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 effects of mercury comprehends the palsy or tremor, with the collateral disorders induced in miners, gilders, and other workmen, whose trade exposes them to the operation of this poison. Under the present head, which might be treated at considerable length as an important branch of medical police, I shall confine myself chiefly to an analysis of an interesting essay by Mérat on the ''Tremblement Metallique'', and to some remarks by Jussieu on the health of the quicksilver miners of Almaden in Spain.

Mérat's account of the shaking palsy induced by mercury is very interesting. The disease, he states, may sometimes begin suddenly; but in general it makes its approaches by slow steps. The first symptom is unsteadiness of the arms, then quivering, finally tremors, the several movements of which become more and more extensive till they resemble convulsions, and render it difficult or impossible for the patient to walk, to speak, or even to chew. All voluntary motions, such as carrying a morsel to the mouth, are effected by several violent starts. The arms are generally attacked first and also most severely. If the man does not now quit work, loss of memory, sleeplessness, delirium, and death ensue. But as the nature of the disease soon renders working almost impossible, he cannot well continue; and in that case death is rare. The concomitant symptoms of the trembling are a peculiar brown tint of the whole body, dry skin, flatus, but no colic, no disorder of respiration, and, except in very old cases, no wasting or impaired digestion. The pulse is almost always slow.—This description agrees with a somewhat later account of the disease by Dr. Bateman, as he observed it in mirror-silverers; and also with some interesting cases recently published by Dr. Bright.

In general the tremors are cured easily, though slowly, several months being commonly required. One of Dr. Bright's patients got almost well in little more than a fortnight under the use of sulphate of zinc. Sometimes, however, the trembling is incurable. I have said the disease is rarely fatal. Mérat quotes three cases only, in one of which death was owing to profuse salivation and gangrene, in the others to marasmus. On the whole, those who are liable to the shaking palsy do not appear liable to salivation. Yet the two affections are sometimes conjoined, as in three of the cases described by Dr. Bright, and in some noticed by Mr. Mitchell among the mirror-silverers of London. Gilders, miners, and barometer-makers are all subject to the disease. Even those who undergo mercurial frictions may have it, according to Mérat; and M. Colson, who confirms this statement, quotes Swédiaur as another authority for it. It is not merely long-continued exposure to mercurial preparations that causes the shaking palsy: a single strong exposure may be sufficient;