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with myrrh. As part of this substance diffolves in water, eight grains were made into an emulsion ; but most of it subsiding, I could not reckon on a solution of more than one or two grains; which nevertheless preserving the flesh longer than the standard, we may account the soluble part of myrrh perhaps about 30 times stronger than sea-salt.

Aloes, Afa fetida, and the Terra Japonica, diffolved in the same manner as myrrh, like it subsided, and with the fame antiseptic force. But gum ammoniac and Sagapenum shewed little of this virtue. Whether it was that they opposed putrefaction less, or that all the antiseptic principle fell with the groffer parts to the bottom. Three grains of opium diffolved in water did not subside, and resisted putrefaction better than the falt. But I observed that more air than usual was generated, and the flesh became tenderer than with any of the stronger antiseptics.

Of all the resinous substances camphire resisted most : two grains dissolved in one drop of spirit of wine, five grains of sugar, and two ounces of water exceeding the standard : tho' during the infusion, most of the camphire flew off, swam a-top, or stuck to the phial. Suppose only the half loft, the remainder is at least 60 times stronger than falt; but if, as I imagine, the water suspended not above a tenth part, then camphire will be 300 times more antiseptic than sea-salt. That nothing might be ascribed to the minute portion of the spirit, used in this experiment, I made another solution of camphire in a drop or two of oil, and found this mixture less perfect, but still beyond the standard.

4. I made strong infusions of camomile flowers, and of Virginian snake-root; and finding them both greatly beyond the standard, I gradually lessened the quantity of these materials, till I found five grains of either impart a virtue to water superior to 60 grains of falt

. Now as we cannot suppose these weak infusions contained half a grain of the embalming part of these vegetables, it follows, that this must be at least 120 times more antiseptic than common falt.

I also made a forong decoction of the Bark, and infused a piece of flesh in two ounces of it strained; which flesh never corrupted, tho' it remained two or three days in the furnace, after the standard was putrid. In this time the decoction became gradually limpid, whilst the grofler parts fublided : By which it appears, that a most minute portion

of

of the bark intimately mixed with water (perhaps less than of the snake-root, or camomile flowers) is possessed of a very extraordinary antiseptic force.

Besides these, pepper, ginger, faffron, contrayerva-root, and galls, in the quantity of 5 grains each, as also 10 grains of dried fage, of rhubarb, and the root of wild valerian*, separately infused, exceeded 6o grains of falt, mint, angelica, ground-ivy, fenna, green tea, red roses, common worniwood, mustard, and horse-radish, were likewise infused, but in larger quantities, and proved more antiseptic than the standard. And as none of these can be supposed to yield in the water above a grain or two of the emhalming principle, we may look upon them all as very powerful resisters of putrefaction. Farther, I made a trial with a decoction of white poppy-heads, and another with the expresied juice of lettuce, and found them both above the ftandard.

By these specimens we may now see how extensive antiseptics are ; since, besides falts, fermented spirits, spices and acids, commonly known to have this property, many resins, astringents, and refrigerants, are of the number; and even those plants called anti-acids, and supposed hafteners of putrefaction; of which class horse-radish is particularly antiseptic. And indeed after these trials, I expected to find all dissolvable substances endowed with some dedree of this quality; till, upon further experiments, I perceived some made no resistance, and others promoted corruption. But before I enter upon that part of my subject, it will be proper to relate some other experiments more nearly connected with the preceding.

5. Having seen how much more antiseptic these infufion's were than fea-falt, I then tried whether plants would

part with this virtue without infusion. For, this purpose, hav. ing three {mail and thin slices of the lean of beef, I rubbed one with the powder of the bark, another with snake-root, and a third with camomile flowers. It was in the heat of fummer, yet, after keeping these pieces for several days, I found the flesh with the bark but little tainted, and the other two quite sweet. The substance of all the three was

* Tho' the experiment was only made with ten grains of the powder of this root, yet, considering how long that quantity refifted putrefaction, we may reckon the valerian among the Atroneft antiseptics.

firm ;

firm; particularly that with the comomile, which was so hard and dry, that it seemed incorruptible. Why the bark had not altogether the same effect, was probably owing to its close texture.

6. I have also made some attempts towards the sweetening of corrupted flesh, by means of mild substances ; because distilled spirits, or strong acids, the only things known to answer this intention, were of two acrid and irritating a nature to be thoroughly useful, when this correction was most wanted. As for salts, besides their acrimony, it is well known, that meat once tainted will not take falt.

A piece of Aesh weighing two drachms, which in a former experiment had become putrid, and was therefore very tender, spongy, and specifically lighter than water, was thrown into a few ounces of the infusion of camomile flowers, after expressing the air, to make it sink in the fluid : The infusion was renewed twice or thrice in as many days ; when, perceiving the Fætor gone, I put the Aeth into a clean bottle, with a fresh infusion; and this I kept all the summer, and have it ftill by me, quite sweet, and of a firm texture *. In like manner I have been able to sweeten feveral small pieces of putrid Alesh, by repeated affufions of a strong decoction of the bark , and I constantly observed, that not only the corrupted smell was removed, but a firma ness restored to the fibres.

Now, since the bark parted with so much of its virtue in water, it was natural to think it would still yield more in the body, when opened by the Saliva and bile; and there fore it was by this antiseptic virtue it chiefly operated. From this principle we might account for its success in gangrenes, and in the low state of malignant fevers, when the humours are so evidently putrid. And for intermittents, in which the bark is most specific, were we to judge of their nature, from circumstances attending them in climates and seasons most liable to the diftemper, we should allign putrefaction as a principal cause. They are the great endemic of all marshy countries, and rage molt after hot summers, with a close and moist state of air. They begin at the end of summer, and continue thro' autumn ; being at the worst, when the atmosphere is most loaded with

* This piece has been kept twelvemonths in the same liquor, and is still firm and uncorrupted.

the

the Efluvia of stagnating water, rendered more putrid by vegetables and animal substances that rot in it. At fuch times all meats are quickly tainted ; and dysenteries, with other putrid distempers, coincide with these severs. The heats dispose the humours to acrimony ; the putrid Efluvia are a ferment; and the fogs and dews, fo common to those climates, stop perspiration, and bring on a fever. The more these causes prevail, the easier it it is to trace this putrefaction of humours. The Nausea, Thirst, bitter Taste of the mouth, and frequent evacuations of putrid bile, are common symptoms and arguments for what is advanced. We shall add, that int moist countries, in bad seasons, the intermittents not only begin with symptoms of a putrid fever, but, if unduly managed, easily change into a putrid and malignant form, with lived spots and blotches, and mortification of the bowels. But, as a thorough discussion of this question might carry us too far from our present subjezt, and be unseasonable here, I shall refer it to its proper place, and only remark, that whatever medicines (befides evacuations and the bark) have been found useful in the cure of intermittents, they are, so far as I know, all highly antiseptic ; such are, myrrh, camphire, camomile Aowers, wormwood, tincture of roses, alum with nutmeg, vitriolic or strong vegetable acids with aromatics.

Thus far, fays Dr. Pringle, I have only related my experiments upon flesh, or the fibrous parts of animals; I Thould next proceed to shew, what effects antiseptics have upon the humours; for, though from analogy we may conclude, that whatever retards the corruption of the solids, or recovers them after they are tainted, will act fimilarly upon the Auids ; yet, as this does not certainly follow, 'I judged it necessary to make new trials ; which, with some experiments on the promoters of putrefaction, the reverse of the former, will be given in our next, from the fame nun. ber of the transactions.

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ART. IV. The Nature of the nervous Fluid, or animal Sp

rits demonstrated, with an introductory Preface. By Macolm Flemyng. M. D. 8vo. is. Millar.

enough to affirm his demonstration of the nature of that most exquisite animal fluid, whose very e istence has been denied by some ; while the precise Analysis or compoVOL. VI.

E

fition

sition of it has been modestly declined by many celebrated physicians, who have nevertheless asserted the action of the nerves to result immediately from the energy of a contained Auid, and not from any chord-like elastic vibration. Now tho' our author takes the existence of this nervous fuid, and, as we imagine, very justly, for granted, we shall beg leave to contract the excellent arguments of Dr. Haller for the secretion of this fluid in the brain, from Dr. Flemyng's own quotation of him, for the satisfaction of any of our medical readers, who might not have fully determined for themselves. on this curious hypothetical subject.

First then Dr. Haller observes, that the external or cortical part

of the brain, which is manifestly very vascular, is continued to, and coheres with, the internal medullary part : and as a great quantity of blood is incontestably carried to the brain, by the carotid and vertebral arteries, if the fibres of the Medulla, which are inextricably connected with the vascular texture of the cortical part, were not hollow, but solid, they must repell the blood by their folidity, and so render its derivation there at least useless. But as the medullary and cortical parts increase alike, their equal growth manifestly points to one common cause of it, to wit, the superior force of the heart extending the blood-veffels; from whence the medullary, as well as cortical part of the brain, must be concluded to be vascular.'

« The Phænomena of wounded nerves, he observes, are inconsistent with their elasticity. A nerve cut asunder does not retract its divided extremities towards the folid parts to which it adheres, but becomes rather longer, extruding its Medulla into a round tubercle. And if it Thook on appulse, like an elastic chord, it should be composed of hard fibres, having their extremities fixed to some firm bodies and bent, since strings otherwise constituted and disposed are inelastic and infonorous. But it is evident that all nerves are medullary and soft at their origin, as well as void of tension; some being soft in every part, as the olfactory nerve, and the foft portion of the auditory nerve, where the greatest vibration might be expected, as it is the instrument of hearing. And tho' they are hard in some places, he affirms they grow. soft in the Vifcera, the muscles, and the sensories, before they exert their functions : besides

, which it is impossible that some nerves, in certain situations, can tremble, as those of the heart, which are faftened to the great vessels and the Pericardium. Furthermore, the influence of an irritated nerve is never propagated upwards,

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