OF ARTS AND SCIENCES. 91 



This shows that when sodium arsenite acts on copper acetate, if there 

 is not a lai-ge excess of arsenic trioxide, we get copper arsenite, 

 •which contains some basic copper acetate, as is the case with the 

 copper sulpliate under like conditions, and tliat the acetic acid gives a 

 brighter shade to tlie color. 



To answer the question as to whether an excess of copper acetate 

 would produce, when mixed with arsenic trioxide, a salt containiajr 

 more basic copper acetate, we have 



Experiment No. 5. 



Copper acetate, 250 grams. 



Arsenic trioxide, 50 „ 



Dissolved in water separately, and mixed the boiling solutions and 

 boiled an hour. The precipitate was green, the filtrate from it was 

 blue, and contained arsenic trioxide, copper, and acetates. The pre- 

 cipitate had this composition : — 



Analysis No. VII. 



Per cents. 



Copper oxide, 50.00 



Arsenic trioxide, 35.57 



Acetic anhydride, 2.47 



"Water, 1 1 .07 



99.11 



This result, deducting hydroscopic water and calculating the per 

 cents anew, gives : — 



100.00 



This is a mixture of copper arsenite and basic copper acetate, almost 

 of exactly the same composition as that obtained by the action of sodium 

 arsenite on copper acetate in Experiment No. 4, and, instead of con- 

 taining a considerable amount of copper acetate, has a very small 

 amount. 



