On the Thames, at London 0.0343
In the streets of London 0.0380
Top of Ben Nevis 0.0327
Dress circle of Haymarket theater (11:30 P.M.) 0.0757
Chancery Court (seven feet from the ground) 0.1930
From working mines (average of 339 samples) 0.7853
Largest amount in a Cornish mine 2.0500

In addition to the consumption of oxygen and production of carbonic acid
by the use of common gas, the gas itself, owing to defectiveness of the
burner, is projected into the air. Now, considering the deleterious
nature of all illuminating gases, the reasons for perfect ventilation of
rooms in which natural gas is used for heating and culinary purposes are
self-evident, not alone as a protection against explosions, but for the
health of the occupants of the house, remembering that a larger supply
of oxygen is said to be necessary for the perfect combustion of natural
than of common gas.

Carbonic oxide, formed by the consumption of carbon, with an
insufficient supply of air, is the fatal poison of the charcoal furnace,
not infrequently resorted to, in close rooms, as a means of suicide.
The less sufficient the air toward perfect combustion, the smaller the
quantity of carbonic acid and the greater the amount of carbonic oxide.
That is to say, at the time of ignition the chief product of combustion
is carbonic oxide, and, unless sufficient air be added to convert the
oxide to carbonic acid, a decidedly dangerous product is given off into
the room. Yet, by means of a flue to carry off the poisonous gases from
burning jets, the combustion of gas, creating a current, is made an aid
to ventilation. Unfortunately, this important fact, if commonly known,