ABSTRACT
Early experimentation on liquefaction of gases aroused the imagination of industrialists like
Carl Linde who was already in the business of manufacturing refrigeration machines with
ammonia as the refrigerant. His company, the Linde Eismachinen AG, was founded in 1871.
With his background, Linde foresaw the possibility of recovering large quantities of oxygen
from the atmosphere, and using it in the metallurgical industry as an enriching agent to
increase operating efficiency in the recovery and production of metals. However, Linde’s
initial trials in 1895 were not very successful, however. He tried to liquefy air by compressing it
to 800 bar, and then expanding it through a throttle valve. He had hoped to cool the
compressed air at a rate of 0.35 of a degree per 1 bar pressure drop. He soon found out
that this procedure did not work. (The processed air was not at its critical temperature, and
was outside of its inversion curve.)
