The bromides, in solution, are readily decomposed and chloride being set free, colors the liquid brown.
In the whole range of heliographic chemicals there is probably not another collection less understood and being so productive of interesting investigation as the bromides.
Bromide of Iodine .-- M.

de Valicours furnishes us with the best method for preparing this mixture: "Into a bottle of the capacity of about two ounces, pour thirty or forty drops of bromine, the precise quantity not being of importance.
Then add, grain by grain, as much iodine as the bromine will dissolve till quite saturated.

This point is ascertained when some grains of the iodine remain undissolved.

They may remain in the bottle, as they will not interfere with the success of the preparation.
"The bromide of iodine thus prepared, from its occupying so small a space, can very easily be carried, but in this state it is much too concentrated to be used.

When it is to be employed, pour a small quantity, say fifteen drops, by means of a dropping-tube, into a bottle containing about half an ounce of filtered river water.