ARSENICAL POISONING FROM SMELTER SMOKE. 
1G7 
the edges seemed to be due to the natural secretion of the mucous 
membrane. This animal had been on pasture but eight or nine 
days, and the ulcer had developed during this short period. 
Another horse, examined on the same day, had an ulcer 
covering nearly the whole surface of the floor of the nostril. 
The lesion was of the same character as in the former case, with¬ 
out any sharply defined border, but shading gradually into the 
normal, surrounding tissue. These animals were pasturing about 
two miles from the smelter. 
Examining the horses on a ranch four miles from the smelter, 
on October 5 the following notes were made: 
“ One colt has a simple erosion of the mucous membrane. 
A second and third have excoriations and cracks extending from 
the lower border of the nostril downwards in one animal and in¬ 
wards in the other. These cracks are located where the parts are 
moistened by the nasal secretion. One of these animals had 
scars of ulcers which it contracted in 1905. In one nostril was 
a crust, having the appearance of black mud, which was dry, 
hard and firmly attached to the hair and skin. When removed, 
there was found to be a loss of epithelium and a granulating 
surface underneath.” 
There was practically no discharge from these ulcers. When 
the crusts were removed, the surface was seen to be simply 
moistened with a very thin layer of pus. 
From this time until January, nasal ulcers were very common. 
In order to obtain some further light on the etiology of these 
ulcers, certain experiments were made, of which a brief account 
will be given. 
Experiments to determine if the ulcers could be reproduced 
by inoculation .—The material for inoculation was obtained by 
scraping the surface of a fresh ulcer, that is, one which had de¬ 
veloped within a few days. The scrapings were made into an 
emulsion or suspension with distilled water and inoculations were 
made as follows: 
October 3, 1906. Horse No. 1 inoculated in left nostril by 
the hypodermic injection of 1 c.c. of suspension; also, inoculated 
