During a late lecture in the laboratory of Yale College, a quantity of fulminating mercury, probably about 100 or 150 grains, lay upon a paper, the paper lay on a small stool, which was made of pine plank, _one inch and a half thick_; a glass gas receiver, 5 or 6 quarts capacity, stood over the powder, as a guard, but without touching it, and stool and all stood on one of the shelves of the pneumatic cistern, surrounded by tall tubes and other glasses, several of which were within 6 or 8 inches. A small quantity of the fulminating powder, at the distance of a few feet, was merely flashed, by a coal of fire, but without explosion. In a manner, not easily understood, the whole quantity of powder under the large glass instantly exploded with an astounding report; _but the glass was not exploded_--it was merely thrown up a little; in its fall it was shattered, and broke a glass which it hit, but no fragment was _projected_, and none of the other contiguous tubes and glasses were even overset, nor were any of a large audience, and some of them very near, even scratched; _but the plank, one and a half inch thick, on which the powder lay, had a hole blown quite through, almost as large as the palm of one's hand_. This is a striking instance to prove that the _initial_ force of this powder, when exploded, is very great, but that it extends but a very little way. If it be strewed through a glass tube of three-fourths of an inch in diameter, and exploded by a coal of fire or hot iron, the tube may be held in the naked hand, and the powder only flashes without breaking the tube, and merely coats it over inside, and that very prettily, with the revived quicksilver. _Fulminating Silver._ Chemists are too well acquainted with the tremendous energy of this preparation, to make any comment upon its powers necessary. Unhappily, however, it is now made a subject of amusement; it is prepared for sale by those who know nothing of it, except as a nostrum, and it is bought by others who have not even this degree of knowledge. It is true it is put up in small quantities, in the little toys called torpedoes, and, if exploded one by one, they will ordinarily do no harm; but as they fall into the hands of children, we can never be secure that they will be discreetly used. A very severe accident, from the unexpected explosion of this substance, occurred some years since in the laboratory of Yale College. (See Bruce's Journal, Vol. I. p. 163.) And, notwithstanding that this occurrence was well known in New-Haven, the same accident, only under a severer form, has again occurred in that town.