Water — 10 drs.
Acetic acid — ½ dr.
Dissolve the protosulphate of iron in the water; then throw in the nitrate of lead in powder; stir with glass rod until it is dissolved; keep stirring while pouring in the acetic acid, and for a few minutes afterwards. Let the precipitate subside, then filter. I have used nothing else for positives on glass since I discovered the preparation. I have not tried it for developing in the wax-paper or other paper process. The liquid is colourless as water when first made. By long keeping it will change colour, but throws down no deposit, nor loses its properties. If those gentlemen who try it would give their opinions of it, I should be obliged.
J. L. Sisson.
Edingthorpe Rectory.
[Since this was in type, Mr. Sisson has written to say, that he has been informed that the use of nitrate of lead has already been recommended by Mr. W. Brown. Mr. Sisson was not aware of that fact, but is unwilling to appear in any way to appropriate to himself the suggestion of another.—Ed.]
Photographic Tent.—Can any of your readers inform me how, or where, to procure an effective tent for photographic operations out of doors? All those I have yet seen are sadly wanting in the two great essentials—portability and cheapness. If any one could suggest the means for supplying the desiderata, it would prove in the coming season a boon to photographers at large, and confer a favour on
M. F. M.
Mr. Wilkinson's simple mode of levelling Cameras.—The following ingenious suggestion appears in the 3rd Number of the Journal of the Photographic Society, and deserves to be widely circulated. "My plan is to place a T-square on the bottom of the camera, and draw one perpendicular line on each side (exactly opposite to each other), either with paint or pencil; or the ends of the camera itself will do if perpendicular to the base. Then, having two musket bullets attached to a silk thread, simply hang them over the camera, and everything required will be attained much quicker by these plumb-lines, and with accuracy equal to the spirit-levels. The advantage of the simple contrivance of two bullets suspended by threads is, that when the thread is laid across the camera, it is at once seen whether the thread touches all the way down both sides; if not, one or other side of the camera is raised, until the thread lies close on each side: this gives the level crossways. The other perpendicular of the line is then sought for, and the back or front of the camera raised or lowered, until the thread cuts the line drawn below. Here then we have the most perfect line that can be obtained, at the expense of two bullets and a bit of silk, answering every purpose of the best spirit-level, and applied in one-half the time. It has since occurred to me, that as we sometimes require to measure the distance for stereoscopic pictures, this thread ought to be about three feet long; and we might as well make three knots, and then we should have the measure of a three-feet rule always with us. It has also occurred to me, that in taking portraits you sometimes require to have a measure of time; and by a little modification we have here the most accurate chronometer that can be produced. Instead of three feet, I make it thirty-nine inches and the decimal necessary, say two-tenths from the centre of support to the centre of the bullet. I then get a pendulum which vibrates to second exactly, from the point of suspension to the point of oscillation. I hang it by a pin, and I there have a chronometer of the greatest possible accuracy; and I can employ it for taking portraits of one, two, three, or four seconds: it will vibrate for a minute. Consequently I have a mode of levelling my camera with the greatest accuracy, a measure of time, and a measure of distance; and all at a cost considerably under one penny."
Antiquarian Photographic Club.—This association for the interchange of photographic views of objects of antiquarian interest, has now nearly attained the number of members to which it is proposed to limit it. For the few remaining vacancies preference will be given, for obvious reasons, to parties resident in varied localities. Any gentlemen or ladies desirous to join the club, may send their names, with specimens of their skill, to the Honorary Secretary, care of Mr. Bell, 186. Fleet Street. The amount of the annual subscription is not yet fixed, but as all that can be required will be to meet the expenses incident to the receipt and interchange of the photographs, it must necessarily be very limited.