Fig. 6.
After this, "Homberg's Pyrophorus," consisting of a roasted mixture of alum and flour, was suggested as a means of obtaining fire. Then comes the "Electrophorus," an electrical instrument suggested by Volta, which was thought at the time a grand invention for the purpose of getting light (Fig. 6 A). The nuisance about this instrument was that it proved somewhat capricious in its action, and altogether declined to work in damp foggy weather. I do not know whether I shall be successful in lighting a gas-jet with the electrophorus, but I will try. I excite this plate of resin with a cat-skin (Fig. 6 B), then put this brass plate upon the resin plate and touch the brass (Fig. 6 C); then take the brass plate off the resin plate by the insulating handle and draw a spark from it, which I hope will light the gas. There, I have done it! (Fig. 6 D.)
Fig. 7.
Well, next after the electrophorus comes the "fire syringe" (Fig. 7). The necessary heat in this case is produced by the compression of air. You see in this syringe stopped at one end, I have a certain quantity of air. My piston-rod (C) fits very closely into the syringe (B), so that the air cannot escape. If I push the piston down I compress the air particles, for they can't get out;—I make them in fact occupy less bulk. In the act of compressing the air I produce heat, and the heat, as you see, fires my tinder.
It was in or about the year 1807 that "chemical matches" were introduced to the public for the first time. These chemical matches were simply sulphur matches tipped with a mixture of chlorate of potash and sugar. These matches were fired by dipping them in a bottle containing asbestos moistened with sulphuric acid. Here is one of these "chemical matches," and here the bottle of asbestos and sulphuric acid. I dip the match into the bottle and, as you see, it catches fire.
Fig. 8.
In the year 1820, Dobereiner, a very learned man, discovered a method of getting fire by permitting a jet of hydrogen to play upon finely-divided platinum. The platinum, owing to a property it possesses in a high degree (which property however is not special to platinum), has the power of coercing the union of the hydrogen and oxygen. Here is one of Dobereiner's original lamps (Fig. 8). I am going to show you the experiment, however, on a somewhat larger scale than this lamp permits. Here I have a quantity of fine platinum-wire, made up in the form of a rosette. I place this over the coal-gas as it issues from the gas-burner, and, as you see, the platinum begins to glow, until at last it becomes sufficiently hot to fire the gas (Fig. 9).