An inert, impalpable powder, suspended in water, immediately produces death, if injected into the jugular vein, because it shuts up the last divisions of the pulmonary artery. If the injected substances are not divided at first in the blood, so as to spread uniformly into the different branches, death does not take place so quickly, because a part of the sanguineous canals remains free for the circulation. This is the case when we inject quicksilver or air in so small a quantity as not to produce instantaneous death. The congestion, in this last case, is often alone sufficient to produce it after a certain time; in the other case, there is added to the obstruction a real pneumonia caused by the presence of quicksilver in the obliterated vessels. We shall now relate four experiments of M. Gaspard, which will show the effects of the stagnation of this fluid in different organs. “_First Experiment._ I introduced into the jugular vein of a small dog, four days old, thirty six grains of quicksilver purified through goat’s skin. Soon after he refused to suck, lost his vivacity, motility and heat, had dyspnoea and fever, and died at the end of twenty four hours, having been all the time much colder to the touch than the other pups with whom he was. On opening the thorax, the lungs were found much inflamed, almost hepatized, heavy, puckered up and full of mercury.” “_Second Experiment._ I injected into the left carotid artery of a sheep, very near the brain, half an ounce of mercury with water; I then tied with a double ligature the open vessel. The animal immediately manifested pain, and was for an instant immoveable, the head inclined, with stupor and a prominence of the eyes, which were extraordinarily open; then bending on the fore legs, twisting of the head and neck on the right shoulder, with a kind of stiffness or convulsive elasticity, which was always present till death, and returned, as by the effect of a spring, when I straightened the neck. Two hours after, standing impossible, state of drowsiness, some convulsive motions of the limbs, the left eye swelled, red and inflamed. The next day, the same state, almost total annihilation of the animal or external life, copious excretion of mucus by the left nostril, the eye still very large and inflamed. The third day, the same state; death took place fifty hours after the injection. On examination of the body it was found that the left eye was in a state of suppuration and contained mercury; the thyroid, pharyngeal auricular, lingual, labial, nasal and cerebral arteries of the left side, were admirably injected with this metal which run out under the instrument; but their capillary terminations contained none of it, and we could see to what ramification, to what sized caliber it had penetrated, and the point where it was unable to pass; the left nasal cavities exhibited a very pretty reticulated