Before concluding these remarks, I would draw attention to the great convenience of the use of a bag of yellow calico, made so large as to entirely cover the head and shoulders, and confined round the waist by means of a stout elastic band. It was first, I believe, used by Dr. Mansell. In a recent excursion, I have, with the greatest ease, been enabled to change all my papers without any detriment whatever, and thereby dispensed with the weight of more than a single paper-holder. The bag is no inconvenience, and answers perfectly well, at any residence you may chance upon, to obstruct the light of the window, if not protected with shutters.
I would also beg to mention that a certain portion of the bromide of silver introduced into the iodized paper seems much to accelerate its power of receiving the green colour, as it undoubtedly does in the collodion. Although it does not accelerate its general action, it is decidedly a great advantage for foliage. Its best proportions I have not been able accurately to determine; but I believe if the following quantity is added to the portion of solution of iodide of silver above recommended to be made, that it will approach very near to that which will prove to be the most desirable. Dissolve separately thirty grains of bromide of potassium, and 42 grains of nitrate of silver, in separate half-ounces of distilled water; mix, stir well, and wash the precipitate; pour upon it, in a glass measure, distilled water up to one ounce; then, upon the addition of 245 grains of iodide of potassium, a clear solution will be obtained; should it not, a few more grains of the iodide of potassium will effect it. It may be well to add that I believe neither of the solutions is injured by keeping, especially if preserved in the dark.
I would here offer a caution against too great reliance being placed upon the use of gutta-percha vessels when travelling, as during the past summer I had a bottle containing distilled water which came into pieces; and I have now a new gutta-percha tray which has separated from its sides. This may appear trivial, but when away from home the greatest inconvenience results from these things, which may be easily avoided.[[10]]
Dishes of zinc painted or japanned on the interior surface answer better than gutta-percha, and one inverted within another forms, when travelling, an admirable lid-box for the protection of glass bottles, rods, &c. On the Continent wooden dishes coated with shellac varnish are almost entirely used.
Footnote 2:[(return)]
In a communication I formerly addressed to my friend the Editor of "N. & Q.," one of the arguments I used in favour of the collodion process was, that the operator was enabled at once to know the results of his attempts; and was not left in suspense concerning the probable success, as with a paper picture requiring an after development.
I made that observation not only from the partial success which had then attended my own manipulations, but from the degree of success which was attained by the majority of my photographic friends. But that objection is now almost entirely removed by the comparative certainty to which the paper process is reduced.
The effect was illustrated in two negatives of the same subject, taken at the same time, exhibited to the meeting, and which may now be seen at Mr. Bell's by those who take an interest in the subject.
For this purpose, strips of wood from 1 inch to 1½ square will be found much more convenient to pin the paper to than the tape or string usually recommended. The pressure of a corner of the paper to the wood will render it almost sufficiently adherent without the pin, and do away with the vexation of corners tearing off.
Some difference of opinion seemed to exist at the reading of the paper, as to the propriety of preparing iodized paper long before it was required for use, and I have since received some letters from very able photographers who have attributed an occasional want of success to this cause. I have, however, never myself seen good iodized paper deteriorated by age. Many friends tell me they have used it when several years old; and I can confirm this by a remarkable instance. On Tuesday (Dec. 6) I was successful in obtaining a perfectly good negative in the usual time from some paper kindly presented to me by Mr. Mackinly, and which has been in his possession since the year 1844. I should add, the paper bears the mark of "J. Whatman, 1842," and has all the characters of Turner's best photographic paper. It appears to be a make of Whatman's paper which I have not hitherto seen, and, from its date, was evidently not made for photographic purposes.