OP ARTS AND SCIENCES. 93 



Analysis No. IX. 



Copper oxide, 

 Arsenic trioxide, 

 Acetic anhydride, 

 Combined water, 

 Hydroscopic water, 



100.04 



This is a confirmation of the preceding result, and seems to prove 

 the existence of a hydrated copper aceto-arsenite. 



Having experimented on an excess of copper acetate with a small 

 amount of arsenic trioxide, the other extreme was now tried, and, as 

 the proportion was 5 to 1 in preceding case, so here 5 to 1 was used. 



Experiment No. 7. 

 Copper acetate, 25 grams. 



Arsenic trioxide, 125 „ 



Dissolved separately, added the copper solution to the arsenic triox- 

 ide, and boiled ; the reaction was as in the preceding cases ; first cop- 

 per arsenite, changing to aceto-arsenite ; this precipitate was filtei'ed 

 off and washed with hot water; the filtrate contained a trace of copper 

 and a large amount of arsenic trioxide. When the excess of arsenic 

 trioxide was waslied out of the precipitate, the latter was dried at 

 100° C. and analyzed. 



Analysis No. X. 



99.91 

 This agrees with the formula, — 



2(CuOC,H,03) 3(CuOAs203) +5H2O, 

 which, calculated in percentages, gives, — 



