FERMENTATION. 385 



Fig. 116. 



of water. To prevent the water from becoming hot a con- 

 stant supply of cold water flows in by the tube H to the 

 bottom of the vessel, the heated water rising and flowing 

 out by the tube G. The condensed liquor, passing out at 

 F, drops into the receiver. 



545. Fusel-Oil. This oily substance, which is very poisonous, was 

 first discovered in the distillation of liquor made from potatoes, and hence 

 has sometimes been called potato-oil. In reality it is amylic alcohol, one 

 of the large class of alcohols mentioned in the fourth column of the table 

 on page 303. Amylic alcohol is produced in the distillation of liquors 

 made from the grains, and occasionally at least in other distillations also. 

 It may be separated from the spirit by filtration through charcoal, this 

 substance absorbing the poison into its pores. But not only is this process 

 often omitted, thus leaving this poison to aggravate the deleterious effects 

 of the alcohol itself, but the fusel-oil is made use of to a large extent by 

 unprincipled manufacturers, of whom there are a great number, in getting 

 up factitious liquors, wines, and cordials. The enormous cheating and 

 destructive poisoning to which the drinkers of spirituous liquors are thus 

 subjected, though extensively known, seem to be little heeded. 



546. Fermentation in Bread. The "raising" is ordinarily 

 accomplished by alcoholic fermentation. The yeast first 



R 



