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. A few simple tests were enough to show me that this other metal was platinum.
"Now, to a chemist, there was something very suggestive in the order in which these changes had been effected. Perhaps you can see the relation, Robert, which they bear to each other?"
"No, I cannot say that I do."
Robert had sat listening to this strange statement with parted lips and staring eyes.
"I will show you. Speaking atomically, bismuth is the heaviest of the metals. Its atomic weight is 210. The next in weight is lead, 207, and then comes mercury at 200. Possibly the long period during which the current had acted in my absence had reduced the bismuth to lead and the lead in turn to mercury. Now platinum stands at 197.5, and it was accordingly the next metal to be produced by the continued current. Do you see now?"
"It is quite clear."
"And then there came the inference, which sent my heart into my mouth and caused my