Ice
water in a solid state. Under ordinary conditions, water changes to ice at 32 deg. F. and 0 deg. C. In freezing, the molecules arrange themselves in hexagonal crystals, as may be seen by the examination of a snowflake. When exposed to the heat of the sun, ice not infrequently falls into six-sided needles or columns. One hundred volumes of water make 109 volumes of ice. Ice is lighter than water and floats, therefore, on its surface, protecting ponds and lakes from being frozen to a greater depth. Ice is far from being rigid. In fact, it is so fluid-like that on the slopes of mountains it runs down slowly, forming oftentimes enormous streams of ice, called glaciers. If a long slab of ice be supported at the two ends, the center will curve downward. A slight jar facilitates the formation of ice. If perfectly quiet, water will cool several degrees below the freezing point without solidifying; but a jar, which, no doubt, facilitates the rearrangement of the molecules, will turn it suddenly into ice. Under pressure sufficient to prevent expansion, water may be cooled far below the freezing point and yet remain a liquid. Seawater frezes at about 27 deg. F. The ice in some way drives down or excludes nearly all of the salt. The people of the Mediterranean early learned the use of ice in cooling drinks. They depended largely, however, on snow brought from the Alps and other mountain peaks.
Artificial ice has been produced for many centuries in oriental countries. Even at the present day the natives of the East Indies manufacture large quantities of ice. They dig a large, shallow pit and fill it level full of crushed sugar-cane stalks to secure perfect drainage. On these beds of dry cane they place shallow earthenware pans of water. The ware is so porous that the pans are no sooner filled with water than moisture appears on the outside. The evaporation of water, as is well known, absorbs immense quantities of heat. Evaporation takes place so rapidly on the outside of these dishes that, when the operation is carried on after nightfall, the water left in the dish is turned into a cake of ice. An establishment of this sort, described by a recent writer, contains 100,000 of these pans and is managed by 300 attendants. They draw water from a well and fill the pans in the day time. In the morning they go about with hooks and lift the cakes of ice from the pans and store them for use. It is necessary to grease the inside of the pan slightly to prevent the cake of ice from adhering to the earthenware. Farmers' boys have long followed a similar method of keeping water cool in the field. If the jug of water be surrounded by a wet bag or sack, the evaporation draws heat from the jug and keeps its contents delightfully cool.
The Australian traveler carries water in a cloth canteen. The small amount of water that escapes through the cloth and evaporates keeps the contents cool. It is even reported that railway companies take advantage of this method to hang cloth tanks of water on the rear platform of observation cars. The breeze created by the motion of the train evaporates the escaping moisture and affords the passengers a delightful drink. The plan seems plausible, at least.
On the same principle, of evaporation, ammonia is used to make ice. The details are too extended for description. In brief, cakes of ice are frozen somewhat like ice cream in freezers. The surounding brine is chilled to a bitter coldness by pipes in which liquid ammonia is evaporated. The brine absorbs the heat from the water and ice forms. The ammonia is used over and over with little loss. Artificial ice costs from fifty cents to $1.50 a ton, but the cost is falling. Very naturally artificial ice is used in warm countries to which the importation of natural ice would be expensive.
The first ice factory in the United States was established in New Orleans in 1866. The extent to which ammonia-made ice is used in the United States may surprise the reader. There are, according to a late census report, 1,500 American ice plants producing between 8,000,000 and 9,000,000 tons of artificial ice yearly. If we take cold storage warehouses into account, nearly half of the ice used in the United States is made by artificial means. Artificial ice is made in the form of briquettes. Throughout the Southern states ice is packed in gunny sacks and shipped to the smaller towns with the utmost regularity. Housekeepers buy their daily brick of ice along with other supplies.
The number of wagons engaged in distributing city ice is very great. In New York and Brooklyn alone there are 1,500 ice wagons. They distribute 5,000,000 tons a year. Philadelphia requires half as much.
Natural ice is harvested at a cost of from twenty-five to eighty cents a ton. The harvest of natural ice is a very important matter in the colder states. The icemen of Maine and the Hudson River put up over 2,000,000 tons a year. The other ice states harvest as much more. The Canadian provinces also harvest large amounts of excellent ice. We used to export ice, particularly to southern Europe and the West Indies. In 1870 our exports of ice rose to 65,000 tons, but improved methods of making artificial ice abroad have reduced our exports to a merely nominal quantity. In seasons of scarcity ice is brought by ships from Norway to New York.
The manufacture of artificial ice is increasing rapidly in European countries. A domestic ice machine not much more complex than an ice cream freezing machine is sold in German markets at fifteen dollars. Artificial ice as clear as crystal is made from the waters of the historic pools of Jerusalem. It is sold to the hotels, hospitals, foreign residents, and wealthy people of the city at two and one-half cents a pound.
There is a newly erected ice plant at Smyrna, built by an American company, and it is now doing a good business. An ice plant here has been making daily about six tons of poor ice, which it sold at $15 per ton. The new company makes from distilled water a fine, clear ice, which it sells at $5 a ton, and although it has been running scarcely thirty days, it is selling twenty-five to forty tons of ice daily.
The company has some unique competition from the mountain folk, who bring to Smyrna snow packed in skins. They save the snow in the winter by having it packed in trenches and covered with pine needles. The Turks are very conservative, and it is difficult to get some of them to use ice instead of the snow to which they have been accustomed for many years, even though the latter costs them one cent a pound, or $20 a ton. The new company puts a block of ice in a box with small circular saws at one end and produces an article that can not be distinguished from snow, and which is sold in successful competition with the mountain snow.--Consular Report.
See Cold Storage; Bacteria; Skating; Glacier; Greenland