404 VINEGAR, CIDER, AND FRUIT-WINES. 



from thoroughly ripe fruit the richer and more durable its taste 

 will be; and the more completely the oxygen of the air is ex- 

 cluded during this process the more perfectly will it retain its 

 color. Rapidity of the drying process sometimes increases the 

 content of sugar by 25 per cent., and this increase is in an exact 

 proportion to a slower or quicker evaporation of the content of 

 water, always provided, however, the fruit does not suffer injury 

 from the heat. 



Any one who has boiled down the juice of the maple, sorghum, 

 sugar-cane, or sugar-beet knows that with slow evaporation sugar is 

 not formed, the content of sugar being then converted into acid. 

 Now, the change of substance must be constantly kept in view : 

 starch is converted into sugar (in this case very largely already in 

 the plant), sugar into alcohol, and alcohol into vinegar. This ex- 

 perience must also hold good in drying fruit. The chemical pro- 

 cess by which the content of starch of the fruit, when brought into 

 a high temperature, is converted into sugar is similar to that during 

 the ripening process on the tree, only it takes place more rapidly. 



A few days of warm sunshine produce sufficient sugar in goose- 

 berries and grapes to change the sour unpalatable fruits to a re- 

 freshing article of food. A few hours in an evaporating appa- 

 ratus, in which the proper degree of heat is maintained, can produce 

 a still greater change, provided the fruit be not placed in it before 

 it has reached perfection in a natural manner. It must be re- 

 membered that 212 F. is the boiling point, and that subsequent 

 treatment, no matter how careful, cannot restore the taste lost in 

 such a temperature. Of no.less importance is another point : the 

 surface of the fruit to be dried must be kept moist and soft, so 

 that the internal moisture may find a way by which it can readily 

 and quickly escape, and a strong hot current of air must uninter- 

 ruptedly pass over the fruit to carry off the escaping moisture. 

 Hence, cold air must under no circumstances have access to drying 

 fruit, and above the latter an aperture must be provided for the 

 escape of the air saturated with moisture. 



The apprehension that fruit cannot be dried in a hot moist ap- 

 paratus is refuted by the well-known scientific fact, that air of the 

 temperature of the freezing point absorbs T J V part of its weight 

 of moisture, and that its capacity for absorption doubles with 

 every 15 C. (59 F.) of higher temperature. Thus, if the tern- 



