428 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



dichromate there is little danger of decomposition of nitric acid or oxides 

 of nitrogen by the oxidized copper. It is to be noted that if the nitric 

 acid is decomposed during the experiment according to the following 

 equation : 



2HNO3 = H 2 + 2N0 2 + 0, 



and is absorbed by the potassium hydroxide as N0 2 , there is a slight 

 loss of oxygen. The proportion of nitric acid present being very small, 

 however, this error could have no appreciable effect on the results. 



It is somewhat surprising that Samples I and II contain the same 

 proportion of volatile matter. This agrees with the result of the silver 

 determinations, however, the samples proving to be otherwise very 

 similar. As is to be expected, Sample III contains less impurity than 

 either of the other two. 



