Experiments and Observations on the Following Subjects / 1. On the preparation, calcination, and medicinal uses of Magnesia Alba. 2. On the solvent qualities of calcined Magnesia. 3. On the variety in the solvent powers of quick-lime, when used in different quantities. 4. On various absorbents, as promoting or retarding putrefaction. 5. On the comparative antiseptic powers of vegetable infusions prepared with lime, &c. 6. On the sweetening properties of fixed air.

by Thomas Henry

When I made the first experiment, I had not observed any discharge of air from the Magnesia and beef, and in the present one no fermentation was perceptible either in number 1 or 2. As this was an unexpected circumstance in the former, I repeated the experiment several times, but the event was always the same.

Magnesia was afterwards compared with crab's eyes, burnt hartshorn, and prepared coral. The mixture with Magnesia grew putrid first, afterwards that with the crab's eyes; the other two remained for some hours longer before the putrid fœtor came on.

From the above experiments it appears that Magnesia Alba, when replete with fixed air, is a stronger septic to animal flesh than any other absorbent which was compared with it; and yet when deprived of its air by calcination, it powerfully resists putrefaction. Dr. Macbride has endeavoured to account for this difference between calcareous earths and quick-lime, by supposing the particles of the lime to insinuate themselves intimately into the texture of the beef, and to prevent the escape of the fixed air, by attracting, absorbing, and thus confining it within the substance of the beef. How far this theory is satisfactory is not my province to determine; and the matter is so obscure, that I do not presume to offer any conjecture of my own, relative to the reason of it.

Nitre is found to be a strong antiseptic when applied to animal flesh, but to resist the putrefaction of bile with a very disproportionate force: and Dr. Percival has lately observed the same difference in the action of the Columbo root. These variations encouraged me to try the effect of Magnesia on gall; but being strongly prepossessed with the notion of its septic quality, I entertained very small hopes of a different event. I was also desirous to compare the action of the calcined Magnesia with the other. The heat used in the succeeding experiments was the same as that in the preceding trials.

EXPERIMENT IV.

To two drachms of fresh ox gall, were added two scruples of Magnesia, and two ounces of water, in one phial. Two scruples of calcined Magnesia with the same quantity of gall and water were placed in another; and a third containing two drachms of bile without any other addition than water, served as a standard, which began to have a rank smell in forty-eight hours, and in sixty hours was highly offensive. The calcined Magnesia and bile emitted a sweetish smell, something resembling that of the urine in a diabetes: the liquor which swam above was quite pellucid and colourless, whereas that of the other Magnesia was turbid and tinged green with the bile. Both were perfectly free from any putrid fœtor; the latter continued so for ten days, and the bile with the calcined Magnesia remained unchanged as long as any notice was taken of it.

EXPERIMENT V.

Twenty grains of Magnesia preserved six drachms of ox's gall free from any signs of corruption for twenty-four hours after the standard containing gall and water, of each six drachms, had become putrid. A scruple of the calcined Magnesia mixed with the same proportions of gall and water, remained without any alteration as long as they were attended to, which was about ten days.

EXPERIMENT VI.

The putrid liquor which had been used as a standard in the fourth experiment, was divided into four parts, one of which was continued as a standard, to another was added about half a drachm of Magnesia, and an effervescence was procured by some drops of oil of vitriol. The offensive smell continued for a few minutes, but was soon much abated, and at length entirely sweetened. To another portion was added twenty grains of Magnesia only, this in fifteen minutes had almost lost its putrid smell, and in two or three hours became quite sweet. To the fourth was added the same weight of calcined Magnesia, which almost instantly deprived the liquor of every degree of putridity. The standard was then mixed with a scruple of crab's eyes, which, for about a minute, seemed to diminish the fœtor, but it then returned as strongly as ever; whereas the others continued sweet for several days.