Hence, statuary, monuments, and all objects of like character, were remarkably well delineated by the original process of Daguerre; the plate being coated with iodine alone.

An excess of bromine, to a certain degree, has the opposite effect; the white portions of the impression appearing of a dull, leaden hue, while those which should be black, or dark, appear quite light.

This being the case, I conclude there must be a point between the two extremes where light and dark objects will be in photogenic equilibrium.

The great object, therefore, is to maintain, as nearly as possible, a perfect balance between the two elements entering into union to form the sensitive coating of the plate, in order that the lights and shades be truly and faithfully represented, and that all objects, whether light or dark, be made to appear so far conformable to nature, as is consistent with the difference in the photogenic energy of the different colored rays of light.

It is this nicely-balanced combination which ensures, in the highest degree, a union of the essential qualities of a fine Daguerreotype, viz., clearness and strength, with softness and purity of tone.
"So far as I know, it is the universal practice of operators to judge of the proportion of iodine and bromine in coating the plate, by two standards of color the one fixed upon for the iodine, the other for the additional coating of bromine.