41. It hath been obferved by fome curious anatomifts, 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 its 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 specific qualities, the fmell 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 visible 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 any fenfible diminution of the oil or water wherein it was lodged.

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 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 escape our niceft fearch. It is evident that nature at the fun's approach vegetates; and

(a) 40.

languishes

languishes at his recefs; this terreftrial 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, άλοχ ̓ οὐραν. ἀτερόεντος.

44. The luminous fpirit which is the form or life of a plant, from whence its 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 fpirit; part of which fpirit 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 fermentation.

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 specific odour and taste of the plant. It is remarked, that diftilled oils added to water for counterfeiting the vegetable water, can never equal it, artificial chemistry falling fhort of the natural.

46. The lefs violence is ufed to nature the better its 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

fragrant. And infufions 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 state by the former. It is also 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 leaft 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 its fulphur and refin, appears to be not well grounded; it being indeed impregnated with a fine acid fpirit, balsamic, cooling, diuretic, and poffeffed of many other virtues (b). Spirits are fuppofed 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 fineft oil, which feemeth only its recep tacle 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 (6) Sect. 42, 44.

(a) Sect. 7.

acid

acid fpirit in tar-water poffeffeth the virtues, in an eminent degree, of that of guaiacum, and other medicinal woods.

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

49. If any one were minded to diffolve fome of the refin, together with the falt 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 spirit that first flies off from the fubject, is perhaps impoffible 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 its refifting putrefaction. Now this quality is as remarkable in tar, with which the ancients embalmed and preserved dead bodies. And though Boerhaave himself, 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 its falt or acid fpirit. It may not, therefore, feem ftrange if this water fhould be found more beneficial for procuring health and long life, than any folution of myrrh whatsoever.

50. Certainly divers refins and gums may have virtues, and yet not be able for their groffnefs to

pafs

pass the lacteals and other finer veffels, nor yet, perhaps, readily impart thofe virtues to a menftruum, that may with fafety and speed convey them throughout the human body. Upon all which accounts, I believe tar-water will be found to have fingular advantages. It is obferved that acid fpirits prove the ftronger, by how much the greater degree of heat is required to raise them." And indeed, there feemeth to be no acid more gentle than this, obtained by the fimple affufion of cold water; which carries off from the fubject the moft light and fubtile parts, and, if one may fo fpeak, the very flower of it's fpecific qualities. And here it is to be noted, that the volatile falt and spirit of vegetables do, by gently ftimulating the folids, attenuate the fluids contained in them, and promote fecretions, and that they are penetrating and active, contrary to the general nature of other acids.

51. It is a great maxim for health, that the juices of the body be kept fluid in a due proportion. Therefore, the acid volatile fpirit in tar water, at once attenuating and cooling in a moderate degree, must greatly conduce to health, as a mild falutary deobftruent, quickening the circulation of the fluids without wounding the folids, thereby gently removing or preventing thofe obftructions, which are the great and general cause of moft chronical difeafes; in this manner answering to the antihyfterics, affa foetida, galbanum, myrrh, amber, and, in general, to all the refins and gums of trees or fhrubs useful in nervous cafes.

52. Warm water is it felf a deobftruent. Therefore the infufion of tar drunk warm, is easier infinuated into all the nice capillary veffels, and acts not only by virtue of the balfam, but alfo by that

D

of