MAGNESIA AS AN ANTIDOTE FOR ARSENIOUS ACIDS. 179 
If the efficiency of this plant depends upon the essential 
oil, as is thought by Dr. Hodges, how can it be supposed 
that a cold infusion is the best form of exhibition ? Can 
an aqueous menstruum remove the oil from the leaves and 
hold it in suspension ? To determine whether the oil was 
removed from the leaves by cold infusion, a portion of the 
leaves were displaced with distilled water after a maceration 
of three hours, and introduced into a small glass retort; they 
were then strongly boiled; the distillate was the same in every 
apparent property, as that from leaves not previously in- 
fused. How this agrees with his opinion that the cold infu- 
sion seems the best form for obtaining its medicinal proper- 
ties, and that the oil is probably the most important princi- 
ple, is not readily perceived. 
U. S. Naval Hospital, New York, August 4, 1846. 
ART. XXXIV.— ON THE EMPLOYMENT OF MAGNESIA IN THE 
TREATMENT OF POISONING BY ARSENIOUS ACID. 
By A. Bussy. 
The results of my investigations are, — 
1. That purified animal charcoal, recently proposed as 
an antidote in cases of poisoning with arsenic, cannot be 
employed with success for this purpose. 
2. That pure but slightly calcined magnesia readily ab- 
sorbs arsenious acid in solution, and forms with it a com- 
pound insoluble even in boiling water. 
3. That, in the gelatinous state, it absorbs it still more 
rapidly. 
4. That animals to which arsenic had been administered 
were constantly saved when sufficient doses of magnesia 
were subsequently given to them. 
5. That this antidote has an advantage over all those 
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