As soon as the acid touches the salt the latter is decomposed, and liberates a gas which ignites the phosphorus, producing much the same appearance as in the last experiment.
Into the half of a broken phial put some chlorate of potash, and pour in some oil of vitriol. The phial will soon be filled with a heavy gas of a deep yellow color. Tie a small test tube at right angles to the end of a stick not less than a yard long, put a little ether into the tube, and pour it gently into the phial of gas, when an instantaneous explosion will take place, and the ether will be set on fire. This experiment should be performed in a place where there are no articles of furniture to be damaged, as the ingredients are often scattered by the explosion, and the oil of vitriol destroys all animal and vegetable substances.
Into a jar containing oxygen gas introduce a coil of soft iron wire, suspended to a cork that fits the neck of the jar and having attached a small piece of charcoal to the lower part of the wire, ignite the charcoal. The iron will take fire and burn with a brilliant light, throwing out bright scintillations, which are oxide of iron, formed by the union of the gas with the iron; and they are so intensely hot that some of them will probably melt their way into the sides of the jar, if not through them.
But by far the most intense heat, and most brilliant light, may be produced by introducing a piece of phosphorus into a jar of oxygen. The phosphorus may be placed in a small copper cup, with a long handle of thick wire passing through a hole in a cork that fits the jar. The phosphorus must first be ignited; and as soon as it is introduced into the oxygen, it gives out a light so brilliant that no eye can bear it, and the whole jar appears filled with an intensely luminous atmosphere. It is well to dilute the oxygen with about one-fourth part of common air, to moderate the intense heat, which is nearly certain to break the jar if pure oxygen is used.
The following experiment shows the production of heat by chemical action alone: Bruise some fresh-prepared crystals of nitrate of copper, spread them over a piece of tin foil, sprinkle them with a little water; then fold up the foil tightly, as rapidly as possible, and in a minute or two it will become red hot, the tin apparently burning away. This heat is produced by the energetic action of the tin on the nitrate of copper, taking away its oxygen in order to unite with the nitric acid, for which, as well as for the oxygen the tin has a much greater affinity than the copper has.
Combustion without flame may be shown in a very elegant and agreeable manner, by taking a coil of platinum wire and twisting it round the stem of a tobacco pipe, or any cylindrical body for a dozen times or so, leaving about an inch straight, which should be inserted into the wick of a spirit lamp. Light the lamp, and after it has burned for a minute or two, extinguish the flame quickly; the wire will soon become red hot, and, if kept from draughts of air, will continue to burn until all the spirit is consumed.
Spongy platinum, as it is called, answers rather better than wire, and has been employed in the formation of fumigators for the drawing-room, in which, instead of pure spirit, some perfume, such as lavender water, is used; by its combustion an agreeable odor is diffused through the apartment. These little lamps were much in vogue a few years ago, but are now nearly out of fashion. Finally, all the readers of this little book should be very careful in performing all experiments. If possible, he should use a room with a stone floor and no curtains, while an outhouse with an earthen floor is still less dangerous.