180 Wisconsin Academy of Sciences, Arts, and Letters. 
13. ) Appearance of the finished product. The 1880 edition is 
the first edition of the U. S. P. that directs the finished product to 
be filtered after the reaction mixture has been allowed to stand 
eight days. Neinhaus 104 points out that this procedure was adopted 
to allow the formation of the precipitate that appears in Fowler’s 
Solution and the subsequent removal by filtration. 
14. ) Qualitative tests. The last edition of the U. S. P., viz. that 
of 1910 is the only one that gives qualitative tests. Apparently 
these were regarded as necessary because of the enforcement of the 
Pure Food and Drugs Act of 1906. The first paragraph of these 
tests is descriptive. The faint opalescence of the solution is due 
to the oils 105 in the compound tincture of lavender; the pink color 
is that of the Santalum Rubrum also in the tincture. The alka¬ 
linity is due to the excess of potassium bicarbonate 105 used in the 
preparation, also to the hydrolysis of the potassium arsenite. 106 
The second paragraph is an identity test for arsenic. Upon 
acidulating the solution with hydrochloric acid and saturating with 
hydrogen sulphide a yellow precipitate of arsenous sulphide is 
formed. This precipitate is soluble in Ammonium Carbonate T. S. 
The reaction with ammonium carbonate has been indicated as 
follows : 105 
2As g S3 F 2(NH 4 ) 2 C O s = 2C 0 2 +NH 4 As0 2 + 3NH 4 AsS 2 
Structurally, the formulas involved may be represented in the 
following manner: 
As — S 
/ONH 4 
F c=0 IFF c F As F As 
As=S \()NH 4 FF) \()NI1 4 \SNH 4 
With Silver Nitrate T. S. the acidulated solution forms a yellow 
precipitate of silver arsenite. This has been expressed by the fol¬ 
lowing equation : 105 
KAsO 2 F H g O F 3AgNO s = 2HNO^F KNO s F As(OAg) 3 
As /TI /OA g /OH /OK /OA g 
\OK F o F N=0 IFF N=0 F N=0 F As—OAg 
\H \() \0 Ag 
104 Pharm. Ztg., 37, p. 331 (1892.) 
105 Commentar zur Pharmacopoeia Helvatica (1896), p. 196. 
1116 Kommentar zum Deutschen Arzneibuch, vol. 2, p. 64. (1910.) 
