194 
Proceedings of the Royal Society 
With. 25 c.c. hydrochloric acid the method becomes a little strained ; 
but it can he perfectly well carried out if care is taken to add the 
permanganate slowly so as to avoid a local excess, which would 
involve oxidation of the hydrochloric acid. This happened in 
experiment No. 6. In No. 5, which was also otherwise unsatis- 
factory, the ferricyanide had produced a precipitate which should 
always he avoided. 
In Table II. will be found the results of experiments on the 
action of chlorate of potash and of perchlorate of potash solutions 
on ferrous sulphate in sulphuric acid and in hydrochloric acid 
solution when left together for a short time. 
Table II. 
Number of Experiment. 
8. 
9. 
10. 
11. 
12. 
13. 
14. 
Ferrous sulphate ( b ), . .c.c. 
10 
10 
10 
10 
10 
10 
10 
Sulphuric acid (H 2 S0 4 ), . ,, 
20 
20 
20 
20 
... 
... 
20 
Hydrochloric acid (12'6HC1), ,, 
... 
... 
... 
... 
10 
10 
... 
Water, ....,, 
30 
30 
30 
30 
40 
40 
30 
Chlorate of potash solution, , , 
... 
... 
... 
8-8 
... 
8-8 
... 
Perchlorate of potash, . ,, 
... 
... 
6-2 
... 
6-2 
... 
... 
Duration of action, . . min. 
... 
... 
1-5 
1*5 
2 
2 
... 
Temperature of mixture, . ° C. 
... 
... 
17 
17 
16-5 
16*5 
... 
Permanganate, . . .c.c. 
11-2 
11*3 
11-3 
11-0 
11*3 
11-2 
11-2 
In experiments 11 and 13 the chlorate of potash solution used 
was not that described above, which is used for all the following 
experiments, but a somewhat weaker one, of which 14*2 c.c. were 
required to oxidise OT gramme of iron. It will be seen that the 
only case which shows any decomposition is No. 11, where 11*0 
instead of 11*2 c.c. permanganate have been used. Hence at ordi- 
nary temperatures the action of chlorate of potash in dilute acid 
solutions does not necessarily begin instantaneously. 
