Rats may be destroyed in their burrows in the fields and along river
banks, levees, and dikes by carbon bisulphid.[7] A wad of cotton or
other absorbent material is saturated with the liquid and then pushed
into the burrow, the opening being packed with earth to prevent the
escape of the gas. All animals in the burrow are asphyxiated. Fumigation
in buildings is not so satisfactory, because it is difficult to confine
the gases. Moreover, when effective, the odor from the dead rats is
highly objectionable in occupied buildings.
Chlorin, carbon monoxid, sulphur dioxid, and hydrocyanic acid are the
gases most used for destroying rats and mice in sheds, warehouses, and
stores. Each is effective if the gas can be confined and made to reach
the retreats of the animals. Owing to the great danger from fire
incident to burning charcoal or sulphur in open pans, a special furnace
provided with means for forcing the gas into the compartments of vessels
or buildings is generally employed.
Hydrocyanic-acid gas is effective in destroying all animal life in
buildings. It has been successfully used to free elevators and
warehouses of rats, mice, and insects. However, it is so dangerous to
human life that the novice should not attempt fumigation with it, except
under careful instructions. Directions for preparing and using the gas
may be found in a publication entitled Hydrocyanic-acid Gas against
Household Insects, by Dr. L. O. Howard and Charles H. Popenoe.[8]
Carbon monoxid is rather dangerous, as its presence in the hold of a
vessel or other compartment is not manifest to the senses, and fatal
accidents have occurred during its employment to fumigate vessels.
Chlorin gas has a strong bleaching action upon textile fabrics, and for
this reason can not be used in many situations.
Sulphur dioxid also has a bleaching effect upon textiles, but less
marked than that of chlorin, and ordinarily it is not noticeable with
the small percentage of the gas it is necessary to use. On the whole,
this gas has many advantages as a fumigator and disinfectant. It is used
also as a fire extinguisher on board vessels. Special furnaces for
generating the gas and forcing it into the compartments of ships and
buildings are on the market, and many steamships and docks are now
fitted with the necessary apparatus.