The course taken by the steam will be readily understood by a glance at the figure. When it has passed through each of the chambers of the analyzer, the mixed vapours of water and spirit pass through the pipe i into the rectifying column. Ascending again, they beat the coiled pipe m, and are partially deprived of aqueous vapours by condensation. Being thus gradually concentrated, by the time they reach the opening at W they consist of nearly pure spirit, and are then condensed by the cool liquid in the pipe falling upon the partition and being carried away by the pipe y to a refrigerator. Any uncondensed gases pass out by the pipe R to the same refrigerator, where they are deprived of any alcohol they may contain. The weak liquor condensed in the different compart ments of the rectifier descends in the same manner as the wash descends in the other column ; as it always contains a little spirit, it is conveyed by means of the pipe S to the vessel L in order to be pumped once more through the apparatus.
Before the process of distillation commences, it is usual, especially when the common Scotch stills are employed, to add about 1 lb. of soap to the contents of the still for every 100 gallons of wash. This is done in order to prevent the liquid from boiling over, which object is effected in the following way :—The fermented wash always contains small quantities of acetic acid ; this acts upon the soap, liberating an oily compound which floats upon the surface. The bubbles of gas as they rise from the body of the liquid are broken by this layer of oil, and hence the violence of the ebullition is considerably checked. Butter is sometimes employed for the same When the still contains a charge of about 8000 gallons, distillation is carried on as quickly as possible until about 2400 gallons have passed over. This portion possesses but little strength, and is known es "low nines." The remainder of the 8000 gallons is received in another vessel for re-distillation, and the low wines are also re-distilled in another still, until the product acquires an unpleasant taste and smell ; these, which are then called "feints," are collected in a vat called the " faints back,' mixed with the impure portions of the first distillation, diluted with water, and re-distilled. The product of a further distillation then yields finished spirit.
In addition to the apparatus already described, the following vessels are employed in the British grain distilleries:— A wash charger, or close-covered vat, the capacity of which must not be less than half that of the largest fermenting vat. This vessel is connected with the still by a close metal pipe, with a
branch to each still provided with cocks. One end of this pipe is fixed to the bottom of the wash charger, and the end of each branch is fixed into the still. The wash charger has also another pipe fitted with a cock, one end of which is fixed to the pipe or trough communicating with the fermenting vats ; it also communicates with another vessel, called the faints receiver, by means of a close pump or meta! pipe and stopcock.
If the still used be of such kind that the products of the first distillation are low wines, another vessel, called a low wines receiver, must be used. This is a covered vessel, having YL pump and discharging cock fixed in it for the conveyance of low wines from the receiver into the low wines and faints charger. There is also a close metal pipe, attached to and leading directly from a safe at the end of the worm, and fixed into the low wines receiver, so that all low wines running into this pipe from the safe shall immediately be discharged into the receiver. This safe is a close vessel into which the low wines, faints, and spirits are made to run as they leave the worm ; it is kept enclosed and secured for the inspection of the excise officers whenever necessary.
The faints receiver is a covered vessel with a pump or discharging cock fixed in it for the con veyance of faints into the low wines and faints charger, and there is a close metal pipe attached to and leading from the safe mentioned above, and fixed into the faints receiver, so that all faints running into this pipe from the s shall be immediately discharged into the receiver. The low wines and faints charger alluded to above is another covered vessel connected with the still by a close metal pipe and cock; one end of this pipe is fixed into the bottom of the charger and the other into the still. This charger communicates directly with the low wines and faints receiver respectively, by pipes, one end fixed to the charger, and the other to the pump or discharging cock.
The spirit receiver is another covered vessel, communicating only with the safe by means of a metal pipe. The spent lees receiver is a vessel connected with the low wines still by a pipe. This vessel has another opening at about one-third of its depth from the top, covered and secured by an internal metal plate, perforated with circular holes of not more than four-tenths of an inch in diameter. When intermediate still chargers are used, they are covered vats, and are connected by pipes with the wash charger and the still.