10 BULLETIN 893, U. S. DEPARTMENT OF AGRICULTURE. 
Repeated exposure causes increased susceptibility, produces cough, 
nausea, and vomiting, and in large quantity may cause unconscious- 
ness. Secondary effects are bronchitis, asthma, shortening of the 
breath, weak, irregular heart action, and gastritis. Liquid chloro- 
picrin has a corrosive action on the skin, producing the effect of a 
severe burn without blistering. A wound thus made is slow to heal. 
Because of the low vapor pressure of chloropicrin, it was necessary to 
force dry air through it, thereby bringing it to the saturation point, 
in order to obtain a concentration comparable with that of the gases 
already discussed. Although water is not soluble in chloropicrin, 
some moisture collects on the top of the liquid when humid air is 
passed through it, thereby causing variable humidity. The concen- 
tration at saturation is but 1.75 per cent at 20°C. The concentration 
was determined by absorption in a 2 per cent solution of sodium 
peroxid in 50 per cent alcohol. Titration by the method employed > 
with phosgene and cyanogen chlorid was used. 
Concentrations of from 0.5 to 1.75 per cent and exposures of from 
seven minutes to two hours were tried on insects. ; 
The minimum lethal dose, with the minimum time, for chloropicrin, 
as compared with that of hydrocyanic acid, is given in Table 7. 
TABLE 7.—Relative insecticidal action of chloropicrin and hydrocyanic acid. 
Chloropicrin (100 per cent Hydrocyanic acid (100 per cent 
lethal). lethal). 
Insects. 7 
Con- | Time | Tem- | Bele Con- | Time | Tem- peo 
cone ofex- | pera- hai cenit ofex- | pera- hie 
tion. Ligiead | ture, ity. | tion. | posure.} ture. oo 
i v* ws 2 
j | 
P. ct. | Min me. PEL Min ae. 
Ants (Monomorium pharaonis L.)-.-- 10.5 | 7 | 20 At SAE LL ee ee eee eee 9 
Ants (Lasius niger L., Var. america- ' 
MUS RTMOCTY,) oe oe ose oe a ee ee pe ee i ea eae | 0.2 30 25 49 
Ants ( Tetramorium caespitum see ). Sei ae Secs eee (eee el meee oe 32 30 25 | 40 
Aphids (Myzus persicae Sulz.). - 2 5 30 | 21 | 40 | 2 60 24 40 
Bedbugs ( Cimez lectularius L.)-...... 1.0 | 30 | 23 40 | 2.0 | 30 27 40 
Beetles, Colorado potato (Leptino- | | 
farsa decemlineata Say)..-.-..---..--|-.------ Peedi oe oe eee ee! (er ee. 5 15 30 40 
Beetle, Colorado potato, larvze_-_~-= -|RSes tise | hae ee ee eee 5 15 30 40 
Beetles, Flat grain (Laemophiaeus | 
Minusiis Olive) a= 22 Soe a= ee 1.5 15 25 | 40 1.0 60 26 40 
Beetles, Potato fiea ( Epitriz cucume- | | 
Wis Hiarris)\ essen seen ee Hl te | 15 22 40 | 95 7 27 40 
Beetles,Sawtooth grain (Silvanus suri- | 
mamnensis\ Us.) oe so 5 22 en ok sect awa 1.0 39 27 | 40 1.0 30 2s 40 
Borers, Grain (Rhizopertha dominica 
Wa b:) te sce oe eee nee ee age 1.0 30 27 40 1.0 30 30 40 
Flies ( Musca domestica L.)-.-.-------- a 7 | 26 | 40 2.1 7 25 40 
Ty Varve 2 oot sees tet Soe ee eee ae see oe lee ee Beets Sal ee eee zs | 30 25 40 
Fly. White (Aleyrodes vaporariorum | 
Westw occ 2c ose eee eee 15 7 21 40 21 7 30 40 
Mite, Phyllostachys Bamboo ( Tarso-| 
NeMUs FS] 9) peek RE pin de Sad 1.0 7 21 | 40 22 60 24 40 
Roaches (Platiella germanica L.)....-.- 5 60 ea 40 a2 15 25 40 
Spiders, Red ( Tetranychus bimacula- 
ji3 Harvey) -=2-22: 2 eS 5 30 21 40 a2 30 2B 40 
Weevils, Flour (Tribolium ferrugi- | 
FIVE AD x52 25 2 es Oe ee 1.0 60 27 | 40 1.0 30 34 40 
Weevils, Rice ( Calandra oryzae L.).-- 1.0 120 20 40 4.0 120 28 40 
1 Not minimum lethal dose. e 3 
2 Impossible to obtain more insects to secure a definite low concentration and exposure. 
