H. C. K.
—— Rectory, Hereford.
PHOTOGRAPHIC NOTES AND QUERIES.
Replies to Photographic Questions.—Sir William Newton is right respecting the active properties of sulphuric acid; it should therefore not be stronger than merely tasting of the acid; but it has appeared to me to possess a superior effect in setting the alkalies free. I believe muriatic acid would have precisely the same effect, or Beaufoy's acetic acid, though it would be rather expensive. Starch would be invaluable both for positives or negatives, if it could be laid on perfectly even; but if pinned up to dry it all runs to one corner, and if laid flat it runs into ridges. Perhaps some artist may be able to favour us with the best mode of treating starch; its non-solubility in cold water makes it an invaluable agent in photography.
The above includes a reply to Mr. J. James' first Query: to his second, the solution may be either brushed or floated, but all solutions require even greater care than doing a water-colour drawing, to lay them perfectly flat. The remaining questions depend for answer simply on the experience of the operator: the formula given was simply for iodizing paper; the bringing out, exposure in the camera, &c., have been so clearly described lately by Dr. Diamond, it would be useless to give further directions at present.
G. H. should dispense with the aceto-nitrate and gallic acid, and bring up with gallic acid and glacial acetic acid only. This makes no dirt whatever, and is quite as effective. The marbling
he alludes to proceeds from the sensitive solution not being sufficiently dry when put into the camera. Even if prepared paper is blotted off, which I think a very bad plan, it should have some time allowed it to dry; also the faintness of the image depends either upon not giving time enough, or the aperture he uses for his lens is much too large; or again, he has not found the true chemical focus,—it varies in single meniscus lenses sometimes as much as three-eighths of an inch nearer the eye than the visual:—all these are causes of indistinct images, and require patience to rectify them.
I beg leave to subscribe entirely to Mr. W. Brown's remarks on the subject of Mr. Archer and collodion. I have one of Mr. Horne's handbills, circulated with the first samples of collodion, headed "Archer's prepared collodion" in 1851, and had some of the earliest in the market. That Mr. Archer should fail in trying his own preparation goes for nothing at all, because, at the best of times, and with the most skilful, failures are often numerous and mortifying, in photography above all other arts; therefore, unless some more correct data are given, the merit rests entirely on Mr. Archer.
Weld Taylor.