A BLOCK THAT STOOD SOME TIME IN THE SUN.
After having performed its work in cooling the brine, the expanded gas is drawn from the pipes by means of powerful steam-pumps, and it is then compressed into a coil of iron pipes kept immersed in a tank of cold running water. This compression of the expanded gas requires very heavy machinery, and the operation develops much heat, which is absorbed by the running water. In other words, the expanding gas having absorbed much heat from the brine, and having been made cold by this means, must be deprived of the heat thus gained by compression again into a coil surrounded by running water, which takes away the heat as soon as it is developed by compression.
Being now restored to the liquid form, the gas is ready to go on another round, and may be used again and again. The only loss of gas sustained is from leaky joints in the pipes.
It is a curious sight to see these pipes and pumps, even in the hottest weather, all coated with a thick layer of snow-white frost, so thick that it may be scraped off with the hands and squeezed into a snowball. The brine-pumps soon lose their characteristic shape, and are scarcely recognizable, looking more like a fantastic snow-drift than a piece of iron machinery.
Sometimes we see fine fruit or a bouquet of handsome flowers which had been so placed in the water as to become frozen in the centre of a large block of crystal ice. Such objects form beautiful ornaments while they last.
Many people believe that coal is really at the foundation of cheap ice, and that it will presently be cheaper to use coal to make ice than to use it in transporting ice to the place where it is wanted. Artificial ice is already produced in considerable quantities in districts where natural ice is also cut for the market.