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A LARGER OBSERVATION. Aristotle has excellently observed the difference between plants and animals, in point of nourishment and recruit, viz. that the bodies of animals remain confined within their own bounds; so that when come to a due magnitude, they are supported and preserved by their aliment, without the new growth of any thing but hair and nails, which are accounted excrementitious.; whence of necessity the juices of animals sooner grow old; whereas trees often put out new branches, new shoots, new fruits ; whence also the other parts become new, and feel not the effects of age, because whatever is green and young, more briskly and strongly attracts the nourishment to itself, than what has begun to grow dry; insomuch that the trunk itself, thro' which the sap is conveyed to the branches, thus comes to be watered, and supplied with a more rich and plentiful aliment,* as remarkably appears from hence, that in the cutting of hedges, the lopping of trees, and the thinning of coppices, the stem or trunk is always invigorated and rendered much longer lived by the loss of its shoots or branches.
* Whence in effect the trunk becomes continually young again. This observation, therefore, is of great importance to the present enquiry, as it may in some degree be transferred from vegetable to animal subjects, and afford a rule for procuring a kind of rejuvenescency; as by the use of frictions, &c. on the external parts of the body, so as to perspire the old juices, and cause those parts more strongly to attract new ones.
THE HISTORY OF DESICCATION, THE PREVENTION THEREOF, AND THE SOFTENING OF DRIED BODIES, WITH REGARD TO THE SECOND ARTICLE OF
THE TABLE OF ENQUIRY.
FIRE or intense heat dries some bodies and melts others ; it dries earth, stone, wood, cloth, hides, and all bodies incapable of melting; but fuses metals, wax, gums, fat, &c.
Even those things that melt in the fire are dried by it at last, if the fire be increased : thus metals, with a violent heat, lose their volatile part; and all of them, except gold, become lighter and more brittle ;* and by a strong fire, oily and fat bodies become scorched, dry, and crusty.
* Even gold itself loses of its weight, and becomes a purple glass, when exposed to the focus of a large lens, or burning concave. See M. Homberg's paper upon the subject. Memoir, de l'Acad. An. 1702.
The open air is manifestly drying, but never: melting; thus the surface of the earth is dried after being wet with showers ; so linen is dried after washing, hy exposing it to the air; and herbs, leaves, and flowers are dried in the shade, &c. but the air performs this much more powerfully when assisted by the sun's rays, or put into motion, as by winds, &c.
Age has a great, though an exceeding slow power of drying, as we see in all bodies, which, unless prevented by putrefaction,* grow dry with age; yet age is nothing of itself, or no more than the measure of time: but the effect is produced by the native spirit of bodies, which drinks up their moisture, and flies off together with it; whilst the external air multiplies itself thereon, and preys upon the native spirit and juices of bodies.t
But cold is properly the greatest drier of all, for there can be no dryness without contraction, which is the proper effect of cold. But as we have a powerful degree of heat in fire, and only a very feeble one of cold, as that of the winter, snow, ice, &c. the arefactions of cold are but
* Do not all bodies, after complete putrefaction, become dry and truly terrestrial ?
+ This might pass for a larger observation of capital im
weak on the earth, and easily destroyed; yet we find the face of the earth more dried by frost and March winds than by the sun, whilst the same wind that licks up the moisture produces cold.*
The smoke of fire gives driness, as we see in the case of flesh suspended in chimnies; and so the fumigations of frankincense, lignum aloes, &c. dry the brain, and stop defluxions.
Salt by continuance dries not only externally but deeply, as appears in the salting of flesh or fish, which, lying long in the salt, are manifestly hardened, even internally.
Hot gums applied to the skin, dry and wrinkle it; so likewise do some astringent liquors.
High rectified spirit of wine dries almost like fire, so far as to harden and blanch the white of an egg put into it, and almost to scorch up bread.
Powders dry like spunges, by sucking up moisture, as we see in throwing sand upon fresh writing. Even a polish, or the close union of a body, not permitting a moist vapour to enter its pores, dries up by accident, as exposing the subject to the air. Thus gems, looking-glasses, and sword-blades, when breathed upon, appear at first covered over with a vapour, which presently vanishes like a light cloud. And so much for the article of desiccation.
* A freezing degree of cold even dries up water, or turns it from a fluid into a solid ; and a still greater degree will. congeal wine, brandy, oil of vitriol, and other mineral acid spirits : a still higher might congeal quicksilver itself, tho this was never experienced in the utmost degrees of cold that men have hitherto been able to produce, not even by the mixture of spirit of nitre and ice.
In the eastern parts of Germany they make use of subterraneous granaries for preserving their corn, by laying straw at the bottom, and all around to some height, in order to repel and suck up the humidity of the cave; by which means they keep their grain for twenty or thirty years not only uncorrupted, but, what makes to the present enquiry, in such a state of freshness as excellently fits it for the making of bread. And the like practice, it is said, has formerly prevailed in Cappadocia, Thrace, and some parts of Spain.
Granaries are commodiously made in garrets or upper rooms, with windows open to the east and north; and some have two floors, an upper and a lower, for this purpose, the upper one being perforated, that the grain may continually fall through the holes thereof, like sand in an hour-glass, and some days after be again thrown back with shovels, so as to keep the grain in continual motion; by which contrivance corruption is not only prevented, but freshness preserved, and dryness retarded; the cause whereof, as we