OXIDATION OF ARSENIC IK DIPPING BATHS. 7 



were analyzed for arsenic in its two forms and were then left at room 

 temperature for varying lengths of time, after which they were again 

 analyzed. Some tests were carried on in open vessels (beakers) and 

 in these the liquid was kept up to its original level or weight by daily 

 additions of water to replace loss by evaporation. 



The following detailed experiments are selected as typical from the 

 considerable number actually performed. 



Experiment 1. — To determine possible influence of high initial 

 percentages of actual arsenious oxid upon oxidation. Total initial 

 volumes, 250 c. c, containing 10 c. c. used bath as inoculum. Carried 

 out in open 800 c. c. beakers, replacing loss by evaporation. 



Table 1. — Influence of high initial percentages of actual arsenious oxid upon oxidation. 



No. of test. 



Per cent actual AS2O3 by analysis. 



Original. \ 10 days. 



20 days. 



30 days. 





0. :00 0. 184 

 . 240 - 234 



0.002 



. nos 





b 



0.001 





.278 

 .316 

 .356 

 .394 



. 276 - 138 



.002 



d 



.312 

 .340 

 .362 



.146 

 .176 

 .232 



.002 





.002 



f 



.002 







Experiment 2. — To determine possible influence of high initial 

 percentages of total arsenious oxid upon oxidation. Total initial 

 volumes, 250 c. c, containing identical initial amounts of actual 

 arsenious oxid, but varying amounts of arsenic oxid. Inoculated 

 and carried out similarly to experiment 1 . 



Table 2. — Influence of high initial percentages of total arsenious oxid upon oxidation. 



No. of test. 



Per cent 

 total 

 As 2 3 . 



Per cent actual AS2O3 by analysis. 



Original. 



10 days. 



20 days. 



30 days. 





0.204 

 .244 

 .284 

 .324 

 .364 

 .404 



0. 084 

 .084 

 .084 

 .084 

 .0X4 

 .084 



0.104 

 .226 

 .201 

 .307 

 .314 

 .316 



0. 013 

 .017 

 .129 

 .179 

 .183 

 .189 





b 



0.001 





.002 



rj . 



.002 





.002 



f . 



.001 







Experiment -i.- To del ermine the rapidity with which reduction 

 may progress. Solution contained no actual As 2 0. t except that 

 introduced in the used bath employed for inoculation, of which 10 

 per c'lii of final volume was added, Solution eontained 0.242 per 

 cenl total arsenious oxid. A portion (test a) was placed in an entirely 

 filled, tightly stoppered bottle, and another portion (test b) left 

 open *<> ill'- uir as in experiments I and 2. 



