444 MICROBIOLOGY OF SPECIAL INDUSTRIES. 



In all cases, it is made by the preparation from saccharine or starchy 

 substances of a sugar solution suitable for the work of yeast, the fer- 

 mentation of this solution, and, finally, the distillation of the alcoholic 

 liquid. 



Where the raw materials are sugary, methods similar to those of wine- 

 making, and where starchy, to those of brewing, are employed, modified 

 to suit the conditions of each case. 



The principal potable alcohols are brandy, made from grapes, rum 

 from sugar cane, and whiskey from rye or other grains. Many other 

 sources are used and any fermented beverage will, by distillation produce 

 a potable spirit varying in character and quality with the source. In- 

 dustrial alcohol may be made from any substance capable of undergoing 

 alcoholic fermentation, the limiting factor in practice being, principally, 

 the cost of the raw material per unit of alcohol. 



METHODS. 



PREPARATION OF THE SUGAR SOLUTION. Saccharine Raw Materials. 

 When spirits are to be made from grapes or other fruit, the juice is fer- 

 mented in the same way as for the corresponding beverage and then 

 distilled. The juice, however, is diluted to 20 Bal. or less, as it is not 

 necessary or desirable to have too much alcohol in the fermented 

 liquid. The product is consumed directly as brandy or used to fortify 

 sweet wines. The principal fruits used besides grapes are apples, 

 peaches, plums and cherries. 



Industrial alcohol has been made from inferior or spoiled fruits and 

 from cannery wastes, but the cost per unit of alcohol is usually high. The 

 difficulties of fermentation are great, owing to the presence of large 

 quantities of molds and other injurious organisms, and the extraction 

 of the juice is troublesome. A careful use of sulphites and pure yeast 

 simplify the process much. 



Sugar cane and its products are used in several ways to produce alcohol. To a 

 limited extent the juice of the cane is fermented directly and distilled. The product is 

 known as Jamaica rum. Much larger quantities of alcohol are manufactured from 

 the cane-sugar molasses and appear in commerce as rum, tajfia, arrack or neutral 

 spirits. 



For the making of Jamaica rum the juice is pressed from the crushed canes, and 

 diluted with 20 per cent of vinasses (the residue of a previous distillation) to increase the 

 acidity, and give the required flavor. 



