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. 114. After having said so much of the uses of tar, I must 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, thac diseases ought not to be irritated by medicines. But no medicine difturbs 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 pre. parative against the small-pox; yet I question whether it may be fitly used in all those various cases wherein I have found tar-water so successful. Pera 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 it agrees best warm, with others cold. It may be a) 103.


made stronger for brute beasts, as horses, in whose disorders I have found it very useful, I believe more so than that bituminous substance callid Barbadoes


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 pint, 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. Ą medicine of fo. great virtue in so many different disorders, and especially in that grand enemy, the fever, must needs be a benefit to mankind in general. There are. nevertheless three sorts of people to whom I would peculiarly recommend it : Sea-faring persons, 11dies, and men of studious and sedentary lives..

117. To failors and all fea-faring persons, who are subject to scorbutic 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 expedicions, 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 fitting pale, puny, and forbidden like ghosts, at their own table, viccins of vapours and indigestion.

119. Studious persons allo. pent up in narrow, boles, breathing bad air, and Itooping over their

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books, are much to be pitied. As they are debar, red the free ufe of air and exercise, this I will vens ture to recommend as the beft fuccedaneum to both. Though it were to be wished, that modern fcholars 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 man ny ailments, particularly a nervous cholic, which rendered my life a burther, 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 healch 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 spirit, 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 thirft, all which virtues are contained in the cold infusion, which draws forth from tar only it's fine flower or quintessence, if I may so say, or the native vegetable spirit, together with a . little yolatile oil...

121. The distinguishing principle of all vege i tables, that whereon their peculiar smell, taste, and specific properties depend, seems to be some

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find feeds, and crude juices høregnated witrated to

extremely fine and subtile spirit, whose immed ate vehicle is an exceeding thin volatile oil, which is it self detained in a groffer 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 Tolar light. The spirit itself is by some supposed to be an oil highly subcilized, 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 fmell and taste, which fly off with the spirit or vegetable falt, without any sensible diminution of the oil.

122. Those volatile falts, 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 conftituent 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-exifted therein; all such falts appearing, from the experiments of signor Reding, 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 salts 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 falls are readily im-, bibed by water,

123. The most volatile of the salts, and the most attenuated part of the oil, may be supposed.

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the first and readieft to, impregnate a cold'infus fion (b.). And this will assist us to account for the virtues of tar water. That volatile acid in vegetables, which refifts putrefaction, and is their great preservative, is detained 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 fec free and obtained pure by cold water,

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 some 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 assimilate (e) the gentler than the stronger acids. . .

, 125. I am very sensible, that on such subjects arguments fall Thort of evidence: and that mine fall short cven 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 renioțe corner. I shall 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 Homberg are all agreed, that the acid is a fine subtile : substance, pervading the whole terraqueous globe;. which producech divers kinds of bodies, as it is uniced to different subjects. This according to


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