iece and were charged
with oil emulsion, thermit and metallic sodium. Sodium decomposes water
so that if any attempt were made to put out with a hose a fire started
by one of these bombs the stream of water would be instantaneously
changed into a jet of blazing hydrogen.

Besides its use in combining and separating different elements the
electric furnace is able to change a single element into its various
forms. Carbon, for instance, is found in three very distinct forms: in
hard, transparent and colorless crystals as the diamond, in black,
opaque, metallic scales as graphite, and in shapeless masses and powder
as charcoal, coke, lampblack, and the like. In the intense heat of the
electric arc these forms are convertible one into the other according to
the conditions. Since the third form is the cheapest the object is to
change it into one of the other two. Graphite, plumbago or "blacklead,"
as it is still sometimes called, is not found in many places and more
rarely found pure. The supply was not equal to the demand until Acheson
worked out the process of making it by packing powdered anthracite
between the electrodes of his furnace. In this way graphite can be
cheaply produced in any desired quantity and quality.

Since graphite is infusible and incombustible except at exceedingly high
temperatures, it is extensively used for crucibles and electrodes. These
electrodes are made in all sizes for the various forms of electric lamps
and furnaces from rods one-sixteenth of an inch in diameter to bars a
foot thick and six feet long. It is graphite mixed with fine clay to
give it the desired degree of hardness that forms the filling of our
"lead" pencils. Finely ground and flocculent graphite treated with
tannin may be held in suspension in liquids and even pass through
filter-paper. The mixture with water is sold under the name of
"aquadag," with oil as "oildag" and with grease as "gredag," for
lubrication. The smooth, slippery scales of graphite in suspension slide
over each other easily and keep the bearings from rubbing against each
other.

The other and more difficult metamorphosis of carbon, the transformation
of charcoal into diamond, was successfully accomplished by Moissan in
1894. Henri Moissan was a toxicologist, that is to say, a Professor of
Poisoning, in the Paris School of Pharmacy, who took to experimenting
with the electric furnace in his leisure hours and did more to
demonstrate its possibilities than an