250 Report oF THE CHEMIST OF THE 
50° and 65° F. These conditions are not easy to secure in 
any ordinary room. Some form of cellar is best adapted to 
secure these conditions. The amount of moisture can be deter- 
mined by an instrument known asa hygrometer, which consists of 
two thermometers; the bulb of one is exposed to the air directly 
and is known as the dry-bulb thermometer ; the bulb of the other 
is wrapped with a piece of cloth, preferably flannel, the lower end 
of which is placed in water, and this is known as the wet-bulb 
thermometer. The dry-bulb thermometer indicates the tem- 
_ perature of the air in the room; the wet-bulb thermometer indi- 
cates a lower temperature because the water evaporates from the 
bulb and the evaporation is accompanied by a lowering of tem- 
“perature immediately around the wet-bulb. The less moisture 
there is in the air, the more rapidly will evaporation take place 
and the lower will be the temperature indicated by the wet-bulb 
thermometer. The greater the moisture, the less will be the 
amount of evaporation, and the smaller the difference between the 
wet and dry-bulb thermometers. When the two thermometers 
_ indicate the same temperature, then there is no evaporation tak- 
ing place at.the wet-bulb thermometer, because the air is satu- 
rated with moisture or holds all that it can at that particular 
temperature. In a curing-room suited for Edam cheese, the 
moisture should be between eighty-five and ninety-five per cent 
or a little short of saturation. When the temperature is between 
50° and 65° F. the moisture is between eighty-five and ninety-five ' 
per cent if the wet-butb thermometer is from one to two degrees 
F. (or $° to 1° C.) below the dry-bulb thermometer. Undoubtedly, 
much better results would be secured in curing Cheddar cheese, 
if some attention were paid to the condition of moisture of the 
air in the curing-room, for it is now extremly rare to find any 
cheese-maker recognizing this condition at all. In the case of 
Edams, the cheese will check or crack and be spoiled for market, 
if the degree of moisture is not kept high enough. At the end of 
this subject, further details are given in TenANG to use of hygro- 
meters in cheese curing. . 
Fig. 2 shows one form of hygrometer. A good hygrometer can 
be purchased for two dollars or more. 
