214 
Relation of Moisture in Air 
[April, 
substance, either animal, vegetable or mineral, with the 
occasional or frequent use of the carcel-lamp as a table 
light. From any English gas-light there arises a current of 
impurities, which in a brief space of time discolours and 
coats with black the interior of the ventilating tubes, or, in 
absence of such protestors, the canopies of glass or metal 
which are usually supplied for unventilated burners ; or 
when this last protection is wanting, the ceiling, even when 
several feet above the burner, is quickly marked by a halo of 
greasy soot, which adheres to it where the ascending current 
impinges. 
The heat emanating from a gas-burner, as compared to 
that from a number of candles giving the same amount of 
light, is very nearly the same, about 7 per cent more heat 
being given out by the candles ; but the fourteen to sixteen 
candles, which represent the single gas-burner, will have 
been dispersed about a room, or even when grouped in threes 
or sevens — as usual in sconces, candelabra, or chandeliers — 
will be spread widely asunder, so that the current proceeding 
upwards from each separate candle will have become diffused 
before reaching the ceiling; and, if the candles give out the 
same impurities (which they do not) as the gas-burners, the 
obvious impurities which make a mark will not be precipi- 
tated to show themselves as spots. Besides this, a room 
lighted by candles will be considered brilliantly illuminated 
by three or four candles, where one gas-burner would have 
been used ; so that one-fourth the quantity of light will be 
made to suffice with candle illumination, to what is requisite 
for gas lighting. The numerous candles come in proximity 
to the objects to be lighted, while the gas-burner, with its 
volume of light and of heat, must be further removed to be 
tolerable, and there is an adtual requirement for more light 
from the latter than the former source to give the same 
effedt in the room. The other substitute for the gas-burner, 
the carcel-lamp, is frequently used in England as the centre- 
piece, singly or in numbers, of the tables in the dining-room, 
drawing-room, or library. Its illuminating power is about 
two-thirds that of a gas-burner, and the quantity of heat 
given out bears very nearly the same relation, — that is, the 
heat from a carcel-lamp is about two-thirds that from a 
single gas-burner of fourteen to sixteen candle-power. As 
the carcel-lamp is movable in a room, and is usually placed 
low down, the chance of the current of air proceeding from 
it defacing the ceiling is much less than from a fixed gas- 
burner, in its usual position of height from the floor. 
What may be the exadt physical or chemical conditions 
