------------------------------------------------------------ | 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. 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_.