302 
Journal of Agricultural Research 
Vol. VIII, No. 8 
Table V .—Results of wounding and treating branches of apple on June 17, IQ12, with 
different arsenicals, 10 gm. each, to show their relative injuriousness 
Extent of injury. 
No. 
Chemical. 
Above 
bandage. 
Below 
band¬ 
age. 
1 
Calcium arsenite. Baker. 
Entire branch. 
Inches . 
19+ 
a 
.do. 
3 
Iron arsenate, Merck. 
inch . 
H 
4 
.do. 
6 inches. 
5 
Copper aceto arsenite, Baker... 
3ft inches. 
6 
.do. 
Entire branch 
5 
7 
Zinc arsenite, ortho. Baker. 
9 inches . 
8 
8 
.do.... 
30 inches 
9 
Zinc arsenite, pyro, Baker. 
10 inches. 
10 
.do...:... 
Streak to tip.. 
Entire branch. 
11 
Zinc arsenite, meta, Baker... 
12 
12 
.do. 
33 
a Nineteen inches below the bandage this branch joined a main limb bearing a dead streak from 
another bandage, and the two ran together. 
It is interesting to compare in Table IV the relative amounts of injury 
from 60 gm. and 10 gm. of the insoluble arsenicals under identical con¬ 
ditions. While there is somewhat greater injury, as a rule, from the 
larger amount, it is not at all proportional to the weights used. 
Table IV also shows that there was no consistent difference between 
the injuries under bandages covered by a rubber dam and those not so 
covered, but kept moist by frequent watering. On the whole, they 
compare about as well as the duplicates in the other tables. 
In general, the injury is much worse on wounded limbs, and nearly 
all the so-called insoluble arsenicals are capable of doing much damage 
to the tree if they gain access to the living tissues. 
EFFECTS OF WASHING THE ARSENICAES 
The question has arisen with much force whether the injuries produced 
in the course of this investigation were due to a portion of the arsenical 
going into solution and exerting a toxic action or to an impurity of a 
more or less soluble nature. This is indeed an important matter, for 
an assumption here without knowledge of the facts may lead one into 
a serious and fundamental error. In our efforts to settle this question 
we have, in the first place, obtained most of our chemicals from reliable 
companies. In some cases we have had special lots manufactured for 
our use, with the distinct understanding that regardless of cost they 
must be free from all soluble arsenical impurities. All of the arsenicals 
received from the Baker Chemical Co. (see p. 287) were of this 
character. To test further the possibility of soluble impurities we 
washed one lot of each of the more important chemicals with many 
changes of distilled water. These were then tested in comparison with 
others from the same containers but unwashed. 
