By taking a ball of solid lead of a smaller size than the calibre of the musket, and placing it on the charge in a gun, and as much or nearly so of powder, over the ball, the effect we are assured is, that when the gun is fired, the ball will pass out without any very sensible force, and even drop a few yards from the gun, although the report will be as great as if the charge and ball had been used in the usual manner. This trick is often performed by jugglers, to the great astonishment of the spectators. The mode of catching a cannon ball is also of the same character.
The proper charge of powder for the cannon, is divided into two unequal portions, the lesser of which is placed in the gun as a charge; the ball is placed on it in the usual way, and the rest of the powder (by much the greater portion,) placed over the ball, the lesser quantity being not more than a twelfth part of the whole. A cannon, so charged, will not project the ball more than 20 yards, where it might be caught with safety.
Any person who has been in the custom of shooting, must have frequently observed, that when the shot happens to be mixed with the powder, its range is impeded; and, under similar circumstances, they have even been found only a few yards from the muzzle of the piece. This fact I have witnessed, although I confess I never once reflected on it.
As to the explanation of this phenomenon, it appears, that it can only be accounted for by referring to the action of two opposite forces, mutually repelling each other, added to that of the charge under the ball; hence, the reaction would be equal, if, under the same circumstances, both charges were alike situated: but the effect of the first charge is so much weakened by the counter effect of the second, that the projectile force of the ball becomes comparatively nothing.
There is another trick very often performed, which, however chemical, is not looked upon in that light, neither do performers attempt to explain it; we mean the exhibition of the Glace Inflammable of the French.
The preparation is made in the following manner: melt some spermaceti over a fire, and add a sufficient quantity of spirit of turpentine, and blend them together. The mixture when cold, will become solid, having somewhat the appearance of ice. If made in hot weather, the vessel containing the melted substances must be immersed in cold water. It does not, we are told, remain in a solid state any length of time.
It floats more or less in the fluid, which of course is the spirit of turpentine. The trick, with this preparation, after having put some of the solid and fluid substance together on a plate, is to pour upon it concentrated nitric acid, or a mixture of eight or ten parts of nitric acid, and two of sulphuric acid; inflammation ensues. It is no other in fact than accension of the oil of turpentine; the addition of the spermaceti is altogether secondary, and its effect, if any, must retard instead of promoting the combustion of the turpentine. The art of making this preparation is in rendering the essential oil solid and transparent, without altering its inflammable properties.
There is another trick performed, by burning a thread, to which an ear-ring is tied, and which, notwithstanding the thread is reduced to a cinder, still holds the ring. This is what the French call the Bague suspendue aux cendres d'un fil. The string is first prepared by soaking it for 24 hours, in a solution of common salt, and drying it; then tying it to a ring, and setting it on fire, avoiding any vibration or oscillation of the string. It is obvious that the salt serves to render the cinder cohesive.
We have an account in Maundrel's Travels from Aleppo to Jerusalem, of the office of the Holy Fire. The ceremony is kept up by the Greeks and Armenians, from a persuasion that every Easter eve, a miraculous flame descends from heaven into the holy sepulchre, and lights all the lamps and candles, as the sacrifice was consumed at the prayers of Elijah.
"On our approaching the holy sepulchre," says Maundrel, "we found it crowded with a numerous and distracted mob, who made a hideous clamour; but with some difficulty pressing through the crowd, we got up in the gallery next to the Latin convent, where we could have a view of all that passed. The people began, by running with all their might, round the holy sepulchre, crying out 'huia,' which signifies, 'This is he,' or, 'This is it.' After this, they began to perform many antic tricks: sometimes they dragged one another along the floor round the sepulchre; sometimes marched round with a man upright upon another's shoulders; at others, took men with their heels upwards, and hurried them about with such indecency, as to expose their nudities; and sometimes they tumbled round the sepulchre like tumblers on a stage. In a word, nothing can be imagined more rude and extravagant than what was acted upon this occasion.