All who will take the trouble to examine the subject, will soon be convinced that the acid softens the silver, bringing it to a state in which it is extremely susceptible of being either oxydized or iodized, according as the circumstances may occur of its exposure to the atmosphere or the iodine." I cannot see the objection to this solution; not, however, in general use.

Our operators do not find it of sufficient importance to the success of their pictures to accept it, the alcoholic solution being in its nature less objectionable.
I will say here, that a plate submitted to only an ordinary polish is found to contain numberless minute particles of the powder made use of.
Should the same plate be buffed for a long time, the polish will nearly all disappear, leaving the cavities in the surface free for the action of agents employed in subsequent operation.

For this reason, I find that great amount of polishing powder should not be applied to the last buff, and it is obvious that three buffs can be employed to adventure; the two last should not receive any polishing materials.

I have examined a plate that was considered to possess a fine finish, and similar had produced good impressions; these same plates, when subjected to a long and light buffing, would present a surface no finer in appearance to the naked eye; but upon exposure to the solar radiation, would produce a well-defined image in one fourth less time than the plate without the extra buffing.
Coating the Plate .-- For this purpose our mechanics and artists have provided a simple apparatus called a coating-box, which is so arranged as to be perfectly tight, retaining the vapor of the iodine or accelerators, and at the same time allowing, by means of a slide, the exposure of the plate to these vapors.

They can readily be obtained by application to any dealer, all of whom can furnish them.
The principal difficulty in coating the plate, is that of preserving the exact proportion between the quantity of iodine and bromine, or quick.