Betas oh ROE With a rahe e = 
a! 
2 
; 
~ 
Arts and Manufactures. 301 
2. A new Photogenic Paper ; by M. Gaupin, (Chemist, Aug. 1845, 
p. 363, from the Bull. de la Soc. d’Encouragement.)—A sheet of white 
paper is exposed for a minute to the vapor of hydrochloric acid; after 
which, a nearly saturated neutral solution of nitrate of silver is passed 
over its surface by means of a brush, (which must not be fastened by 
metal ;) the paper is then allowed to dry, and the dry sheet is placed 
in the focus of the camera obscura; and on removing it, and wetting 
the paper with a nearly saturated solution of sulphate of iron, slightly 
acidulated with sulphuric acid, the image before invisible immediately 
appears. In order to fix the image, it must be well washed, first with 
pure water, and afterwards with water containing 10 per cent. of caus- 
tic ammonia. If the parts which ought to be white have a yellow tint, 
the paper, before being allowed to dry, must be washed in water acidu- 
lated with hydrochloric acid. 
The image, of course, is reversed. In order to reproduce this image 
in its true position, it is placed upon a sheet of paper similarly prepared, 
and exposed to the action of light, until the edge of the paper (project- 
ing beyond that upon which is the reversed image) becomes blackened ; 
it is then washed in the solution of caustic ammonia, without treating it 
. with sulphate of iron. 
In order to reproduce the reversed images, they must be varnished, 
which removes the inequalities from the paper, and materially assists 
the operation. Jc at: B. 
3. Improvement in Photography; by W. H. Hewerr, (Phil. Mag., 
Noy. 1845, p. 405.)—This improvement consists in using the vapor of 
ammonia as an agent to accelerate the action of light upon the plate. 
The effect is produced upon a simple iodized plate, but still more upon 
a plate prepared in the ordinary way, with both jodine and bromine. 
By this means, the author obtained impressions instantaneously in the 
sunshine, and in five to ten seconds in a moderate light ; and he hopes 
to be able to take moving objects. It cam be applied by exposing the 
prepared plate over a surface of water, to which a few drops of am- 
monia have been added, (sufficient to make it smell of ammonia,) or 
the vapor can be introduced into the camera during the action. In fact, 
the presence of ammonia in the operating room appears to have a good 
effect, as it also neutralizes the vapors of iodine and bromine that 
may be floating about, and which are so detrimental to the influence of 
the light upon the plate. : » ALS. 
4. Wood for supporting Rails in Railways.—M. Boucuerts renders 
wood for railways proof against decay, by saturating it, according to a 
method of his own, with either a sulphate of copper, ora double chloride 
of mercury and soda, or with chloride of calcium and pyroligneous 
