16 
BULLETIN 102, UNITED STATES NATIONAL MUSEUM. 
MORE GAS IS USED FOR COOKING IN WINTER THAN IN SUMMER. 
The heating value of the gas in winter will not be any lower than 
in summer, because the heating value is increased 1 per cent for each 
5° of decrease in temperature of the gas, and will actually be higher 
during the low temperature period in winter than it is in summer. 
However, the starting temperature of the food and water that must be 
heated in cooking will be much lower in winter than in summer; 
therefore, a larger quantity of heat will be needed to bring the food 
or water to the boiling point. The radiating loss from the cooking 
vessel and burner, because of the low temperature of the surround- 
ing air, will also be much higher in winter than in summer, and thus 
will increase the gas consumption. 
RUSTING OF OVENS AND BURNERS. 
Rusting of ovens can almost be eliminated by opening the oven 
door slightly for a few minutes after the burners are lighted. This 
permits escape of the greater part of the moisture, which is produced 
by combustion, and prevents too rapid condensation. 
Oven linings and burners are best protected from rust by the appli- 
cation of oil or grease, free from salt. This should be done while 
the oven or burner is warm, as often as may be necessary. 
STEPS NECESSARY FOR CORRECT HOUSE HEATING. 
a. The gas must be burned with perfect combustion. However, 
this is merely the first step. 
b. The combustion products must be made to deliver the most of 
their heat into the air or water that is to be heated, and before leav- 
ing the heating device, and going into the flue, should be cooled to 
within 100° of the air or water that is heated. This requires ade- 
quate heat-radiating surface, a feature lacking in many appliances. 
F ailure to appreciate the importance of this second step, rather than 
merely obtaining perfect combustion, is responsible for the gross 
waste of gas in so many heating devices. 
c. The radiant-fire heater works on the same principle as the in- 
candescent mantle lamp ; the coarse or heavy radiant element replaces 
the fragile mantle. However, the radiant-fire heater should never 
be operated so the radiants glow more than three-quarters of the 
distance from the bottom to the top. When this rate is exceeded, 
carbon monoxide is liberated in more or less dangerous quantities. 
d. With hot-air furnaces or steam or hot-water boilers, the use 
of a thermostat for controlling the gas will give more uniform and 
better temperature conditions in the living rooms and also save gas. 
