FERMENTATION. 249^ 



in this manufacture is still practised upon the banks of the 

 Rhine, and in Germany ; by the second, for which we are 

 indebted to modern chymistry, the fecula is converted into a 

 saccharine substance, and thus rendered susceptible of the 

 vinous fermentation. 



I shall describe concisely both of these processes, because 

 they may be made to enter advantageously into a system of 

 labor for an extensive farm, both on account of the liquor 

 obtained, and of the food which is furnished for animals by 

 the mash. 



The old method may be reduced to the two following 

 operations. 



A cask which will contain about two English hogsheads 

 is set up on one end, and a square opening made in the 

 head, through which the potatoes are thrown in ; another 

 small opening is formed in one of the staves on a level with 

 the bottom of the cask, and serves for taking the potatoes 

 out. The potatoes are boiled by steam introduced into 

 the cask by a tube passing through the lower end of it. 

 As soon as the potatoes are boiled, they are crushed as 

 perfectly as possible between two wooden cylinders, each 

 of which is furnished at one end with a driving wheel, put 

 in motion by a crank. The pulp of the potatoes is thrown 

 into a tub where it is made to ferment : the vinous fermen- 

 tation would not however take place in it, if it were not ex- 

 cited by the addition of leaven ; the leaven used is made in 

 the following manner. 



To 4 pounds of malt are added one pint of beer yeast, 

 and about 44 pounds of the potato pulp ; these are worked 

 carefully together and diluted with ten or eleven gallons 

 of water at the temperature of 40° Reaumur, (^= 122° 

 Fahrenheit,) and the vessel containing the mixture is cov- 

 ered over. The paste thus made ferments and rises, and 

 at the end of twenty-four hours, it is mixed with the body 

 of pulp deposited in the vat, some hot water is thrown in 

 upon it, and the whole is stirred constantly, till the tem- 

 perature of the liquid stands at from 15° to 18° Reaumur, 

 (z=: to 65^° and 72^° Fahrenheit,) and the specific gravity 

 marks 6° or 7° upon the aerometer, (= specific gravity of 

 1.044 to 1.052.) 



During fermentation, care must be taken that the tem- 

 perature of the place should not vary more than from 20° 

 to 25° Reaumur, (= to 77° and 88° of Fahrenheit;) and 

 without this the fermentation will lansfuish and never be 



