with a blast, nor by confining heat in a furnace, but in an exhausted
bulb we can concentrate any amount of energy upon a minute button.
Leaving practicability out of consideration, this, then, would be the
means which, in my opinion, would enable us to reach the highest
temperature. But a great difficulty when proceeding in this way is
encountered, namely, in most cases the body is carried off before it
can fuse and form a drop. This difficulty exists principally with an
oxide such as zirconia, because it cannot be compressed in so hard a
cake that it would not be carried off quickly. I endeavored repeatedly
to fuse zirconia, placing it in a cup or arc light carbon as indicated
in Fig. 23. It glowed with a most intense light, and the stream of the
particles projected out of the carbon cup was of a vivid white: but
whether it was compressed in a cake or made into a paste with carbon,
it was carried off before it could be fused. The carbon cup containing
the zirconia had to be mounted very low in the neck of a large bulb,
as the heating of the glass by the projected particles of the oxide
was so rapid that in the first trial the bulb was cracked almost in an
instant when the current was turned on. The heating of the glass by
the projected particles was found to be always greater when the carbon
cup contained a body which was rapidly carried off--I presume because
in such cases, with the same potential, higher speeds were reached,
and also because, per unit of time, more matter was projected--that
is, more particles would strike the glass.

The before mentioned difficulty did not exist, however, when the body
mounted in the carbon cup offered great resistance to deterioration.
For instance, when an oxide was first fused in an oxygen blast and
then mounted in the bulb, it melted very readily into a drop.

Generally during the process of fusion magnificent light effects were