110 
POPULAR SCIENCE REVIEW. 
colour throughout its mass, commencing from the surface. On removing it 
from the light this colour gradually disappeared, and the chloride resumed 
its former aspect. The experiment, frequently repeated with the same 
tube, always produced the same result. The experiment shows the fallacy 
of considering that the chloride, when darkened by the action of light, 
must be decomposed into a violet sub-chloride of silver and free chlorine. 
One of the editors of the British Journal of Photography, commenting on 
the above, says : It will be remembered that when chlorme acts upon 
water, hydrochloric acid is produced and oxygen. In M. Morren’s experi- 
ments the only object on which the influence of this oxygen could be 
expended was the altered chloride of silver ; and we learn from the second 
experiment that the colour of the changed compound was not violet but 
hrown, indicating a difierent result from that which we are accustomed to 
observe under ordinary circumstances. But here it is not improbable that 
the oxygen may come into play, and the product be an oxychloride of silver 
instead of a simple sub-chloride ; but if it be true that the oxygen can 
combine with this violet compound, it becomes a question how far oxygen 
may be essential in the ordinary printing process on plain salted paper. . . 
If this apparent consequence, derivable from the results of M. Morren’s 
experiments, be proved, it would most materially alter our views, not only 
of the modus operandi of light on chloride of silver, but also those on toning 
and flxing.” 
Exhibition of Photographs. — The London Photographic Society recently 
opened a photographic exhibition gratuitously for one week in the Archi- 
tectural Gallery, 9, Conduit Street, Regent Street. The collection, if not 
a very large one, was good ; and considering that the exhibition was only 
advertised in the pages of the photographic serials, it attracted a very fair 
attendance of visitors. There was plenty of inartistic and tasteless work 
on the walls, but there were also some photographs of peculiar excellence 
and beauty, at the head of which, for such technical artistic qualities as 
roundness, relief, and perfection of light and shade, stood the works of M. 
Salomon, of Paris. Respecting the origin of this gentleman’s startling 
and wonderful superiority, a controversy now divides our photographic 
brethren, some asserting that it is due to the negatives having been skilfully 
touched upon and improved by an artist,' and others loudly and emphatically 
denying this, and attributing it solely to the superior taste and knowledge 
of artistic effect which M. Salomon, being a sculptor of repute, is supposed 
to possess. Our own opinion supports either of these views ; and we, more- 
over, believe that, in addition to artistic skill exercised in both these ways, 
the larger portion of such excellences as we find in the French photo- 
grapher’s marvellously finished portraits is due to a degree of artistic treat- 
ment in the process of printing, the great value and power of which is 
little understood in this country. As superior for their expression of senti- 
ment, fee lin g, and imagination, as M. Salomon’s works are for the above 
qualities, were the photographic pictures of 0. G. Rejlander, on the preparing 
and selecting of which for exhibition, however, a little more neatness and care 
might have been profitably displayed. Some very fine specimens of carbon- 
printing were exhibited by M. Cherrill, and some excellent landscapes by 
Mr. Frank Howard. Mr. Dunmore, a good and tasteful operator, seems to 
