. Water vapor
having a great power of absorbing radiant heat from the burning gas
becomes heated, and diffusing itself about the room, causes great
feeling of oppression; the air also being highly charged with
moisture, is unable to take up so rapidly the water vapor which is
always evaporating from the surface of our skin, whereby the functions
of the body receive a slight check, resulting in a feeling of
_malaise_.

Added to these, however, is a far more serious factor which has, up to
the present, been overlooked, and that is that an ordinary gas flame,
in burning, yields distinct quantities of carbon monoxide and
acetylene, the prolonged breathing of which in the smallest traces
produces headache and general physical discomfort, while its effect
upon plant life is equally marked.

AMOUNT OF OXYGEN REMOVED FROM THE AIR, AND CARBON DIOXIDE AND WATER
VAPOR GENERATED TO GIVE AN ILLUMINATION EQUAL TO 32 CANDLE POWER.

(The amount of light required in a room 16' X 12' x 10'.)

|Quantity of | | Products of Combustion| |
| Materials | Oxygen | | Carbon | |
Illuminant | Used | Removed |Water Vapor| Dioxide |Adults|
--------------+------------+----------+-----------+-----------+------+
Sperm Candles |3,840 grains|19.27 c.f.|13.12 c.f. |13.12 c.f. | 21.8 |
Paraffin Oil |1,984 " |12.48 c.f.| 7.04 c.f. | 8.96 c.f. | 14.9 |
Gas (London)--| | | | | |
Burners: | | | | | |
Batswing | 11 c.f. |13.06 c.f.|14.72 c.f. | 5.76 c.f. | 9.6 |
Argand | 9.7 c.f. |11.52 c.f.|12.80 c.f. | 5.12 c.f. | 8.5 |
Regenerative| 3.2 c.f. | 3.68 c.f.| 4.16 c.f. | 1.60 c.f. | 2.6 |

Ever since the structure of flame has been noted and discussed, it has
been accepted as a fact beyond dispute that the outer almost invisible
zone which is interposed between the air and the luminous zone of the
flame is the area of complete combustion, and that here the unburnt
remnants of the flame gases, meeting the air, freely take up oxygen
and are converted into the comparatively harmless products of
combustion, carbon dioxide and water vapor, which only need partial
removal by any haphazard process of ventilation to keep the air of the
room fit to support animal life. I have, however, long doubted this
fact, and at length, by a delicate process of analysis have been ab