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to drink tar-water which prevented the erysipelas. ..6. T never knew any thing so good for the ftomach as tar-water : it cures indigestion and gives a good appetite. It is an excellent medicine in an asthma. It imparts a kindly warmth and quick circulation to the juices, without heating, and is therefore useful, not only as a pectoral and balsamic, but also as a powerful and fafe deobstruent in cachectic and hysteric cases. As it is both healing and diuretic, it is very good for the gravel. I believe it to be of great use in a dropsy, having known it cure a very bad anafarca in a person whose thirst, though very extraordinary, was in a short time removed by the drinking of tar-water.

7. The ufefulness of this medicine in inflammatory cafes is evident, from what has been already obferved (a). And yet some perhaps may suspect that, as the tar itself is fulphureous, tar-water must be of a hot and inflaming nature.

But it is to be noted, that all balsams contain an acid spirit, which is in truth a volatile falt. Water is a menftruum that diffolves all forts of salts,' and draws them from their subjects. Tar, therefore, being a balsam, it's falutary acid is extracted by water, which yet is incapable of diffolving it's gross refinous parts, whose proper menftruum is fpirit of wine. Therefore tar-water, not being impregnated with resin, may be safely ufed in inflammatory cases; and in fact it hath been found an admirable febrifuge, at once the safest cooler and cordial.

8. The volatile falts separated by infusion from tar, may be supposed to contain it's specific vir

Mr. Boyle, and other later chemists, are agreed, that fixed falts are much the same in all bodies. But it is well known that volatile falts da greatly differ, and the easier they are separated fa) Sect. 5.

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from the subject, the more do they possess of it's, specific qualities. Now the most easy féparation is by infusion of tar in cold water, which to smell and taste fhewing it self well impregnated, may be presumed to extract and retain the most pure volatile and active particles of that vegetable balsam.

9. Tar was by the ancients esteemed good against poisons, ulcers, the bites of venomous creatures, also for pthisical, fcrophulous, paralytic and asthmatic persons.

But the method of rendering it an inoffensive medicine and agreeable co the stomach, by extracting it's virtues in cold water, was unknown to them. The leaves and tender tops of pine and fir are in our times used for diet-drinks, and allowed to be antiscorbutic and diuretic. But the most elaborate juice, falt, and spirit of those evergreens are to be found in tar ; whose virtues extend not to animals alone, but also to vegetables. Mr. Evelyn, in his treatise on Forest trees, observes with wonder, that stems of trees, smeared over with tar, are preserved thereby from being hurt by the invenomed teeth of goats and other injuries, while every other thing of an unctuous nature is highly prejudicial to them.

10. It seems that tar and turpentine may be had more or less, from all sorts of pines and firs whatsoever ; and that the native spirits and essential salts of those vegetables are the same in turpentine and common tar. In effect this vulgar tar, which cheapness and plenty may have rendered contemptible, appears to be an excellent balfam, contain: ing the virtues of most other balsams, , which it easily imparts to water, and by that means readily and inoffensively insinuates them into the habit of

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11. The resinous exsudations of pines and firs are an important branch of the materia medica,

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and not only useful in the prescriptions of physicians, but have been also thought otherwise conducive to health. Pliny tells us, that wines in the time of the old Romans were medicated with pitch and resin ; and Jonítonus, in his Dendrographia, observes, that it is wholefome to walk in groves of pine trees, which impregnate the air with balsamic particles. That all turpentines and refins are good for the lungs, against gravel also and obstructions, is no fecret. And that the medicinal properties of those drugs are found in tar-water, without heating the blood, or disordering the stomach, is confirmed by experience : and particularly that pthifical and afthmatic persons receive speedy and great relief from the use of it.

12. Balsams, as all unctuous and oily medicines, create a nauseating in the stomach. They cannot therefore be taken in fubftance, fo much or so long, as to produce all those falutary effects, which, if thoroughly mixed with the blood and juices, they would be capable of producing. It must therefore be a thing of great benefit, to be able to introduce any requisite quantity of their volatile parts into the finest ducts and capillaries, so as not to offend the stomach, but, on the contrary, to comfort and strengthen it in a great degree.

13. According to Pliny, liquid pitch (as he calls it) or tar, was obtained by setting fire to billets of old fát pines or firs. The first running was tar, the latter or thicker running was pitch. Theophrastus is more particular : he tells us the Mace. donians made huge heaps of the cloven trunks of those trees, wherein the billets were placed erect beside each other. That fuch heaps or piles of wood were sometimes a hundred and eighty cubits. round, and fixty or even a hundred high : and that having covered them with fods of earth to 5

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prevent the flame from bursting forth (in which case the tar was loft) they set on fire those huge heaps of pine or fir, letting the tar and pitch run out in a channel.

14. Pliny faith, it was customary for the ancients, to hold fleeces of wool over the steam of boiling tar, and squeeze the moisture from them, which watery substance was called pislinum. Ray will have this to be the same with the piffelæum of the ancients; but Hardouin in his notes on Pliny, thinks the piffelæum to have been produced from the cones of cedars. What use they made of these liquors anciently I know not : but it may be presumed they were used in medicine, though at present, for ought I can find, they are not used at all.

15. From the manner of procuring tar (a) it plainly appears to be a natural production, lodged in the vessels of the tree, whence it is only freed and let loose (not made) by burning. If we may believe Pliny, the first running or tar was called cedrium, and was of such efficacy to preserve from putrefaction, that in Egypt they embalmed dead bodies with it. And to this he ascribes their mum. mies continuing uncorrupted for so many ages.

16. Some modern writers inform us that tar flows from the trunks of pines and firs, when they are very old, through incisions made in the bark near the root ; that pitch is tar inspiffated ; and both are the oil of the tree grown thick and ripened with age and sun. The trees, like old men, being unable to perfpire, and their secretory ducts obftructed, they are, as one may say, choaked and ftuffed with their own juice.

17. The method used by our colonies in America, for making tar and pitch, is in effect the faine with that of the ancient Macedonians

(a) Sect. 13.
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appears from the account given in the Philosophical Transactions. And the relation of Leo Africanus, who describes, as an eye witness, the making of tar on mount Atlas, agrees in substance with the methods used by the Macedonians of old, and the people of New England at this day.

18. Johnstonus in his Dendrographia, is of opi. nion, that pitch was anciently made of cedar, as well as of the pine and fir grown old and oily. It should seem indeed that one and the same word was used by the ancients in a large sense, so as to comprehend the juices issuing from all those trees. Tar and all sorts of exsudations from evergreens are, in a general acceptation, included under the name resin.

Hard coarse resin or dry pitch is made from tar, by letting it blaze till the moisture is spent. Liquid refin is properly an oily viscid juice, oozing from the bar of evergreen trees, either spontaneously or by incision. It is thought to be the oil of the bark infpiffated by the sun. As it issues from the tree it is liquid, but becomes dry and hard being condensed by the sun or by fire.

19. According to Theophrastus, resin was obtained by stripping off the bark from pines, and by incisions made in the silver fir and the pitch pine. The inhabitants of mount Ida, he tells us, îtripped the trunk of the pine on the sunny side two or three cubits from the ground. He observes that a good pine might be made to yield resin every year ; and indifferent every other year; and the weaker trees once in three years ; and that three runnings were as much as a tree could bear. It is remarked by the same author, that a pine doth not at once produce fruit and resin, but the former only in its youth, the latter in its old age.

20. Turpentine is a fine resin. Four kinds of this are in use. The turpentine of Chios or Cy

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