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114. After having faid so much of the uses of tar, I muft farther add, that being rubb'd on them it is an excellent preservative of the teeth and gums; that it sweetens the breath, and that it clears and strengthens the voice. And, as its effects are various and useful, so there is nothing to be feared from the operation of an alterative so mild and friendly to nature. It was a wise maxim of certain ancient philosophers, that diseases ought not to be irritated by medicines. But no medicine di. fturbs the animal economy less than this(a), which, if I may trust my own experience, never produces any disorder in a patient when rightly taken.
115. I knew indeed a person who took a large glass of tar-water just before breakfast, which
gave him an invincible nausea and disgust, although he had before received the greatest benefit from it. But if the tar-water be taken and made in the man, ner prescribed at the beginning of this essay, it will, if I mistake not, have enough of the salt to be useful, and little enough of the oil to be inoffensive. I mean my own manner of making it, and not the American ; that sometimes makes it too strong, and sometimes too weak; which tar-water, how. ever it might serve as there used, merely for a preparative against the small-pox; yet I question whether it may be fitly used in all those various cafes wherein I have found tar-water so successful. Per. sons more delicate than ordinary may render it palatable, by mixing a drop of the chemical oil of nutmegs, or a spoonful of mountain wine in each glass. It may not be amiss to observe, that I have known fome, whose nice stomachs could not bear it in the morning, take it at night going to bed without any inconvenience; and that with some ic agrees best warm, with others cold. It may be
made stronger for brute beasts, as horses, in whose disorders I have found it very useful, I believe more so than that bituminous substance call's Barbadoes tar.
116. In very dangerous and acute cases much may be taken and often; as far as the stomach can bear. But in chronical cases, about half a pini, night and morning, may suffice; or in case so large a dose should prove disagreeable, half the quantity may be taken at four times, to wit, in the morning, at night going to bed, and about two hours after dinner and breakfast. A medicine of so great virtue in so many different disorders, and especially in that grand enemy, the fever, must needs be a benefic to mankind in general. There are nevertheless three forts of people to whom I would peculiarly recommend it : Sea-faring persons, ludies, and men of studious and sedentary lives.
117. To failors and all sea-faring persons, who are subject to fcorbutic disorders and putrid fevers, especially in long southern voyages, I am persuaded this tar-water would be very beneficial. And this may deserve particular notice in the present course of marine expeditions, when so many of our country-men have perished by such distempers, contracted at sea and in foreign climates. , Which, it is probable, might have been prevented, by the copious use of tar-water.
1.18. This fame water will also give charitable, relief to the ladies (a), who often want it more than the parish poor ; being many of them never able to make a good meal, and ficting pale, puny,, and forbidden like ghosts, at their own table, victims of vapours and indigestion.
119. Studious persons allo pent up in narrow boles, breathing bad air, and Itooping over their
books, are much to be pitied. As they are debar, red the free use of air and exercise, this I will ven4 ture to recommend as the best fuccedaneum to both. Though it were to be wished, that modern scholars would, like the ancients, medicate and converfe more in walks and gardens and open air, which, upon the whole, would perhaps be no hindrance to their learning, and a great advantage to their health. My own sedentary course of life had long Gnce thrown me into an ill habit, attended with many ailments, particularly a nervous cholic, which rendered my life a burthen, and the more fo, be cause my pains were exafperated by exercise. But since the use of tar water, I find, though not a perfect recovery from my old and rooted illness, yet such a gradual return of health' and ease, that I esteem my having taken this medicine the greatest of all temporal blessings, and am convinced that, under providence, I owe my life to it.
120. In the distilling of turpentine and other balsams by a gentle heat, it hath been observed, that there risech firft an acid spirit (n) that will mix with water ; which fpirit, except the fire be very gentle, is lost.
This grateful acid fpirit that first comes over, is, as a learned chemist and physician informs us, highly refrigeratory, diuretic, fudorific, balsamic or preservative from putrefaction, excellent in nephritic cases, and for quenching thirst, all which virtues are contained in the cold infusion, which draws forth from tar only it's fine flower or quintessence, if I may fo say, or the native vegetable spirit, together with a little yolatile oil.
121. The distinguishing principle of all vegetables, that whereon their peculiar smell, tafte, and specific properties depend, seems to be some i
extremely fine and subtile spirit, whose immed ate vehicle is an exceeding thin volatile oil, which is it felf detained in a grosier and more viscid refin or balfam, lodged in proper cells in the bark and seeds, and most abounding in autumn or winter, after the crude juices have been thoroughly concocted, ripened, and impregnated with folar light. The spirit itself is by some supposed to be an oil highly subtilized, so as to mix with water. But such volatile oil is not the spirit, but only it's vehicle. Since aromatic oils, being long exposed to air, will lose their specific fimell and taste, which fly off with the spirit or vegetable falt, without any sensible diminution of the oil.
122. Those volatile salts, that are set free and raised by a gentle heat, may justly be supposed essencial (a), and to have pre-existed in the vegetable ; whereas the lixivial fixed salts obtained, by the incineration of the subject, whose natural confticuent parts have been altered or destroyed by the extreme force of fire, are by later chemists, upon very good grounds, supposed not to have pre-existed therein; all such falts appearing, fron the experiments of signor Rediy not to preserve the virtues of the respective vegetable subjects; and to be alike purgative and in an equal degree, whatsoever may be the shape of their points, whether sharp or obtuse. But although fixed or lixivious falts may not contain the original properties of the subject ; yet volatile falts raised by a Night heat from vegetables are allowed to preserve their native virtues: and such falts are readily im-. bibed by water,
123. The most volatile of the salts, and the most attenuated part of the oil, may be supposed. .
the first and readiest to, impregnate a cold'infusion (b). And this will assist us to account for the virtues of tar water. That volatile acid in vegetables, which relists putrefaction, and is their great preservative, is decained in a subtile oil mircible with water, which oil is it self imprisoned in the resin or grosser part of the tar, from which it iş eally sec free and obtained pure by cold wa
124. The mild native acids are observed more kindly to work upon, and more thoroughly to diffolve, metallic bodies, than the strongest acid fpirits produced by a vehement fire ; and it may be suspected, they have the same advantage as a medicine. And as no acid, by the observation of fume of the best chemists, can be obtained from the subítance of animals thoroughly assimilated, it should follow, that the acids received into a healthy body must be quite subdued and changed by the vital powers: but it is easier to subdue and aflimilate (e) the gentler than the stronger acids.
| 125. I am very sensible, that on such subjects arguments fall short of evidence: and that mine fall short even of what they might have been, if I enjoyed better health, or those opportunities of a learned commerce, from which I am cut off in this remote corner. I fhall nevertheless go on as I have begun, and proceed by reason, by conjecture, and by authority, to cast the best light I can on the obscure paths that lie in my way.
126. Sir Isaac Newton, Boerhaavę, and Hom- ; berg are all agreed, that the acid is a fine subtile substance, pervading the whole terraqueous globe ; which produceth divers kinds of bodies, as it is united to different subjects. This according to (b) 1, 7.