virtues seem to be in tar water in a mild and salutary degree.

59. It is the general opinion that all acids coagulate the blood. Boerhaave excepts vinegar, which he holds to be a soap, inasmuch as it is found to contain an oil as well as an acid spirit. Hence it is both unctuous and penetrating, a powerful antiphlogistic, and preservative against corruption and infection. Now it seems evident that tar water is a soap as well as vinegar. For though it be a character of resin, which is an inspissated gross oil, not to dissolve in water,* yet the salts attract some fine particles of essential oil: which fine oil serves as a vehicle for the acid salts, and shews itself in the colour of the tar water: for all pure salts are colourless. And though the resin will not dissolve in water, yet the subtile oil, in which the vegetable salts are lodged, may as well mix with water as vinegar doth, which contains both oil and salt. And as the oil in tar

so the acid salts do Tar water therefore

water discovers itself to the eye, manifest themselves to the taste. is a soap, and as such hath the medicinal qualities of soap.

60. It operates more gently as the acid salts lose their acrimony being sheathed in oil, and thereby approaching the nature of neutral salts, are more benign and friendly to the animal system: and more effectually, as by the help of a volatile, smooth, insinuating oil, those same salts are more easily introduced into the capillary ducts. Therefore in fevers and epedemical distempers it is (and I have found it so), as well as in chronical diseases, a most safe and efficacious medicine, being good against too great fluidity as a balsamic, and good. against vicidity as a soap. There is something in the fiery corrosive nature of lixivial salts, which makes alkaline soap a dangerous remedy in all cases where an inflammation is apprehended. And as inflammations are

* Sect. 47.

often occasioned by obstructions, it should seem an acid, soap was much the safer deobstruent.

61. Even the best turpentines, however famous for their vulnerary and detergent qualities, have yet been observed by their warmth to dispose to inflammatory tumours. But the acid spirit* being in so great proportion in tar water, renders it a cooler and safer medicine. And the ethereal oil of turpentine, though an admirable dryer, healer, and anodyne, when outwardly applied to wounds and ulcers, and not less useful in cleansing the urinary passages and healing their ulcerations, yet is known to be of a nature so very relaxing as sometimes to do much mischief when taken inwardly. Tar water is not attended with the same ill effects, which I believe are owing in a great measure to the ethereal oils being deprived of the acid spirit in distillation, which vellicating and contracting as a stimulus might have proved a counterpoise to the excessive lubricating and relaxing qualities of the oil.

62. Woods in decoction do not seem to yield so ripe and elaborate a juice, as that which is deposited in the cells or loculi terebinthiaci, and spontaneously oozes, from them. And indeed though the balsam of Peru obtained by boiling wood and scumming the decoction, be a very valuable medicine and of great account in divers cases, particularly asthmas, nephritic pains, nervous cholics, and obstructions, yet I do verily think (and I do not say this without experience) that tar water is a more efficacious remedy in all those cases than even that costly drug.

63. It hath been already observed that the restorative pectoral antihysterical virtues of the most precious balsams and gums are possessed in a high degree by tar water. And I do not know any purpose answered by the wood drinks, for which tar water may not be used with at least equal success. It contains the virtues even

* Sect. 7, 8.

+ Sect. 9. 21, 22, 23.

of guaicum, which seems the most efficacious of all woods, warming and sweetening the humours, diaphoretic and useful in gouts, dropsies, and rheums, as well as in the foul disease. Nor should it seem strange, if the virtues obtained by boiling an old dry wood prove inferior to those extracted from a balsam.

64. There is a fine volatile spirit in the waters of Geronster, the most esteemed of all the fountains about the Spa, but whose waters do not bear transporting. The stomachic, cardiac, and diuretic qualities of this fountain somewhat resemble those of tar water, which, if I am not greatly mistaken, contains the virtues of the best chalybeat and sulphureous waters; with this difference, that those waters are apt to affect the head in taking, which tar water is not. Besides, there is a regimen of diet to be observed, especially with chalybeat waters, which I never found necessary with this. Tar water layeth under no restraint either as to diet, hours, or employment. A man may study or exercise or repose, keep his own hours, pass his time either within or without, and take wholesome nourishment of any kind.

65. The use of mineral waters, however excellent for the nerves and stomach, is often suspended by colds and inflammatory disorders; in which they are acknowledged to be very dangerous: whereas tar water is so far from hurting in those cases, or being discontinued on that account, that it greatly contributes to their cure.*

66. Cordials, vulgarly so called, act immediately on the stomach, and by consent of nerves on the head. But medicines of an operation too fine and light to produce a sensible effect in the prima via, may, nevertheless, in their passage through the capillaries; operate on the sides of those small vessels, in such manner as to quicken their oscillations, and consequently the motion of their contents, producing, in issue and effect, all the

* Sect. 7.

benefits of a cordial much more lasting and salutary than those of distilled spirits, which by their caustic and coagulating qualities do incomparably more mischief than good. Such a cardiac medicine is tar water. The transient fits of mirth, produced from fermented liquors, and distilled spirits, are attended with proportionable depression of spirit in their intervals. But the calm cheerfulness arising from this water of health (as it may be justly called) is permanent. In which it emulates the virtues of that famous plant Gen Seng, so much valued in China as the only cordial that raises the spirits without depressing them. Tar water is so far from hurting the nerves, as common cordials do, that it is highly useful in cramps, spasms of the viscera, and paralytic numbness.

67. Emetics are on certain occasions administered with great success. But the overstraining and weakening of nature may be very justly apprehended from a course of emetics. They are nevertheless prescribed and substituted for exercise. But it is well remarked in Plato's Timæus that vomits and purges are the worst exercise in the world. There is something in the mild operation of tar water, that seems more friendly to the economy, and forwards the digestions and secretions in a way more natural and benign, the mildness of this medicine being such that I have known children take it, for above six months together, with great benefit, and without any inconvenience: and, after long and repeated experience, I do esteem it a most excellent diet-drink, fitted to all seasons and ages..

68. It is I think allowed that the origin of the gout lies in a faulty digestion. And it is remarked by the ablest physicians, that the gout is so difficult to cure, because heating medicines aggravate its immediate, and cooling its remote cause. But tar water, although it contains active principles that strengthen the digestion beyond any thing I know, and consequently must be

highly useful, either to prevent or lessen the following fit, or by invigorating the blood to cast it upon the extremities, yet it is not of so heating a nature as to do harm even in the fit. Nothing is more difficult or disagreeable than to argue men out of their prejudices, I shall not therefore enter into controversies on this subject, but if men dispute and object, shall leave the decision to time and trial.

69. In the modern practice, soap, opium, and mercury, bid fairest for universal medicines. The first of these is highly spoken of. But then those who magnify it most, except against the use of it in such cases where the obstruction is attended with a putrefactive alkali, or where an inflammatory disposition appears. It is acknowledged to be very dangerous in a pthisis, fever, and some other cases, in which tar water is not only safe but useful.

70. Opium though a medicine of great extent and efficacy, yet is frequently known to produce grievous disorders in hysterical or hypochondriacal persons, who make a great part, perhaps the greatest, of those who lead sedentary lives in these islands. Besides, upon all constitutions dangerous errors may be committed in the use of opium.

71. Mercury hath of late years become a medicine of very general use. The extreme minuteness, mobility, and momentum, of its parts, rendering it a most powerful cleanser of all obstructions, even in the most minute capillaries. But then we should be cautious in the use of it, if we consider, that the very thing which gives it power of doing good above other deobstruents, doth also dispose it to do mischief. I mean its great momentum, the weight of it being about ten times that of blood, and the momentum being the joint product of the weight and velocity, it must needs operate with great force; and may it not be justly feared, that so great a force entering the minutest vessels, and breaking