336 
POPULAR SCIENCE REVIEW. 
forth and for ever, a matter of ease and certainty, do away with all the 
well-known chances of failure, and considerably reduce the quantity of 
materials required. Naturally enough, such statements created a sensation in 
the photographic world, and considerable anxiety was expressed as to when, 
where, and how such a grand secret would be divulged. After some little 
time had passed, filled with vain conjectures and eager appeals, Mr. 
McLachlan stated that he had no intention of selling this wonderful process 
or preserving it a secret, but that he wished it to be tested before it was 
published, and for this purpose he desired the formation of a committee to 
consist of gentlemen connected neither with the profession nor with the 
literature of photography. Two gentlemen were at length selected as re- 
positories of the great secret — a member of the Chemical Society, who con- 
tributes to a photographic contemporary, Mr. Spiller of the Woolwich 
Arsenal, and Mr. Peter Le Neve Foster, M.A., Secretary of the Society of 
Arts. The report of these gentlemen, after a lapse of some time, was read 
at a meeting of the Photographic Society, in Conduit Street, Eegent Street. 
In this it was very cautiously stated that experiments had been tried, and 
some of the expected conditions had been arrived at. At the May meeting 
of the Photographic Society Mr. McLachlan produced a long paper, which 
was read by the chairman. In this communication the chief conditions laid 
down as elements of invariable success, were : 1. The use of a discoloured 
deliquescent sample of nitrate of silver, about the nature of which the author 
could give, or at least gave, no information. 2. A collodion rendered slightly 
alkaline with caustic potash. 3. The use of a dark green dirty-looking 
protosulphate of iron for development. To make the bath complete it 
must be kept constantly in sunlight during three months of the brightest 
summer weather, and when used must be slightly alkaline. Of course, as 
the process requires three months for the preparation of the bath, little has 
been said practically on the matter, although it has given rise to a good 
many vague assertions and much theorising. 
Neiu Pocket Camera . — The Illustrated Photographer has called attention 
to the advantages of employing apparatus of an extremely portable character 
for the pocket, constructed to take pictures of a very small size, suitable for 
the enlarging process of printing. A consequent demand for such cameras 
has been replied to by Messrs. Negretti and Zambra, who have introduced 
an apparatus for landscape photography, the whole of which may be carried 
in the pocket with the exception of the trip od stand, which forms a walking 
stick, such as we called attention to in our last photographic summary. 
The camera in question is made on the principle of the Kinnear, or bellows 
camera, and is for plates 3^ inches square. It has a folding tail-board, on 
which, when the camera is up, a little japanned case for carrying the dark 
slides in, is placed, and there forms at once the focussing screen, and supplies 
a magnifying glass, fixed in the right position for focussing. A simple and 
effective ball and socket arrangement, with a clamp screw for fixing, is at- 
tached to the tripod, so that the lens can be depressed or elevated j and the 
legs of the stand, diverging from immediately beneath the camera, although 
light and portable, are not the less rigid and firm. 
A Neio Stereoficope. — Messrs. Murray and Heath have introduced what 
they term a new “ Panoramic Stereoscope,” with slides of a peculiar kind, 
