The maturation of fruits, although not thoroughly examined, seems to be a change of the same kind, that is, sugar is formed at the expence of the other prihciple of the unripe fruit. The maturation of fruits is intimately connected with a certain species of decay, as exemplified in the firmer fruits. The rotten part of many pears is remarkably sweet, and the sac charine matter does not begin to be formed in the medlar until its decomposition be far advanced, In other instances, as in the apple, the decayed part is intensely bitter ; and the softer juicy fruits grow mouldy and offensive. The art of preserving fruits consists in being able to prevent and retard these changes. A certain proportion of moisture seems to be necessary for their decay ; and hence, by care ful exsiccation, grapes are converted into raisins, plumbs into prunes, and figs are dried. But by care fully excluding them from the air, they may even be preserved without dissipating their natural moisture. Thus currants, cherries, and damsons, gathered per fectly dry and sound, may be put into bottles, clo sed with cork and rosin, and buried in a trench, with the cork downwards. Fine bunches of grapes may also be preserved in bags, by closing the cut end of the stalk with wax, which prevents the escape of moisture, or they may be packed in very dry bran or sand. Some may even be preserved by being kept immersed in water. This is constantly prac tised in regard to the cranberry, and sometimes suc ceeds with apples.
The preservation of fruit is in many countries an object of much importance. In some, the great object is to preserve the fruit in as natural a state as possible. This is particularly the case in re gard to winter apples, and pears, and grapes. The time for gathering fruits depends upon their expo sure, and the manner of gathering them influences their keeping. After having prepared the fruit-room, a fine day is to be chosen, and, if possible, after two or three preceding days of dry weather, and, about two in the afternoon, the fruit is to be gathered, and deposited in baskets of a moderate size, taltieg care that none of it receive any bruise or blemish, for the injured part soon rots and spoils the sound fruit in contact with it. As the summer fruits ripen more quickly after they are pulled, only a few days con sumption should be gathered at once, by which means we can enjoy them for a greater length rof time. Autumn apples and pears should be gathered eight days before they are ripe ; and, indeed, some kinds never become fit for eating, on the tree. If they have been necessarily gathered in wet weather, or early in the morning, they should be exposed a day to the sun to dry, and they should on no account be wiped, which rubs off the bloom, as it is called, which, when allowed to dry on some fruits, consti tutes a natural varnish, closing up the pores, and preventing the evaporation of the juices. They
should not be laid in heaps, which causes them to sweat, and undergo a slight fermentation; for fruit thus treated, if it does not spoil, gets dry and mealy ; and hence, in this country, the ordinary apples, im ported from England and the Continent, are inferior to our own. The principal requisites for a good fruit-room are great dryness, and equality of tempe. rature, and the power of excluding light. Some cu rious persons preserve fine pears, by passing a thread through the stalk, of which they seal up the end with a drop of sealing wax, enclose each separately in a cone of paper, and hang them up by the thread brought through the apex. Experience has also proved, that grapes keep better when hanging than when laid upon a table. The cut end should be clo sed with wax, which prevents exhalation. Some hang them by the stalk, others by the point of the bunch, as the grapes are thus less pressed against each other ; but it is in both cases necessary to visit them from time to time, and cut off, with a pair of scis sors, every berry that is mouldy or spoiled.
More artificial modes for preserving grapes in a succulent state are sometimes used, and become ne cessary for their transportation to distant countries. They are often packed with bran and saw-dust, and Apicius says, they may be preserved in barley. The same classical gourmand was well acquainted with the use of water in preserving the grapes. in their natural state. " Take grapes from the vine without wounding them. Boil rain-water down to a third, and put it into a vessel into which you also put the grapes. Close the vessel with pitch and gypsum, and place it in a cool situation, to which the sun has not ac cess, and when you please you will have .green grapes. The water may be given to sick persons as hydromel." The boiling of the water so long is un necessary, as a much shorter time would be suffi cient to expel the air, which is probably the man ner in which it has some effect. The water will ac quire a slight acidity from the grapes: and hence it was given, sweetened with honey, as a pleasant drink to the sick.
Animal substances in general, when deprived of life, have a natural tendency to undergo the putre factive fermentation. Before this is established, they pass through a series of successive changes, which are intimately connected with our subject. After death, the bodies of animals cool more or less ra pidly, according to the temperature and conduct ing power of the air, or other substances with which they are in contact. In fact, they do not differ in this respect from an equal mass of any other mat er, heated artificially to the same temperature, and having the• same conducting power. As this, how ever, is very weak, the-bodies of animals cool very slowly after death.