By the British laws a distiller is not allowed to brew and distil at the same time but he must work alternately, one week, for instance, at fermentation, and next week at distillation.
In fermenting solutions of sugar mixed with good yeast, the attenuation has been carried down to 0·984, and even 0·982, that is, in the language of the excise, 16 and 18 degrees below water, from 1·060, the density at which it was originally set in the tun. This was excellent work done on the scale of a great distillery nearly 30 years ago, when distillation from sugar was encouraged, in consequence of bad corn harvests.
In an experiment which I made in 1831 for the information of a committee of the House of Commons, on the use of molasses in the breweries and distilleries, I dissolved 1 cwt. of raw sugar in water; so as to form 741⁄2 gallons, inclusive of 2 gallons of yeast. The specific gravity of the mixture was 1·0593 on the 31st of March. By the 6th of April, that is in 6 days, the gravity had sunk to 0·992, or 8 degrees under water, which was reckoned a good attenuation, considering the circumstances and the small quantity operated upon. By distillation it afforded at the rate of 14·875 gallons of proof spirits for 100 gallons of the wash.
When the distillers first worked from sugar, they only obtained upon an average from 1 cwt. 10·09 gallons imp. of proof spirit; but they afterwards got no less than 11·92 imp. gallons.
The following experiment, which I made upon the fermentation of West India molasses into spirits, for the information of the said committee, may prove not uninteresting to my readers. 150 libs. were dissolved in water and mixed with 2 gallons of yeast, weighing exactly 20 libs. The wash measured 70 gallons, and had a spec. gravity of 1·0647 at 60° F. In two days the gravity had fallen to 1·0055; in three days to 1·0022; and in five days to 1·001. The temperature was kept up at from 80° to 90° F., during the two last days, by means of a steam pipe, to favour the fermentation. The product of spirits was 11 gallons, and 35⁄100 of a gallon. Now 150 libs. of the above molasses were found to contain of solid matter, chiefly uncrystallizable, 112 libs. And as 112 libs. of sugar are estimated by the revenue laws to afford by fermentation 111⁄2 gallons imp. of proof spirit, the result of that experiment upon molasses must be considered satisfactory, bearing in mind that the saccharine substance in molasses has been not only partially decomposed by heat, but is mixed with some of the glutinous or extractive matter of the cane.
Since the alteration of the excise laws relative to distillation in 1825 and 1826, when permission was given to set the wort at lower gravities, the quantity of spirits produced from 1 quarter of corn has been much increased, even up to fully 20 gallons; and the proportion of malt has been much diminished. The latter was soon reduced from three-sevenths malt, and four-sevenths barley, or two-fifths malt and three-fifths barley, to one-fifth of malt, and now to one-tenth or even one-sixteenth.
A discussion having lately taken place in Ireland between certain persons connected with the distilleries and the officers of the excise, whether, and to what extent, raw grain worts would pass spontaneously into the vinous fermentation, the Board in London requested me to superintend a series of researches in a laboratory fitted up at their office, to settle this important point. I shall content myself here with giving the result of one experiment, out of several, which seems to me quite decisive. Three bushels of mixed grains were taken, consisting of two of barley, one half of oats, and one half of malt, which, being coarsely ground by a hand-mill, were mashed in a new tun with 24 gallons of water at 155°. The mash liquor drawn off amounted to 18 gallons, at the density of 1·0465; and temperature of 82° F. Being set in a new tun, it began to ferment in the course of 12 hours, and in 4 days it was attenuated down to gravity 1·012. This yielded, upon distillation in low wines, 3·22 gallons, and by rectification, in spirits, 3·05; while the quantity equivalent to the attenuation by the tables was 3·31, being an excellent accordance in such circumstances.
The inquisitorial regime imposed by law upon our distilleries, might lead a stranger to imagine that our legislators were desirous of repressing by every species of annoyance the fabrication of the fiery liquid which infuriates and demoralizes the lower population of these islands. But alas! credit can be given them for no such moral or philanthropic motive. The necessity of the exchequer to raise a great revenue, created by the wasteful expenditure of the state, on the one hand, and the efforts of fraudulent ingenuity on the other, to evade the payment of the high duties imposed, are the true origin of that regime. Examinations in distilleries are constantly made by the officers of excise. There is a survey at 6 o’clock in the morning, when the officers take their accounts and gauges, and make calculations which occupy several hours. At 10 o’clock they again survey, going over the whole premises, where they continue a considerable time, frequently till the succeeding officer comes on duty; at 2 in the afternoon another survey takes place, but not by the same people; at 6 in the evening the survey is repeated; at 10 there comes another survey by an officer who had not been engaged in any of the previous surveys of that day. He is not relieved till 6 o’clock next morning. In addition to these regular inspections, the distilleries are subject to frequent and uncertain visits of the surveyor and general surveyor. “We are never,” says Mr. Smith, the eminent distiller of Whitechapel, “out of their hands.”[24]
[24] Report of Committee on Molasses, 2198.