_Three New Processes by Mr. Lyte._--Will you kindly allow me room in
your pages for the insertion of the following three processes, which may
not, perhaps, be uninteresting to some of your readers? The first is
respecting a very excellent combination with which to excite collodion.
The second is on the subject of a capital developing agent, and, I
believe, a partially new one. The third, a certain improvement in the
production of positives on albumen paper.
To make my collodion, I use the Swedish filtering paper, as recommended
by the Count de Montizon, Mr. Crookes, &c., not so much on account of
its superior properties, as the easier manipulation, and the greater
certainty of obtaining a completely soluble substance. Having obtained a
clear and tolerably thick collodion, take
Rectified spirits of wine 1 oz.
Iodide of ammonium 45 grs.
Bromide of ammonium 12 grs.
Chloride of ammonium 1 gr.
Iodide of silver, freshly precipitated from the ammoniated nitrate, as
much as the solution thus produced will take up--a small excess, which
will settle at the bottom, will not signify. Nearly the same compound,
one which is equally good, is produced as follows. Take
Rectified spirits of wine 1 oz.
Iodide of ammonium 50 grs.
Bromide of ammonium 12 grs.
Chloride of silver 5 grs.
Whichever of these two sensitizers is used, take 1½ drachms, and add to
every ounce of the collodion.
Collodion thus prepared is _most_ rapid in its action, giving a deep
negative (with Ross's sixteen guinea lens, and the developing agent
I shall hereafter describe) in ten seconds in clear weather, and
instantaneous positive pictures, which may be afterwards darkened with
the solution of terchloride of gold, in chloride of ammonium. It does
not easily solarize, and, what is best of all, gives the most pleasing
half-tones.
I find it preferable, in taking landscapes, to rather increase the
quantity of the iodide of ammonium, in order to give complete opacity to
the sky; but if the operator pleases, he may produce the most admirable
effect with the above-named proportions, by painting in clouds at the
back of the plate with Indian ink: and this latter plan is preferable, as
the addition of more of the iodide lowers the half-tones.
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If more of the chloride than above specified be added, it will cause the
plate to blacken all over during development, before the extreme lights
are fully brought up.