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 some care, as it supplies the physician with the most convenient and effectual antidote against the effects of the poison.

If a solution of albumen, for example that procured by beating white of eggs in water, is dropped by degrees into a solution of corrosive sublimate, a white flaky precipitate is immediately thrown down, which when separated and dried forms horny masses, hard, brittle, and pulverizable. The precipitate is soluble in a considerable excess of albumen; so that wherever albumen abounds in any fluid, to which corrosive sublimate has been added, a portion of the mercury will always be found in solution. The precipitate is also soluble in a considerable excess of corrosive sublimate. The dry precipitate I have found to contain 6 per cent. of metallic mercury.

The action of casein as it exists in milk is precisely the same. A solution of corrosive sublimate, poured into a large quantity of milk, causes no change; but if the proportion of salt be considerable, a flaky coagulum is formed, and the milk becomes clear. The principles, osmazôme and gelatin, are similar in their effects, though not quite so powerful. Urea has no chemical action with corrosive sublimate. Of the compound animal fluids, blood and serum have the same effects as albumen.

Many insoluble animal principles, as well as all the soft solids of the animal body, act in the same manner with vegetable gluten. Fibrin, for example, coagulated albumen, or coagulated casein, acts precisely in the same way. Muscular fibre, the mucous and serous membranes, the fibrous textures, and the brain, have all the same effect: they become firmer, brittle, white, and a white powder detaches itself from their surface, which contains mercury and animal matter. This chemical action, which Taddei has proved to take place in the living as well as in the dead dody, is the source of the corrosive property of the poison, as was first pointed out by Berthollet in his essay formerly quoted.

In all of the compounds thus formed by vegetable and animal substances, the presence of mercury is easily proved by boiling the powder in a solution of caustic potass. The organized matter is dissolved; a heavy, grayish-black powder is formed, which is protoxide of mercury; and if this be collected in the way formerly described, it forms running quicksilver when heated.

A difference of opinion prevails as to the nature of the changes effected by the mutual action of corrosive sublimate and organic matter. For example, in the instance of the action of albumen, which has been most carefully examined, Berzelius and Lassaigne regard the precipitate as a compound of bichloride of mercury with albumen. Professor Rose and Dr. Geoghegan have proved it, in their opinion, to be a compound of binoxide of mercury and albumen without any chlorine. And according to Boullay it is composed of albumen