Uses of the Potato 279 



15, where it can be examined for its purity and strength. The 

 steam pressure in the apparatus is registered by the pressure gauge 



16. The alcohol afterwards passes tlirough the test box into the 

 storage tank 17 to be denatured. 



Wood alcohol and benzin are generally used as denaturing agents, 

 though other ingredients may be used. The ingredients used must 

 be authorized by the Bureau of Internal Revenue. 



Preparation of green barley malt. — There are two operations — 

 the first being to steep or soak the grain, and the second, sprouting 

 or growing it. The steeping consists of soaking the grain in water 

 until it has absorbed sufficient moisture to enable it to sprout when 

 spread upon the malting floor. Good barley malt can be obtained 

 from a good grade of barley properly steeped (for two or tliree days) 

 and grown for a long interval of time (12 to 20 days) with a fair 

 amount of moisture at a temperature not to exceed 60°-63° F. The 

 malt should be thoroughly crushed before using. 



Control of operation. — It is advisable to operate a distillery only 

 during the colder months, for instance from early autumn until late 

 spring. During this time the temperature of the cooling water will 

 be considerably lower, and the amount of water required correspond- 

 ingly less, and the time required for cooling decidedly shortened. 

 This means a shorter working day and consequently less Avear on the 

 machinery and a considerable saving of fuel. It is essential that a 

 distillery be oj^erated daily and not intermittently, as each day's work 

 depends in a greater or less degree both upon that of the preceding 

 and the following day. Another very important point is cleanliness, 

 and upon this depends the final yield of alcohol in a great measure. 

 Many injurious organisms will breed and work into the mash and 

 hinder the process of fermentation. This may be remedied by run- 

 ning water through the apparatus at the end of the day's work, and the 

 walls of the building should be kept from mold by whitewashing. 



Preparation of a potato-yeast mash. — The yeast mash is prepared 

 in a wooden tub equipped with a rake for stirring and with proper 

 piping for heating and cooling. The volume of the yeast should be 

 from 2 to 3 per cent of the main mash to be fermented and increased to 

 ten times that of the yeast mash used to start it. Rye is best used 

 to start with, and later the potatoes may be substituted. The rye 

 and malt are mashed together. The malt should be left to work for 

 about three hours, by which time the formation of the sugar will be 

 complete. The gravity should be 20°-24° Balling. Then the mash 



