396 Miscellaneous fntelligeme. 



are always of uniform composition, so that when the air thus 

 contained is analyzed, it is always found to be of the same 

 composition as atmospheric air. 



When fruits separated from the tree, but capable of com- 

 pleting their own ripening, are placed in media free from 

 oxygen, they do not ripen: the power, however, is only sus- 

 pended, and may be re-established by placing the fruit in an 

 atmosphere capable of taking carbon from it. But if the fruit 

 remain too long in the first situation, although it preserves the 

 same external appearance nearly, it has entirely lost the power 

 of ripening. 



Hence it results, that most fruits and especially those that 

 do not require to remain on the tree, may be preserved for 

 some time, and the pleasure they afford us thus prolonged. 

 The most simple process consists in placing at the bottom of a 

 bottle, a paste formed of lime, sulphate of iron, and water, 

 and afterwards to introduce the said fruit, it having been pulled 

 a few days before it would have been ripe. These fruits are 

 to be kept from the bottom of the bottle, and as much as pos- 

 sible from each other, and the bottle to be closed by a cork 

 and cement. The fruits are thus placed in an atmosphere free 

 from oxygen, and may be preserved for a longer or shorter 

 time according to their nature ; peaches, prunes, and apricots 

 from twenty days to a month; pears, and apples for three 

 months. If they are withdrawn after this time, and exposed 

 to the air, they ripen extremely well ; but if the times men- 

 tioned are much exceeded they undergo a particular alteration, 

 and will not ripen at all. 



Ripe fruit exposed to the air rots and decays. In this case 

 it first changes the oxygen of the surrounding air into carbonic 

 acid, and then liberates from itself a large quantity of the same 

 acid gas. It appears that the presence of oxygen gas is neces- 

 sary to the rotting or decay of fruits, when it is absent, a differ- 

 ent change takes place. 



When the fruit cannot ripen except on the tree, its ripening 

 is not produced by a chemical change of the substances it con- 

 tained whilst still green, but by the change of new substances 

 furnished to it by the tree, and when it ajjpears to lose the acid 

 taste it had in its unripe state, it is because that taste is hidden 

 by the large quantity of sugar it receives in ripening. 



In the fruits which ripen off the tree, the quantity of sugar is 

 also found considerably to increase ; and in this case, it must 

 be formed at the expense of the substances previously in the 

 fruit. Gum and lignin are the only principles, the proportion 

 of which diminish at the same time ; it is therefore natural to 

 conclude, that it is the portions of these substances which have 

 disappeared, that have been converted into svitrar: and as the 



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