92 
Mr Foster, Estimation of Copper. 
Results : — 
(1) 20-92 c.c. KMn0 4 sol. (4) 20-90 c.c. KMn0 4 sol. 
(2) 20-92 „ „ (5) 20-90 „ 
(3) 21-00 „ 
A mean of 20 - 91 c.c. gave 99 - 84 °/ 0 of the Cu actually present. 
Estimation of the copper in a sample of the Electrolytic Copper. 
I. 3T8 gms. of copper was dissolved in nitric acid and the 
solution made up to 500 c.c. 
The grape sugar solution used contained 2*7 gms. of the sugar 
in 500 c.c. and about 30 c.c. was required to ensure the complete 
reduction of the 20 c.c. of the copper solution. 
Results : — 
(1) 20-46 c.c. KMn0 4 sol. 
(2) 20-48 „ 
(3) 20-47 „ 
^1 c.c. KMn0 4 sol. 
A mean of 20"46 gives 99"4°/o of the whole of the copper in 
the solution. 
[The copper used in this series of experiments was found to 
contain about '5 °/o of silver.] 
II. 3"5 gms. Cu in 500 c.c. 20 c.c. of this solution was used 
for each titration. 
(4) 20-45 c.c. KMn0 4 so]. 
(5) 20-42 „ 
(6) 20-48 „ 
20 
19-90 
x -00316 gm.^ . 
Results : — 
(1) 22-10 c.c. KMn0 4 sol. 
( 2 ) 22-00 „ 
(3) 22-10 „ 
A mean of 22-06 gave 100-07°/ 0 
of Cu. 
The sugar solution used was somewhat concentrated and 
excess was added. It is difficult no doubt to wash away com- 
pletely the brown liquid produced during the reduction, when 
this is thick, as is the case when strong solutions of sugar are 
used. This may possibly explain why the result in this series is 
a little higher than it ought to be. 
Hydroxylamine as Reducing Agent : — 
The solution used contained 6 gms. CuS0 4 , 5H a O in 500 c.c. 
1 c.c. KMn0 4 solution contained '00316 gm. KMn0 4 . 
I. The hydroxylamine was used in the form of hydrochloride. 
The following numbers were obtained for 20 c.c. of the solution. 
