Part 4

The same quantity of Peruvian bark, and of lime water, without the addition of any fresh lime, being rubbed in the same manner, afforded a tincture tasting strongly of the bark, nearly of the same colour as the simple tincture obtained by proof spirit, and retaining its transparency when blown into. This tincture was much more strongly impregnated than one made by triture with common rain water only. And by this process, allowing a few hours for maceration, an infusion is prepared, greatly superiour in strength to any decoction, infusion, or tincture of bark I ever saw.

From the result of these experiments I suspect, that by using a greater quantity of lime in the sixteenth and twentieth experiments than the vegetable could saturate with fixed air, the water became so impregnated with lime as to be more unfit to act on the vegetable. From the purple colour of the residuum of number 2, it was evident that the galls were decompounded, but the water was not capable of dissolving and suspending the particles. Dr. Percival[u] mentions his having unsuccessfully repeated Dr. Macbride's experiment with bark and quick-lime. To what then can this difference be owing? Perhaps it may be accounted for thus: It seems probable that the lime used by Dr. Macbride, not being fresh calcined, had recovered part of its air; for he says, "It will no doubt be reckoned superfluous, that lime water is ordered to be added to these several substances, when they are also to be rubbed along with quick-lime; but the reason is this. _If the lime were so quick and fresh as to raise heat when common water is poured on it, the solution might then be made without the aid of lime water; but, as it will for the most part happen, that the lime kept in the shops will not be perfectly fresh, it will be best that the prescriber should direct lime water to be used._" On the contrary, Dr. Percival used _lime fresh from the kiln_. These circumstances, if my theory be just, would greatly vary the event of the experiment; and the trials I have here recited seem to prove, that so great a quantity of lime, and even a much smaller than is directed by Dr. Macbride, if fresh, instead of increasing, diminishes the solvent power of water on astringent vegetables.

[u] Percival's Essays Medical and Experimental, 2d Edit. p. 65.

But as different drugs yield their virtues with more ease, and in greater quantity to some menstrua than to others, it seemed probable, that even a very small quantity of lime might render water less solvent of particular vegetables, than it is in its pure state, though with others as large or perhaps a greater quantity than what I had used might be necessary: and as the determination of this point might be of some use in pharmacy, the following experiments were made; in the relation of which I shall make use of numbers as before, viz. the vegetable rubbed with four ounces of distilled water will be distinguished by number 1, that with two scruples of lime and four ounces of lime water, number 2, and that with lime water only, number 3.

EXPERIMENT XXII.

Two drachms of snake root were rubbed for fifteen minutes with the above-mentioned different proportions of distilled water, quick-lime and lime water, and lime water alone.

Number 1 was a dark brown tincture, tasting strongly of the serpentaria.

Number 2, straw coloured, taste of the lime disagreeable, that of the root not distinguishable.

Number 3, amber coloured, tastes of the root.

EXPERIMENT XXIII.

Two drachms of Columbo being triturated in the same manner,

Number 1, dark brown tincture; tastes much of the Columbo.

Number 2, yellow; faint taste of the Columbo, but that of the lime very disagreeably prevalent.

Number 3, colour as number 1; but tastes more highly of the Columbo.

EXPERIMENT XXIV.

Two drachms of contrayerva root with the same treatment yielded in the following proportions:

Number 1 gave a pale brown tincture, tasting of the contrayerva.

Number 2, bright amber colour; taste of the lime so strong as to admit of no other.

Number 3 exceeded number 1 both in colour and taste.

EXPERIMENT XXV.

Jalap being triturated in the same proportions,

Number 1 dark brown; taste of the jalap strong.

Number 2 pale yellow; taste of the lime predominant, though that of the jalap perceptible.

Number 3, colour not quite so high as number 1, but equal in taste.

EXPERIMENT XXVI.

The result of the same trial with ipecacuanha was, that number 1 was of a light brown colour, tasting highly of the ipecacuanha.

Number 2 was of a deep yellow, having the same disagreeable taste of the lime complained of in the other tinctures, but that of the ipecacuanha scarcely perceptible.

Number 3 produced a tincture of the colour of red port wine, strongly flavoured with the ipecacuanha, though it had not so much of the distinguishing sharpness of that root as number 1.

EXPERIMENT XXVII.

The different tinctures of rhubarb, prepared in the same manner as above, had the following appearances:

Number 1 brown, with a yellowish tinge, strongly impregnated with the taste of the rhubarb.

Number 2 deep yellow, taste of the lime as in the other tinctures prepared with it.

Number 3 crimson; taste of the rhubarb strong, but unequal to number 1.

None of the tinctures prepared with lime water grew turbid from a stream of fixed air being conveyed into them.

Hence it appears that the triture of quick-lime with all the above roots did not in the least degree promote, but rather impede their solution in water; that lime water extracts the soluble parts of many, and especially their colouring principles, more powerfully than distilled water; but that this is by no means always the case, as in three instances out of six, the tinctures prepared with distilled water exceeded those with lime water in taste, and in two instances were superiour, and in one equal in colour.

CHAP. IX.

ON THE COMPARATIVE ANTISEPTIC POWERS OF VEGETABLE INFUSIONS PREPARED WITH LIME, &c.

Sir John Pringle, in the Appendix to his excellent Observations on the Diseases of the Army, allows lime water to possess but a slight antiseptic quality. Doctor Macbride on the contrary asserts, that it has great power in resisting putrefaction, but at the same time acknowledges that it destroys the cohesion of the constituent particles of animal substances, and therefore cannot be called a _true_ antiseptic, as it absorbs the fixable air from them, and only preserves them sweet by confining it within their texture, into which the lime is enabled to insinuate itself in this dissolved state. As even this effect, if possessed by the tinctures of the antiseptic vegetables prepared with lime or its water, would be an objection to their administration in putrid diseases, I resolved to determine by experiment, how far their antiseptic powers were increased or diminished by this mode of preparation: and I thought it probable, as those prepared with the latter contain no lime when filtered, and yet in the extraction of the tinctures the vegetables are deprived of, at least, a part of their air, they might be rendered less able to resist putrefaction than either the infusions prepared with distilled water, or those with the addition of quick-lime. How far this reasoning was just, the result will discover.

EXPERIMENT XXVIII.

Pieces of beef, each weighing about two drachms, were separately infused in the different tinctures of Peruvian bark, snake root, Columbo, and contrayerva, prepared with lime, lime water, and distilled water, as in the preceding experiments; and the bottles containing them were exposed for two days to a degree of heat equal to that of the human blood. They were afterwards suffered to remain without any artificial heat, the temperature of the air being warm. The tincture of Columbo prepared with quick-lime was the only one not tried, the bottle containing it having been broken.

After thirty-six hours infusion they were all sweet, except the infusion of Columbo in distilled water, which began to emit a disagreeable, though not putrid foetor. The beef in it, and in the tincture of the same root in lime water, was swelled, and whiter than before infusion. That in the tincture of bark prepared with quick-lime, had its texture greatly destroyed, was of a chocolate colour, but sweet. That in aqua calcis, the same in colour, shrivelled, firm, and sweet. The pieces of beef in the tinctures of snake root and of contrayerva with quick-lime, had more the appearance of calf's lights than of beef, were quite spongy, but had acquired no putrid smell. Those in the lime and distilled water, firm, and shewing no signs of putrescency.

On the fifth day the infusion of Columbo in lime water was very offensive, though the beef when taken out of it was not putrid. That of the same root with distilled water had made no further progress. The tincture of snake root in distilled water was grown turbid, and had lost colour, which it seemed to have imparted to the beef. This and all the others continued sweet.

On the tenth day the beef in the distilled water and Columbo, as on the fifth. That in the lime water and Columbo, putrid.

The contrayerva infusion in distilled water had acquired a disagreeable foetor, but the beef was not yet putrid. That with lime water and that with quick-lime still sweet.

The infusion of bark with distilled water smelled rather musty; the beef in it sweet. The two infusions of the same with lime and lime water shewed no further change.

The tincture of snake root in distilled water had a scum on the surface; beef not putrid. The other two tinctures of the same root unchanged.

On the eleventh day, the beef in the infusions of Columbo and of contrayerva in distilled water beginning to putrefy, and

On the fourteenth day, both entirely putrid. The infusion of bark in distilled water mouldy, but the beef sweet.

The beef in the snake root and distilled water, putrid on the sixteenth day; and the infusion of contrayerva with lime water beginning to be offensive, but the beef in it not yet putrid; but

On the nineteenth it was quite putrefied. The snake root infusion in lime water, mouldy on its surface; no change in the beef; but this likewise became putrid in a few days more.

The remaining tinctures, viz. those of the bark, snake root, and contrayerva with quick-lime, and that of the bark with lime water, remained above five weeks without any further change. Some time after, the beef in the snake root became septic. The other three were unaltered at the end of six weeks from their first immersion; and though the infusion of bark in distilled water was very mouldy, the beef in it was free from any putrid foetor. But it should be observed that all the tinctures in the preparation of which quick-lime had been added to the lime water, had a peculiar odour during the whole time, from which the others were exempt.

From this experiment we may conclude that lime water, when used in such a quantity in extracting the virtues of vegetables, as not to be saturated with the fixed air it receives from them, _strongly_ counteracts putrefaction, though it at the same time destroys the texture of animal bodies exposed to its action. But when employed for the same purposes, in such proportion as to be fully saturated with air; it abstracts nothing from, but rather increases the antiseptic power of the vegetable; nor does animal flesh immersed in tinctures thus prepared, suffer any diminution in the cohesion of its fibres.

CHAP. X.

ON THE SWEETENING PROPERTIES OF FIXED AIR.

The very curious fact, that fixed air not only preserves bodies from becoming septic, but is also possessed of the power of restoring sweetness to them when actually putrid, seemed to be established by a number of very accurate experiments adduced in support of the doctrine by its ingenious author. This has, however, lately been controverted by a learned writer, who has favoured the public with _an Experimental Inquiry concerning the causes which have been generally said to produce putrid diseases_, in which he has recounted several experiments, in direct contradiction to those of Dr. Macbride. The authorities of both these gentlemen deserve considerable attention, and it might seem presumption in me to attempt to decide between them, had I only my own opinion to adduce; but as the accuracy of the following trials was witnessed by a Physician, well known for his medical and philosophical writings, I feel the less diffidence in submitting them to the public. They were made with a view, only, to my own information, having in one of the former chapters recommended Magnesia to be taken in the act of effervescence with an acid, as a corrector and evacuant of putrid bile; but as the event appeared to be so satisfactory, and as a determination of this point is the more important, from the late introduction of fixed air as an article of the materia medica, I hope I shall not be deemed to have impertinently obtruded into the dispute by relating them, and endeavouring to point out what, probably, has been the cause of Dr. Alexander's drawing conclusions, so contrary to those of the other celebrated experimentalist.

In the experiments which Dr. Alexander has related in support of his opinion, he has made use of the following methods. He included pieces of putrid mutton in bladders, one containing _four ounces in measure_ of fixed air from fermenting wort; another the same quantity from wort with a piece of putrid mutton in it; and the third, only _about half the quantity_ from a mixture of bread, water, and saliva. In another experiment, he exposed a slice of beef that had just begun to have the putrid smell, to a stream of air brought over from an effervescing mixture of distilled vinegar and salt of wormwood. In a third, the putrid flesh was suspended in the neck of a wide mouthed bottle, while _four ounces_ of distilled vinegar were made into _spirit. minderer._ In a fourth, _four ounces_ of air from bottled small beer were confined twenty-four hours with the putrid substance, which in a fifth experiment was put into the neck of a bottle of small beer, while it fermented before the fire for half an hour. In a sixth, the septic body was included in a bottle with _eight ounces_ of air from an effervescing mixture of common vinegar and salt of hartshorn. In one only, out of all these experiments, he found the beef in any-wise sweetened, and even in that single instance, though he at first thought the piece a little changed, yet when washed it recovered its putrid smell. However he confesses, that by bringing over fixed air from several other fermenting and effervescing mixtures, on pieces of meat just beginning to putrefy, they were rendered a little sweeter, though never to such a degree, as entirely to lose their putrid taint.

So very different an account of so interesting a subject was truly mortifying: The old adage, _experientia fallax, judicium difficile_, seemed to be too applicable to the present occasion. Some cases, in which fixed air used medicinally as an antiseptic, appeared to have produced good effects, had occurred to some of my medical friends[v], and I even flattered myself that I had directed it to good purpose in an instance or two. But if the theory on which this practice was founded should be false, the whole superstructure seemed likely to be destroyed. On revising Dr. Alexander's book, I imagined that I had discovered some thing in the conducting of his experiments, which might account for their terminating so differently from those of Dr. Macbride.

[v] See Dr. Percival's Experiments and Observations, p. 72; Dr. Priestley's papers on factitious air; and Mr. White's Treatise on the Management of Pregnant and Lying-in Women, p. 203.

The largest quantity of fixed air which Dr. Alexander made use of in any of these experiments was _eight ounces in measure_, and in one instance, only two ounces were employed to sweeten the putrid substance. In that where the meat was suspended in a wide mouthed bottle while the vinegar was made into _spirit. minderer._ no method seems to have been taken to retard the too rapid flight of the fixed air, which, from the quick distribution of the salt, would be soon dissipated. From hence I suspected, that a larger atmosphere, or a longer continued stream of fixed air might be requisite to restore septic bodies to perfect sweetness; and in order to decide this point, the following experiments were instituted, having previously obtained some slices of beef so exceedingly putrefied as to render the foetor of them scarcely tolerable.

EXPERIMENT XXIX.

A bottle capable of containing three pints was filled with water, and inverted into a bason of the same; a tube which communicated with another bottle, in which was an effervescing mixture of chalk and oil of vitriol, was then introduced into the mouth of the former, and a stream of fixed air continued, till the whole of the water was driven out by it. A piece of the above-mentioned putrid beef, fastened by a string to a cork, was conveyed into the bottle, which was corked before it was taken out of the water. The beef, after having been suspended in this atmosphere of fixed air for thirteen hours, was very considerably, though not entirely sweetened. _But the air in the bottle seemed to have acquired all the putrid smell of which the flesh had been deprived._ Another slice of the same beef was not at all sweetened by exposure, during the same time, to the open air.

EXPERIMENT XXX.

A piece of this beef suspended all night in the neck of a bottle of artificial Pyrmont water[w], was rendered less putrid, though not near so much altered as that in the foregoing experiment. The water was strongly impregnated with the putrid effluvia.

[w] See Dr. Priestley's Directions for impregnating Water with fixed Air.

EXPERIMENT XXXI.

Two drachms of Magnesia Alba diluted with two ounces of water were placed in a quart bottle, to which was added a sufficient quantity of the strong spirit of vitriol to let loose all the fixed air from the Magnesia, during the separation of which, another equally putrid piece of beef was suspended in the bottle, which was so corked as to retard, though not totally prevent the escape of the air. Another piece of the same beef, was exposed in like manner to the vapour arising from the addition of oil of vitriol to two drachms of chalk diluted with water. They were suffered to remain for twenty two minutes, and being then examined were absolutely free from any putrid foetor, and though well washed in water continued quite sweet.

EXPERIMENT XXXII.

Air expelled from Magnesia by the nitrous acid, sweetened a piece of the same putrid flesh suspended in the neck of the bottle during the effervescence. The beef smelled of the nitrous acid, but remained equally sweet when washed from it in water. Very little change was produced in another piece exposed to the smoaking spirit of nitre.

It may be some additional evidence in support of the sweetening properties of fixed air, to declare that the highly offensive, sanious discharge of a cancer has been rendered considerably sweeter by it[x]; and that I have seen a case of a dysenteric fever, attended with extremely foetid and bloody stools, in which fixed air was directed, by the Physician who attended, to be thrown into the intestinal tube by way of clyster; the consequences of which were the correction of the putrid smell of the discharges, and the reduction of the inflation of the abdomen, together with contributing considerably to the ease of the patient after each injection of air[y]. A third case of this kind has very lately occurred to Dr. Percival, in which the injection of fixed air removed the foetor of the stools, and the patient recovered without the assistance of any other medicine, except the moderate use of wine as a cordial, and of a decoction of Peruvian bark during the convalescent state. I have also experienced the removal of a very large and deep slough, and the healing of the ulcer in the putrid sore throat, more expeditiously by the inspiration of fixed air than by any other method.[z]

[x] Directions for impregnating Water with Fixed Air, by Joseph Priestley, L.L.D. F.R.S.

[y] This case, together with another similar to it, will probably appear more fully in the next volume of the Philosophical Transactions, with Dr. Priestley's papers on factitious air.

[z] The patient in this last case being a lady in the country, at such a distance that I could not frequently visit her; by continuing to inspire the fixed air, after the ulcer was cleansed, and in a healing state, brought on a considerable inflammation of the fauces.

One circumstance in the twenty ninth experiment peculiarly attracted my attention, viz. that the air in the bottle was so very putrid, though the beef exposed to it was restored to sweetness. The septic effluvium therefore did not appear to be destroyed, but to have changed place. From this fact it occurred to me that there might possibly be an affinity between the fixed air and the septic particles, and that this air might act as a menstruum on the effluvia emitted by putrid bodies. I have since had the pleasure to see that Dr. Priestley, whose investigation into the nature of factitious air has lately been laid before the Royal Society, and must contribute to exalt him to a still higher rank as a Philosopher, has taken notice of something similar hereto. I am sensible that difficulties attend this theory. Doctor Percival, in the second volume of his Essays, which is now in the press, has offered some ingenious conjectures on the subject, and to them I refer the reader. I shall only mention one experiment which seems to give some force to this doctrine.

EXPERIMENT XXXIII.

Slips of linen cloth dipped in very rancid oil, had their rancidity much diminished by exposure to a stream of fixed air from an effervescent mixture of chalk and spirit of vitriol. But a pint bottle of the same oil being saturated with this vapour, was equally offensive as before the air was thrown into it, though the oil appeared to absorb a considerable quantity of air.

Dr. Macbride exposed a piece of rag dipped in lixivium tartari, and another tinged blue by the scrapings of raddishes, to the vapour arising from a large vat of melasses wash in high fermentation, without any change being effected in either, which could be supposed to proceed from an acid vapour. But as water impregnated with fixed air has evidently an acidulous taste, and it seemed probable that some of the vitriolic acid might be volatilized during the effervescence which proceeds from its admixture with the alkaline body, when the air is procured from these substances, it was apprehended that the antiseptic and sweetening powers of air thus obtained, might depend on the acid contained in it. In order to evince how far this conjecture was just, Doctor Percival was so obliging to assist me in suggesting and making the following experiments.

EXPERIMENT XXXIV.

Twenty drops of syrup of violets mixed with a glass-full of water were changed into a lively red by the addition of one drop of dilute spirit of vitriol. The season of the year did not allow us to use the fresh juices of vegetables, but this trial shews the genuineness of the syrup of violets, and that it was a sufficiently delicate test of acidity.

EXPERIMENT XXXV.

A paper besmeared with this syrup, was placed over a vessel which contained an effervescing mixture of chalk and oil of vitriol. No change of colour took place except in one small point[aa], which had probably been accidentally touched by the vitriolic acid.

[aa] In making this experiment, if the vegetable juice be placed too near to the effervescing mixture, some particles of the acid will be forced up to it, together with the air, and may occasion an erroneous conclusion to be drawn from it.

EXPERIMENT XXXVI.