FARM MANAGEMENT 129 



is to be used in the same manner as the temporary house no inside 

 lining will be necessary. The packing used about the mass of ice 

 may be allowed to come in direct contact with the wall. A 13-inch 

 brick wall or a 12-inch concrete wall will provide the necessary 

 strength. The masonry walls are not as good nonconductors as 

 timber walls. It will therefore be necessary for the protection of the 

 ice to rely on the packing material rather than on the wall itself. 



Harvesting the Ice. The source of the ice supply will vary with 

 local conditions. In many sections lakes, rivers, or large streams will 

 afford a supply of suitable ice without special plan or preparation on 

 the part of man. In other instances, where such natural sources are 

 not easily accessible, small streams or even the water from a spring 

 can be stored in an excavation or by means of a dam, so as to afford 

 sufficient water surface to provide the desired ice supply. The harvest 

 area or surface will depend upon the tonnage to be stored and the 

 normal thickness of the ice in the locality. 



The stream or pond from which the supply of ice is taken should 

 be fed from a source free from contamination or pollution. If the 

 stream is so sluggish that water weeds thrive in it, all vegetation must 

 be removed to prevent its freezing in the ice. Decaying vegetable 

 matter frozen in the ice is very objectionable, because as the ice melts 

 this matter is deposited in the ice box or refrigerator, rendering it 

 unnecessarily filthy and dangerous to health. 



Ponds in which green spawn or alga? grow profusely can be rid 

 of these pests by the use of copper sulphate. The crystals can be 

 placed in a cloth sack, which is hung to a pole and trailed through 

 the water until the salts are dissolved. One or two treatments of .the 

 sulphate during the season at the rate of 1 pound to 100,000 gallons 

 of water will be sufficient to keep down such growth and make the 

 water clear and pure. It is impossible to have pure ice unless the 

 pond or stream is clean and the water is free from contamination. 



The ice itself must be packed so as to prevent as completely as 

 possible the circulation of air through the mass. The more nearly 

 the mass of ice approaches that of a solid cube, both in shape and 

 texture, the easier, with good drainage and insulation, will be the 

 keeping problem. The keeping of ice depends upon the shape of the 

 mass, its insulation, its drainage, and its solidity. The ease and 

 rapidity with which ice can be gathered depend upon the condition 

 and location of the field and the character of the tools and con- 

 veniences at hand for doing the work. 



If the ice field is covered with snow the formation of ice will be 

 retarded, as the snow acts as a blanket and raises the temperature, 

 thus retarding the ice formation. If the ice sheet is sufficiently thick 

 and snow falls upon it, the snow must be removed before harvesting 

 can proceed ; or if, on the other hand, it is desirable to increase the 

 thickness of the ice after the snow falls, the field may be flooded and 

 the snow saturated with water, which is allowed to freeze, thus adding 

 a layer of snow ice. Flooding on small fields may be accomplished 

 in either of two ways : ( 1 ) by overflowing, which consists merely in 

 conducting water to the field, or by piercing the ice field here and 



