FISH OIL AS ADHESIVE IX ARSENATE-OF-LEAD SPRAYS 5 
the mixture, and undoubtedly the oil attached itself more or less to 
the particles of arsenate of lead. 
It was observed that linseed oil mixes well with the mixture, 
spreads very well over the plate, and when dry adheres strongly to 
the glass. Fish oil mixes practically as well as the linseed oil and is 
nearly as adhesive. Corn oil mixes readily and spreads fairly well 
over the plate, but does not adhere so strongly as does linseed oil or 
fish oil. Soy-bean oil does not mix well with the spray solution; even 
after violent agitation of the mixture the oil rises quickly to the sur- 
face. It does not adhere strongly to the glass plate. Chinese wood 
: oil mixes readily and spreads fairly well over the plate, but does not 
adhere to the surface nearly so well as linseed oil or fish oil. It dries 
more rapidly than any of the other oils used. Cottonseed oil mixes 
fairly well with the mixture and is next to corn oil in its adhesiveness. 
In this experiment linseed, fish, and corn oils gave the most satis- 
factory results. The mixtures containing one-fourth of 1 per cent of 
oil proved practically as efficient as those containing twice that pro- 
portion. 
In the summer of 1923 standard arsenate-of-lead mixtures, each 
containing one-fourth of 1 per cent of one of the oils previously men- 
tioned, were sprayed upon foliage, and observations were made 
frequently during the season. On June 15 of that year a few wood- 
land trees — oak, birch, maple, and hickory — were sprayed with the 
arsenate-of-lead mixture containing linseed oil, and some oak, birch, 
hickory, beech, and maple trees with the mixture containing fish oil. 
On July 12 a few birch, oak, cherry, hazel, and ash trees were sprayed 
with the arsenate-of-lead mixture containing corn oil. Each of these 
three sprays, when applied to the foliage, has about the same spreading 
qualities. 
On September 30 the last examination of the sprayed foliage was 
made. From the time of the application of the linseed-oil and fish- 
oil sprays to this date 5.74 inches of rain had fallen, and 4.95 inches 
from the time of application of the corn-oil spray. It was found that 
very little of the linseed-oil and fish-oil mixtures had been washed off. 
More of the corn-oil mixture had left the foliage, in spite of the fact 
that the linseed-oil and fish-oil sprays were subjected to a greater 
amount of rainfall. It was evident that corn oil is not quite so 
efficient an adhesive as is linseed oil or fish oil. 
In the course of this season a few experiments were conducted with 
other materials as spreaders and stickers; some of the substances used 
were auto soap, powdered glue, and a proprietary casein product. 
Soap was used at the rate of 2 pounds to 100 gallons of water, and the 
arsenate-of-lead mixture containing this material was sprayed June 
11, 1923, on the foliage of oak, cherry, birch, hazel, and maple trees. 
This material caused the spray to spread entirely over the surface of 
the leaf, and in all the experiments made no other substance used 
could quite compare with soap as a spreader. After a total of 4.15 
inches of rain had fallen since the application of the spray on June 11, 
the foliage was examined on July 31, 1923, and practically all of the 
material was found to have been washed from it; only a very small 
quantity of the poison could be seen. On September 30 hardly a 
trace of the spray could be found remaining. 
As the results of the experiments with powdered glue and the 
proprietary casein product did not show much promise, no details 
