15 



apple, or pear, on a grater, to a pulp, wash this with cold water on ;i, 

 fine sieve — the turbid liquid which passes through deposits a fine flour 

 of starch, of which not even a trace can be detected in the ripe fruit. 

 This after-ripening, as it is called, is purely a chemical process. It is 

 the starch being transformed into sugar : the more starch unripe fruit 

 contains, the sweeter does it become when ripe." 



Starch proper docs not decay. It must first be turned into sugar ; 

 but the change is made with extreme slowness at 34°. After the 

 saccharine change, though putrefaction is greatly retarded at 34°, yet 

 comparatively, its progress is easy and rapid. In this house the mo^t 

 tender fruits, if put in immediately when made, keep better than the 

 most hardy sorts, if not put in till full-ripe. And Avith the same fruits, 

 decay is not one-tenth as rapid in the former case as in the latter. It 

 "was formerly believed, both in this country and in Europe, that delicate 

 fruits, such as tender apples, pears and grapes, would not keep well in 

 an atmosphere lower than 40° F. The appended report on pears, kept 

 from August till March, proves the erroneousness of this opinion. 

 These pears were never above 36°, (the house then was imperfect.) 

 and a good part of the time as low as 34°. Sour fruits will not bear as 

 much cold as sweet ones. Tiie Catawba grape will suifer no harm at 

 26° ; while 32° will be as cold as is safe for a lemon. But all provi- 

 sions for diflTerent degrees of coldness, by means of ice alone, in regard 

 to fruits, is useless — as all of them should be in a temperature as cold 

 or colder than ice alone can make them. Some advantage would be 

 secured to the grape, and Sweet apple, by a greater degree of cold 

 than 34°. Refrigerating mixtures might secure this, but the cold pro- 

 cuced in this way is instantaneous, and temporary in its action. They 

 would need constant renewal, day and night, to keep up an equal tem- 

 perature — and we do not think that the comparatively slight advantage 

 gained could ever justify the labor and money expended. The decay 

 below 40°, was caused, hitherto, not by a cold atmosphere, but by the 

 impossibility of making a cold one dry. 



There are but two known modes in practical use for drying air. One 

 mode consists in throwing it upon ice, or an ice-cold surfece ; the other 

 in exposing it to absorbents. Nearly all the conservatories, and experi- 

 ments, hitherto, have concerned the former method, which must ever be 

 imperfect and unsatisfiictory ; for by it the air gives up only so mucli 

 vapor as is in excess of its capacity at 32°. It is still as wet as it can 

 be at this ice-cold temperature, and does not become dry till it rises to 

 40°, or above it. 



