of the conditions under which we expect to see heat generated—is the apparatus to be seen in this exhibit which may be appropriately termed the "water-pail forge." This consists of an ordinary wooden pail filled with water into which dips a metal plate connected with one terminal of the electric circuit. The other terminal is attached to a pair of blacksmith's tongs, with which the operator picks up and holds the piece of metal to be heated. Immediately upon his plunging this into the water the liquid begins to sputter and the metal to glow, until in a few seconds it is brought to a welding heat and is then speedily melted. The heating is so rapid that neither the water nor the metal a few inches away are more than slightly warmed. This curious phenomenon appears to be due to the localization of the resistance of the circuit at the surface of the heated metal by the interposition of a layer of hydrogen between the metal and the liquid. This is the explanation offered by two Belgian engineers who recently brought out the process abroad with apparently no knowledge of its prior use in this country. In their apparatus they used a glass jar lined with lead which formed the positive pole. The water was acidulated to render it conducting. When the circuit is completed by the immersion of the metal to be heated the current decomposes the liquid, the oxygen going to the lead plate and the hydrogen to the iron or other immersed metal and preventing any direct contact of the metal and the liquid. As hydrogen is a very poor conductor of electricity, the resistance would then be localized at the surface of the metal plate, with the result of heat being rapidly developed at this point. An American investigator, Mr. Jules Neher, who has experimented with the process, regards the heating as being due to the formation of an arc between the heated metal and the liquid, as he has observed that the heating does not take place if the metal be immersed before the current is turned on, the energy of the current then being spent in the electrolysis of the liquid. His explanation is that immediately the metal touches the liquid hydrogen begins to be liberated and, interposing itself between the metal and the liquid, draws an arc in the act of pushing the two asunder. This arc formed under water quickly raises the metal to a high temperature. Whatever the precise explanation, it certainly is a most astonishing thing to see pieces of iron and steel glowing at a white heat and running away in melted globules while surrounded by water. The capabilities of the apparatus would appear to be almost unlimited, and it is not too much to say that it is destined to find wide application in the arts. The operator has at his command the practically unlimited energy of electricity, and should be able to reach temperatures with it heretofore unattainable. The Belgian experimenters are reported to have succeeded in fusing carbon, and it has been suggested that
