SOLID
AIR
The
Manufacturer and Builder
Professor
Dewar communicated to the Royal Society at its
meeting on Thursday, March 9, [1893] a most interesting
development of his experiments upon air at very low
temperatures. Our readers are already familiar
with the fact that he has liquefied air at
ordinary atmospheric pressure. He has now succeeded
in freezing it into a clear, transparent solid.
The precise nature of this solid is at present
doubtful, and can be settled only by further research. It
maybe a jelly of solid nitrogen containing liquid
oxygen, much as calves’ foot jelly contains
water diffused in solid gelatine, or it may be a true
ice of liquid air, in which both oxygen and
nitrogen exist in the solid form. The doubt arises from
the fact that Professor Dewar has not been able
by his utmost efforts to solidify pure oxygen,
which, unlike other gases, resists the cold
produced by its own evaporation under the air pump.
Nitrogen, on the other hand, can be frozen with
comparative ease. It has already been proved
that in the evaporation of liquid air nitrogen
boils off first. Consequently the liquid is
continually becoming richer in that constituent which has
hitherto resisted solidification. It thus becomes
a question whether the cold produced is
sufficiently great to solidify oxygen, or whether its
mixture with oxygen raises its freezing point,
or whether it is not really frozen at all, but merely
entangled among the particles of solid
nitrogen, like the rose water in cold cream. The result,
whatever may be its precise nature, has been
attained by use of the most powerful appliances
at command—a double set of the vacuum screens
already described in our columns, combined with
two powerful air pumps. Upon either view of
its constitution, the new solid is in the highest
degree interesting and hopeful.
Article from The Manufacturer and
Builder: A Practical Journal of Industrial Progress magazine,
July 1893, published by Western and Company, New York. (source)
