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 and death in half an hour; and there was no particular morbid appearance in the body.—Half a grain killed another in four days; and in addition to the preceding symptoms, there was palsy of the hind legs for a day before death. Six grains of the sulphate introduced into the stomach killed a dog in half an hour, without producing any appearance of inflammation.

These experiments prove that it is not by causing local irritation that this poison proves fatal. But its mode of action is more distinctly shown in the later and more accurate experiments of Orfila. He found that twelve or fifteen grains of the neutral acetate generally killed dogs within an hour; and that besides the usual symptoms of irritation in the stomach, they often had insensibility, almost always convulsions, and immediately before death rigidity, or even absolute tetanus. He likewise remarked violent convulsions and insensibility when a grain of this salt was injected into the veins; and death was then seldom delayed beyond ten minutes. In no case was there any particular morbid appearance, except loss of contractility in the voluntary muscles. More recently results nearly the same have been obtained by Mitscherlich; and when doses of two drachms of sulphate of copper were given, he observed after death pale blueness of the villous coat of the stomach, mingled with brownness,—the apparent effect of chemical action.

Allied to these results are those obtained by my late colleague, Dr. Duncan, and by Mitscherlich, when the sulphate was applied to a wound. Dr. Duncan observed that death took place in twenty-two hours, and the body was every where in a healthy state. Mitscherlich found that a drachm of either sulphate or acetate proved fatal in four hours, with symptoms of extreme prostration. The experiments of M. Smith, repeated by Orfila, are at variance with these; for one or two drachms of the acetate applied to a wound in the thigh of a dog caused only local inflammation, and no constitutional symptoms.

It follows from the researches now detailed, that the salts of copper act in whatever way they are introduced into the system, and the more energetically, the more directly they enter the blood. The inquiries of Mr. Blake farther show, that when injected into the blood-*vessels, they act with peculiar force in exhausting muscular irritability, and occasion death by paralysing the heart if they are injected into a vein. Six grains of the sulphate injected into the jugular vein of a dog reduced the force of the heart's contractions, and fifteen grains arrested them in twelve seconds, leaving in the dead body distension of the heart, loss of contractility, and florid blood in the left cavities. Ten grains injected into the aorta through the axillary artery caused no sign of obstruction in the capillary system; and small doses of three or four grains occasioned vomiting, dyspnœa, and