1821.] New Scientific Books. 471 



than a common hydrometer graduated for the purpose, a thermometer 

 being attached to mark the precise temperature at the time of making 

 the experiment. 



XIII. Maturation of Fruits. 



M. Berard has been engaged in a course of experiments to determine 

 what chemical changes take place during the maturation, ripening, 

 and decay of fruits of various kinds: his general results are stated 

 as follows ; viz. 



" Fruits act upon atmosperical air in a different manner to leaves. 

 The former at all times, both in light and darkness, part with carbon 

 to the oxygen of the atmosphere, to produce carbonic acid, and this 

 loss of carbon is essential to ripening, since the process stops, if the 

 fruit is immersed in an atmosphere deprived of oxygen, and the fruit 

 itself shrivels and dies. This occurs equally to those fruits which, 

 when gathered green, are able to ripen of themselves, though separated 

 from their parent tree ; but in these, the ripening process may be by 

 this means delayed for a certain time, and be completed by restoring 

 them to an oxygenized atmosphere. In this manner, peaches, plums, 

 apples, pears, &c. may be preserved unspoiled from three to ten or 

 twelve weeks, inclosed in an air-tight jar, with a quantity of lime and 

 sulphate of iron worked up into a paste with water, which has the pro- 

 perty of abstracting oxygen from the air which is in contact with it. 

 The passing from ripeness to decay in fruits is also characterized by 

 the production and evolution of much carbonic acid, and equally 

 requires the presence of an oxygenized medium. The internal 

 changes produced in fruits by the ripening process are particularly dis- 

 tinguished by the production of sugar, which does not exist in any 

 considerable quantity in immature fruits ; and it appears to be produced 

 at the expense of part of the gum, and especially of the ligneous 

 fibre."— (Phil. Mag.) 



Article XI. 

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