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.