even the erasure for a new secretary's name is
discernible in the accompanying specimen, which was obtained with one of
Ross's landscape lenses, without any stop whatever being used, and after an
exposure of five minutes _during a heavy rain_. The sky is scarcely so
dense as could be desired, which will be fully accounted for by the dull
state of the atmosphere during the exposure in the camera.

Having selected your paper as free from blemishes as possible, which is
most readily ascertained by holding it up to the light (as the rejected
sheets do perfectly well for positives, it is well to reject _all_ those
upon which _any_ doubt exists), mark the smoothest surface;--the touch will
always indicate this, but it is well at all times not to handle the
surfaces of papers more than can be avoided. There is much difference in
various individuals in this respect; some will leave a mark upon the
slightest touch, whereas others may rub the paper about with perfect
impunity.

I prefer paper iodized by the single process; because, independently of the
case and economy of time, I think more rapidity of action is attained by
paper so treated, as well as that greater intensity of the blacks, so
requisite for producing a clear picture in after printing.

To do this, take sixty grains of nitrate of silver and sixty grains of
iodide of potassium, dissolve each separately in an ounce of distilled
water, mix and stir briskly with a glass rod so as to ensure their
_perfect_ mixture; the precipitated iodide of silver will fall to the
bottom of the vessel; pour off the fluid, wash once with a little distilled
water, then pour upon it four ounces of distilled water, and add 650 grains
of iodide of potassium, which _should_ perfectly redissolve the silver and
form a clear fluid. Should it not (for chemicals differ occasionally in
their purity), then a little more should be very cautiously added until the
fluid is perfectly clear.

The marked side of the paper should then be carefully laid upon the surface
of this fluid in a proper porcelain or glass dish. Then immediately {598}
remove it, lay it upon its dry side upon a piece of blotting-paper, and
stroke it over once or twice with a glass rod; this as effectually expels
all the particles of air as complete immersion; it is also more economical,
and has the advantage of requiring much less time in the after-immersion in
the hypo. when it is required to remove the iodide. Either pin the pap