D. E. SALMON. 
o()G 
No. of Sample. 
Distance from 
Smelter, 
Miles. 
Parts As 2 0 3 
Per Million. 
I .... 
. 2 S. 
254 
587 
1,015 
902 
545 
c> 
. 4.5 N.N.E. 
. * S.E. 
0 •••• 
4 . . . . 
5 . . . . 
kJ 
. 2 S. 
. 3 s.w. 
These analyses give an average, with five samples, of 660 
parts of arsenious acid per million, an enormous quantity, which 
was far beyond any anticipations that were harbored by the 
writer before the analyses were made. It may, therefore, be ad¬ 
mitted that all of these lines of evidence are in harmony with 
the theory that the ulcers are caused by the direct action of arsenic 
at the point where the lesion appears, while the presence of so 
much arsenic in the crusts and tissues of the ulcers, considered 
in connection with the other lines of evidence, must be accepted 
as direct and convincing proof that this is the cause. 
7. Why arc not similar lesions observed in other species of 
animals ?—This is a question that was often asked by persons 
opposed to the arsenical theory, and, while it is by no means 
necessary that it should be answered in order to establish that 
theory, it is, nevertheless, desirable that it should receive some 
attention. Comparing equine and bovine animals, it must be ad¬ 
mitted by all that the horse bites closer to the ground than the 
steer or cow, and this fact, together with the use of the mobile 
upper lip, makes it probable that more dust is raised and drawn 
into the nostrils by the horse when eating grass at pasture than 
by bovine animals. Secondlv, the skin and mucous membrane 
at the entrance to the nasal chambers of the horse are much 
thinner, softer and more sensitive than those of the cow, and, 
no doubt, would be affected much more easilv; besides, the tissues 
of the horse are, in general, more easily irritated and inflamed 
than are those of the cow. Thirdly, the bovine animal has an 
