Langenhan—The Arsenical Solutions. 
179 
It becomes apparent that the London Pharmacopoeia followed 
Fowler’s formula and that when, in 1851, the Imperial pint of 
20 fid. oz. was substituted for the wine pint of 16 lid. oz. the amounts 
of arsenic trioxide and potassium carbonate were increased ac¬ 
cordingly leaving the percentage of arsenic trioxide the same. In 
1885, however, the strength of the solution was made approximately 
that of one per cent, as had been done by the U. S. Pharmacopoeia 
of 1880 published in 1883. The more accurate approximation was 
made in 1898. With the abandonment of the old systems in 1914, 
the exact ratio of 1 to 100 was the simplest and hence the only 
natural one. 
This does not imply, however, that the finished product contains 
1 p. c. of arsenic trioxide or its chemical equivalent, for the Arseni 
Trioxidum of the U. S. P. and the Arsenous Anhydride of the B. P. 
are not necessarily 100 p. c. As 2 0 3 . For further details on the 
percentage strength of the solution see No. 14. 
The “fifteen ounces and a half,” the weight equivalent of Fowl¬ 
er’s pint can be explained by calling attention to his statement in 
his original report (p. 80) in which he points out that the weights 
are expressed in Troy ounces and wt. avoirdupois “is always im¬ 
plied in the medical profession. ’ ’ According to the London Phar¬ 
macopoeia of 1836 (Phillips translation) the “wine” pint is equiva¬ 
lent to 7290 grains, and the Troy ounce contains 480 grains. Hence 
7290 grains (the equivalent of the wine pint) are equal to 15.1 
Troy ounces and not 15.5 ounces as stated by Fowler. 
In 1837, Salles points out that whereas in those pharmacopoeias, 
in which the same system of weights and measures is used (Apothe¬ 
caries weights and Wine measure) viz. “American of 1820, Ant¬ 
werp of 1812, Batavia (Dutch) of 1805, Belgian of 1825, Edin¬ 
burgh of (?),, Hanover of 1823,” etc. the strength of the finished 
product is the same, in the French Codex of 1818 it is different 
because the formula of the London Pharmacopoeia has been used 
“more or less literally” without taking into consideration the dif¬ 
ferences in weights and measures. Whereas the ‘ ‘ oxide of arsenic ’ ’ 
content of the London Pharmacopoeia is one-one hundred and 
twentieth, that of the .French Codex is one-one hundredth. In 
order to correct this discrepancy, he suggests a formula, based on 
that of the London Pharmacopoeia (1:120) expressed in grammes 
or “parts by weight” so that it may be translated in any language 
and system without alteration of the strength of the finished 
product. 
