THE POTATO 291 



alcohol are (1) the preparation of the mash or wort, 

 (2) the fermentation of the mash or wort drawn off 

 from the mash tun, and (3) the distillation of the 

 dilute alcohol formed in the beer or wash from the 

 fermentation tanks. The preparation of mash in- 

 cludes (1) the treatment of the material used with 

 hot water to form a paste of the starch or the sugar, 

 and () the action of the malt or ferment on the 

 paste to convert the starch into fermentable sugar. 



"The object of the mash tun is to reduce the 

 starch in the ground grain to a pasty, gummy mass, 

 in order that the ferment of the malt may act upon 

 it vigorously and convert it into sugar. If the 

 mashing be done before the addition of the malt 

 the temperature may be raised to that of boiling 

 water. If, however, the malt be added before 

 the mashing begins, the temperature should not 

 rise much, if any, above 140 degrees F., since the 

 fermenting power is retarded and disturbed at 

 higher temperature. The mashing is simply a 

 mechanical process by means of which the starch 

 is reduced to a form of paste and the temperature 

 maintained at that point which is best suited to 

 the conversion of starch into sugar. 



"The mash, after the starch has all been con- 

 verted into sugar, goes into fermenting tanks, 

 which in Scotland are called ' wash backs' when the 

 yeast is added. They often have a stirring ap- 

 paratus whereby the contents can be thoroughly 

 mixed with the yeast and kept in motion. This 

 is not necessary after the fermentation is once 

 well established, but it is advisable, especially in 

 the early stages, to keep the yeast well distributed 

 throughout the mass. In these tanks the fer- 

 mentations are conducted, the temperature being 

 varied according to the nature of the product to 



