ICE IN TROPICS

Dominion, Volume 28, Issue 86, 5 January 1935, Page 17

ICE IN TROPICS

A QUEER CRAFT’S MISSION.

It seems something of a paradox to go out into tropical seas to make ice, but this is what the French scientist Georges Claude has set out to Jo oti his ship the Tunisie, . A curious craft she looks, her funnel and masts almost hidden by the great pipes, cylinders, and reservoirs pilei', on her deck. This apparatus weighs 250 tons, but the Tunisie will not be top-heavy, as iu her holds she carries 5000 tons of coal. Accompanying her is a cargo boat carrying 2200 feet of thick piping in sections. When the Tunisie reaches a point some 12 miles off Rio de Janeiro she will anchor, the piping will be lowered to the bottom of the sea, and cold water will bo pumped up into the complicated mechanism which is to produce the artificial ice. It is well known that half a mile below the surface of the sea--the temperature of the water is only a few degrees above freezing-point The reason why ice can be made even iu such a hot temperature is due to the sudden change from heat to cold producing' energy which can be economically made use of. Extreme cold is produced by the expansion of gases; when a gas is compressed its temperature rises, and when the reverse takes place, and. it is rarefied, it rapidly becomes cold.

This principle is used in refrigeration. Air in a cylinder is first compressed and thus becomes hot. A current of cold water is then poured on the cylinder to reduce the temperature of the air within to that of the air outside. The condensed air is next allowed to expand, and in the couise of this expansion its temperature falls to many degrees below freezing-point. Heat and cold brought together wilt always mingle until a mean temperature is reached, with the result that any warmer body, like a tank of water, which is placed in the ice-cold air win drop in temperature until it freezes.