Part 4 (1/2)

THE DISAPPEARING PHOTOGRAPH.

A method of making a photograph which can be made to appear at will is thus described in _Les Recreations Photographiques_.

Take a convex watch crystal, V, or any similar larger gla.s.s if desired--for instance, those used for colored photographs; clean the gla.s.s well, place it perfectly level, convex side down, and fill it even full with a mixture of white wax and hog's lard. When it has solidified, apply to the back a flat gla.s.s plate, P, cut exactly to the largest dimensions of the convex gla.s.s, secure the gla.s.ses together with a strip, B, of gold-beater's skin, fastened by strong glue as shown in the figure. Now mount a portrait, with the front towards the convex gla.s.s, on the plate P. The combination is now ready; by heating it the wax between the two gla.s.ses melts and becomes transparent, allowing the portrait to be seen; on cooling it will lose its transparence and the portrait will disappear.

[Ill.u.s.tration: FIG. 36.]

FREAK PICTURES WITH A BLACK BACKGROUND.

If an object be placed against a non-actinic background and an exposure made, the black parts surrounding it will not have any effect upon the plate, and the object can be s.h.i.+fted to another part and another exposure made. In a recent article published in _La Nature_, and translated in the _Scientific American_, a number of curious effects obtained by photography by M. R. Riccart, of Sainte-Foix-les-Lyons, are described and ill.u.s.trated.

[Ill.u.s.tration: FIG. 37.--A DECAPITATION.]

The system employed by the author of these photographs is that of the natural black background obtained through the open door of a dark room, combined with diaphragms skillfully arranged in the interior of the apparatus, between the objective and sensitized plate. This is the surest method of obtaining the desired effect with the greatest precision, without the junctions being visible, and with perfect sharpness in the cutting of the parts removed. For this effect, it is necessary to place the diaphragm at three or four centimeters from the ground gla.s.s, in the last folds of the bellows of the camera.

[Ill.u.s.tration: FIG. 38.--ANOTHER DECAPITATION.]

The following are a few data as to the manner in which the scenes that we reproduce were obtained. The first, representing a decapitation by means of a saber (Fig. 37), was taken by means of an exposure in which the head was placed upon the block, the subject inclining forward upon his knees, and a diaphragm, occupying about two-thirds of the plate, completely masking the body up to the neck. Then, without changing the position of the apparatus, the diaphragm was placed on the other side in order to conceal the head, and the body was photographed in the second position along with the person representing the executioner. It would have been possible, by a third exposure, to so arrange things as to make the executioner the decapitated person. It was by the same process that the three following scenes were obtained: A person with his head placed before him in a plate (Fig. 38); a man carrying his head in a wheelbarrow (Fig. 39); and a person to whom his own head is served in a plate (Fig. 40). Such scenes may be varied to any extent.

Fig. 41 is a photograph of a decapitation, while Fig. 42 is made by two exposures of an individual at different distances but so combined as to give the appearance of one exposure. Fig. 43 is that of a person in a bottle. The individual represented was first photographed on a sufficiently reduced scale to allow him to enter the bottle. This exposure was by using a screen containing an aperture, as for the Russian background. But this precaution was taken merely to conceal the floor, and yet it would perhaps be preferable in such a case to have the subject stand upon a stool covered with a very black fabric.

However this may be, when once the first impression has been made, there is nothing more to be done than to photograph the bottle on a larger scale and the result is obtained.

[Ill.u.s.tration: FIG. 39.--THE HEAD IN THE WHEELBARROW]

[Ill.u.s.tration: FIG. 40.--THE HEAD UPON A PLATE.]

HOW TO COPY DRAWINGS.

There are three princ.i.p.al methods of copying mechanical drawings, tracings, sketches, etc. These are: (1) A process to obtain white lines upon a blue ground; (2) a process by which blue lines upon a white ground are obtained; and (3) a process giving black or violet-black lines upon a white ground.

[Ill.u.s.tration: FIG. 41.--THE SAWED-OFF HEAD.]

The first process is undoubtedly the simplest, as after printing upon the paper it is developed and fixed by simple immersion in cold water; but, at the same time, the white lines on the blue ground are not so clear and effective as the other processes. The cyanotype paper, as it is called, can be obtained ready for use at any draughtsman's stores, but if you prefer to make it yourself, here is the recipe: Two solutions are made--20 parts of red prussiate of potash are dissolved in 100 parts of water, and 10 parts of ammonio-citrate of iron in 60 parts of water. These two solutions should be mixed together immediately before using, and the operation must be performed in the dark. Paper is floated on this solution, or applied with a broad camels-hair brush, and hung up to dry. If it is well dried and carefully preserved from light, moisture and air, this paper will keep for some time. After printing--which, when sufficient, should show the lines copied of a yellow color upon a blue ground--the prints should be washed in several waters, and if a few drops of chlorine water or dilute hydrochloric acid be added to the was.h.i.+ng water, the blue ground will appear much darker and the lines rendered clearer and whiter. The commercial paper sold is generally prepared by this method.

[Ill.u.s.tration: FIG. 42.--THE REDUCTION.]

[Ill.u.s.tration: FIG. 43.--MAN IN A BOTTLE.]

Blue prints may be given a black tone by plunging them into a solution of 4 parts of caustic potash in 100 parts of water; then, when the blue color has entirely disappeared under the action of the potash, and a yellowish color has taken its place, they are immersed in a solution of 4 parts of tannin in 100 parts of water; then was.h.i.+ng them again, we obtain prints whose tone may be a.s.similated to that of pale writing ink.