The use of liquid sulphurous acid in siphons does not offer the same inconveniences.  These siphons contain about one and a half pounds of sulphurous acid.  The proportion necessary to effect the sterilization of the culture broths is one siphon per 706 cubic feet.  In such a case the modus operandi is as follows:  In the middle of the room is placed a vessel, which is connected with the exterior by means a rubber tube that passes through a hole in the door.  After the door has been closed, it is only necessary to place the nozzle of the siphon in the rubber tube, and to press upon the lever of the siphon valve, to cause the liquid to pass from the siphon to the interior of the vessel.  The evaporation of the liquid sulphurous acid proceeds very rapidly in the free air.  This process is an exceedingly convenient one; it does away with danger from fire, and it leaves the gildings and metallic objects that chance to be in the room absolutely intact.  Finally, the acid’s power of penetration appears to be still greater than that which is obtained by the combustion of sulphur.  It has but one drawback, and that is its high price.  Each siphon is sold to the public at the price of one dollar.  To municipalities using sulphurous acid in this form the price would be reduced to just one-half that figure.

It will be seen, then, that for a room of 3,530 cubic feet capacity the cost would be $5.00 or $2.50.

The combustion of sulphide of carbon furnishes an abundance of sulphurous acid, but has hitherto been attended with danger.  This, however, has recently been overcome by the invention of a new burner by Mr. Ckiandi Bey.  The general arrangement of this new apparatus is shown in Figs. 2 and 3.

Mr. Ckiandi’s burner consists of an external vessel, A B C D. of tinned copper, containing a vessel, I H E F, to the sides of which are fixed three siphons, R, S.

[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.