The significance of the above-quoted extract will be readily perceived when we come to consider the action of the direct planetary electrical currents upon the solar envelope, the effects in both cases being substantially identical. The quantity and intensity of the electric current, as it passes through the incandescent arc to the negative pole, and thence back to the dynamo, are diminished exactly in proportion to the energy expended in the generation of the light and heat of the arc. It is precisely the same as in the operation of a turbine water-wheel; if working at its highest efficiency, the discharged water is almost deprived of force: its gravity has been converted into work. In the electric light this conversion is only partial, owing to atmospheric and other conditions; but in the case of the solar envelope and its core, it is nearly, if not altogether, perfect, so that the currents of electricity are almost entirely converted into light and heat, or expended in the electrolytic decomposition of the surrounding aqueous vapors, and do not reappear as electricity, but as converted solar energy. Brilliant, however, as the light rays are in a powerful arc lamp,--perhaps the nearest to solar light we can produce,--the obscure heat rays are far more numerous and powerful. On page 476 of the work just cited a table is given, showing the proportion of visible and invisible rays emitted by different illuminants, and with the electric lamp, even, ninety per cent. of all the rays emitted by the voltaic arc are heat rays, which are obscure and invisible. But the startling effects of electricity of large quantity and high potential, in the decomposition of water, are far more strikingly exhibited by an apparatus shown in 1893 at the Chicago Exhibition by a firm from Brussels, and which is described in the Electrical Review as follows: "An ordinary wooden pail is three-quarters filled with water slightly acidulated; a lead plate about nine inches broad by sixteen inches long dips to the bottom of the pail and is connected to an incandescent dynamo machine capable of giving over one hundred and fifty ampères. The iron rod, or article to be heated, is connected to the pole of the dynamo and simply dipped into the water; it immediately becomes heated and rapidly rises to a melting temperature; only that portion of the metal completely immersed becomes heated, and the heating is so rapid that neither the water nor that portion of the metal out of the water becomes very warm. Wrought iron and steel actually melt if long enough held under water. A carbon rod subjected to this process becomes amorphous carbon, proving that a temperature of at least four thousand degrees Centigrade has been reached, and it is stated that with two hundred and twenty volts' pressure a temperature of eight thousand degrees Centigrade has been reached. There are various theories to account for this phenomenon, but from close observation it appears to be a case of arc heating.