[Illustration: FIG. 3.--SECTION OF THE APPARATUS.]

To operate the burner, we place the cylindrical tube, K L M N, in the
inner vessel, and pour sulphide of carbon into it up to the level _aa_.
This done, we fill the external vessel with water up to the level _bb_.
Thanks to the siphons, the water enters the inner vessel, presses the
sulphide of carbon, which is the heavier, and causes it to rise in the
tube up to the level _a'a',_ where it saturates a cotton wick, which is
then lighted. The upper end of the tube is surmounted with a chimney, PQ.
which quickens the draught.

The combustion may be retarded or quickened at will by causing the level
_bb_ of the water to rise or lower.

The burner is placed in the room to be disinfected, which, after the wick
has been lighted, is closed hermetically. When all the sulphide is burned
it is replaced by water, and the lamp goes out of itself.

The combustion proceeds with great regularity and without any danger. It
takes about five and a half pounds for a room of 3,500 cubic feet
capacity. The process is sure and quite economical, since sulphide of
carbon is sold at about five cents per pound, which amounts to 25 cents
for a room of 3,500 cubic feet capacity. The burner costs ten dollars,
but may be used for an almost indefinite period.

The process of producing sulphurous acid by the combustion of sulphide of
carbon is, as may be seen, very practical and advantageous. It does not
affect metallic objects, and it furnishes a disinfecting gas
continuously, slowly, and regularly.