l888.-\ PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 81 



lowing a deficiency of 0.0901 gram in the amount of silver precipi- 

 tated, which indicates that 2.G15 per cent, of the copper entered into 

 he reaction without precipitating- a corresponding amount of silver. 

 Expressed atomically we have : 



Cu present as Cn s O 11.8:17-63.4=0.1867 4.477 



Cu not precipitating silver 2. 645-H33. 4=0. 0417 1 



While these results are not as close as could be desired, yet cousider- 

 ug the difficulties in the case arising out of the fact that all the exper- 

 mental errors are thrown upon the 1.493 per cent, of G, they show that 

 or every ICu in the Cu 2 entering into the reaction, one Cu did not re- 

 luce its corresponding amount of Ag. Taken in connection with the 

 liscovery of nitrite of copper in the filtrate from the silver and basic 

 ptrate, these figures clearly establish the reaction as follows : 



Reaction on treating copper containing Cu 2 with AgN0 3 in neutral solution. 

 4Cu:0+CiH-6A g N0 3 +6H,0=2Hr,Cn 4 N i O i: +CuN J 4 +6Ag 



Five grams of the first fusion were mixed with 55 grams of the pure 

 opper and thoroughly fused. Treated in the same way as the second 

 ample, this material yielded the following results: 



lab. taken. Insol. Ca Sol. Ca Fe Agppt. Total Cu O Fe Insol. Cu 



, ,.,,,,, n -.„* , „. Percent. Percent. Percent. Percent. 



3.2626 0.2471 2.9801 0.000490 10.3304 98.915 1.070 0.015 7 58 



3.5278 0.2781 3.2092 0.000455 11.1430 98.890 1.097 013 7*88 



3.3826 a 2966 3.0479 0.000560 10.6036 9^.873 1.110 017 8*77 



Average 98. 893 1. 092 0. 015 8. 08 



Percent. Percent. 

 1. 092 0=9. 75 Cu,0 

 8. 08 Cu=9. 10 CiioO 



The composition of the material is therefore 



Per cent. 

 90,235Cu 

 9. 750 CuiO 

 0. 015 Fe 



100. 000 



Proc. X. M. 88- 



vWr, %,(&%* 



