Vol, II, No. 4.) Silver Diowide and Silver Perowynitrate. 153 
[N.S.] 
the time when the color appeared equal in intensity to that of one 
of a series of standard solutions of ammonio-citrate of iron con- 
tained in similar test-tubes, There was some difficulty in that the 
ammonio-citrate of iron solutions had a warmer brown color than 
that of the solution under investigation, One set of observations 
is given in the following table :— 
Concentration 
o 
Time (t) | citrate of 
(mins.). iron m 
(x) (gms. per 
itre), 
0-0 50 
15 25 
25 12'5 
5°0 6°25 
80 3°12 
5 1°56 
125 0-78 
15°0 0°39 
Temp. 31° C, 
Strength of nitrie acid Sp. G. 1°357 at 85° F, 
© Loganthmue lurve 
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