Imatges de pàgina


On the Bad Effects of the Incautious Use of Magnesia. By


[From the Journal of Science and the Arts, No. II, for 1816.] At a time when domestic empiricism is so prevalent as at present, it is important to point out the dangers which may arise from the uses, or rather the abuses of the most simple remedies.

Every medical practitioner must have repeatedly witnessed the serious, and sometimes the fatal consequences attendant upon the imprudent use of the stronger medicines, which are so extensively supplied for family consumption, particularly preparations of antimony, mercury, and opium, which, under a great variety of seducing forms and titles, are constantly em. ployed; generally, however, they are, I believe, not sufficiently aware of the prejudicial effects of the too liberal use of magnesia; either those which may arise from its chemical action upon the urine, which are more immediately observable and common, or which may arise from its mechanical action, as an extraneous insoluble substance, and which are more remote, obscure, and rare.

I need not dilate upon the former, but may refer to my brother's observations upon that subject, published in the Philosophical Transactions for the year 1810, which, I regret, are too little attended to; and with respect to the latter, shall confine myself to the recital of the following case.

A lady was recommended to take magnesia, in consequence of some very severe nephritic attacks, accompanied with the passage of gravel. She was desired to take a tea-spoonful every night; and Henry's calcined magnesia was preferred, as that always operated upon the bowels and carried itself off," which other magnesia did not, but, on the contrary, felt heavy and uneasy in the stomach. The dose was gradually increased to two tea-spoonfuls, in order to produce effect upon the bowels, which this quantity never failed to do; the symptoms for which it was ordered were soon removed, but the plan was persevered in for two years and a half, with little intermission or irregularity; so that as the average weight of a teaspoonful is at least forty grains, and the average dose was a tea-spoonful and a half, it may be presumed that she took during the above period between nine and ten pounds troy.

In the course of the last autumn she suffered severely by a miscarriage, and shortly afterwards by an attack of biliary calculi; subsequent to which she became sensible of a tender. ness in the left side just above the groin, connected with a deep-seated tumour, obscurely to be felt upon pressure, and subject to attacks of constipation, with painful spasmodic action of the bowels, tenesmus, and a highly irritable state of stomach; these attacks recurred every two or three weeks, varying in violence, but requiring the use of active remedies; during one of them, about the middle of last March, a large quantity of sand was voided by the rectum, attended with a peculiar acute and distressing pain in the seat of the tumour above mentioned. This was lost. The following day, however, the same kind of evacuation happened again, and to the same extent, which being saved and measured, was found to amount to two pints. Another attack took place upon the 5th of April, when several irregular lumps of a soft light brown substance were voided, having the appearance of a large mass broken down, and when dry extremely friable: a part of each of these two last were subjected to a careful analysis, and found to consist entirely of sub-carbonate of magnesia concreted by the mucus of the bowels, in the proportion of about 40 per cent.

The use of magnesia was now given up, and that of an active purgative medicine enjoined, with some other necessary directions, and there is every appearance of returning health, although some slight attacks have recurred, and small portions of the same concretion still occasionally come away.

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An instance, in many respects resembling this, has lately occurred in the practice of some gentlemen of eminence in this town, in which not only large quantities of a concretion of a similar description were voided, but upon examination after death, which took place perhaps six months after any magnesia had been taken, a collection, supposed to be from four to six pounds, was found embedded in the head of the colon, which was of course much distended. Some notes which were made of this case are, I fear, not to be found.

The Marquis of RIDOLFI's Method of separating Platina from the other metallic substances which are found with it in the state of Ore; from the Giornale di Scienze ed Arti," published at Florence.

[From the Journal of Science and the Arts, No. II, for 1816.]

The Marquis Ridolfi, after giving a detail of various experiments which he has made upon platina, proceeds thus: “No one has been able to combine sulphur with platina, so as to form a sulphuret of that metal. From this peculiarity of platina, the idea struck me, that if one could convert the other metallic substances found in platina into sulphurets, it would be easy to purify that metal. With this view, I took an ounce of crude platina, and separated from it some of the extraneous substances usually mixed with it. I washed it with nitro-muriatic acid, diluted with four times its weight of water. I then washed it in hot water, with a view of removing portions of iron and of gold which might be in the powder; but I afterwards found these washings useless. I then melted the mass with half its weight of pure lead, and threw it into cold water, and thus obtained an alloy which was pulverised and mixed with an equal portion of sulphur. I threw the mixture into a white-hot Hessian crucible, which was instantly covered, and let it remain in an intense heat for ten minutes. I then suffered it to cool gradually. It contained much dross, and a brittle


metallic button composed of platina, lead, and sulphar. I then again fused it with a small addition of lead, and when it had cooled I found that the sulphur was in the dross, and that there only remained an alloy of platina and lead.

I then heated this alloy to whiteness, and beat it with a hot hammer on a hot anvil, which forced out the lead in fusion. Here I must observe that unless the alloy is white-hot the beating must be suspended, as it will break.

I thus obtained platina so pure as to make with it a capsule, a spoon, wire, and leaves which were nearly as thin as gold leaf. It was ductile, malleable, and as tenacious as that ob-' tained from the ammoniacal muriate. Its specific gravity was 22,630.

This description is sufficient to show the purity of the platina. I repeated the process several times. I did not always find the platina in a lump at the bottom of the crucible; it was sometimes scattered in globules amongst the dross. In this case it is only necessary to heat the mass with a little diluted sulphuric acid, the globules are soon liberated from the dross, and sink to the bottom of the crucible. Collect and wash them, and submit them to the same operation of the hammer, as if the platina had been found united in one mass with the lead. I did not ascertain whether all the metals contained in the ore had become sulphurets, but they were all separated from the platina during the fusion and the formation of the sulphuret of lead.

Proceedings of the Royal Society of London. [From the Journal of Science and the Arts, No. II, for 1816.] Feb. 29. A paper was communicated by Mr. Ivory, containing an investigation of the theory of capillary attraction, a subject which, notwithstanding the numerous and important experiments that have been made upon it, still remains in much obscurity. Mr. Ivory advocates the Newtonian hypo



thesis, and adduces several proofs of the correctness of Mr. Leslie's enquiries, published in the year 1802 in the Philosophical Magazine. The paper contained a series of mathematical investigations relating to the subject, which were not of a nature to be read before the Society.

The reading of a letter from Dr. Brewster to the President was commenced, and continued during two successive sittings, "on the communication of double refraction to glass and other substances, by mechanical compression."

March 14. A Paper by Charles Babbage, Esq. F.R. S. was received, containing further remarks on the calculus of functions; the details were not such as could be entered into at a public meeting of the Society; the paper, therefore, was merely announced.

March 21. Sir Everard Home communicated some experiments to ascertain the mode of action of specific medicines: they related principally to that singular and efficacious remedy, the eau medicinale d'Husson. A variety of facts and statements were adduced, to prove that these medicines produce their effects by entering the blood, and acting directly upon the affected parts. Thus, mercury requires to be received into the circulation, before it can act upon the syphilitic virus, or remove the primary symptoms of the disease; and the eau medicinale must enter the blood before it can remove the gout. Mercury, and the eau d'Husson, are regarded as the only two known specifics; and it is assumed, though we think that farther researches are required to give firmness to the conclusion, that the eau medicinale is a vinous infusion of the roots of Colchicum autumnale, or meadow saffron. In the course of his communication Sir Everard throws out some curious hints upon the modus operandi of other medicines. Some acting upon the secretions of the stomach, and thus indirectly modifying the constitution of the blood; while others produce their effects in consequence of direct mixtures with that fluid. This is sometimes the case where we should least expect it. An infusion of ipecacuanha thrown into a vein excites vomiting, and opium produces drowsiness, and colchicum sickens, and perhaps cures the gout. Is it legitimate VOL. II. 3 Z

No. 24.

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