To prevent solarization, coat a plate as usual, expose to the action of light any required time (according to circumstances), say from quarter to one half more time than would be required in the ordinary method of procedure; observe, before putting the plate in the mercury box, place it over the vapor of iodine, bromine, or chlorine, etc.

(carefully excluding the light), for a very brief period, great care being required to have the selected vapor very much diluted with air, in order to success.

Many experiments will be required ere arriving at satisfactory results.
Specimens now unknown to general operators, for harmony of effect, have been, and may again be produced by the method pointed out above.

I have found the best general effect, and the most certain result to follow from the use of the vapor of chlorine--but this requires more than ordinary care.

I would, therefore, recommend the use of iodine.
Thus: to a few grains of iodine, add an ounce of warm water (which will become tinged with iodine); when cold, to half a pint of pure water in a new and clean coating box, put, of the above, fifty drops; stir and mix well this small quantity of iodine in with the water; in ten minutes this box will be ready for use.