TOXIC ACTION OF CERTAIN GASES. ihc 
ILLUMINATING GAS. 
The results of a series of experiments with illuminating gas on the 
same varieties of insects as were employed in the tests previously 
discussed, using a concentration of 3 per cent and an exposure for 
two hours, showed that it is not toxic to insects. Consequently no 
detailed data are given. 
CARBON MONOXID. 
Carbon monoxid also proved to be nontoxic to insects at a con- 
centration of 3 per cent and an exposure for two hours. The same 
varieties of insects were used as in the preceding tests. 
SUMMARY. 
The results of the action on insects of all the gases tested, with the 
exception of illuminating gas and carbon monoxid, are given in 
Table 9. 7 
CONCLUSIONS. 
Phosgene is not useful as an insecticide, because of its toxicity 
toward human beings, its high vapor pressure, the difficulty of con- 
trolling it, and its comparatively low toxicity toward insects. Neither 
does it possess any value as a fungicide. 
Arsine has no advantage other than ease of generation, and pos- 
sesses Many disadvantages as an insecticide. Its toxicity toward 
insects is comparatively low, it is injurious to plants, and has no 
effect on fungi. 
Illuminating gas in concentrations up to 3 per cent and for expo- 
sures up to two hours is not toxic to insects. 
Carbon monoxid in concentrations up to 3 per cent and for expo- 
sures of two hours is not toxic to insects. 
Of the gases tested, cyanogen chlorid and chloropicrin give promise 
of being useful for fumigation purposes. Neither of these, however, 
can be used in greenhouse fumigation, because of their injurious 
action on plants. Nevertheless they probably can be used im the 
fumigation of stored products. 
The efficiency of chloropicrin as an insecticide is undoubted. In 
general, it is More poisonous to stored-product insects than hydro- 
eyanic acid. Other advantages which it possesses are ease of handling 
and control, low toxicity toward human beings, ease oi detection, and 
noninflammability. Its disadvantages are its adherent quality, which 
makes it necessary to air the material for some time after it has been 
fumigated, its corrosive action on metals, its severe lachrymal effect, 
and its low volatility. The last objection may be partially overcome 
by pouring the dose required on paper, thereby increasing the evap- 
orating surface. 
