192 
Proceedings of the Poyal Society 
University laboratory, and was very pure. On analysis the follow- 
ing results were obtained : — 
Weight of salt, . . . 0*6208 grammes. 
Weight of salt after heating (KC1), 0*3330 „ 
Difference oxygen, . . 0*2878 ,, 
Chlorine in residue, . . 0*1581 „ 
Whence we have the following composition per cent. : — 
Found in 
Calculated 
Salt. 
in KC10 4 . 
Potassium, 
LO 
00 
t-j 
GO 
28*22 
Chlorine, . 
25*46 
25*61 
Oxygen, . 
46*36 
46-17 
100*00 
100*00 
3*0938 grammes KC10 4 oxidise 10 grammes iron from the ferrous 
to the ferric state. 3*0940 grammes were dissolved in warm water 
and made up to a litre at 9° C. 
Nitrate of Potash. — 6*018 grammes K1ST0 3 oxidise 10 grammes 
iron from the ferrous to the ferric state. 6*019 grammes were dis- 
solved in water and made up to a litre. The nitrate of potash was 
purified by recrystallisation. 
The sulphuric acid used to acidify the solutions was made by 
diluting 1 part by weight of pure oil of vitriol with 9 parts by 
weight of water. It contains, therefore, very closely one gramme- 
molecule per litre (H 2 S0 4 ). 
PermoMganate of Potash . — This solution was made by dissolving 
3*163 grammes crystallised salt in water and making up to a 
litre. 3*162 grammes = =0*02KMnO 4 . Tested with the 
ou 
double sulphate of iron and ammonia, 17*9 c.c. were found to be 
required to oxidise 0*1 gramme iron from the ferrous to the ferric 
state. 3*163 grammes KMn0 4 oxidise 5*602 grammes iron from 
ferrous to ferric, therefore 17*9 c.c. of the above solution ought to 
oxidise 0*1003 gramme iron. 
It is well known that the use of permanganate of potash for 
titrating ferrous salts in hydrochloric acid is discouraged, and indeed 
prohibited by the highest authorities in analytical chemistry. As a 
matter of fact, however, there is very little inaccuracy attending its 
