302 NEW METHOD OP PREPARING IODIDE OP POTASSIUM. 
of der that the whole of tfre iodate may be decomposed, that 
for every atom of carbonate of potash used, there should be 
present 2 atoms of protoxide of iron. The quantities there- 
fore should be 2 atoms or 280 parts of protosulphate of iron, 
which are to yield 2 atoms of protoxide, 1 atom or 125 
parts of iodine, and 1 atom or 83.5 parts of carbonate of 
potash. On account, however, of the liability of the prot- 
oxide of iron to become peroxidized, it is better to take 
rather more of the protosulphate. 
The protoxide, when washed, is to be mixed with the 
iodine and carbonate of potash, half a pint of water being 
used to an ounce of iodine. The mixture is at first to be 
gradually heated, and then boiled for half an hour. The 
solution afterwards ought to be exactly neutral to slightly 
redden litmus-paper ; if iodine be in excess, more carbon- 
ate of potash must be added; if, on the contrary, it is alka- 
line, more protoxide of iron and iodine. The sesquioxide 
of iron remaining, after being well washed, may be heated 
red-hot for a few minutes; a beautifully pure preparation 
remains, which on account of its easy solubility in hydro- 
chloric acid might be advantageously used in the prepara- 
tion of the TV. Ferri Muriatis. 
Ibid., from Ibid. 
