as minute points which were easily separable from
the mass by the action of acids. Thus the wonderful transformation from
sugar to the diamond was accomplished.

It should be mentioned that iron, silver, and water, alone possess the
peculiar property of expanding when passing from the liquid to the solid
state.

The diamonds so obtained were of both kinds. The particles of white
diamond resembled in every respect the true brilliant. But there was also
an appreciable quantity of the variety known as the "black diamond."
These diamonds seem to approximate more closely to carbon as we are most
familiar with it. They are not considered as of such value as the
transparent form, but they are still of considerable commercial value.
The _carbonado_, as this kind is called, possesses so great a degree of
hardness that by means of it it is possible to bore through the hardest
rocks. The diamond drill, used for boring purposes, is furnished around
the outer edge of the cylinder of the "boring bit," as it is called, with
perhaps a dozen black diamonds, together with another row of Brazilian
diamonds on the inside. By the rotation of the boring tool the sharp
edges of the diamonds cut their way through rocks of all degrees of
hardness, leaving a core of the rock cut through, in the centre of the
cylindrical drill. It is found that the durability of the natural edge of
the diamond is far greater than that of the edge caused by _artificial_
cutting and trimming. The cutting of a pane of glass by means of a ring
set with an artificially-cut diamond, cannot therefore be done without
injuring to a slight extent the edge of the stone.

The diamond is the hardest of all known substances, leaving a scratch on
any substance across which it may be drawn. Yet it is one whose form can
be changed, and whose hardness can be completely destroyed, by the simple
process of combustion. It can be deprived of its high lustre, and of its
power of breaking up by refraction the light of the sun into the various
tints of the solar spectrum, simply by heating it to a red heat, and then
plunging it into a jar of oxygen gas. It immediately expands, changes
into a coky mass, and burns away. The product left behind is a mixture of
carbon and oxygen, in the proportions in which it is met with in
carbonic-anhydride, or, carbonic acid gas deprived of its water. This is
indeed a strange transformation, from the most valuable of all our
precious stones to a compo