340 MARKET DAIRYVING 
mechanical refrigeration, ice is indispensible in furnish- 
ing the best quality of milk and cream. A low enough 
temperature cannot be secured with water alone, neither 
can the cooling be accomplished as quickly as is desirable 
for best results. Furthermore, a satisfactory cold storage 
cannot be had without the use of ice. 
Cooling Power of Ice. A great deal of cooling can 
be done with a comparatively small amount of ice. This 
is due to the latent or “hidden” cold in ice. Thus to 
convert one pound of ice at 32° F. into water at the same 
temperature requires 142 units of heat, or, in other words, 
enough cold is given out to reduce the temperature of 
142 pounds of water one degree Fahr. 
Construction of Ice House. To keep ice satisfactorily 
three things are necessary, (1) good drainage at the bot- 
tom, (2) good insulation, and (3) abundant ventilation 
at the top. - 
Good drainage and insulation at the bottom can be se- 
sured by laying an eight-inch foundation of stones and 
gravel and on top of this six inches of cinders, the swhole 
being underlaid with drain tile. One foot of sawdust 
should be packed upon the cinders and the ice laid directly 
upon the sawdust. 
Satisfactory walls are secured by using matched boards 
on the outside of the studs and common rough boards 
on the inside, leaving the space between the studs empty. 
The ice should be separated from the walls by one foot of 
sawdust. 
Where no solid foundation walls are provided, earth 
must be banked around the ice house to prevent the en- 
trance of air along the base. 
The space between the sawdust covering on top of the 
ice and the roof should be left clear. Openings in the 
