Mr Foster, Estimation of Copper. 
97 
the case with zinc, nickel and iron, but these complications are 
not, as we have seen, always due entirely to the same cause. 
The investigation seems to show that the method of Schwarz* 
modified as described above is capable of giving very good results 
with solutions containing copper alone, but that it cannot be 
applied to mixtures of copper and those metals with which it is 
usually associated in alloys and ores. 
The investigation described above was undertaken at the 
suggestion of Mr H. 0. Jones, M.A., Clare College, to whom the 
author is indebted for much advice and assistance during the 
progress of it. 
* Schwarz, in his paper on the estimation of copper (Annalen cler Chemie und 
Pharmacie, Vol. 84, p. 84 (1852)) gives only one titration number for each analysis 
carried out by him. It is not possible therefore to say whether his numbers were 
consistent or not, or whether he used the mean of all the numbers obtained by 
him, or only the more favourable ones. 
VOL. XIV. PT. I 
7 
