“This twelfth series is interesting.  So far only radium, thorium, and uranium are generally known.  We know that the radioactive elements are constantly breaking down, and one often hears uranium, for instance, called the ‘parent’ of radium.  Radium also gives off an emanation, and among its products is helium, quite another element.  Thus the transmutation of matter is well known within certain bounds to all scientists to-day like yourself, Professor Kennedy.  It has even been rumoured but never proved that copper has been transformed into lithium—­both members of the hydrogen-gold group, you will observe.  Copper to lithium is going backward, so to speak.  It has remained for me to devise this protodyne apparatus by which I can reverse that process of decay and go forward in the table, so to put it—­can change lithium into copper and copper into gold.  I can create and destroy matter by protodyne.”

He had been fingering a switch as he spoke.  Now he turned it on triumphantly.  A curious snapping and crackling noise followed, becoming more rapid, and as it mounted in intensity I could smell a pungent odour of ozone which told of an electric discharge.  On went the machine until we could feel heat radiating from it.  Then came a piercing burst of greenish-blue light from a long tube which looked like a curious mercury vapour lamp.

After a few minutes of this Prescott took a small crucible of black lead.  “Now we are ready to try it,” he cried in great excitement.  “Here I have a crucible containing some copper.  Any substance in the group would do, even hydrogen if there was any way I could handle the gas.  I place it in the machine—­so.  Now if you could watch inside you would see it change; it is now rubidium, now silver, now caesium.  Now it is a hitherto unknown element which I have named after myself, presium, now a second unknown element, cottium—­ah!—­there we have gold.”

He drew forth the crucible, and there glowed in it a little bead or globule of molten gold.

“I could have taken lead or mercury and by varying the process done the same thing with the gold series as well as the gold group,” he said, regarding the globule with obvious pride.  “And I can put this gold back and bring it out copper or hydrogen, or better yet, can advance it instead of cause it to decay, and can get a radioactive element which I have named morganium—­after my first name, Morgan Prescott.  Morganium is a radioactive element next in the series to radium and much more active.  Come closer and examine the gold.”

Kennedy shook his head as if perfectly satisfied to accept the result.  As for me I knew not what to think.  It was all so plausible and there was the bead of gold, too, that I turned to Craig for enlightenment.  Was he convinced?  His face was inscrutable.

But as I looked I could see that Kennedy had been holding concealed in the palm of his hand a bit of what might be a mineral.  From my position I could see the bit of mineral glowing, but Prescott could not.