39S 
D. E. SALMON. 
Harkins and Swain that 30.8 grains of soluble arsenic, calculated 
as trioxide, in flue dust, plus about 3 grains soluble arsenic on the 
ration of hay, or in all a daily dose of 33.8 grains (2.2 grams) 
may not only cause symptoms of poisoning, but fatal results in 
less than three weeks. 
This experiment of Harkins and Swain is worthy of special 
attention for the reason that the arsenic was in the form of flue 
dust and hay dust, that is, in the form in which it was habitually 
ingested by the animals of the Deer Lodge Valley. In this form 
it is easily moistened by water, and no doubt the soluble part is 
dissolved in a very short time after it reaches the stomach. We 
should, therefore, expect poisoning with minimum doses, and 
much more regular and constant results from arsenic in this 
form than from white arsenic in powder. As a matter of fact, 
the result obtained by Harkins and Swain in this experiment dif¬ 
fers little, if at all, from that which follows the administration of 
arsenic in solution. 
Finlay Dun (7) says that “Thirty grains daily dissolved in 
potassium carbonate destroyed a horse in four days.” 
The following is a summary of an experiment made by the 
writer, bearing upon this point: 
A horse of about 850 pounds, in moderate condition of flesh, 
with good circulation and respiration, and that had not been ex¬ 
posed to the arsenical smoke-products, was selected. 
August 29, 1906. There was administered 20 grains of ar- 
senious acid in powder. 
August 30. Administered 40 grains dissolved in potassium 
carbonate solution and mixed with bran. 
August 31. Animal slightly dull; appetite diminished. Re¬ 
peated dose of 40 grains. 
September 1. Animal apparently normal. Repeated dose 
of 40 grains. 
September 2. Animal quite ill; dull; no appetite; excrement 
covered with thick, stringy, white mucus; pulse almost imper¬ 
ceptible; artery tense; respiration accelerated; urine voided in 
small quantities; slight paralysis shown by difficulty of walking: 
