Evening star. [volume] (Washington, D.C.) 1854-1972, 1939-07-09
What dry ice really is
and how il works
by
J. y. Ra1cli6

wv likely that in at least half dozen
w spots in the United States news
papers are reporting heat wave. Yet in these
same areas certain groups of workers are
dressed for Dakota blizzard.
They wear long underwear and heavy socks.
Thick wooden trousers are tucked in heavy
shoes, and their ears are muff1ed. In the place
where they work the temperature hangs
around ten below zero - far colder than it is
at the moment in the North Polar regions.
These are the storage men who handle the
very coolest product in modern commerce -
dry ice.
Dry ice is the miracle baby of new in
dustry: an infant prodigy that bucked the
tide of depression and grew Justify while other
businesses were languishing.
1t has revolutionized the ice cream business
Not 50 many years ago when housewife
wanted ice cream for dinner she had to plan
for it we'll in advance 1t was delivered,
packed in quantities of ice, in freezer the
size of a bushel basket. The freezer hung
around on the back porch until someone
thought to call for it week or 50 later. All
Ill oil, TIC CICdlu VII IilC uAAlCi AiCuu ACP1S-
sented serious business.
Today? The process is utterly painless
Someone stops in a drugstore few hours
before mealtime to pick up cardboard con-
tainer of ice cream. A pat of dry ice the size
of sausage cake will keep it in excellent con-
dition for hours. Most drugstores have
supply of the new refrigerant on hand to care
for cash-and-carry ice-cream trade. This use
of dry ice is the one with which most people
are familiar. There are scores of other uses
that consume thousands of tons of this new
product annually. Let's look at some of them.
In melting, dry ice passes directly into
gaseous stage, generating huge quantities of
carbon dioxide This fact is utilized by drilers
to clean wells. A chunk of carbon-dioxide ice
is dropped in the well, and the well is sealed.
When pressure has had time to generate the
cap is removed and the well blows clean. In
its liquid form cartridges of carbon dioxide
are valuable in coal mining Packed in bore
hole and sealed there, the cartridge releases
its stored-up pressure and blasts down coal.
One nurseryman had bright hunch He
had an order to transplant large tree. Such
jobs, he knew, were always tedious. Dirt fell
away from the roots and the tree was fire.
quently damaged beyond repair. Dry ice
solved his problem. First the nurseryman
soaked the earth around the tree with water
and then laid slabs of the ice on top of the
ground around the tree trunk. When the ball
of earth around the roots was frozen into a
hard lump he picked the tree up with crane
and moved it without trouble.
In medicine dry ice packed in pencil
shaped receptacle is helpful in desensitizing
areas of skin about to undergo painful treat
ment. 1t is useful in the machine trades and
the aeronautics industry where one metal
member must fit tightly against another Take
airplane rivets for instance Rivets are chilled
with dry ice. They contract. Then they are
inserted in the holes drilled for them and
expand to make a snug fit
Industries that must handle spongy and
gummy materials have found dry ice an in
valuable aid. Getting sharply trimmed edge
on a sponge-rubber bath mat would be diff
fcult with ordinary cutting tools. But once
dry ice freezes that rubber into hard, in
elastic mass it can be cut with precision. Dry
ice also aids in making golf balls. Liquid centers
are frozen and the ball is wound around them.
One municipal water company struck on a
novel use after large main had broken.
Under usual repair practice the water would
have been shut off and all residents between
the break and the valve would have been