The well-known experiment of the electrolysis of water will, of course, occur to you. But I found that in the case of elemental solids the effect was a remarkable one. The element slowly decreased in weight, without perceptibly altering in composition. I hope that I make myself clear to you?"
"I follow you entirely," said Robert, deeply interested in his companion's narrative.
"I tried upon several elements, and always with the same result. In every case an hour's current would produce a perceptible loss of weight. My theory at that stage was that there was a loosening of the molecules caused by the electric fluid, and that a certain number of these molecules were shed off like an impalpable dust, all round the lump of earth or of metal, which remained, of course, the lighter by their loss. I had entirely accepted this theory, when a very remarkable chance led me to completely alter my opinions.
"I had one Saturday night fastened a bar of bismuth in a clamp, and had attached it on either side to an electric wire, in order to observe what effect the current would have upon it. I had been testing each metal in turn, exposing them to the influence for from one to two hours. I had just got everything in position, and had completed my connection, when I received a telegram to say that John Stillingfleet, an old chemist in London with whom I had been on terms of intimacy, was dangerously ill, and had expressed a wish to see me. The last train was due to leave in twenty minutes, and I lived a good mile from the station, I thrust a few things into a bag, locked my laboratory, and ran as hard as I could to catch it.
"It was not until I was in London that it suddenly occurred to me that I had neglected to shut off the current, and that it would continue to pass through the bar of bismuth until the batteries were exhausted. The fact, however, seemed to be of small importance, and I dismissed it from my mind. I was detained in London until the Tuesday night, and it was Wednesday morning before I got back to my work. As I unlocked the laboratory door my mind reverted to the uncompleted experiment, and it struck me that in all probability my piece of bismuth would have been entirely disintegrated and reduced to its primitive molecules. I was utterly unprepared for the truth.
"When I approached the table I found, sure enough, that the bar of metal had vanished, and that the clamp was empty. Having noted the fact, I was about to turn away to something else, when my attention was attracted to the fact that the table upon which the clamp stood was starred over with little patches of some liquid silvery matter, which lay in single drops or coalesced into little pools. I had a very distinct recollection of having thoroughly cleared the table before beginning my experiment, so that this substance had been deposited there since I had left for London. Much interested, I very carefully collected it all into one vessel, and examined it minutely. There could be no question as to what it was. It was the purest mercury, and gave no response to any test for bismuth.
"I at once grasped the fact that chance had placed in my hands a chemical discovery of the very first importance. If bismuth were, under certain conditions, to be subjected to the action of electricity, it would begin by losing weight, and would finally be transformed into mercury. I had broken down the partition which separated two elements.
"But the process would be a constant one. It would presumably prove to be a general law, and not an isolated fact. If bismuth turned into mercury, what would mercury turn into? There would be no rest for me until I had solved the question. I renewed the exhausted batteries and passed the current through the bowl of quicksilver. For sixteen hours I sat watching the metal, marking how it slowly seemed to curdle, to grow firmer, to lose its silvery glitter and to take a dull yellow hue. When I at last picked it up in a forceps, and threw it upon the table, it had lost every characteristic of mercury, and had obviously become another metal.