not fully account for all the phenomena they observed in handling
liquefied air, and in 1898 Professor Ramsay was again able to electrify
his audience at the Royal Society by the announcement of the discovery,
in pretty rapid succession, of three other elementary substances as
constituents of the atmosphere, these three being the ones just referred
to--krypton, neon, and zenon.

It is a really thrilling experience, standing in the presence of the
only portions of these new substances that have been isolated, to hear
Professor Ramsay and Dr. Travers, his chief assistant, tell the story
of the discovery--how they worked more and more eagerly as they found
themselves, so to say, on a "warmer scent," following out this clew
and that until the right one at last brought the chase to a successful
issue. "It was on a Sabbath morning in June, if I remember rightly,
when we finally ran zenon down," says Dr. Travers, with a half smile;
and Professor Ramsay, his eyes twinkling at the recollection of this
very unorthodox procedure, nods assent. "And have you got them all
now?" I queried, after hearing the story. "Yes; we think so," replied
Professor Ramsay. "And I am rather glad of it," he adds, with a half
sigh, "for it was wearisome even though fascinating work." Just how
wearisome it must have been only a professional scientific investigator
can fully comprehend; but the fascination of it all may be comprehended
in some measure by every one who has ever attempted creative work of
whatever grade or in whatever field.

I have just said that the little test-tubes contain the only bit of
each of the substances named that has ever been isolated. This statement
might lead the untechnical reader to suppose that these substances, once
isolated, have been carefully stored away and jealously guarded, each
in its imprisoning test-tubes. Jealously guarded they have been, to be
sure, but there has not been, by any means, the solitary confinement
that the words might seem to imply. On the contrary, each little whiff
of gas has been subjected to a variety of experiments--made to pass
through torturing-tubes under varying conditions of temperature, and
brought purposely in contact with various other substances, that its
physical and chemical properties might be tested. But in each case the
experiment ended with the return of the substance, as pure as before, to
its proper tube. The precise results of all these experiments have been
communicated