D. E. SALMON. 
404 
age fatal dose of arsenic for man is 3 grains, there are some in¬ 
dividuals who are paralyzed by one-thirtieth of that quantity 
(i/ioth grain) daily for three weeks; others that are severely 
poisoned by one-forty-eighth of that quantity (i/i6th grain) 
daily, and occasional individuals who present well marked symp¬ 
toms after taking one-sixtieth of that quantity (i/20th grain) 
daily. 
If the same proportion held true for horses and cattle, admit¬ 
ting the average fatal dose to be 60 grains in solution, some in¬ 
dividuals would be poisoned by 2 grains daily, others by 1% 
grains daily, and a very small proportion by 1 grain daily, if con¬ 
tinued a considerable time. It is not known that this proportion 
holds true for these animals, but the writer is convinced, both 
from an examination of the literature and from his personal ob¬ 
servation, that there are some individuals very much more sus¬ 
ceptible than the average. 
The Condition of the Animals With Relation to the 
Estimated Dose of Arsenic. 
The average daily dose of 13.6 grains of soluble arsenic taken 
by horses and cattle of the Deer Lodge Valley, as estimated from 
the chemical investigations, not only includes the factor of time 
(that is to say, the average for the different months of the year), 
but, also, the factor of location (that is the average of different 
ranches which were variously affected according to distance, cur¬ 
rents of air, etc.). It is, therefore, manifestly impossible to draw 
conclusions from it as to any particular ranch. What it indi¬ 
cates is that the average quantity of arsenic ingested daily was 
somewhat below the toxic dose for animals of ordinary suscep¬ 
tibility. This explains why the great majority of the animals, at 
certain seasons of the year, presented no symptoms of arsenical 
poisoning. It probably is the explanation of the good condition 
of many cows, owned by citizens of Anaconda, which were per¬ 
mitted to pasture in the neighborhood of the smelter; but the ex¬ 
tent to which the pasture of these cows was supplemented by ar¬ 
senic-free food is unknown. At all events, cases of acute poison- 
