4 BULLETIN 893, U. S. DEPARTMENT OF AGRICULTURE. : 
PHOSGENE. 
Phosgene, or carbonyl chlorid (COCl,), molecular weight 98.92, 
has a liquid density, at 20° C. under its own pressure, of 1.38. Its 
boiling point is 8.2°C. The vapor pressure at 20° C. is 1,216 mm. of 
mercury. Itis corrosive to metals and a decolorizer. It is extremely 
toxic to human beings, and is rather difficult to handle and control. 
The concentration of the gas-air mixture was determined by 
allowing the gas air to pass into a solution of 5 per cent alcoholic 
sodium hydroxid solution for one minute, then neutralizing with 
acetic acid and titrating with N/10 silver nitrate. Concentrations 
of from 0.5 to 4 per cent and exposures for from seven minutes to 
two hours were tried. The minimum lethal dose of phosgene, with 
the minimum time to kill, as compared with that of hydrocyanic 
acid, is given in Table 1. 
TABLE |.— Relative insecticidal action of phosgene and hydrocyanic acid. 
Phosgene (100 per cent lethal). Set neaenees per cent 
Insects. 
Con- | Time | Tem- | Rela- | Con- | Time | Tem- } Rela- 
centra-| ofex- | pera- |tivehu-] centra-| ofex- | pera- {tive hu- 
tion. |posure.| ture. |midity.| tion. | posure.| ture. |midity. 
Ants (Monomorium minimum Buck- 
ley, Lasius niger L., var. ameri- | P. ct. Min. min IPNGiz Min. SE! 
CONUSMEIMELY) ese atoeee cee eee see 0.5 30 19 DOM Ee SE So EN | AS Wee eae yer a ee = 
Ants ( Tetramorium caespitum Fab.) -|....---- [a Meee an Otic | ea SN 0.2 30 25 40 
Aphids (Myzus persicae Sulz)..-...-- 1.0 | 30 | 31 40 2 60 24 40 
Bedbugs ( Cimez lectularius L. ua Puls Dt 20 120 26 40 250 30 27 40 
Bedbug (Cimex lectularius L.) eggs... 2.0 120 24 ADH s. 22 a See eee acc a ae 
Be -etles, Colorado potato (Leptino- | 
tarsa decemlineata Say)...........--- 4.0 | 120 30 40 5 15 30 40 
Beetle, Colorado potato (Leptinotarsa 
d2cemlineata Say) larve ...-........ 4.0 120 30 40 5 15 30 40 
Beotles, Flat grain (Laemophlacus 
HOCROTOES. CUENR))s5 donee aéucceucceeos= 1.0 120 | 29 40 1.0 60 26 40 
Beetles, Potato flea ( Epitrix cucumeris 
ELATBIS) sasticiericise oe Sans oecaee eee 1.0 60 30 40 5 7 27 40 
Beetles, Sawtooth grain (Silvanus | 
SUMPLENLCTUSES Hae) eae eee ee 1.0 120 | 28 40 1.0 30 28 40 
Borers, Grain (Rhizopertha dominica_ 
MAD core set eee ate ok ea ae 2.0 60 29 40| 1.0 30 30 40 
ad THATS les Dane Wa Pp Gabe eal ie A agen OU ne 8 2.5 26 40 3.1 37 23) 40 
Bl yslanyce eset ceed a nee ape eee 53.0 120 | 26 40 Sal 30 25 49 
Fly, White (A leyrodes vaporariorum | 
Wi CSTW) Bas eee tices ae ene I 1.0 30 22 40 3.1 37 30 40 
Lice, Body (Pediculus corporis Deg.) 
(CRASS, ia ee eae eR Me 63.0 120 23 40!) ster ss|ec hones eee eee 
Mite, Phyllostachys bamboo (Tar- 
SOMEIMUSISD 9) eee eee eee eee 1 30 25 40 a2 60 24 40 
Roaches (Blzttella germanica L.)}....-.- 15 120 27 40 57 15 25 40 
Roach (Bilattella germanica L.) egg | 
BOGS: ASL Rte an ee eee ae ween 3.0 120 30 AOU ee coe es eeeacel Sousa | eee 
Spiders, Red ( Tetranychus bimacu- 
latvusrElargey) eee eee eee eee a) 60 31 40 o2 30 | 23 40 
Weevils, Flour (TVribolium ferrugi- 
TCWG Babee. coos ees eee 74.0 120 23| 40 1.0 30|.. 38 40 
4.0 120 26 49 4.0 120 | 28 40 
Weevils, Rice ( Calandra oryzae sas ‘ 
| | 
1 Musca domestica L.; Calliphora vomitori1 L.; Muscina stabulans Fall. 
2 Equal to or less than but not more than. 5 90 per cent killed. 
3 Not minimum lethal treatment. 6 90.6 per cent killed. 
4 Muscina stabulans Fall. 786 per cent killed. 
The results in Table 1 show that in every case phosgene is less 
effective as an insecticide than hydrocyanic acid. 
