Langenhan—The Arsenical Solutions. 
161 
of 1880 which directed that the solution be filtered after standing 
eight days, to remove the precipitate formed. The editor of the 
Chemiker Zeitung 52 calls attention to a previous custom of neutral¬ 
izing the excess alkali with acetic acid 53 to prevent this same reac¬ 
tion. Evidently in a parallel line of thought Garraud 54 suggests 
using a standard alkali 55 to avoid excess alkalinity in the finished 
product. 
Seemingly most writers support the third theory, viz. the action 
of the alkali on the ingredient or ingredients of the alcoholic tinc¬ 
ture or spirit used. M. Goeldner 56 suggests the use of phenol- 
phthalein as coloring agent in place of such a pigment as that of 
red saunders of the compound tincture of lavender, evidently as¬ 
suming that the alkali and the pigment from the red saunders 
cause the precipitate. J. Luettke 57 attributes the “dirty color” 
appearing in the P. G. solution to the action of the alkali and com¬ 
pound spirit of melissa 58 and suggests avoiding this by neutraliz¬ 
ing the solution. Nienhaus 51 claims that the alkali and aromatic 
tinctures and even distilled spirits used in the various pharma¬ 
copoeias are the main causes of the precipitate. He -substitutes 
melissa water for the alcoholic distillate in the P. G. solution, and 
does not obtain a precipitate. The substitution of compound 
spirit of melissa by melissa water is also recommended by Pascal 59 
and Menhaus, 60 while Mueller 60a suggests using the simple spirit of 
melissa. An unsigned article 61 states that the precipitate is due 
to the action of the excess alkali on the red saunders. The “query” 
editor of the Druggists Circular 62 suggests all of the already men- 
62 Chem. Ztg., 16, p. 174 (1892.) 
53 To what extent the solution is neutralized is not made clear. As the alka¬ 
linity of the solution is supposed to be, in part, due to the hydrolysis of the 
formed arsenite (see qualitative tests No. 13) a complete change to potassium 
acetate might take place if sufficient acid were added, before the solution 
would respond to a “neutral test.” 
64 Pharm. Ztg., 39, p. 753; from Bull. Soc. Pharm. de Bordeux (1894.) 
65 Here again the alkalinity due to any potassium arsenite present has been 
overlooked, apparently, or it. has been assumed that the alkalinity is negligible. 
K Ber. d. Pharm. Gesellch., 2, p. 127 (1892.), see also p. 302. 
57 Pharm. Centralh., 559 (1890.) 
68 Compound Spirit of Melissa P. G. is prepared by macerating a mixture of 
melissa leaves, lemon peel, nutmeg, cinnamon and cassia buds with hydro¬ 
alcohol and subsequently distilling until a definite amount of distillate has been 
obtained. This spirit apparently contains only volatile matter as compared 
with the Compound Tincture of Lavender U. S. P. which is prepared by macera¬ 
tion and filtration. 
69 Pharm. Ztg., 50, p. 1009 (1905.), from Bull. Commercial. 
60 Nat. Drug., 21, p. 22 (1893.) 
6° a Ber. d. pharm. Ges., 2, p. 302 (1892). 
81 Proc. A. Ph. A., 46, p. 694 (1896.) from Merck’s Report 
82 Drug. Cir., 52, p. 223 (1908.) 
11—S. A. L. 
