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and spirits of all the bodies we know : from which general aggregate or mass, those that are proper being drawn in, through the fine vessels of the leaves, branches, and stem of the tree, undergo in it's various organs, new alterations, secretions, and digestions, till such time as they assume the most elaborate form.

37. Nor is it to be wondered, that the peculiar texture of each plant or tree, co-operating with the solar fire and pre-existing juices, mould so alter the fine nourishment drawn from earth and air (a), as to produce various specific qualities of great efficacy in medicine : especially if it be considered that in the opinion of learned men, there is an influence on plants derived from the sun, besides it's mere heat. Certainly doctor Grew, that curious anatomist of plants, holds the solar infuence to differ from that of a mere culinary fire, otherwise than by being only a more temperate and equal heat.

38. The alimentary juice taken into the lacteals, if I may so fay, of animals or vegetables, consists of oily, aqueous, and saline particles, which being disfolved, volatilised, and diversy agitated, part thereof is spent and exhaled into the air ; and that part which remains is by the æconomy of the plant, and action of the sun, strained, purified, concocted, and ripened into an inspiffated oil or balsam, and deposited in certain cells placed chiefly in the bark, which is thought to answer the panniculus adiposus in animals, defending trees from the weather, and, when in sufficient quantity, rendering them evergreen. This balsam, weeping or sweating through the bark, hardens into resin ; and this most copiously in the several species of pines and firs, whose oil being in greater quantity, and more tenacious of the acid spirit or vegetable soul (as perhaps it may not improperly be called) abides the action of the sun, and attracting the fun beams, is thereby exalted and enriched, so as to become a most noble medicine ; such is the last product of a tree, perfectly maturated by time and fun.

39. It is remarked by Theophrastus, 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 shewech the nature of the plant, and that, therefore, trees yielding resin should be cut after germination. It seems also very reasonable to suppose the juice of old trees, whose organs bring no new fap, should be better ripened than that of others.

40. The aromatic flavours of vegetables seem to depend upon the sun's light, as much as colours. As in the production of the later, the reflecting powers of the object, so in that of the former, the attractive and organical powers of the plant co-operate with the sun (a). And as from Sir Isaac Newton's experiments it appears, that all colours are virtually in the white light of the sun, and shew themselves when the rays are separated by the attracting and repelling powers of objects, even so the specific qualities of the elaborate juices of plants, seem to be virtually or eminently contained in the solar light, and are actually exhibited upon the separation 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 observed by some curious ana. tomists, that the secretory vessels 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 sort ; by which means so many various juices are secreted in different parts of the body. And perhaps there may be something analogous to this, in the fine absorbent vessels of plants, which may co-operate towards producing that endless variety of juices, elaborated in plants from the same earth and air.

42. The balsam or effential oil of vegetables contains a spirit, wherein consist the specific qualities, the smell and taste of the plant. Boerhaave holds the native presiding spirit to be neither oil, salt, earth, or water ; but somewhat too fine and subtile to be caught alone and rendered visible to the eye. This when suffered to fly off, for instance, from the oil of rosemary, leaves it deftitute of all flavour. This spark of life, this spirit or soul, if we may so say, of the vegetable departs without any sensible diminution of the oil or water wherein it was lodged.

43. It fhould seem that the forms, fouls, or principles of vegetable life, fubfist in the light or solar emanation (a), which in respect of the macrocosm is what the animal spirit is to the microcosm ; the interior tegument, the subtile instrument and vehicle of power. No wonder then that the ens primum or scintilla spirituosa, as it is call. ed, of plants should be a thing so fine and fugacious as to escape our nicest search. It is evident that nature at the sun's approach vegetates ; and

(a) 40.

languishes

languishes at his recess; this terrestrial globe seeming only a matrix disposed and prepared to receive life from his light ; whence Homer in his hymns stileth carth the wife of heaven, daogioveavs asepoevlos.

44. The luminous spirit which is the form or life of a plant, from whence it's differences and properties flow, is somewhat extremely volatile. It is not the oil, but a thing more subtile, whereof oil is the vehicle, which retains it from flying off, and is lodged in several parts of the plant, partia cularly in the cells of the bark and in the seeds. 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 effen. tial oil animated, as one may fay, with the flavour of the plant, is very different from any spirit, that can be procured from the same plant by fermentation.

45. Light impregnates air (a), air impregnates vapour ; and this becomes a watery juice by diftil. lation having risen first in the cold still with a kindly gentle heat. This fragrant vegetable water is poffeffed of the specific odour and taste of the plant. It is remarked that distilled oils added to water for counterfeiting the vegetable water can never equal it, artificial chemistry falling short of the natural.

46. The less violence is used to nature the better it's produce. The juice of olives or grapes issuing by the lightest pressure is best. Resins that drop from the branches spontaneously, or ooze upon the sightest incision, are the finest and most

(a) 37. 43.

fragrant.

fragrant. And infusions are observed to act more strongly than decoctions of plants, the more subtile and volatile salts and spirits, which might be loft or corrupted by the latter, being obtained in their natural state by the former. It is also obseryed that the finest, pureft, and most volatile part is that which first ascends in distillation. And, indeed, it should seem the lightest and most active particles required least force to disengage them from the subject.

47. The salts, therefore, and more active spirits of the tar are got by infusion in cold water : but the resinous part is not to be dissolved thereby (a). Hence the prejudice which some perhaps may entertain against Tar-water, as a medicine, the use whereof might infame the blood by it's sulphur and resin, appears to be not well grounded; it being indeed impregnated with a fine acid fpirit, balsamic, cooling, diuretic, and possessed of many other virtues (6). Spirits are supposed to consist of salts and phlegm, probably too somewhat 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 distillation. Thus much is allowed, that the water, earth, and fixed falt are the same in all plants; that, therefore,. which differenceth a plant or makes it what it is, the native spark or form, in the language of the chemists or schools, is none of those things, nor yet the finest oil, which seemeth only it's receptacle or vehicle. It is observed by chemists, that all sorts of balsamic wood afford an acid spirit, which is the volatile oily falc of the vegetable : Herein are chiefly contained their medicinal virtues, and by the trials I have made it appears, that the

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