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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 sun beams, is thereby exalted and enriched, so as to become a ihost noble medicine; such is the last product of a tree, persectly maturated by time and sun.

39. It is remarked by Theophrastus, that all plants and trees while they pat forth have most humour, but when they have ceased to germinate and bear, then the humour is strongest and most lheweth the nature of the plant, and thar, therefore, trees yielding refin should be cut aster 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 tb depend upon the sun's lights 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-operatate with the sun (a). And as from Sir Ifaac Newton's experiments it appears, that all colours are virtually in the white light of the fun, and shew themselves when the rays are separated by the attracting and repelling powers of object?, even so the specific qualities of the elaborate juices of plants, feerri to be virtually or eminently contained in the solar light, and are actually exhibited Upon the separation of the rays, by the peculiar potters 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,

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411 It hath been observed by some curious an*-. 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 fame' earth and air.

42. The balfam or essential 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, falt, 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 destitute of all flavour. This spark of lise, this spirit or soul, if we may so fay, of the vegetable departs without any sensible diminution of the oil or water wherein it was lodged.

43. It should seem that the forms, souls, or principles of vegetable lise, subsist in the light or solar emanation (a), which in respect of the macrocosm is what the animal spirit is to the macrocosm; the interior tegument, the subtile instrument and vehicle of power. No wonder then that the ens primum or scintilla spirituofa, as it is called, of plants should be a thing so fine and sugacicious as to escape our nicest search. It is evident that nature at the fun's approach vegetates j and

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languishesathis recess; this terrestrial globe seeming only a matrix disposed and prepared to receive lise from his light; whence Homer in his hymns styleth earth the wise of heaven, «Ao^' oufo»5 dstptrns.

44. The luminous spirit which is the form or lise of a plant, from whence it's disserences 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, particularly in the cells of the bark and in the seeds. This oil purified and exalted by the organjeal 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 essential oil animated, as one may fay, with the flavour of the plant is very different from any spirit, that can be procured from the fame plant by fermentation.

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

. 46. The less violence is used to nature the better its 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 slightest incision, are the finest and most

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t;' fragrant. flagrant. And insusions are observed to act more strongly than decoctions of plants, the more subtile and volatile falts and spirits, which might be: lost or corrupted by the latter, being obtained in their natural state by the former. It is also obscr-. ved that the finest, purest, and most volatile part is that which first ascends in destination. And, indeed, it should seem the lightest and most active. particles required least force to disengage them from the subject.

47. The silts, therefore, and more active spirits, of the tar are got by insusion 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 inflame the blood by it's sulphur and resin, appears to be not well grounded; it being indeed impregnated with a fine acid spirit, balfamic, cooling, diuretic, and possessed of many other virtues (b). Spirits are supposed to consist of falts and phlegm, probably too somewhat of a fine oily nature, differing from oil in that it mixeth with water, and agreeing with oil, iri that it runneth in rivulets by destination. 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 spark or form, in the language of the :hemists or schools, is none of those things, nor pet the finest oil, which scemeth only it's receptacle or vehicle. It is observed by chemists, that. . ill sorts of balfamic wood afford an acid spirit,; which is the volatile oily falt of the vegetable :i Hlerein are chiefly contained their medicinal virtues,. ind by the trials I have made it appears, that the

/aJ Sect. 7. (b) Sect. 4?, 44. : acid acid spirit m tar-water, poflefleth the virtues, iir an eminent degree, of that of guaiacum, and other medicinal woods.

48. Qualities in a degree too strong for human nature to subdue, and assimilate to it self, must hurt the constitution. All acids, therefore, may not be usesul or innocent. But this seemeth an acid so thoroughly concocted, so gentle, bland, and temperate, and withal a spirit so fine and volatile, as readily to enter the smallest veflels, and be assimilated with the utmost ease.

49. If any one were minded to dissolve some of the resin, together with the falt or spirit, he need only mix some spirit of wine with the water. But such an intire solution of resins and gums, as to qualify them for entering and pervading the animal system, like the fine acid spirit that first flies off from the subject, is perhaps impossible to obtain. It is an apopthegm of the chemists, derived from Helmont, that whoever can make myrrh soluble by the human body, has the secret of prolonging his days: and Boerhaave owns that there seems to be truth in this, from it's resisting putrefaction. Now this quality is as remarkable in tar, with which the ancients embalmed and preserved dead bodies. And though Boerhaave himself, and other chemists before him, have given methods for making solutions of myrrh, yet it is by means of alcohol which extracts only the inflammable parts. And it doth not seem that any solution' of myrrn is impregnated with it's falt or acid spi-' tit. It may not, therefore, seem strange if this water should be found more beneficial for procuring health and long lise, than any solution of myrrh whatsoever.

50. Certainly divers resins and gums may have Virtues, and yet not be able for their grosthess to

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