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POPULAR SCIENCE REVIEW. 
PHOTOGRAPHY. 
Photographic Engraving . — A cheap and efficient method of engraving, 
direct from an artist’s drawing or photograph, was one of the earliest 
suggestions arising out of the introduction of photography, although it is 
one of the latest to be fairly carried out. Some of the art’s most able 
and daring experimentalists have devoted their attention to the idea, and 
almost every mode by which a surface for printing can be obtained, has 
been duly tested for this purpose. Thus, we have had photo-gal vano- 
graphy, photoglyph y, photo-lithography, photo-zincography, and photo- 
block-printing. Each of these has been found more or less unsatisfactory, 
one requiring too much assistance from the graver, another failing in the 
registration of the more subtle gradations of tone, &c. Early, however, in 
the present year there was presented to the readers of one of our con- 
temporaries— the Photographic News — a specimen of an engraving process, 
called the “photo-electric,” introduced by Mr. Duncan C. Dallas, which 
was certainly far in advance of anything of the kind we have yet seen. 
This specimen, unassisted by the engraver’s hand, was a reproduced 
photograph, having not only all the beauties of the original, but also all 
its faults. It had the same want of relief in the relative parts of fore- 
ground objects, and the same imperfect expression of light and space, 
while the tasteless substitution of white paper for a softly retiring sky 
destroyed everything like tone and brilliancy in the other portions of the 
picture. But even this process has its failing, and this will be found in the 
heavy opacity of the deepest shadows, which is due, we are informed, to a 
defect in the ink-holding capacity of the surface in such parts of the plate. 
The number of impressions which a plate engraved by this process will 
produce — if the method of steel-facing be adopted — is unlimited ; and its 
inventor informs us, that its cost is about half that of a plate engraved in 
the ordinary way. The process is at present a secret one. 
Carbon Printing . — A very generally admitted need of permanency in 
photographs long since originated a desire for producing them in some 
such reliable material as the ordinary printing ink-carbon. At a meeting 
of the North London Photographic Association, which took place early 
in January, Mr. G. W. Simpson called attention to some very marked 
improvements made by Mr. Pouncy in his carbon-printing process. The 
early experiments of this gentleman, although frequently pressed upon 
the attention of the photographic world, as productive of perfect results, 
were really very unsatisfactory, but the specimens introduced on this 
occasion were remarkably promising and attractive. The process by 
which these were produced is thus described. A thin oiled paper is coated 
with a mixture of printer’s ink and asphaltum, thinned with a saturated 
solution of bichromate of potash dissolved in turpentine. After being 
exposed to light under a negative, with the side not prepared in contact 
with the glass, it is submitted to the action of turpentine, which dissolving 
out more or less such portions of the prepared coating as have been par- 
tially or entirely secluded from the light, thus forms the image. This 
