12 BULLETIN 102, UNITED STATES NATIONAL MUSEUM. 
atmospheric air. About 4| cubic feet of air must be mixed, by the 
gas consumer at his burning appliances, with each cubic foot of 
manufactured gas in order to insure perfect combustion. If not 
enough air is mixed with the gas, the combustion will be imperfect 
and wasteful. 
When manufactured gas is burned by complete combustion, each 
cubic foot of the gas will form one-half cubic foot of carbon dioxide 
and 1 cubic foot of steam. This carbon dioxide is the same sub- 
stance that is exhaled from the lungs. 
The combustion of 1,000 cubic feet of manufactured gas will form 
1,000 cubic feet of water vapor or steam, which when condensed, will 
make approximately 4J gallons of water. It is this water vapor that 
causes the bakers and broilers of stoves to rust, and, when gas is used 
in open fires without flues, may make the walls and windows “ sweat.” 
WHAT MAY HAPPEN WHEN GAS IS BURNED. 
If the combustion of manufactured gas is not complete, carbon 
monoxide will be formed instead of carbon dioxide. This carbon 
monoxide is a deadly poison and, therefore, dangerous, and for this 
reason a room in which gas is burned should be ventilated. Although 
carbon monoxide itself is odorless, an offensive odor is usually pro- 
duced by the improper combustion conditions that produce carbon 
monoxide. Therefore, an offensive odor from burning gas is an 
almost infallible indication of carbon monoxide generation. The 
poisonous action of carbon monoxide gas is so marked that one-tenth 
of 1 per cent is enough to in time produce fatal results. This pois- 
onous gas is especially likely to be formed : 
a. .During first few minutes’ operation of any automatic water 
heater. 
b. When the inner cone of any blue flame impinges on a metal 
surface. 
c. When a luminous flame is deflected and impinges on a cool sur- 
face. 
d. When any flame is not supplied with sufficient air. 
e. When a radiant fire heater is operated so that the radiants glow 
more than three-quarters of the distance from the bottom to the top. 
COMBUSTION PRODUCTS OF GAS CAN NOT BE DESTROYED. 
The inevitable products, carbon dioxide and water vapor, can not 
be destroyed, although the water vapor when it is cooled will con- 
dense to a liquid. There have been many claims made by manufac- 
turers of heating devices that their devices absorb the combustion 
products, but all such claims are untruthful. 
