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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, io as to become a moft noble medicine ; futh is the laft 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 mofr humour, but when they have cealed to germinate and bear, then the humour is ftrongeft and moft fhevrah the nature of the plant, and that, therefore, trees yielding rcfin fhould be cut after germination. It feems alfo very reafonable 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 jhat 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 themfelves when the rays are feparated by the attracting and repelling powers of objects, even fo the fpecific 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.

(*J 36,37

41. It hath been obferved by fome curious anatomifts, that the fecretory veflcls 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 endlefs variety of juices, elaborated in plants from the fame earth and air.

42. The balfam or eflential oil of vegetables contains a fpirit, wherein confift the fpecific qualities, the fmell and tafte 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 rofcmary, leaves it deftitute of all flavour. This fpark of life, this fpirit or foul, if we may fo fay, of the vegetable departs without any fenfible diminution of the oil or water wherein it was lodged.

43. It mould feem that the forms, fouls, or principles of vegetable life, fubfift in the light or iblar emanation (a), which in refpect of the macrocofm is what the animal fpirit is to the macrocofm; 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 efcape our niceft fcarch. It is evident that nature at the fun's approach vegetates; and

(a) 40.

languifhes

languifhes at his recefs; this terrefirial globe feeming only a matrix difpofed and prepared to receive life from his light; whence Homer-in his hymns ftileth earth the wite of heaven, £Ao^' «v'^*»» «Vi^01 »7«.

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 organicat powers of the plant, and agitated by warmth, becomes a proper receptacle of the fpirit; part of which fpirit exhales through the leaves and flowers,' and part is arrefted by this unctuous humour that detains it in the plant. It is to be noted this efTential 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 fermentation.

45. Light impregnates air (a), air impregnates vapour ;and this becomes a watery juice by diftilJation having rifen firft in the cold Hill with a kindly gentle heat. This fragrant vegetable water is poffefled 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 ir, artificial chemiftry falling fhort of the natural.

46. The Jefs violence is ufed to nature the better it's produce. The juice of olives or grapes iffuing by the lightef t preffure is beft. Refins that drop from the branches fpontaneoufly, or ooze upon the flightef t incifion, are the fi.nelr, and molt

(•) 37- 43

fragrant. fragrant. And ihfufions are obferved to act more ftrongly 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 ftate by the former. It is alfo obferved that the fineft, pureft, and moft volatile part is that which firft afcends in diftillation. And, indeed, it mould feem the lighteft and moft active particles required leaft force to difengage them from the fubject.

47. The falts, therefore, and more active fpirits 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 againft 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 fpi.rit, balfamic, cooling, diuretic, and poflefied of many other virtues (b). Spirits are iuppofed 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 Ipark or form, in the language of the chemifts or fchools, is none of thoie things, nor yet the fineft oil, which feemeth only it's receptacle or vehicle. It is obferved by chemifts, that all forts of b.iliamic wood aftbrd 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 ir appears, that the

*

(aj Sc«3. 7. (I) Seft. 4z, 44,

acid fpirit in Tar-water poflefieth the virtues, ia an eminent degree, of that of guaiacum, and to her medicinal woods.

48. Qualities in a degree too ftrong for human nature to fubdue, and affimilate to itfelf, muft hurt the conftitution. All acids, therefore, may not be ufeful or innocent. But this feenTeth an acid fo thoroughly concocted, fo gentle, bland, and temperate, and withal a fpirit fo fine and volatile, as readily to enter the fmalleft vefiels, and be affimilated with the utmoft eafe.

49. If any one were minded to diflblve fome of the refin, together with the fair or fpirit, he need only mix fome fpirit of wine with the water. But fuch an intire folution of refins and gums, as to qualify them for entering and pervading the animal fyftem, like the fine acid fpirit that firft flies off from the fubject, is perhaps impofilble to obtain. It is an apophthegm of the chemifts, derived from Helmont, that whoever can make myrrh foluble by the human body, has the fecret of prolonging his days: and Boerhaave owns that there feems to be truth in this, from it's refifting putrefaction. Now this quality is as remarkable in tar, with which the ancients embalmed and prefervect dead bodies. And though Boerhaave himfelf, and other chemifts before him, have given methods for making folutions of myrrh, yet it is by means of alcohol which extracts only the inflammable parts. And it doth not feem that any folution of myrrh is impregnated with it's fait or acid fpirit. It may not, therefore, feem ftrange if this water mould be found more beneficial for procuring health and long life, than any folution of myrrh whatfoever.

50. Certainly diver* refins and gums may have virtues, and yet not be able for their groflhefs to>

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