"It is, but not as strong as this new substance we have in combination with the silver here. So I think I'll try a little electrolysis--or, in plain English, electro-plating." As he spoke, the professor clipped a couple of platinum electrodes to the basin, one at each end. To the anode he attached one of the negatives, to the cathode a small piece of iron. "Now then, we'll soon see." He passed a low current into the wires, through a rheostat, with startling results. There was a sudden foaming of the solution and a weird vapor rose from it, luminous, milky, faintly orange. * * * * * For a moment, all they could do was stare. Then Professor Wentworth switched off the current and stepped toward the tank. Waving away that orange gas, he reached for the cathode and held it up. It was no longer iron, but silver, now. "Plated, you see!" he exclaimed in triumph. "Yes, but those fumes!" cried Jim. "Why, they were the same color as the--the Fire Ants, as you call them." "I know." The professor was not as calm as he pretended. "We have released some of their actinic rays captured by the negative, in prying loose our excess silver. Later I shall repeat the process and capture some of that vapor for analysis. At present, let us have a look at the negative already treated." He lifted the anode from the solution now, removed the negative, and held it up. A smile of satisfaction broke over his face, followed by a shudder. "There you are, Jim! Have a look!" Jim looked, with Joan peering over his shoulder, and his pulses tingled. It was a clear shot of that scattering half-circle of fiery termites, taken after he got away and swept back over them. "Say, that's wonderful!" he exclaimed. "Wonderful--but horrible!" echoed Joan. "I'll admit they're not much on looks," laughed Carter. "But their homely maps are worth a lot to me--ten thousand dollars, in fact!" He told her why, and what he proposed to do with the money, and Joan thought it a very good idea. While this was taking place, Professor Wentworth was re-developing the rest of the negatives. At last all had been salvaged, even those taken in the terrific heat over that weird glass city out there, and Jim was preparing to bear them back to Overton in triumph. He had thanked the kindly professor from the bottom of his heart, had even told him something of what he had been telling Joan. There remained but to put one last question, then go. "Summing it all up, what do you make of those nightmares?" he asked. "Do you think they can be destroyed?" Professor Wentworth did not reply at once. "I can perhaps answer your question better when I have analyzed this specimen of gas," he said at length, holding up a test-tube in which swirled a quantity of that luminous, milky orange vapor. "But if you wish to quote me for publication, you may say that when I have learned the nature of it, I shall devote all my energies to combating the menace it constitutes."