Feb. 19,1917 Arsenical Injury through the Bark 0} Fruit Trees 
299 
The same compounds were used as on the unwounded branches just 
described. The strengths varied between 1 to 10,000 and 1 to 1,000,000. 
In a strength of 1 to 1,000,000 none of the chemicals caused injury. In 
a strength of 1 to 100,000 there was no injury other than a slight dis¬ 
coloration of the margin of the wounds, except in the case of potassium 
arsenate, which in one of the duplicate treatments killed the bark for 
yi to ¥% inch around the wound. In a strength of 1 to 50,000 practi¬ 
cally no injury was caused by potassium arsenate, potassium arsenite, or 
sodium arsenate. The bark was killed for to yi inch about the wound 
by arsenic acid and for yi to % inch by sodium arsenite. Ammonium 
arsenate caused a spot y 2 by 1 inch about the wound. When used in a 
strength of 1 to 10,000, there was some injury from every chemical, and 
in most cases definite streaks ran up and down from the wounds. The 
average length of these streaks from the top of the ‘one running up from 
the wound to the bottom of the one running down was as follows: Arsenic 
acid, 16 inches; ammonium arsenate, 2 inches; potassium arsenate, 4 
inches; potassium arsenite, % inch; sodium arsenate, % inch; sodium 
arsenite, iX inches. As these figures are averages for four wounds in 
each case, they probably give a fair idea of the toxicity of the soluble 
arsenical compounds. 
It may be seen that when the limbs are not wounded they will with¬ 
stand much stronger solutions than if the bark is ruptured. A strength 
of 1 to 10,000 materially injured wounded limbs; but 10 times that 
strength, or 1 to i,ooo, caused very little injury to unwounded limbs, and 
in most cases none at all. 
Turning now to a consideration of the relative injuriousness of the 
so-called insoluble arsenicals, we find much wider differences than in 
the solubles. Here we have to deal with two factors: The solubility of 
the chemicals under the conditions of the experiments and the toxicity 
of the part in solution. 
To get a comparison of the effects of different insoluble arsenicals on 
unwounded branches, the following were applied in 6o-gm. quantities: 
Arsenic trioxid, Baker. 
Arsenic trioxid, Merck. 
Arsenic trisulphid, Baker. 
Arsenic trisulphid, Merck. - 
Calcium arsenite, Baker. 
Calcium arsenite, Merck. 
Copper aceto arsenite, Ansbacher. 
Copper aceto arsenite, Baker. 
Two unwounded branches were treated with each chemical. The 
severest injury was caused by arsenic trioxid, arsenic trisulphid, cal¬ 
cium arsenite, and Baker’s triplumbic lead arsenate. These all pro¬ 
duced streaks extending up and down from the bandages for several 
Lead arsenate, diplumbic, Baker. 
Lead arsenate, diplumbic, Swift. 
Lead arsenate, triplumbic, Baker. 
Lead arsenate, triplumbic, Grasselli. 
Lead arsenate, technical, Merck. 
Zinc arsenite, ortho, Baker. 
Zinc arsenite, ortho, California Spray Co. 
