PHOTOGRAPHY AND SOME OF ITS APPLICATIONS. 
633 
and the positions of the sitter and the velvet curtain are 
reversed, and the plate is once more exposed. When deve- 
loped there will be but one picture, in which the two figures 
of the one individual are represented in different attitudes. 
This is what is termed a binograph. The invisible photo- 
graph is another of the recent innovations. When first 
examined, it appears to be a blank sheet of paper devoid of 
interest ; but when it has been immersed in water for a few 
moments, it becomes an exquisite transparency, which, upon 
being again dried, returns to its former condition. The 
paper, upon which the photograph is taken in the usual 
manner, is prepared by immersion in a solution of gelatine of 
twenty grains to the ounce, drying and subsequent immersion 
in solution of bichromate of potash and water. Photographs 
on enamel and china are other interesting varieties, whose 
merits we cannot now discuss. 
We have been able to sketch only a few of the many 
industrial and scientific applications of which photography is 
capable, but we have written enough to show that the subject 
is one of the highest importance, and worthy of the most 
studious attention. Photography is a veritable slave of the 
lamp,^'’ who patiently awaits our desires, and who is capable 
of displaying still greater wonders than those which she has 
already achieved, should we demand further proofs of her 
powers. 
Note. — Since this article was set up,^^ we have seen a 
description of a new process of photo-engraving, which pro- 
mises to eclipse in excellence and beauty everything of its 
kind which has heretofore been attempted. This novel 
method, which we owe to Mr. Walter Woodbury, we shall 
describe fully in our next number. At present we can only 
state, that one of the principal features in the process is the 
employment of a printing material composed of gelatine and 
Indian-ink, or some other colour. 
