166 Wisconsin Academy of Sciences, Arts, and Letters. 
It has been commonly assumed that the original amount of water 
used was reduced for the purpose of accelerating the reaction be¬ 
tween the acid and the alkali carbonate and thus increasing the 
rate of solution. Thus E. Martin 77 modified the U. S. P. process 
by dissolving 64 grains each of arsenic trioxide and potassium bi¬ 
carbonate in two or three drams of water with the aid of heat. 
When solution was effected he added the remainder of the water. 
This procedure he claimed decreased the time ordinarily required 
to make Fowler’s solution. Gr. Hamel 78 placed the arsenic trioxide 
and potassium carbonate, (3 grams each) in a test tube moistened 
the mixture with a few drops of water and applied heat until a 
liquid mass resulted. This he then diluted with a few mils of 
water and heated until solution took place, after which more water 
was added, up to the required volume. P. Maysse 79 modified the 
‘ ‘ Codex ’ ’ method by heating one gram each of arsenic trioxide and 
potassium carbonate with five drops of water, in a test tube, until 
the solution took place and then diluting up to 100 cc. 
In order to test the correctness of this explanation, experiments 
on the rate of solution in varying concentrations were performed. 
A.) One gram of arsenic trioxide and two grams of postassium 
bicarbonate (the ratio of As 2 0 3 and KHC0 3 used in the U. S. P.), 
were mixed with 25 mils, 50 mils, 100 mils, and 200 mils respec¬ 
tively, of boiling water, and the time required to obtain a clear 
solution noted. The effervescence, caused by the decomposition of 
the bicarbonate, had a tendency to carry the arsenic trioxide up 
the sides of the container, hence to interfere with the action of the 
solvent, even though a stirrer was used and vigorously at that. 
To eliminate this objectionable feature the following modification 
was adopted. The potassium bicarbonate was dissolved in water, 
(20 gm. in sufficient water to make 100 mils.) and the solution 
boiled until no more carbon dioxide was apparently given off. This 
required about 30 minutes. An aliquot portion of this solution, 
representing the amount of potassium acid carbonate desired, was 
diluted with water up to a definite volume and the mixture heated 
to boiling. The required weight of arsenic trioxide was introduced 
into a test tube of suitable capacity, the boiling solution of the 
potassium salt poured on to this and the tube immediately im- 
77 Am. Jour. Pharm., 44, p. 202 (1872.) 
78 Pharm. Ztg., 61, p. 402 (1906.) 
79 Bull, des sc. pharmacol. 13, p. 106 (1906); through Digest of Comments, 
1906. 
