96 
Mr Foster, Estimation of Copper. 
in the estimations with grape sugar and a solution containing 
only copper. The results were as follows : — 
(1) 24-95 c.c. KMn0 4 sol. 
(2) 24-92 „ 
(3) 25-10 „ 
(4) 25-20 „ 
(5) 24-80 „ 
(6) 25-10 c.c. KMn0 4 sol. 
(7) 24-90 „ 
(8) 25-10 „ 
(9) 25-10 „ 
20 c.c. Cu sol., 25 c.c. K 2 C0 3 sol., 20 c.c. phenyl hydrazine HC1 ; 
(5 gms. is 500 c.c.) being used in each titration. 
As the actual amount present required 25 , 20c.c. it will be 
seen that in all the numbers except one the results are lower 
than they ought to be, but the discrepancy is not great. Phenyl 
hydrazine appears to behave somewhat similarly to NH 2 OH but 
not to the same extent. The washing with alcohol lengthens 
somewhat the time for each titration but this would not be a 
serious objection if the reducing agent had been quite satis- 
factory. 
In another series the numbers obtained were : — 
(1) 21-15 c.c. KMn0 4 sol. 
(2) 21-60 „ 
(3) 21-70 „ 
(4) 22-15 „ 
(5) 21-65 „ 
(6) 21-60 c.c. KMn0 4 sol. 
(7) 21-20 „ 
(8) 20-50 „ 
(9) 20-30 „ 
( 10 ) 21-20 „ 
In this series 
The copper actually present required 22-05 c.c. 
all the numbers except one are below this. 
VI. Copper and Nickel. 
It was found almost impossible to filter the precipitate (even 
with the Gooch filter), in any reasonable time, and the method 
was regarded as impracticable with solutions containing nickel in 
any considerable quantity. 
******* 
Though not fulfilling the expectations formed of it at first, it 
would appear that the method described would be applicable to 
solutions containing copper alone, or with alkali metals only in 
addition. Grape sugar appears to be the only reducing agent 
admissible, for with hydroxylamine and phenyl hydrazine the re- 
results are invariably low for the reason already given. It is 
better however not to have great excess of sugar as the rather 
thick brown liquid formed during the boiling may be difficult to 
remove completely from the Cu 2 0 precipitate. 
It is obvious that complications may arise when other metals 
are present and grape sugar is used to reduce, and this is especially 
