LIQUID AIR AND ITS. POSSIBILITIES
in 1869 discovered the cause of failure on the part of former
scientists, and from this year dates the new method of treating
gases for their liquid state.
By this new fact the secret of obtaining the liquid of all gases
was learned and upon it scientists worked until finally in 1877
two reports of success were received simultaneously by the Royal
Institute of London. Pictet reported a method of liquefying
oxygen which was somewhat long and circuitous, while Gailletet
described a method based upon the principle which is how used
and by which large quantities of liquid air are secured at a very
low cost.
Honor is due an American however for demonstrating that
liquid air is a commercial success, yet Dr. Linde a German
scientist has the privilege of installing the first plant which shall
do service commercially.
Let us ask ourselves what is a solid, a liquid, or a vapor, or
why does a substance assume one of these three forms ? Why is
water once a solid and again a vapor ? You say at once because
of the differende of temperature. Certainly, and this is the con
dition which governs the form of any substance or element.
Let us imagine ourselves to inhabit the sun, then what would be
the constituents of our rain ? A liquid having a very high boil
ing point to be sure. Again, suppose the temperature of the
atmosphere at-200° C. to be as common and comfortable to us as
6o° F.; then what would constitute the dew and the rain ? It
would be a mixture of oxygen and nitrogen in the same propor
tion as we find it in the atmosphere. Hence we find that whether
a substance is solid, liquid, or vapor its form is dependent upon
its temperature; a relative condition only.
Pictet in bis method of liquefying oxygen used several liquids
as •auxiliary means of obtaining a low temperature. First he
liquefied sulphur dioxide by means of pressure. Then by boil
ing this in a partial vacuum he secured a temperature,--r r e C.,
much lower than its critical temperature by means of which he
obtained liquid ethylene. He then boiled this liquid ethylene
in a partial vacuum in the same manner as he did the liquid of
sulphur dioxide thus securing, again, a fall of temperature
which reached 119° C. He thus secured a sufficiently low tem
perature to liquefy the oxygen.
The method as improved by Dr. Linde of Munich and the