ALCOHOL 



23 



only in preparing spirituous beverages of 

 somewhat higher alcoholic strength than 

 coulfl be obtained by fermentation alone. 

 The first stills were very crude and sim- 

 ple in design, and were incapable of pro- 

 ducing distillates of great strength from 

 the wine which invariably was used as 

 the material for distillation. It was in- 

 deed found by the early chemists that if 

 the first weak distillate was subjected to 

 a second and third distillation its alco- 

 holic strength could be raised (though at 

 the expense of a material diminution in 

 its volume) to such an extent that it 

 would burn, but the expensiveness of the 

 product thus obtained was too great to 

 allow its use for any industrial purposes. 

 At present wine and other fermented 

 fruit juices are distilled only for the 

 production of potable spirits: and indus- 

 trial alcohol is made altogether by the 

 distillation of fermented saccharine solu- 

 tions which are prepared either directly 

 from raw materials containing sugar, such 

 as molasses, or from starchy materials 

 like potatoes or the cereal grains, after a 

 preliminary treatment which converts 

 their starch into sugar. 



Theory of Alcoholic Fermentation 



The process of alcoholic fermentation 

 is established whenever yeast is allowed 

 to act on sugar solutions of moderate 

 strength at temperatures between 50 de- 

 grees and 90 degrees Fahrenheit. Theo- 

 retically the process consists of a simple 

 splitting up of sugar into alcohol and 

 carbonic acid gas, any given amount of 

 sugar yielding proportionate and perfectly 

 definite amounts of these two products of 

 its decomposition. This is illustrated in 

 the following example: 



The chemical composition of dextrose, 

 which is the form of sugar occurring in 

 most ripe fruits, is represented by the 

 formula CrH,-Ot, which signifies that one 

 molecule or unit of the compound sub- 

 stance dextrose is made up of six atoms 

 or units of the element carbon, 12 of 

 the element hydrogen, and six of the ele- 

 ment oxygen. When fermentation takes 

 place, the molecule of dextrose breaks up 

 substantially as is indicated by the fol- 

 lowing equation: 



C,H^O, = 2 C,H,OH + 2 CO.. 



This signifies that after fermentation 

 is over the dextrose will have disappeared 

 and in its place will be found an amount 

 of alcohol containing all the hydrogen, 

 two-thirds of the carbon, and one-third 

 of the oxygen of the sugar, and an amount 

 of carbon dioxid containing one-third of 

 its carbon and two-thirds of its oxygen. 

 Theoretically the total weights of the al- 

 cohol and carbon dioxid which are pro- 

 duced in the fermentation should equal 

 exactly the weight of dextrose which is 

 decomposed, and 100 pounds of the sugar 

 should yield 51.11 pounds of alcohol and 

 48.89 pounds of carbon dioxid. 



In practice, however, the decomposition 

 is never complete, nor is it ever so simple 

 as is indicated by the foregoing equation. 

 Only in carefully conducted laboratory 

 work is it ever possible to ferment any 

 sugar completely; and even then, as a re- 

 sult of life processes of the yeast which 

 are not yet understood by chemists or 

 biologists, small and varying proportions 

 of sugar escape transformation into al- 

 cohol, and are converted instead into 

 other substances. According to the inves- 

 tigations of Pasteur, 100 pounds of dex- 

 trose, instead of yielding the theoretical 

 weights of alcohol and carbonic acid in- 

 dicated by the equation, will produce in 

 laboratory practice the following amounts 

 of fermentation products: 



Pounds. 



Alcohol 48.55 



Carbon dioxid 46.74 



Glycerin 3.23 



Organic acids 62 



Miscellaneous 1.23 



Total : .: 100.37 



The fact that the total weight of the 

 fermentation products exceeds slightly the 

 weight of sugar fermented is explained 

 on the ground that the formation of cer- 

 tain of the by-products is accompanied by 

 the absorption and fixation of slight 

 amounts of water. 



In manufacturing work, such complete- 

 ness of fermentation may be taken as an 

 ideal toward which one is to strive. Ac- 

 cording to the skill of the distiller, the 

 character of his mechanical equipment, 



