1 878.] 
to Health and Comfort. 
215 
accompanying the manifestation of bad gas in England 
might call for a long discussion in reply. It can be said at 
once that the indications on the ceilings are almost entirely 
those of atmospheric impurities and condensation of water. 
Soot, dust, and organic matter in suspension in a saturated 
humid air— wherein the humidity is the vehicle which car- 
ries these substances, and is not free to disperse them from 
the general saturation — will be and are deposited on the 
first objeCt of cooling and contact. This view of the case 
is not a mere guess. The faCt that there is a general dis- 
coloration of ceilings from gas-burners in England, as con- 
trasted with those of the Continent, where the air is uni- 
formly a little more dry, and where the use of bituminous 
coal is unknown, so that its particles of carbon dust do not 
form a part of the common impurities of the air; and also 
as contrasted with the ceilings in this country; this fadt is 
certain, and from it the connection of pure air with the 
cleanliness of gas burning is made evident. While English 
gas is much more carefully purified and treated than any in 
the world, the standard of its excellence is not only the 
highest, but it is made strictly up to this standard. Yet 
any sulphurous or sulphuric acids which emanate from gas 
lights are at once absorbed by the vapour present, and if 
the atmospheric condition does not facilitate the diffusion of 
this vapour, these acids are retained in the ascending 
column to exert their energies on the objects of first con- 
tact, and afterwards retained in the room to act generally 
on any sulphur absorbent, colours or materials, as they do 
in England and do not in this country. It is probable in 
our climate, and in that of the Continent, much of the 
humidity of combustion, and of the deleterious gases, 
either evolved by or inherent to the illuminating gas, as 
well as the organic impurities, dust or soot, in the air burnt 
or heated by the aCt of burning, is diffused at once into the 
tenuous vapour of the surrounding air. Not only before 
passing four or five feet from the burner, so that no conden- 
sation takes place on the ceiling, but also so thoroughly 
diffused as to prevent, in great degree, those chemical 
actions which prove so objectionable from the burning of 
the best purified coal gas in England. 
§ It has been shown how nearly impracticable it is to 
procure in winter, with the average temperature of winter, 
which is 34 0 , a summer temperature and humidity in our 
houses. The difficulties of effecting this with 34 0 for the 
temperature of the external air are enhanced greatly as the 
