case, and not desirable. When the bubbles of carbonic acid mount in rapidsuccession, it is reckoned an excellent sign. If the tun be small, and stand in a coolapartment, it should be started at a higher temperature than in the reverse predicament.Should the fermentation be suffered to flag, it is in general a hopeless task to restorevigorous action. Some try the addition of bubs, that is, of some wort brought into a stateof rapid fermentation in a tub, by a large proportion of yeast, but seldom with mt ! c ,success. Indeed, the law prohibits the addition of any wort to the tun at a later P erl °than 24 hours after it is set; so that if bubs are used afterwards, the distiller is aptincur a penalty. .
The maximum quantity of proof spirits obtained on the great scale at any time 1raw grain mixed with from one fourth to one eighth of malt, seems to be 22 gallons pquarter. > . .
By the British laws a distiller is not allowed to brew and distil at the same tibut he must work alternately, one week, for instance, at fermentation, and next weedistillation. been
In fermenting solutions of sugar mixed with good yeast, the attenuationearried down to 0-984, and even 0-982, that is, in the language of the excise, 16 angrees below water, from 1-060, the density at which it was originally set in the tun. ^ s-was excellent work done on the scale of a great distillery nearly 30 years ago, w efiliation from sugar was encouraged, in consequence of bad corn harvests. _ ^ the
In an experiment which I made in 1831, for the information of a committee e( jHouse of Commons , on the use of molasses in the breweries and distilleries, 1 yeast.1 cWt. of raw sugar in water, so as to form 74J gallons, inclusive of 2 gallons 01 ) of -The specific gravity of the mixture was 1-0593 on the 31st of March. By the ^ ichApril, that is, in 6 days, the gravity had sunk to 0-992, or 8 degrees under auan fitywas reckoned a good attenuation, considering the circumstances and the sma spiritsoperated upon. By distillation it afforded at the rate of 14-875 gallons of pr°°for 100 gallons of the wash.