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Heating, Lighting, and Refrigeration: Harvest

To Harvest Commercial Ice.-Ice has been an important article of commerce since the time of Nero, and in cold countries family ice houses are very common. Sometimes these storage places are merely pits or caves under ground, or partly under ground, but an ice house wholly above ground is to be preferred.

Ice from salt or brackish water is nearly pure, as freezing expels the mineral ingredients, but it is sufficiently contaminated on the surface to be unfit for many purposes. Hence the best ice crop is usually gathered from fresh-water ponds, or lakes, or in rivers above tide water. A great deal of ice is also manufactured artificially. Commercial ice houses are usually built of wood, having hollow walls that may be double, triple, or quadruple, the spaces between being filled with sawdust, spent tan bark, HEATING, LIGHTING, AND REFRIGERATION or some other poor conductor of heat.

In harvesting ice the usual practice is to scrape the snow from the surface of the ice by means of a scraper drawn by horses, to plane off the soft porous top of the ice if necessary by means of a horse planer, and to mark the ice into blocks by running a series of grooves about 5 feet apart and 3 inches deep so as to make blocks 5 feet square. Ice is usually cut when it is about 2 feet thick. After the ice has been marked one row of block is usually cut through by means of a handsaw, and pushed under out of the way or pulled up on the ice. The succeeding blocks are pried off with a crowbar, towed to the landing place, and loaded into wagons or run up an inclined plane to the storehouse and packed away. The blocks are stood on end in a solid mass. A space is left between the ice and the walls of the ice house in which are gutters and drainways to receive and carry off the drainage from the melted ice.

Ice-Domestic Harvest.-To gather ice for home use, cut it as soon as it is thick enough, and before the surface has been covered with snow or has had a chance to freeze and thaw a number of times. If a light snow "To Gather Ice for Home Use." falls before the ice is gathered it is advisable to clear off a sufficient space before a thaw sets in. A horse plow for marking the ice is desirable, and one can usually be borrowed if necessary, but a crosscut saw may be used. After one row of blocks has been sawed out it is only necessary to saw across the ends of the blocks. They may be separated lengthwise by marking with an ax and splitting off with an ice pick or chisel. It is not desirable to cut cakes larger than 2 by 3 feet if the work is to be done by hand. Provide a runway or ice ladder about 26 inches wide and 12 feet long to reach from the sled into the water.

Drive two upright planks or timbers into the ice, and attach a crossbar at the top of the sled on which to support one end of the runway, the other reaching down in the water. Two men with ice hooks can pull a cake 3 feet long, 2 feet wide, and 18 inches or more in depth up this runway and load it upon the sled without undue exertion.

To Preserve Ice. -The two requisites to preserve ice are the exclusion of heat and outer air, and the drainage of the water produced by melting without at the same time allowing the cold air surrounding the ice to escape.

A piece of ice of 50 pounds weight exposed at a temperature of 80°, but placed on cross slats so as to be perfectly drained, will not melt under twenty-four hours. But if exposed at the same temperature in a tight vessel that will retain the water produced by melting, it will dissolve in six or seven hours. Hence ice houses, refrigerators, or ice boxes should have double sides, bottom and top, with a space between the casings filled with nonconducting materials to keep out the external heat, all doors and other apertures should be sealed as nearly air-tight as possible, and the contents should be arranged to provide perfect drainage.

All water must be removed at once, and the drainage pipe must be fitted with a trap so that cold air cannot escape nor outer air be admitted. If these principles are observed, any ingenious person can build an ice house or refrigerator, or design one to be built by a local carpenter that will answer all practical purposes.