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and fpirits of all the bodies we know from which general aggregate or mafs, thofe that are proper being drawn in, through the fine veffels of the leaves, branches, and ftem of the tree, undergo in it's various organs, new alterations, fecretions, and digestions, till fuch time as they affume the moft elaborate form.

37. Nor is it to be wondered, that the peculiar texture of each plant or tree, co-operating with the folar fire and pre-exifting juices, fhould fo alter the fine nourishment drawn from earth and air (a), as to produce various fpecific qualities of great efficacy in medicine: efpecially if it be confidered that in the opinion of learned men, there is an influence on plants derived from the fun, befides it's mere heat. Certainly doctor Grew, that curious anatomist of plants, holds the folar influence to differ from that of a mere culinary fire, otherwife than by being only a more temperate and equal heat.

38. The alimentary juice taken into the lacteals, if I may fo fay, of animals or vegetables, confifts of oily, aqueous, and faline particles, which being diffolved, volatilised, and diverfly agitated, part thereof is spent and exhaled into the air; and that part which remains is by the economy of the plant, and action of the fun, ftrained, purified, concocted, and ripened into an infpiffated oil or balfam, and depofited in certain cells placed chiefly in the bark, which is thought to answer the panniculus adipofus in animals, defending trees from the weather, and, when in fufficient quantity, rendering them evergreen. This balfam, weeping or fweating through the bark, hardens into refin; and this moft copiously in the feveral species of pines and

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firs, whofe oil being in greater quantity, and more tenacious of the acid fpirit or vegetable foul (as perhaps it may not improperly be called) abides the action of the fun, and attracting the fun beams, is thereby exalted and enriched, fo as to become a most noble medicine; fuch is the last product of a tree, perfectly maturated by time and fun.

39. It is remarked by Theophraftus, that all plants and trees while they put forth have most humour, but when they have ceased to germinate and bear, then the humour is strongest and most fheweth the nature of the plant, and that, therefore, trees yielding refin fhould be cut after germination. It feems alfo very reasonable to fuppofe the juice of old trees, whofe organs bring no new fap, fhould be better ripened than that of others.

40. The aromatic flavours of vegetables feem to depend upon the fun's light, as much as colours. As in the production of the later, the reflecting powers of the object, fo in that of the former, the attractive and organical powers of the plant co-operate with the fun (a). And as from Sir Ifaac Newton's experiments it.appears, that all colours are virtually in the white light of the fun, and fhew themselves when the rays are feparated by the attracting and repelling powers of objects, even so the specific qualities of the elaborate juices of plants, feem to be virtually or eminently contained in the folar light, and are actually exhibited upon the feparation of the rays, by the peculiar powers of the capillary organs in vegetables, attracting and imbibing certain rays, which produce certain flavours and qualities, in like manner as certain rays, being reflected, produce certain colours,

(a) 36, 37:

41. It hath been obferved by fome curious anatomists, that the fecretory veffels in the glands of animal bodies are lined with a fine down, which in different glands is of different colours. And it is thought, that each particular down, being originally imbued with it's own proper juice, attracts none but that fort; by which means fo many various juices are fecreted in different parts of the body. And perhaps there may be fomething analogous to this, in the fine abforbent veffels of plants, which may co-operate towards producing that endless variety of juices, elaborated in plants from the fame earth and air.

42. The balfam or effential oil of vegetables contains a fpirit, wherein confift the fpecific qualities, the smell and taste of the plant. Boerhaave holds the native prefiding fpirit to be neither oil, falt, earth, or water; but fomewhat too fine and fubtile to be caught alone and rendered vifible to the eye. This when fuffered to fly off, for inftance, from the oil of rosemary, leaves it deftitute of all flavour. This fpark of life, this fpirit or foul, if we may fo fay, of the vegetable departs without fenfible diminution of the oil or water wherein it was lodged.

any

43. It fhould feem that the forms, fouls, or principles of vegetable life, fubfift in the light or folar emanation (a), which in refpect of the macrocoẩm is what the animal fpirit is to the microcofm; the interior tegument, the fubtile inftrument and vehicle of power. No wonder then that the ens primum or fcintilla fpirituofa, as it is called, of plants fhould be a thing fo fine and fugacious as to escape our niceft fearch. It is evident that nature at the fun's approach vegetates; and

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languishes at his recefs; this terrestrial globe seeming only a matrix difpofed and prepared to receive life from his light; whence Homer in his hymns ftileth earth the wife of heaven, ἄλοχ ̓ οὐρανῶ ἀφερόεντος.

44. The luminous fpirit which is the form or life of a plant, from whence it's differences and properties flow, is fomewhat extremely volatile. It is not the oil, but a thing more fubtile, whereof oil is the vehicle, which retains it from flying off, and is lodged in feveral parts of the plant, particularly in the cells of the bark and in the feeds. This oil purified and exalted by the organical powers of the plant, and agitated by warmth, becomes a proper receptacle of the spirit; part of which spirit exhales through the leaves and flowers, and part is arrested by this unctuous humour that detains it in the plant. It is to be noted this effential oil animated, as one may fay, with the flavour of the plant, is very different from any fpirit, that can be procured from the fame plant by fer

mentation.

45. Light impregnates air (a), air impregnates vapour; and this becomes a watery juice by diftillation having rifen firft in the cold ftill with a kindly gentle heat. This fragrant vegetable water is poffeffed of the fpecific odour and tafte of the plant. It is remarked that diftilled oils added to water for counterfeiting the vegetable water can never equal it, artificial chemistry falling short of the natural.

46. The lefs violence is ufed to nature the better it's produce. The juice of olives or grapes iffuing by the lighteft preffure is beft. Refins that drop from the branches fpontaneously, or ooze upon the flighteft incifion, are the finest and most

(a) 37-43

fragrant.

fragrant. And infufions are obferved to act more strongly than decoctions of plants, the more fubtile and volatile falts and fpirits, which might be loft or corrupted by the latter, being obtained in their natural state by the former. It is alfo obferved that the fineft, pureft, and most volatile part is that which firft afcends in diftillation. And, indeed, it should seem the lightest and most active particles required least force to difengage them from the fubject.

47. The falts, therefore, and more active spirits of the tar are got by infufion in cold water: but the refinous part is not to be diffolved thereby (a). Hence the prejudice which fome perhaps may entertain against Tar-water, as a medicine, the ufe whereof might inflame the blood by it's fulphur and refin, appears to be not well grounded; it being indeed impregnated with a fine acid fpirit, balfamic, cooling, diuretic, and poffeffed of many other virtues (b). Spirits are supposed to confift of falts and phlegm, probably too fomewhat of a fine oily nature, differing from oil in that it mixeth with water, and agreeing with oil, in that it runneth in rivulets by diftillation. Thus much is allowed, that the water, earth, and fixed falt are the fame in all plants; that, therefore, which differenceth a plant or makes it what it is, the native fpark or form, in the language of the chemifts or schools, is none of thofe things, nor yet the finest oil, which feemeth only it's receptacle or vehicle. It is obferved by chemifts, that all forts of balfamic wood afford an acid fpirit, which is the volatile oily falt of the vegetable : Herein are chiefly contained their medicinal virtues, and by the trials I have made it appears, that the (b) Sect. 42, 44.

(a) Sect. 7.

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