In operation the mash is admitted into the heater D through G until the heating tank is nearly filled. A certain amount of mash is then allowed to run into the still A through the pipe d. The cock in d is closed and the fire lighted.
The vapors from the still are condensed in worm C and the condensed liquid drops down into compartment E. Any vapor passing through B and C so highly heated as to be uncondensed in coils C passes through the layer of liquid in compartment E, collects in the highest portion of the compartment and passes through pipe M to coil K where it is entirely liquefied. If the liquid in E rises beyond a certain level it passes through pipe e back to the still. Any vapors which may collect in the upper part of D pass into the small bent pipe opening into the first coil of worm C. Water for rinsing the heater D may be drawn through cock s from the tub J and warm water for rinsing the still, through pipe d from the heater.
Another form of compound still is shown in Fig. [13]. In this the still S is divided into an upper and lower compartment by a concavo-convex partition d, having at its crown an upwardly extending tube t from which projects side tubes p. A pipe P opens above and extends from tube t. C is the mash heater and condenser. Connected to the head of the still is a pipe T through which the vapors pass to a condensing coil f formed on the wall of the heater C. At its bottom the coil f extends out of the heater, through the water tub W and out to receiver as at F. In the heat of this heater is a valve V whereby any vapors which may arise from the heated mash are conducted by pipe U to T.
The heater C is filled through funnel Y and the mash is admitted to the still through pipe b having cock a. The pipe P extends to the upper part of the water tub W and then downward to the bottom, where it again enters the still.
An opening in the partition d is controlled by a valve G which allows liquid in the upper compartment of the still to flow into the lower. Spent mash may be drawn off through c and the height of the water in tub W be regulated by pipe Z.
Fig. 13.—Compound Still.
The operation of this still is similar to Dorn’s still. Mash is put into C and a quantity of it is let into the upper compartment of the still and into the lower compartment by valve G. This valve is closed and the fire started. The vapors pass upward through t. If they are quite highly vaporized they pass onward up P, are condensed in their passage through the cool water tub and return as liquid to the upper compartment where they are further heated.