Cold Storage

a method of preserving perishable goods, such as fruit, dairy products, eggs, and meats, by storing them in a warehouse in which the air is kept at a low temperature by artificial means. The underlying principle to which cold storage owes its success is the important fact that bacteria cannot work in the cold, and that in consequence decay and putrefaction cannot take place in a cold room. Milk and butter keep well surrounded by the water of a cool spring. A cool cellar has a preservative influence. A refrigerator kept cool by the use of ice is a household convenience, especially in the city. A commodious refrigerator has become a necessity to the hotelkeeper. The butcher and the grocer must now provide large refrigerators for the perishable portion of their wares.

Cold storage warehouses are refrigerators on a large scale. Some are cooled by ice, but the immense cold storage plants that have sprung up of late are cooled by means of ammonia without the use of an ounce of natural ice. The reader may have noticed on a hot day that a little water sprinkled on the floor cools off a room delightfully. This is due to the fact that in evaporating or drying up, as the water on the floor quickly does, a great amount of heat is taken from the air of the room, leaving it cool. On somewhat the same principle ammonia is used to produce frost in a cold storage warehouse. It is evaporated in a system of pipes through the center of which run inner pipes containing a brine made of calcium chloride and water which becomes intensely cold without freezing. That is to say, the pipe of brine is surrounded by a larger pipe in which ammonia is evaporated, with the result of taking the heat out of the brine, and leaving it intensely cold like that in an ice cream freezer. The cold brine is forced through a second system of pipes somewhat like a steam heating system, suspended usually on the walls, or to the posts that support the floors of the various rooms of the warehouse. By governing the flow of brine, a room may be chilled simply, or it may be made so cold, even on a hot midsummer day, that its contents freeze solid. Both the brine and the ammonia are used over and over, like the steam in a heating plant. In an efficient plant or system, a ton of coal will furnish the power requisite to produce a cooling effect equivalent to that of from eight to fourteen tons of ice. Ice cannot be handled so efficiently nor so economically, to say nothing of the economy of space and the neatness of the ammonia process. The capacity of an ammonia refrigerating machine is stated in terms of which the cooling influence of a ton of ice is the unit. A five hundred ton machine, such as is used in connection with large breweries and packing houses, is a plant whose cooling capacity may be represented as equal to the effect that might be obtained by bringing 500 tons of ice into the building daily.

Poultry, fish, and game may be frozen solid, in which condition they will keep sound for an indefinite period. Ordinarily meats are kept at or near the freezing temperature. Fruits are placed in a cold, but not freezing room. Eggs are kept fresh in cold storage from two to six months, but it is difficult to keep them from spoiling on account of moisture. Butter keeps well, but must not be frozen. It requires pure air or it will taint.

Cold storage is one of the most satisfactory means of keeping furs. Insects, especially moths, cannot work in the cold. Most large cities now have cold fur storage rooms in which furs may be hung up on hooks and checked till wanted.

Refrigerated cars and ships are now used on a large scale for the transportation of perishable articles. The fruit and vegetable centers of California and the South send their products to market in ice-cooled cars which are refilled with ice by the railway companies at regular stopping places. In the summer season refrigerated cars make regular trips of once a week and upward over nearly all lines of railroad, delivering fresh meats and fruits, and collecting eggs and dairy products. The butcher, grocer, and local merchant regulate their orders and shipments accordingly. The meat raisers of Argentina send their products to European markets in refrigerated ships. A storage house at Dubuque, Iowa, belonging to the Fruit Dispatch Co., is cooled by four miles of pipes. It is capable of receiving a banana train of forty-four cars. The cars stand on track in hot weather and are cooled off after their hot journey from the Gulf. In midwinter the same plant is used to warm up the cars and their contents. About 3,000 cars or $2,000,000 worth of bananas are sheltered in this warehouse yearly.

The transportation and preservation of perishable produce has become one of the most serious problems which can engage the attention of engineers and others interested in the efficacious and rapid dispatch of foodstuffs from one part of the world to the other. Statistics and statements from high authorities go to show that the transport and preservation of perishable produce is an enormous and growing business, and likely in the future to be one of the most important in the world.

In spite of the careful fostering of home industries intended to provide the food supply of the United Kingdom, the imports of provisions are regularly increasing. Instead of drawing on near-by countries, the English people are looking more and more to their colonies in distant parts of the world for these supplies. This is made possible by the present methods of refrigeration.

There are 358 ships engaged in the trade of the United Kingdom that are fitted in part or throughout with a total refrigerating capacity of 36,266,000 cubic feet. Of this number, 71 ships, with a capacity of 3,341,000 cubic feet for perishable produce, bring supplies from the United States; from Australia and New Zealand, 92 ships, with 15,514,000 cubic feet cold-storage capacity, bring chiefly beef, mutton, and butter; from Canada come 47 ships, with 1,829,000 cubic feet capacity, chiefly with meats and dairy products. The number of ships coming from South America carrying refrigerated cargo is not given, but their capacity for this class of goods is placed at 7,611,000 cubic feet.

The port of London is at the head of the list in the number of vessels and their carrying capacity, and takes most of the Australian and New Zealand cargoes, while Liverpool is second and takes most of the North and South American cargoes. However, the shorter trips of the Liverpool steamers bring the yearly sailings and capacity as high or higher than those of London.

As the large quantities of foodstuffs arriving in this country can not be distributed direct to consumers, cold-storage warehouses have increased at the various seaports, in large centers of population, and at the principal distributing markets. The approximate refrigerating capacity of these warehouses in the principal towns varies from that of London, 9,000,000 cubic feet, to that of Hull, 250,000 cubic feet. The total capacity of these warehouses is not far from 23,000,000 cubic feet.

The value of butter imports into the United Kingdom increased from $38,920,417 in 1887 to $108,951,120 in 1907, the largest increase coming from Australia. In meat imports the value increased from $188,160,046 in 1903 to $202,651,818 in 1907. The average annual value of imported fruits, apples, apricots, peaches, oranges, pears, plums, lemons, and bananas for five years, from 1900 to 1904, was $38,086,016, while for the imports of 1907 the value was $45,257,228.--Vice-Consul W. J. Sulis, of Liverpool, in Consular and Trade Reports.