FPXCTION.] RIPENING OF FRUITS BLETTING. 257 



the aqueous products, render it proportionally less, without 

 its being absolutely so. But the gummy, mucilaginous, or 

 gelatinous matters, appear very susceptible of changing into 

 sugar; thus, Couverchel found that, if we treat Apple jelly 

 with a vegetable acid dissolved in water, we obtain a sugar 

 analogous to that of Grapes ; that the gum of Peas, placed 

 with oxalic acid, in a temperature of 125 Reaum., changed 

 to sugar ; that gum extracted from starch, if mixed with the 

 juice of green Grapes, rendered the latter saccharine; and 

 finally that tartaric acid will produce the same effect by aid 

 of heat : this is the reason why most fruits become sweet 

 when cooked. 



" Other matters offer remarkable disparities between one 

 fruit and another : thus malic acid keeps diminishing in 

 Apricots and Pears, augmenting in Currants, Cherries, Plums, 

 and Peaches. Gum keeps diminishing in Currants, Cherries, 

 Plums, and Pears, and augmenting in Apricots and Peaches. 

 Animal matter keeps diminishing in Apricots and Plums, 

 and increasing in Currants, Peaches, Cherries, and Pears. 

 Lime, which never exists except in small quantity, seems 

 generally to diminish, probably because evaporation becomes 

 less with maturity. 



" After the period which is generally called that of ripeness, 

 most fleshy fruits undergo a new kind of alteration ; their 

 flesh either rots or blets.* These two states of decomposition 

 cannot, according to Berard, take place, except by the action 

 of the oxygen of the air, although he admits that a very small 

 quantity is sufficient to cause it. He succeeded in preserving 

 for several months, with little alteration, the fleshy fruits 

 which were the subjects of the foregoing experiments, by 

 placing them in hydrogen or nitrogen gases. All fruits at 

 this extreme period of their duration, whether they decay or 

 whether they blet, form carbonic acid with their own carbon 

 and the oxygen of the air, and moreover disengage from 

 their proper substance a certain quantity of carbonic acid. 



"Bletting is in particular a special alteration. I have 



* May I be forgiven for coining a word to express that peculiar bruised 

 appearance in some fruits, called llc**i by the French, for which we have no 

 equivalent English expression ? 



VOL. II. S 



