"What is that?"

"The possession for half an hour of that mysterious steel casket which you
carry about with you, and full permission to analyze and test its
contents."

"Your analysis of the contents," returned Sir Philip, dryly, "would leave
you as ignorant as before of the uses to which they can be applied; but I
will own to you frankly, that it is my intention to select some confidant
among men of science, to whom I may safely communicate the wonderful
properties which certain essences in that casket possess. I invite your
acquaintance, nay, your friendship, in the hope that I may find such a
confidant in you. But the casket contains other combinations, which, if
wasted, could not be resupplied,--at least by any process which the great
Master from whom I received them placed within reach of my knowledge. In
this they resemble the diamond; when the chemist has found that the
diamond affords no other substance by its combustion than pure
carbonic-acid gas, and that the only chemical difference between the
costliest diamond and a lump of pure charcoal is a proportion of hydrogen
less than 1/100000 part of the weight of the substance, can the chemist
make you a diamond?

"These, then, the more potent, but also the more perilous of the casket's
contents, shall be explored by no science, submitted to no test. They are
the keys to masked doors in the ramparts of Nature, which no mortal can
pass through without rousing dread sentries never seen upon this side her
wall. The powers they confer are secrets locked in my breast, to be lost
in my grave; as the casket which lies on my breast shall not be
transferred to the hands of another, till all the rest of my earthly
possessions pass away with my last breath in life and my first in