As previously stated, mashes to-day are mostly prepared by steaming and disintegrating in a mash cooker of the type shown in Figs. 1 and 41 or in Henze steamers, from which the mash is blown into the preparatory mash vat, where it is stirred and brought to the proper temperature for fermentation. A convenient arrangement of mash cooker, coolers, pump and vats is shown in Fig. 1. Where Henze steamers are used they are arranged in batteries, the blow-off pipes being connected to the preparatory mash vats. These are preferably provided with water cooled stirrers consisting of a frame of straight and vertical tubes mounted on a tubular arm projecting from a tubular shaft, and rotated in a horizontal plane within the closed mash vats, by suitable gears. The rotation of the arm stirs and automatically mixes the mash while cooling it. Another form of cooler is shown diagrammatically in Fig. 4. Whatever form of cooling apparatus is used, attention should be paid to the ease with which the stirrers or tubes can be kept clean, and to the strength of the apparatus, gears, etc. Concentrated or thick mashes require that the stirrers be of massive construction, capable of being rapidly rotated in the liquid. In preparatory mash vats for use with concentrated mashes, means must also be provided for clearing the mash. These mash cleaners and husk removers usually form part of, or are attached to the vat itself and are driven by gearing from the main shaft carrying power to the mashing room. A good idea of the general arrangement and correlation of the various apparatus of a plant may be gathered from the sectional view of a grain distillery shown in Fig. 55. It will be seen from this that the mashing apparatus, steamers and mixers are located on the several floors of one building and in such relation to each other that the several operations of saccharifying are carried on in a continuous movement of mash towards the fermenting vats. [Illustration: FIG. 55.--Continuous Grain Alcohol Distillery--Barbet's System.] Adjoining the fermenting vat room is a section of the plant given up to the manufacture of pure yeast and this and the fermenting rooms are level with the ground, have solid walls whereby a uniform temperature is obtained, and plenty of space for proper ventilation of the vats. A gallery traverses the room about midway the height of the vats so that convenient access may be had to them. The distilling room is high enough to allow for the setting of the various columns, separators and condensers at their proper heights relative to each other, and should be so arranged as to its several floors or stages that access to the various pipes and apparatus may be easily had. The steam generator for the column is located in an adjacent room.