The very feeble shadows of the feet can be easily touched away with pencil.
Single persons or groups of two or three figures can be photographed in this peculiar style with very good effect.
For heads and busts expose in the usual manner, but to obtain silhouettes similar to those our grandmothers had cut in black paper, and long before photography was thought of, cut an appropriate mask of black paper to cover the part not wanted during printing.
FIG. 35.
It should be borne in mind that in this class of work the white background only is the object to be photographed, hence the necessity of but very short exposures. With longer exposures absolute blacks and whites are impossible.
[PHOTOGRAPHING THE INVISIBLE.]
The following is a curious and interesting experiment, based upon the peculiar property possessed by fluorescent substances of altering the refrangibility of the chemical light rays. Take a colorless solution of bisulphate of quinine, and write or draw with it on a piece of white paper. When dry the writing or design will be invisible, but a photograph made of it will show them very nearly black.