COLLODIO-BROMIDE.
Inlast week’s issue your idea of combining silver with a new base in the collodio-bromide is so good that I think it just as well to mention that the very notion of acetate of silver has been carried out by me a dozen years ago, although in another form. I made a collodion for wet-plate work in which an iodide was used with about an equal part of acetate of soda; the collodion was accelerated to such a degree that my exposure was reduced to about a fourth of what I would have given without the acetate. The plate developed beautifully and free from fog. Here, again, comes in the law of compensation; my thoroughbred collodion was, at the end of a dozen hours, as slow as a team of oxen, as vitality seemed to expend itself in onecoup d’état, and the second day it was capital——for cleaning plates.
A bromo-iodised collodion could not be stimulated with any such exertion. Since practising the collodio-bromide process I have often promised myself an experiment in this direction; but, somehow or other, partly from my failure when bromide was in the collodion, the trial has ended in the intention only.
Mr. Henry Cooper’s success with lactate of ammonia has inspired me with a strong hope that collodio-bromide is to be the perfection of “everything to be desired” in dry-plate work.
I am glad to learn that Col. Wortley has found out the conditions of making a bromised collodion which arrives at maturity without passing through that infantile existence which I have always regarded as unfavourable to the best results. When I made the statement in your Journal, it was from the united experience of all my collodio-bromide acquaintances, which, if pinned together, would, in respect of mere lapse of time, extend over the greater part of a century.
Although bromised collodion will give good results when freshly made, the development of the image is almost a matter of physical force—more ammonia, more silver, and such like—in order that the excellent prints expected from your exertions may be superb indeed, in consequence of the labour bestowed on the negative.
I do not condemn Col. Wortley’s mode of working, for I have lately seen some of his negatives possessing the very highest qualities attainable by any process; but, in support of my own recommendation that the collodion should be left to ripen as a means of lightening our labours in the dark room, I may state that for over two years I never used silver as an intensifier, alkaline development giving me always the right density, and occasionally too much. With an “infant” collodion silver is the only “soothing syrup” that affords nourishment to the sickly image.
J. W. Gough.