_Mr. Lyte's Treatment of Positives._--It would be quite superfluous, after
the very excellent communication of MR. POLLOCK, were I to give a detailed
account of my method of printing albumen positives, as, in the main, we
both follow the process of Mr. Le Gray. But as we both have our own
improvements on the original process, I will ask for space in which to
record our differences in manipulation.
First, in regard to the chloride of gold, I always find, and I believe such
is the experience of many photographers, that all salts of gold, though
they heighten the effect at first, have a slow, but sure, destructive
action on the picture.
Next, I find that acetic acid, by generating sulphurous acid, has a similar
effect, and my care was to try and make a solution which should be free
from these defects. I first take my positive, which, as a general rule, I
print at least half as dark again as the shade required. This done, I wash
it well with water, and next with salt and water in the proportion of about
half a grain per gallon, or quite a tasteless solution; this removes all
the nitrate of silver from the paper, or if there is any left, the bath of
salt decomposes it, leaving none in the texture of the paper to unite with
the hypo., which otherwise forms a sticky substance, difficult to remove,
which may be readily seen on looking through a positive which has been too
hastily finished in the usual way, giving a dark shade, and a want of
transparency to the lights. I then place the picture in a bath composed as
follows:
Sodae hyposul. 3 oz.
Argent. chlorid. 70 grs.
Potassii iodidi 5 grs.
Pyrogallic acid 1-1/2 to 2 grs.
The iodide of potassium I add on the same principle as MR. POLLOCK's iodide
of silver, but as being {16} more convenient, as immediately on being added
it decomposes some of the chloride of silver, and forms iodide of silver. I
am happy to find that MR. POLLOCK confirms me in the use of this salt;
which I had long thought to improve the tone of my pictures. The liquid,
which will become rapidly very dark coloured, must be set aside in an open
vessel in a warm place for some weeks, _e.g._ till, when a positive is
placed in it, left for a short time, and then washed with water, it shows
clean and not mottled in the light. The solution may be kept always
exposed, and much improves by this: if _much_ used, it should be
replenished with a simple solution of hypo. three ounces or two ounces to
the pint; if little used, it may be filled up as much as evaporates with
pure water.
The positive is left in this solution till the required tint is obtained,
when it is to be placed in plain hypo. two ounces to the pint, and in about
a quarter of an hour transferred to a basin of pure water, and well washed
in several waters. The other detail of MR. POLLOCK's process is so
admirably and clearly given, and so like that I pursue, that I will not
trouble your columns with it again.
The after-bath of pure hypo. is not absolutely necessary; and where it is
desired to obtain fine olive, and dark sepia, and black tints, a better
tone results from washing well, long, and frequently, with water alone.
This bath also gives very rich tints with paper, prepared without albumen:
viz.--
Chloride of ammonium 5 grs.
Water 1 oz.
Lay the paper on this, and then hang it up to dry, and excite with
ammonio-nitrate containing seventy grains of nitrate of silver to one ounce
of water. Should the above solution not give the requisite tints soon after
being made, add more chloride of silver; but bear in mind that the solution
will then soon become saturated when setting positives, and when this
occurs it must be rectified by the addition of a small portion of fresh
hypo. alone.