must be properly prepared for the flame, and the operation of the torches
for best results requires careful and correct regulation of the gases and
the flame produced.

Finally, the different metals that are to be welded require special
treatment for each one, depending on the physical and chemical
characteristics of the material.

It will thus be seen that the apparently simple operations of welding and
cutting require special materials, instruments and preparation on the part
of the operator and it is a proved fact that failures, which have been
attributed to the method, are really due to lack of these necessary
qualifications.


OXYGEN

Oxygen, the gas which supports the rapid combustion of the acetylene in the
torch flame, is one of the elements of the air. It is the cause and the
active agent of all combustion that takes place in the atmosphere. Oxygen
was first discovered as a separate gas in 1774, when it was produced by
heating red oxide of mercury and was given its present name by the famous
chemist, Lavoisier.

Oxygen is prepared in the laboratory by various methods, these including
the heating of chloride of lime and peroxide of cobalt mixed in a retort,
the heating of chlorate of potash, and the separation of water into its
elements, hydrogen and oxygen, by the passage of an electric current. While
the last process is used on a large scale in commercial work, the others
are not practical for work other than that of an experimental or temporary