314 PROCEEDINGS OF THE AMERICAN ACADEMY. 



to 200 or 300 mmg. phosphorus is necessary. The color of the bands 

 was a bright yellow, somewhat resembling that from hydrogen sul- 

 phide. Hydrochloric acid makes the band a bright lemon yellow, but 

 without increasing its length. The yellow turns slowly brown when 

 exposed to light. Auric chloride acts very slowly, giving at first a 

 characteristic brownish red, which changes to purple. Ammonia acts 

 more slowly than on the arsenic band, giving a less intense black. 



Stihine. The solutions used were made from a sample of pure tar- 

 tar emetic, which had been shown to be free from arsenic. They con- 

 tained respectively 1.0, 0.1, and 0.01 mg. of antimonious oxide per 

 cubic centimeter. Volumes corresponding to 10, 30, 50, and 70 mmg. 

 of the oxide were added to separate bottles and the reduction carried 

 on for thirty minutes. No color was obtained in any case. Hydrochlo- 

 ric acid did not develope. Auric chloride brought out slowly a purple 

 color, duller finally than that of a similarly treated arsenic band. Am- 

 monia turned the band quite quickly black, and a comparison with the 

 arsenic ammonia standards showed amounts equal to about 20 to 40 

 per cent of the arsenic values. On further reduction for thirty minutes, 

 with fi-esh strips, there was no additional deposit on the paper which 

 could be developed by ammonia. Continuing the experiments, it was 

 found necessary to add 100 mmg. of antimonious oxide before any vis- 

 ible band was obtained, and 200 mmg. before the band appeared to be 

 of the same length as that from 30 mmg. of arsenious oxide. The color 

 was a faint gray when first visible ; darker with increasing amounts. 

 The development with hydrochloric acid and auric chloride or with 

 ammonia showed of course that the paper had been originally affected 

 over a much gi-eater length than was then visible. 



These results agree with those obtained by Franceschi,27 who 

 found by the action of stibine on mercuric chloride a white body to 

 which he gave the formula SbHHgsClo, analogous to the formula as- 

 signed by him to the red arsenic compound. Dowzard,^^ also, was 

 unable to obtain a stain on mercuric chloride paper from 0.01 to 

 0.1 mg. of tartar emetic, v;hile irom 0.2 mg. he got a faint black- 

 ish brown color, a result which is essentially confirmed by our 

 experiments. 



Comparative Effect of Reagents. From the necessary amounts of 

 each substance, as shown by the above trials, approximately equal 

 color bands were prepared from arsine, stibine, phosphine, and hydro- 

 s' L'Orosi, 13, 397 (1890). 28 jour. Chem. Soc, 79, 715 (1901). 



