one to the pyramid or burned down a house to
roast a pig. Not until his laboratory is as cool and calm and
comfortable as the forest and the field can the chemist call himself
completely successful.

But in spite of his clumsiness the chemist is actually making things
that he wants and cannot get elsewhere. The calcium carbide that he
manufactures from inorganic material serves as the raw material for
producing all sorts of organic compounds. The electric furnace was first
employed on a large scale by the Cowles Electric Smelting and Aluminum
Company at Cleveland in 1885. On the dump were found certain lumps of
porous gray stone which, dropped into water, gave off a gas that
exploded at touch of a match with a splendid bang and flare. This gas
was acetylene, and we can represent the reaction thus:

CaC_{2} + 2 H_{2}O --> C_{2}H_{2} + CaO_{2}H_{2}

calcium carbide _added_ to water _
gives_ acetylene _and_ slaked lime

We are all familiar with this reaction now, for it is acetylene that
gives the dazzling light of the automobiles and of the automatic signal
buoys of the seacoast. When burned with pure oxygen instead of air it
gives the hottest of chemical flames, hotter even than the oxy-hydrogen
blowpipe. For although a given weight of hydrogen will give off more
heat when it burns than carbon will, yet acetylene will give off more
heat than either of its elements or both of them when they are separate.
This is because acetylene has stored up heat in its formation instead of
giving it off as in most reactions, or to put it in chemical language,
acetylene is an endothermic compound. It has required energy to bring
the H and the C together, therefore it does not require energy to
separate them, but, on the contrary, energy is released when they are
separated. That is to say, acetylene is explosive not only when mixed
with air as coal gas is but by itself. Under a suitable impulse
acetylene will break up into its original carbon and hydrogen with great
violence. It explodes with twice as much force without air as ordinary
coal gas with air. It forms an explosive compound with copper, so it has
to be kept out of contact with brass tubes and stopcocks. But compressed
in steel cylinders and dissolved in acetone, it is safe and commonly
used for welding and melting. It is a marvelous though not an unusual
sight on city streets to see a man with blue glasses on cutting down
through a steel rail with an oxy-acetylene