New YorRK AGRICULTURAL EXPERIMENT STATION. 307 
pound of arsenic acid is sprayed on each tree in one season. 
Soil near the bases of these trees taken from depths of 4-12 
inches yielded 25.5-61.3 parts of arsenic acid per million parts 
of soil. Most Colorado soils are said to contain from 0.2 to 1 
per ct. of alkalis (‘‘sodic carbonate, sodic sulphate and sodic 
chloride”), and Headden thinks that the accumulated insol- 
uble arsenic salts are converted to soluble compounds by the 
alkalis in sufficient quantities to cause the death of the trees. 
“ The crown of the tree is found to be girdled, the bark on 
portions of the trunk dead and sunken and most of the roots 
dead, their bark destroyed and the woody tissue discolored, 
usually a light shade of brown and sometimes exteriorly black- 
ened.” ‘“ The limbs and branches of trees affected in this 
way usually, but not invariably, present a case of ‘ black 
heart.’ ”’ 
Samples of wood were taken from 11 apple and 8 pear 
trees and all gave the arsenic test. From 1.25 to 12.77 parts 
of arsenic per million of wood tissue were found in the few 
cases in which quantitative determinations were made. To test 
the toxic properties of arsenic .05 to .56 gram portions of “ sodic 
arsenite” were added to the soil of herbaceous greenhouse 
plants “in two and a quarter to three-inch pots,” resulting in 
the death of all treated plants. A case is cited where some 
arsenite of soda was said to have been emptied into an irri- 
gating ditch twelve feet from an apple tree; two days after- 
ward one of its large ditch-ward branches appeared diseased. 
A dead, decorticated root was found to extend to the ditch 
while some other roots seemed normal. <A strip of bark on the 
trunk, between the affected root and branch, was found to be 
brown and dead. Thus it seemed that the arsenite of soda was 
absorbed by the tree, causing the death of both root, branch 
and intervening bark. The typical “black heart” of the af- 
fected trunk and branch was present. The root contained 34.5 
parts of arsenic acid per million parts of tissue. 
The solubility of lead arsenate was tried by suspending 1 
gm. in 2 |. of water and adding 2 gms. of Glauber’s salt. 
