COLD STORAGE, a method now generally employed for preserving perishable articles of food by the use of machines which reduce the temperature of the air. The same .method is used extensively for preserving articles other than food which are destructible by high tem perature. Refrigeration is often called ice making, but in a cold-storage building the area kept at a certain temperature bv the frozen liquid is small compared with that kept at a proper temperature by ammonia and other sub stitutes for ice. Perhaps no producc ever came into common use more rapidly than air treated according to the cold-storage method, unless • electricity or steam be excepted. It is now in dispensable in connection with. some of the largest business enterprises, which, without it, would soon cease to exist One of the most important uses of cold storage is in the trans portation of beef, fruit and vegetables, etc., from place to place and from one country to another, especially from the United States and South Arnerica to Europe.
The extensive systems employed in breweries, provision depots, dairies and distilleries have familiarized the public with the use of cold air; and no modern hotel or apartment house on a large scale is constructed without a plant for producing it by some process. . It is as much. a portion of the mechanical equipment. as the elevator motor, or the lighting and heating apparatus. It is also being introduced for cooling purposes in theatres and other audi toriums; it maintains a pleasant temperature during the heated term in the hospital ward, and .several companies have been formed to distribute it in cities through mains, a.-2 water and gas are supplied to the consumer. In some of the largest pacicing-houses of Kansas City and Chicago, not a pound of ice is used in a year for preservative purposes, although every department where the products of the beef, sheep and hog are stored any length of time is required to be at a temperature near.or below the freezing point. Plants are now being made in this country to generate cold air for butter and butterine factories, ice-cream factories, chemical works, sugar refineries, molasses fac tories, paraffine works, oil refineries, stearine factories, chocolate factories, morgues, office buildings, skating rinks, steel-tempering plants, blast-furnaces, laundries, glue works, dry-plate works, dynamite-works, paint factories, soap factories, fur storage, India-rubber works and plants for seasoning lumber—a list including some of the country's most important industries.
While an extensive variety of machinery is being manufactured for refrigeration under a score of patents, the aim of all the inventors is the same — to perfect the most economical process to remove the heat from a certain tem perature level to a higher level, discharging it at this point. With one ton of coal, a cold-air equivalent of from 8 to 14 tons of ice has been produced, the quantity varying according to the process employed. In the United States the refrigerating machines use anhydrous ammonia as the agent for generating low temperatures, mostly in conjunction with brine made from chlonde of calcium and water. The ammonia is circulated through a series of pipes in which it evaporates. Then, in its gaseous form, it is pumped by the machine into the condensers and liquefied The brine-cooler consists of a double pipe-coil. A small quantity of ammonia is injected through a needle valve, which allows a very fine streatn to pass into the space be tween two pipes, running in a coil approximately 300 feet long surrounding a pipe containing the brine. From this coil the ammonia gas is drawn to the machine. The gas is forced thence into other coils, called the ammonia condensers, which have water circulating over them. It is now in a heated condition from the compres sion. The water running over these coils cools off the gas, and at the same time condenses it into liquid anhydrous ammonia. In this form the ammonia is conducted to a receiving tank, and from there it again passes through the needle-valve into the brine-cooler, going through the same circuit again and again. The brine-cooler represents the apparatus where the brine and ammonia systems are in conjunction, the brine being pumped through the cooler, and from there through coils of pipe in the room in which it is desired to reduce the temperatures. This is sometimes to 20° F. below zero for freezing fish, sometimes to 32° F. for preserv ing meat, and often to 50° F. for preserving fruits and other perishables. The temperature is easily adjusted to the required degree by con trolling the brine-flow in the piping. By les sening or increasing the flow in a single pipe, a wide range of temperature can be produced. Thus the same room can be used either for freezing the articles it contains, or merely for chilling them.