, of course, vary with the kind
of burner used.

Roughly speaking, the ordinary types of burner give the following
results:

------------------------------------------------------------
| Illuminating | Products of Combustion
| Power in | per
Name of Burner. | Candles per | Candle Power.
| c.f. of gas |------------------------
| Consumed. | Carbon | Water
| | Dioxide. | Vapor.
-----------------+-----------------+------------+-----------
Batswing. | 2.9 | 0.18 c.f. | 0.46 c.f.
Argand. | 3.3 | 0.16 c.f. | 0.40 c.f.
Regenerative. | 10.0 | 0.05 c.f. | 0.13 c.f.
-----------------+-----------------+------------+------------

So that the regenerative forms of burner, by giving the greatest
illuminating power per cubic foot of gas consumed, yield a smaller
amount of vitiation to the air per candle of light emitted.

An ordinary room, say 16' X 12' X 10', would not be considered
properly illuminated unless the light were at least equal to 32 candle
power; and in the table below the amount of the oxygen used up and the
products of combustion formed by each class of illuminant and burner
in attaining this result are given, the number of adults who would
exhale the same amount during respiration being also stated.

From these data it appears, according to rules by which the degree of
vitiation of the air in any confined space is measured by the amount
of oxygen used up and carbon dioxide formed, that candles are the
worst offenders against health and comfort. Oil lamps come next, and
gas least. This, however, is an assumption which practical experience
does not bear out. Discomfort and oppression in a room lighted by
candles or oil are less felt than in one lighted by any of the older
forms of gas burner; and the partial explanation of this is to be
found in the fact that, when a room is illuminated with candles or
oil, people are contented with a feebler and more local light than
when using gas. In a room of the size described, the inmates would be
more likely to use two candles placed near their books, or on a table,
than thirty-two scattered about the room.

Moreover, the amount of water vapor given off during the combustion of
gas is greater than in the case of the other illuminants