Uses of the Potato 275 



convert the starch of the potatoes into sugar, there will be needed 

 the green malt yielded by 120 pounds of barley, which at 70 cents a 

 bushel will cost SI. 75. 



The cost of fuel varies with the fireman, but with proper care and 

 efficient use one ton at $4 should be enough for a day's operation. 

 Three men will be required, consisting of a fireman and two laborers. 

 This will total up to about S33 for daily operating expenses. 



Operating a distillery. — The first process is to wash and then 

 cool the potatoes so that the starch present can be thoroughly 

 converted into sugar by the action of the malt. The potatoes are 

 placed in a vacuum cooker and steamed until they are thoroughly 

 cooked. The steam pressure in the cooker is allowed to rise to 50 or 

 60 pounds. The entire time required for warming the potatoes and 

 reaching the maximum pressvu*e should be about one hour. The 

 potatoes are stirred and the pressure held for about ten more minutes 

 to insure a good cooking of the starch. Then the temperature of 

 the cooked potatoes is allowed to fall to 212° F. The temperature 

 of the cooked potatoes is fiu*ther reduced by means of the vacuimi 

 pump to 140-145 F.° at which point the malt necessary to change 

 the starch to sugar is added. About 2 pounds of malt is added for 

 each 100 pounds of potatoes mashed. The green malt is crushed 

 between rolls, while dried malt is ground in a mill before using. 

 About fifteen minutes before the mash in the cooker is ready for 

 malting, the malt already ground is mixed with water at the rate of 

 1 gallon of water to 2.5 pounds of dried malt, or f gallon of water to 

 same amount of green malt. This is prepared in a tub above the cooker 

 and is dropped into the cooker Avhen the temperature is down to 140° 

 to 145° F. The diastase in the malt will dissolve the cooked starch 

 and convert it into a fermentable sugar in about fifteen or twenty 

 tninutes, during which time the mash should be constantly stirred. 

 This is kept up until the test for complete conversion shows no starch. 

 This test consists in filtering a little of the mash into a white porce- 

 lain dish and adding a few drops of iodine solution (2.5 drams potas- 

 sium iodide and 75 grains iodine to 1 quart water and shake). If 

 the mixture is blue, it shows the presence of starch, and it is then 

 necessary to add more malt, or allow more time for conversion. The 

 cleaned mash is pumped through the mash cooler, where it is re- 

 duced to the " pitching " (tliis means temperature in which yeast 

 can ferment) temperature, by circulating a constant stream of cold 

 water around the pipes through which the mash goes. Tliis tempera- 



