to a very extended heated service; whilst it effects the evaporation of the alcohol from the wash by passing a current of steam through it.
Coffey’s Still.
The wash is pumped from the ‘wash charger’ into the worm-tub, which passes from top to bottom of the rectifier. In circulating through this tube it experiences a slight elevation of temperature. Arrived at the last convolution of the tube in the rectifier, the wash passes by the tube M in at the top of the ‘analyser.’ It falls, and collects on the top shelf till this overflows, whence it falls on the second shelf, and so on to the bottom. All the time this operation is going on steam is passed up from the steam boiler through fine holes in the shelves, and through valves opening upwards. As the wash gradually descends in the analyser it becomes rapidly weaker in alcohol, partly from condensation of steam which is passed into it, and partly from loss of alcohol, either evaporated or expelled by the steam, till when it arrives at the bottom it has parted with the last traces of spirits.
At the same time the vapour, as it rises through each shelf of the analyser, becomes constantly richer in alcohol, and contains less and less water because of its condensation; it then passes from the top of the analyser in at the bottom of the lower compartment of the rectifier. Here it ascends in a similar way, bubbling through the descending wash, until it arrives at F, above which it merely circulates round the earlier windings of the wash pipe; the low temperature of which condenses the spirits; which, collecting on the shelf at F, flows off by the tube into the finished spirit condenser.
To still further effect a saving of heat, the water for supplying the boiler is made to pass through a long coil of pipe, immersed in boiling spent wash, by which means its temperature is raised before it enters the boiler.
Another variety of distillatory apparatus is that of Siemens’ (see page 1566), much employed in the distillation of brandy.
It consists of two mash stills set in a boiler, and capable of being alternately used by means of the three cocks (a, b, and c). L is the boiler; P one of the mash retorts; K is the low wine receiver; R the fore warmer, a reservoir in which the condensed water intended as feed water of the boiler is collected; C is the dephlegmator; B a reservoir for the vapours condensed in C.
From the dephlegmator the vapour passes to a condenser, not shown in the engraving.
The mash warmer consists of a cylindrical portion (i i), the lower part of which has an indentation (c). In the cylinder is placed a narrower portion (o o) of the real mash, containing a vessel, fitted with the heading tube (f n). The upper part of the fore warmer is fitted to the lower part by means of the flange (h h); r is a stirring apparatus, which is frequently