93 
arsenic to an avoirdupois pound of the sample peelings. This would 
mean that one would have to eat approximately four pounds of 
apple peelings to get a grain of arsenic if the fruit were taken the 
day after spraying from a tree which had received four times the 
usual strength of this insecticide. 
Another tree, a Benoni, differed especially in two respects from 
the foregoing. It had been sprayed three times by the owner earlier 
in the season, and it was sprayed twice by us — June 9 and July 4 — 
but with arsenate of lead in the strength usual in practical orchard 
work, that is 125^ ounces of acetate of lead and 5 ounces of arsen- 
ate of soda to 50 gallons of water. The earlier sprayings were as 
follows: First spraying about April 3, before the appearance of 
the bloom, with 3 pounds copper sulphate, 5 to 6 pounds lime, 2 
ounces arsenate of soda, and 2 ounces Paris green, to 50 gallons 
water; second spraying about April 26, just after the bloom had 
fallen, with 2 pounds copper sulphate, i pound Lorenberg's arsenate 
of lead, 2 ounces Paris green, 3 to 4 pounds lime, and 50 gallons of 
water. Rain fell more or less for three days after this second 
spraying. The third spraying, about May 3, was with 2 pounds 
copper sulphate, 3 to 4 pounds lime, i pound Lorenberg's arsenate 
of lead, 2 ounces Paris green, and 50 gallons of water. 
From this tree six apples averaging two inches in diameter were 
picked July 5, the day after our own second spraying, with the pre- 
cautions described above. The peelings tested by Dr. Dehn yielded 
32.9 parts of arsenious acid per million, equivalent to .2303 grains 
of arsenic per pound of the samples. 
It will be noticed that, although the insecticide here used con- 
tained only one fourth as much of the arsenate as that applied to 
the Duchess tree, the percentage of arsenic remaining on the fruit 
was nearly as large. 
The third tree treated was a Rome Beauty, sprayed, like the 
preceding, three times, April 3, April 26, and May 3, approxi- 
mately, with combinations of Bordeaux mixture and arsenical in- 
secticides, and further sprayed, June 9 and July 4, with home-made 
arsenate of lead at the rate of 121^ — 5 — 125/^; that is, like the 
first tree, with four times the usual strength. 
The apples were picked from this tree September 4, two full 
months from the time of spraying. Those chosen showed more 
than the average amount of residue of the insecticide on the fruit. 
They were picked into baskets, poured into a box where they were 
packed closely by hand, and shipped to the office at Urbana, being 
given average shipping treatment. Ten apples were later taken 
from the box and carefully peeled, the peelings being submitted, as 
before, to Dr. Dehn for examination. Notwithstanding the long 
exposure in the orchard, the report on the arsenical contents of this 
