"Wonderful!" ejaculated Carton. "What is it?"
"Thermit," was all Kennedy said, as just a trace of a smile of satisfaction flitted over his face.
"Thermit?" echoed Carton, still as mystified as before.
"Yes, an invention of a chemist named Goldschmidt, of Essen, Germany. It is composed of iron oxide, such as conies off a blacksmith's anvil or the rolls of a rolling-mill, and powdered metallic aluminum. You could thrust a red-hot bar into it without setting it off, but when you light a little magnesium powder and drop it on thermit, a combustion is started that quickly reaches fifty-four hundred degrees Fahrenheit. It has the peculiar property of concentrating its heat to the immediate spot on which it is placed. It is one of the most powerful oxidizing agents known, and it doesn't even melt the rest of the steel surface. You see how it ate its way directly through this plate. Steel, hard or soft, tempered, annealed, chrome, or Harveyized—it all burns just as fast and just as easily. And it's comparatively inexpensive, also. This is an experiment Goldschmidt it fond of showing his students—burning holes in one—and two-inch steel plates. It is the same with a safe—only you need more of the stuff. Either black or red thermit will do the trick equally well, however."
Neither of us said anything. There was nothing to say except to feel and express amazement.
"Someone uncommonly clever or instructed by someone uncommonly clever, must have done that job at Langhorne's," added Craig. "Have you any idea who might pull off such a thing for Dorgan or Murtha?" he asked of Carton.
"There's a possible suspect," answered Carton slowly, "but since I've seen this wonderful exhibition of what thermit can do, I'm almost ashamed to mention his name. He's not in the class that would be likely to use such things."
"Oh," laughed Kennedy, "never think it. Don't you suppose the crooks read the scientific and technical papers? Believe me, they have known about thermit as long as I have. Safes are constructed now that are proof against even that, and other methods of attack. No indeed, your modern scientific cracksman keeps abreast of the times in his field better than you imagine. Our only protection is that fortunately science always keeps several laps ahead of him in the race—and besides, we have organized society to meet all such perils. It may be that the very cleverness of the fellow will be his own undoing. The unusual criminal is often that much the easier to run down. It narrows the number of suspects."
"Well," rejoined Carton, not as confident now as when he had first met us in the laboratory, "then there is a possible suspect—a fellow known in the underworld as 'Dopey' Jack—Jack Rubano. He's a clever fellow—no doubt. But I hardly think he's capable of that, although I should call him a rather advanced yeggman."
"What makes you suspect him?" asked Kennedy eagerly.