ost wholly
disappears. From this it will readily be perceived that the middle
shades are the ones to be desired for representing the harmonious
blending of the lights and shades.

Then, if we examine, with respect to strength, or depth of tone, and
sharpness of impression, we see that the light coating, produces a very
sharp but shallow impression; while the other extreme gives a deep but
very dull one. Here, then, are still better reasons for avoiding
either extreme. The changes through which the plate passes in coating
may be considered a yellow straw color or dark orange yellow, a rose
color more or less dark in tint, or red violet, steel blue or indigo,
and lastly green. After attaining this latter color, the plate resumes
a light yellow tint, and continues to pass successively a second time,
with very few exceptions, through all the shades above mentioned.

I will here present some excellent remarks upon this subject by Mr.
Finley. This gentleman says:

"It is well known to all who have given much attention to the subject,
that an excess of iodine gives the light portions of objects with
peculiar strength and clearness, while the darker parts are retarded,
as it were, and not brought out by that length of exposure which
suffices for the former. 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 k