90 ANNUAL REPORTS OP DEPARTMENT OF 
than expected. This was proved to be due partly to absorption by the water 
condensed on the windows and elsewhere In the house, and partly to decompo- 
sition of the oicotine by contad with the metal of the boiler and exit tube. 
This decomposition was studied further and found to vary greatly from metal 
t<> metal. Bj simply atomizing a oicotine solution and blowing the spray about, 
it was found possible to reach a concentration of <».<«; m- r of nicotine per liter. 
( HEMICAL INVESTIGATIONS ON OILS AND OIL EMI I SIO 
The laboratory at Wooster, Ohio, continued the study of oil emulsions and 
their effect on insects. The greatest attention was paid to the problem ol 
termining the amount of oil deposited on foliage. The investigation of tin' 
so-called plate method was completed, ii being clearly demonstrated thai this 
pimple procedure is ool reliable since there Is ool always a constant relation- 
ship between the deposil on the plate and that on the foliage, and when ther< 
the proportiona Lty constanl differs with nature of oil, nature of emulsifler, and 
even with concentration of oil. However, an extraction method was developed. 
This method, involving extraction of fresh leaf disks with petroleum ether and 
subsequent recovery of the extracted oil, appears satisfactory, permitting the 
determination of both petroleum and fatty oils with an accuracy oi 
oi- better. 
The attempt was also continued to increase the effectiveness of oil sprays by 
incorporating in them other toxic materials. Of eighl materials tried against 
mealybugs, oicotine and lauryl thiocyanate showed a definite advantage. Of 
eight materials tested lor their effect On eggs of the fruit-tree leaf roller, only 
nicotine showed any significant increase in kill, and part of this may have been 
due to increased oil deposit Of 12 materials tried in pine oil emulsions against 
overwintering codling moth larvae, only nicotine and alphanaphthylamine showed 
any promise. 
Certain vegetable oils, namely, orange oil, pine oil. peanut oil. corn oil, and 
cottonseed oil. were compared in emulsion form with petroleum-oil emulsions and 
all were found to he inferior. The drying oils proved less effective than the / 
nondrying ones, probably because of lesser penetration. / 
CHEMICAL INVESTIGATIONS ON ACCESSORY MATERIALS FOR USE WITH 
INSE( TI( IDES 
The study Of accessory spray materials, which was begun last year, was 
continued along three lines, namely, a study of definite soap solution--, a study 
of proprietary wetting agents, and a study of materials suitable for specific 
purposes. 
The work with soaps included a determination of the surface tensions and 
spreading coefficients of some of the combinations of oleic, myristic, lauric, 
palmitic, and normal capric acids with the hydroxides and carbonates of sodium 
and potassium and with ammonium hydroxide. All the acids behaved quali- 
tatively like oleic, with, however, quantitative differences. The a-caprate 
mixture- do not have as high wetting powers as do those made from the acids 
oi higher molecular weight, and no caprate mixture showed a positive spreading 
coefficient An excess of -.odium carbonate ha- been found in each case to 
produce less effect upon the wetting properties than an excess of the hydroxide. 
and oleic acid is less affected by sodium carbonate than are the other acids. 
The relationship between concentration on the one hand and both Interfadal 
tension and spreading coefficient on the other was determined for 19 proprietary 
compounds, many of them being of the sulphated or sulphonated alcohol types 
which are claimed to be unaffected by adds. It was found I hat acids ami alkalies 
do have a pronounced effect on the wetting properties* although the compounds 
are apparently unaffected and are not rapidlj decomposed. 
Special efforts were made to And suitable wetting agents for the homologues of 
parts green, for lead arsenate, and tor phenothiazine. Certain materials appear 
suitable for these purposes, but in many cases they cause excessive run off. ami 
the total deposit obtained Is, with lead arsenate, for Instance, less than with that 
material alone. Some evidence indicates that a flocculated spray material may 
give the heaviest ami most uniform deposit 
id oi rERMiNi i in roxicrn op new inse< nciDAi compounds, « SING 
GOLDFISH 
the relationship of \,,\\, itj to chemical structure was continued 
throughout the year. Attention was diverted, however, from the complex ma- 
