When gas is burnt in an apartment the following facts must be borne in mind, in addition to the foregoing, for the purposes of ventilation: -

One cubic foot of ordinary London coal gas produces, in burning, two-thirds of a cubic foot of carbonic acid, about the amount produced per hour by the respiration of one adult man, - and as an ordinary fish-tail gas-burner consumes about 3 cubic feet of gas per hour, it produces in that time as much carbonic acid as the respiration of three adults. In addition to this there are various highly injurious emanations from the burning gas. Therefore gas not only consumes the air, but poisons it as well!