244 UNCONSCIOUS NERVOUS OPERATIONS 



fungus known as the yeast plant is the active agent in 

 producing the changes which occur. The sugar of the 

 fruit or plant must be in solution, and the germs of the 

 yeast must in some way be introduced. 



Alcohol is one of the products of vinous fermentation. 

 It is composed, like sugar, of carbon, hydrogen, and oxy- 

 gen, but in proportions different from their proportions 

 in sugar. The drinks which contain alcohol differ widely 

 in flavor according to their sources, and also vary in the 

 amount of alcohol which appears in them. In cider and 

 some kinds of beer the proportion may be as low as 2 per 

 cent. As alcohol is a very volatile fluid, it may be readily 

 separated from the other substances in the fermented 

 liquor by the process called distillation. This is the driv- 

 ing off of the alcohol in the form of vapor by the applica- 

 tion of heat, and its recondensation, by cooling, to liquid 

 again. In this way is obtained the strong alcohol which 

 is mixed with various coloring and flavoring matters to 

 form the spirituous liquors of commerce. Whether a 

 drink contains the 2 per cent of alcohol found in cider, 

 or the 50, or more, per cent found in whisky, or the 

 90 per cent of " cologne spirits," the alcohol is in all 

 cases identical in its nature and properties. 



356. Properties of Alcohol. Pure spirit, or "absolute 

 alcohol," is a colorless, volatile liquid with a strong affin- 

 ity for water, which it rapidly absorbs from the atmos- 

 phere or from any other substance containing water with 

 which it comes in contact. Alcohol burns readily in the 

 open air, that is, it is quickly oxidized and changed in its 

 chemical composition. It is a powerful solvent, dissolv- 

 ing many substances not soluble in water. Though itself 

 the product of fermentation, it is a preventive of putre- 

 faction. that is, it preserves animal tissue from decay 7 



