There are three main methods of saccharifying the fecula or starch of the potato. The first and most important by reducing the tubers to a pulp, and malting the entire mass. The second and third, by rasping the potatoes and so separating the fecula or starch grains from the mass, and then making a thin liquor or wash containing this fecula. Originally, in the first process, the washed potatoes were submitted to the action of boiling water, but later cooking by steam at a temperature of 212∞ F. was used, as being much more convenient to handle and more effective in action. The object of steaming is to break the coating and reduce the contents thereof to a pasty condition, wherein the starch is more effectively acted on by the malt and yeast. Ordinary steaming does not, however, render the pulp sufficiently pasty; some of the starch remains undissolved and is lost, hence in the modern practice, steam is turned into the steaming vat under a pressure of three or four atmosphere (45 to 60 lbs. to the square inch). High pressure steaming will be later described but the simple and older method of mashing and apparatus therefor, used prior to 1870, was as follows: Fig. 41 shows a section of a steaming vat. This consists of a conical wooden tub _H_ provided at its top with a suitable cover _O_ having a trap or door _P_ for putting in the potatoes. This as shown, consists of a hinged lid, having a button _p_ or other fastening means. This lid and cover should be of course steam tight, and it would be better to have it clamped down by a screw clamp than held by a button. Somewhat above the bottom of the vat, a steam inlet pipe _I_ enters, connected at its other end by a coupling _i_ with a suitable steam generator (see Fig. 43), Preferably the outlet of this pipe is screened by a perforated plate _M_ so that it may not be clogged by the pulp. It is also best that a filling piece be placed at the junction of the bottom with the sides in order that there be no sharp corner from which the pulp may not be easily cleaned out. [Illustration: FIG. 41.--Steaming Vat for Potatoes.] The bottom of the vat may either have a discharge door at the side as in Fig. 44 or at the bottom, as in Fig. 41. An under side view of the latter construction is shown in Fig. 42. The bottom of the vat is made in two parts or doors _J K_. These are held closed by a transverse bar _L_ inserted at its end into a stirrup _l¥_ and supported at its other end by a button _l_, or other means. While various forms of steam generators may be used, Fig. 43 shows a simple construction well adapted to the needs of a small distillery. _D_ designates the brick work of a furnace, and _A_ the boiler. This is so set that an annular space _E_ surrounds the sides of the boiler, through which the products of combustion must pass. [Illustration: FIG. 42.--Bottom of Steaming Vat.]