The Photographic News.
Vol. 10, No. 416.
August 24, 1868. p.402
BY M. CAREY LEA.*
INTO THE CIRCUMSTANCES UNDER WHICH SILVER IS FOUND IN
THE WHITES OF ALBUMEN PRINTS
Fixed with Hyposulphite of Soda.
In the following trials the paper was sensitised upon a 40-grain
acidulated bath, and was then fumed five minutes with ammonia.
(7) Lime toning.--Hydrosulphate of ammonia applied to the whites
gave an indication slightly less than the average.
(5) Benzoate of gold toning.--About the same as the last.
(9) Citrate of gold toning.--About the same, or a little more
indication of silver.
(10) A portion of the same print was toned in a bath prepared as
follows :--Two ounces of hyposulphite of soda were dissolved in
eight ounces of hot water, and chloride of gold corresponding to one
grain metallic gold was added while hot. The bath was used two or
three hours after mixing. This bath toned to a rich purple black.
Marks made on the whites with hydrosulphate of ammonia could not be
found after drying, thus indicating a complete absence of
A print was made on paper sensitized on a 40-grain acidulated
bath, fumed ten minutes with ammonia, and printed under a strong
negative. It was then cut up.
(11) A portion was toned with alkaline chloride, and fixed with
hyposulphite for a comparison. It gave, with sulphydrate of ammonia,
results similar to those already noted.
(12) Toned in the same way, and fixed with sulphocyanide of
potassium **--Result, with sulphydrate
of ammonia, about the same as the foregoing.
(13) Toned and fixed in a bath of sulphocyanide of potassium and
choloride of gold.--Result as before. A camel's-hair pencil dipped
in dilute sulphydrate of ammonia, and drawn across the whites,
leaves a well-marked pale buff streak.
(14) Toned and fixed in a bath of sulphocyanide of potassium and
fulminating gold.--Result the same. (In fixing with sulphocyanide,
it appears more difficult to keep the whites clean than with
Fixing and Toning Bath.
(15 and 16) Two further trials were made with the fixing and
toning bath of hyposulphite and gold. In these the same bath as
before was used, now four and five days old respectively. The
results were the same. Whilst in every other case the marks produced
by the sulphydrate were clear and well marked, in these last, as
well as in (4) and (10), the marks were either invisible, or could
only be found by close and attentive inspection. This result was to
me altogether unexpected. The fixing and toning bath has been so
loudly accused of all sorts of mischief, especially of being "wrong
in principle" (which it certainly is not), that I was extremely
surprised to find it possess this very striking superiority in so
important a point.
I did not, however, rest contented even with these repeated
trials. Having printed a number of prints from various negatives, I
toned some of them in the ordinary methods, and fixed and toned some
with the hyposulphite and gold. I then applied the sulphydrate to
the high lights, and found that in all cases the same superiority
existed. In fact, all the prints which had been so toned and fixed
could be picked out by mere inspection of the sulphydrate
I am, therefore, prepared to state, as a fact that does not admit
of a doubt, that a print fixed and toned with hypo and gold contains
less silver in the whites than when treated in any other of the
methods which I have described. My remarks must be understood as
applying to a bath properly managed. If the same bath is used until,
by the action of the chloride of silver upon the hyposulphite, a
quantity of tetrathionate of soda is formed, the results as respects
the silver in the whites may be different. That is a point which I
have not cared to examine; it would have no real value, whatever the
result might be, as the use of such a decomposed bath is to be
condemned on other grounds.
I am aware that the ground which I have taken here--namely, that
a fixing and toning bath gives the purest whites, chemically
speaking--will be apt to arouse much opposition. To such as may call
my results in question, I say, prepare the bath as directed at (10),
and observe the results. These are matters that must be judged by
experience, not by theory. Nor is it to be supposed that I have been
influenced in my conclusions by a prejudice in favour of this
method. On the contrary, my prejudices were the other way. I had
read such bitter attacks upon this mode of proceeding, that, except
while making these experiments, I have never used it, but have toned
and fixed separately.
I now come to another part of the same subject; a part in which I
regret that I have not been able to arrive at any positive
conclusions as satisfactory as I could wish. I think, however, my
results will be worth stating briefly, both because I may save
others the trouble of making similar investigations, and because, by
illustrating the extraordinary tenacity with which the silver
remains combined with the albumen, they give greater completeness to
an examination which has required no small expenditure of time and
The existence of silver in the highest lights, the purest whites
of the finished picture, cannot be looked upon otherwise than as a
very great evil. So long as it is there, there are far fewer chances
for the permanence of the print; and if any way could be found for
removing it, without injury to the rest of the picture, it would be
a great advantage. This is a very difficult problem, and one which I
have been as yet unable to solve. It was at one time asserted that
fixing by sulphocyanide of ammonium removed this portion of the
silver; but this again was contradicted and, as we have seen, very
properly. Indeed, if there exists any preference in this respect, it
is in favour of the hyposulphite. But the difference is too
inconsiderable to be worthy of attention.
There is another important point to be borne in mind, which
follows directly from the examinations here recorded, and which has
not before been adverted to. As the silver in the whites is not
there by any action of light, hut simply in combination with the
albumen, this peculiar combination of silver and albumen is
necessarily present in every part of the picture. It is not more
present in the high lights than in the deep shadows, though its
presence can only be made evident to the eyes in the former. The
silver is present in an entirely different form from the reduced
silver which constitutes the body of the picture until it is toned;
it is liable to be differently affected by all external
circumstances, and undoubtedly forms an element of weakness in the
The fact that silver is present, not by any influence of light,
but simply in combination with the albumen, seemed to establish a
possibility that some means might be found of dissolving it out, it
seemed possible that some reagent could be found, which would either
dissolve out this silver, or bring it into a condition of solubility
in hyposulphite. Could such a reagent be found, it might either,
according to its nature, be placed in the gold toning bath, if
capable of such application without injury to the bath, or the
prints might be passed through the solution immediately after their
first washing. The following substances were examined
Ferrocyanide of potassium.
Ferridcyanide of potassium.
Iodide of potassium.
Bromide of potassium.
Chloride of ammonium.
Acetate of soda.
Phosphate of soda.
The papers, after being cleared of free nitrate of silver by
washing, were placed in solutions of these respective substances for
about ten minutes. They were then placed in a very strong solution
of hyposulphite for a quarter of an hour, and then thoroughly
washed. On testing them with sulphydrate of ammonia, together with a
portion of the same prints treated in the ordinary way, on
comparison no difference could be found, except that the paper
treated with iodide of potassium gave a darker shade than any of the
rest. In fact, iodide of silver dissolves in hyposulphite of soda
much more slowly than chloride or bromide. A piece of paper prepared
with iodide of silver retained its yellow colour almost unimpaired
after fifteen minutes' exposure to a strong hypophosphite bath; some
even remained at the end of half an hour. After eighty-five minutes
the silver was perfectly gone, but sulphydrate of ammonia still
produced the buff streak.
It follows, therefore, that no substance (as far as these
experiments go), is capable of dissolving out the silver from the
* Continued from p. 395.
** The ammonium salt at the time
when these trials were made was not to be had here. I therefore
employed sulphocyanide of potassium of my own preparation and
*** Quite recently I have repeated
these experiments with a similar result.