to the greater advantage, the increased cultivation of the black currant plant seems essential: It is easy of increase, greatly productive, and its fruit, in general, can scarcely form too large a proportion of the mixture Recipe.

Take, black currants,

red ditto,

white ditto,

ripe cherries (black hearts are the best),

rasberries,

each an equal, or nearly an equal quantity. If the black currants be the most abuḥdant, so much the better.-To 4lb of the mixed fruit, well bruised, put one gallon of clear soft water. Steep three days and nights, in open vessels, frequently stirring up the mass. Then strain through a hair sieve. The remaining pulp press to dryness. Put both liquids together, and to each gallon of the whole put 3lb. good, rich, moist sugar, of a bright yellowish appearance.— Let the whole stand again three days and nights, frequently stirring up as before, after skimming off the top. Then tun it into casks, and let it remain, full and purging at the bung-hole, about two weeks. Lastly, to every 9 gallons put one quart of good brandy, and bung down. If it does not soon drop fine, a steeping of isinglass may be introduced, and stirred into the liquid, in the proportion of about half an ounce to nine gallons.

N. B. Gooseberries, especially the largest, richflavoured, may be used in the mixture to great advantage; but it has been found the best way to prepare them separately, by more powerful bruising, or pounding, so as to form the proper consistence in pulp; and by putting six quarts of fruit to one gallon of water, pouring on the water at twice; the smaller quantity at VOL. XIII.-SECOND SERIES.

H

night,

night, and the larger the next morning. This process, finished as aforesaid, will make excellent wine, unmixed; but this fluid, added to the former mixture, will sometimes improve the compound.

An Enquiry into the Causes of the Decay of Wood, and the Means of preventing it. By Dr. PARRY.

From the LETTERS and PAPERS of the BATH and WEST of ENGLAND SOCIETY.

THE power of wood in different forms to supply luxury, to promote science, and to guard and prolong human life, has made the means of preserving it from decay highly interesting to mankind. With this view various premiums have been offered by this and other economical societies. The object of the following discussion is to suggest the best means of prevention, chiefly by inquiring into the nature and sources of the evil against which it is intended to guard.

Wood, when killed by being separated from its root, is subject to gradual destruction from two causes-rotting, and the depredations of insects.

Of the rot there are two supposed kinds, as they affect wood, first, in the open air, or secondly, under cover.

The first is that which in the terms of our premium, Class VII. No. 3, is said to occur to "barn and other out, side-doors, weather-boarding, gates, stiles, and implements of husbandry." To which, if there were any need of this minute specification, might have been added posts, rails, paling, water-shoots, and various other objects.

The second is well known under the name of the dryrot, the cause and prevention of which are the subjects of a pren.ium by the Society of Arts in London.

Animal and vegetable substances possess certain com mon properties and movements, which constitute what is called life. When that state ceases, and these properties and motions no longer exist, the bodies become subject to the chemical and mechanical laws of all other

matter.

When perfectly dry, and in certain degrees of temperature, both seem to be scarcely capable of spontane ous decay. On this principle vast quantities of salmon are annually conveyed in a frozen state to London from the North of England and Scotland; and the inhabitants of the still more Northern regions constantly preserve their food by freezing, unchanged through the longest winters. The gelatinous and other soluble parts of animal substances, when extracted by boiling, and kept in a soft moist state, very readily putrefy. But if the same matter be dried by a gentle heat, and secluded from moisture and air by being kept in bottles or metallic cases, it will remain very long without decay. This is the theory of that well-known and useful substance, portable soup. In the burning climate of Africa, when it is intended to preserve a dead animal for food, all that is necessary is to cut the muscular parts into thin strips, from which, in a few hours, the heat of the sun exhales all moisture, reducing them to a substance like leather or horn, which proves to be unsusceptible of future decay from putrefaction. So also entire human bodies, buried in the arid sands of those countries, have often been found converted by exhalation and absorption of their natural moisture into a dry hard sort of mummy, incapable of any farther change from the agency of those causes, to which, in such situations, they are exposed.

Similar causes produce the same effects on wood. Even under less rigid circumstances of this kind, as in the roofs and other timber of large buildings, it continues for an astonishing length of time unchanged; witness the timber of that noble edifice Westminsterhall, built by Richard II. in 1397; and the more extraordinary instance quoted by Dr. Darwin, in his ingenious work the Phytologia, of the gates of the old St. Peter's church in Rome, which were said to have continued without rotting from the time of the Emperor Constantiue to that of Pope Eugene IV. a period of eleven hundred years. On the other hand, wood will remain for ages with little change, when continually immersed in water, or even when deeply buried in the earth; as in the piles and buttresses of bridges, and in various morasses. These latter facts seem to shew that if the access of atmospherical air is not necessary to the decay of wood, it is, at least, highly conducive to it.

In posts fixed in the ground and exposed to the weather, we constantly find that part soonest decay, which is just above or within the ground. So also where there is an accidental hole in an exposed surface, or any artificial cavity, as in a mortise and tenon, or the part. where pales nearly touch the rails on which they are nailed, there the wood universally begins first to moulder away. The same thing happens with regard to horizontal rails themselves, which, when made of the same materials, rot much sooner than the pales which they support. These facts are very easily explained. They clearly shew, that the great cause of decay is the constant action of water aided by air, which most affects those points where it is most retained, but has less operation, where, as in the perpendicular pales, it chiefly runs

eff by its own gravity, so that the little which remains is easily and quickly abstracted by the co-operating power of the sun and wind.

The change which I am describing is the consequence of putrefactive fermentation; a chemical operation, in which the component parts of the wood form new com‐ binations among themselves, and with the water which is essential to the process. The precise nature of these new compounds has not been ascertained; but, so far as they are known, consist of certain gases, or species of air, which fly off, and leave behind a powder, consisting chiefly of carbon or charcoal, and the earth which entered into the original composition of the wood.

Besides this chemical change depending on water, that substance tends to destroy wood exposed to the open air by a mechanical operation. Every farmer is acquainted with the power of winter in mouldering down the earth of his fallows. It is equally well known that porous freestone splits and shivers during severe winters. These effects are produced by frost, which, acting on the water in the pores or interstices of these substances, expands it by conversion into ice, and thus bursts the minute cells in which it was contained. There can be no doubt that a similar operation takes place to a certain extent in exposed wood, and thus in some degree promotes its destruction.

It appears, then, that the contact of water and air are the chief causes of the decay of wood. If, therefore, any means can be devised, by which the access of moisture and air can be prevented, the wood is so far secure against decay. This principle may be illustrated by supposing a cylinder of dry wood to be placed in a glass tube or case, which it exactly fills, and the two

ends