PHOTOGKAPHY AND SOME OE ITS APPLICATIONS. 627 
produce a picture_, but to give those portions of the layer 
which have been least exposed to light a power of swelling to 
a greater height under the influence of water than those 
portions which have been more fully submitted to the sun^s 
action. What a wonderful result this is ! A picture is pro- 
duced which_, when thrown into water^ absolutely presents 
relief- elevations and depressions in accordance with the lights 
and shades. As soon as this gelatine plate has been sufficiently 
exposed_, it is then (after removing excess of bichromate) given 
a series of coatings of a solution of nitrate of silver in alcohol^ 
the silver being then deposited in the metallic form by apply- 
ing to it a solution of pyrogallic acid. In this stage we have 
a gelatine surface picture_, coated with metallic silver. The 
plate is now thrown into water^ and in a short time the picture 
appears in relief. All the photographic operations are now 
over. The picture in relief has been produced^ and it presents 
a surface of metallic silver_, upon which copper may be easily 
deposited. Space does not permit us to describe the further 
phases of the photo-galvanograph^ which^ however_, are merely 
those observed in the production of a stereotype : by galvanic 
action metallic copper is deposited upon the gelatine plate^ 
and in a few days a perfect copper-plate^ which may be em- 
ployed for printing, is produced. 
Of the applications of photography to the fine arts there are 
two or three that are especially worthy of notice — jpliotosculp- 
ture, the crystcd cube miniature, and the hurnt-in photographs 
in china and glass. Of these, the first, which is the invention 
of M. Willieme, a Frenchman, is perhaps the best known 
in England. M. Olaudet, who tried to introduce photosculp- 
ture into these countries, has taught us all about it, though 
we fancy he has not found the invention valuable in its com- 
mercial bearings. To those unfamiliar with the processes of 
photo sculpture it is almost impossible to conceive that by any 
photographic appliances a perfectly solid bust of a sitter can 
be obtained. Yet is it quite true that photography is capable 
of doing all that M. Willieme contends for. We may observe, 
however, that the sculp toFs chisel is brought into operation, 
and that though the greater part of the work is chemical and 
mechanical, the hand of the artist is required to give those 
finishing touches, which no mere physical contrivances could 
effect. The principle of the process of photosculpture is based 
upon the fact, that a solid image is nothing more than a 
multitude of profiles placed side by side like the radii of a 
circle. If a sculptor was acquainted with the exact nature of 
each of these profiles, his work would be easy enough. Let us 
see how M. Willieme utilizes this fact. The person whose 
bust is desired, is placed in the centre of a circular room in 
