FERMENT OILS. 359 



rushing do\Yn the tube it is known that the maximum power of 

 the pump is attained. Fig. 2 represents Finkener's arrangement. 

 Fis. 3 is such as used at the London University. Fig. 4 is Geissler's. 

 All these are supplied by Townson and Mercer, of London ; also 

 Fig. 7, Korting's-' Water- Jet Vacuum Pump"; this is made entirely 

 of metal and has a vacuum-gauge attached ; with a head of 15 

 feet of water (a tlow of If galls, per minute) it gives an almost 

 perfect vacuum. The water supply-pipe should be as straight as 

 possible, without any sharp bends, and be of at least J -inch bore, 

 to ensure the full power of this pump. The discharge pipe fixed 

 to its lower end should end below water, by being dipped in a 

 vessel partly filled with water, and the water-cock must be full 

 open while working. 



" Oil of Potato " is truly a ferment oil, but although of an oily 

 nature, cannot be strictly classed as an " essential oil " ; it is rather 

 an " ethereal oil," and is closely allied to alcohol in its properties. 

 As fusel oil, or crude hydrated oxide of amyl it has already been 

 described in a foot-note to page 284. It is a component part of 

 the spirits obtained both from corn and potatoes, and these liquors 

 owe their peculiar smell to its presence. The greater intoxicating 

 power of whisky (more especially that from raw un malted grain) 

 than other spirit, is due to the larger quantity of fusel oil which it 

 contains. The oil is oenerated during; the fermentation of the 

 mash ; it exists ready formed in the fermented liquids, and distils 

 over with alcohol when a gentle heat is applied. It is observed 

 that a greater quantity of alcohol is obtained when the mash is 

 made quite neutral by ashes or by chalk, and that the proportion 

 of oil in the spirit is also increased. In producing a fine-flavoured 

 brandy from corn, the exertions of the distiller are directed as 

 mirch as possible to lesserr the formatiorr of fusel oil during the 

 fermentation of his worts, and to eliminate during the distillation 

 and rectification of his liquors, the greatest possible proportion of 

 that with which they may be contaminated. Considering the 

 deleterious nature of fusel oil, it should, as far as possible, be 

 eliminated from all spirituous beverages ; when swallowed it 

 occasiorrs nausea, giddiness, headache, &c. : in larger quarrtities it 

 causes ^'omiting, delirium, oppressive respiration and lessened 

 sensibility to pain ; its vapour also produces these effects. In 



