-7- 
Di-(p-chlorophenyl)acetio acid (m.p. 163-164 c C)was prepared by 
heating l,l-di(p-chlorophenyl)2,2-dichloroethylene with alcoholic 
potassium hydroxide in a sealed Carius tube at 150-160° for 20 hours, 
--Grummitt et al. (19 1). 
DDT is very sensitive to alkaline materials. It "dehydrohalogenates* 
upon heating slightly above its melting point. The technical grade, 
•which contains appreciable quantities of the heat-sensitive o,j3*-isomer, 
may begin to oleave hydrogen chloride at 50°C. At 80° a 90-"percent lose 
of insecticidal efficacy occurs within 24 hours. The heat-induced de- 
composition of DDT appears to be auto catalytic, the liberated hydrogen 
chloride initiating further decomposition. In the absence of excessive 
temperatures, the primary decomposition product, DDD ^meaning the 
ethylene derivative, also known as TDE - RCR] is more stable than the 
parent compound. Contrary to the early reports, under summer field con- 
ditions in southern California, where leaf temperatures may exceed 125°F. 
and fruit temperatures 135°, DDT was found to lose its residual effect 
very quickly. Usually 2 weeks was more than sufficient to eliminate 
toxic effects. Experiments performed under winter conditions, however, 
indicated little, if any, loss of toxicity over several months. These 
results, and similar reports from other investigators, suggest that ultra- 
violet energy, between 2875 and 3100 A. U., may be another catalyst for 
the dehydrohalogenation of DDT, although Garman and Towns end report that 
sun-lamp irradiation does not destroy the effectiveness of DDT as a dust. 
Light may break DDT down to j3,p , -dichlorobenzophenone.--Gunther (195 ) . 
Gesarol AK-20 spray proved to be entirely compatible with wettable* 
sulfur. — Conklin (116 ). 
DDT is a rather stable compound. Long periods of exposure to the 
air have caused no appreciable ohange. Irradiation of the solid materi- 
al, spread in a thin layer, for 35 hours with a 100-watt mercury-vapor 
lamp, lowered its melting point by only 2°C. Similarly, an alcoholic 
solution of pure DDT showed no change after exposure to sunlight for 
over a year. DDT in alcoholic solution is readily decomposed by alka- 
lies to 2 f 2-bis(p-chlorophenyl)l,l-dichloroethylene, m.p. 88-89° • DDT 
was decomposed wnen heated with an equal weight of the following materi- 
als for 1 hour at 115-120*: Kaolin, fuller's earth, iron rust, ferric 
chloride, nicotine, and certain samples of talc and pyrophyllite. DDT 
was not decomposed when heated with calcium oxide, hydrated lime, or 
commercial lime-sulfur; and was only slightly decomposed (4 to 7 percent) 
when heated with bordeaux mixture or sulfur. Commercial grades of sodi- 
um fluoride, sodium fluosilicate, cryolite, paris green, calcium arse- 
nate, and lead arsenate showed no catalytic activity in decomposing DDT. 
Likewise, pure rotenone and pyrethrum were found to be inactive. Dolo— 
mitic limestone was the only fertilizer tested which showed catalytic 
ectivity. Heating the mixture for 1 hour produced 0.89 mole of hydro- 
chloric acid. The catalytic action persisted after the limestone had 
