PHOTOGRAPHY. 
59 
paper, or cloth, as an additional precaution in packing and in case of 
emergencies. 
Sensitive films in rolls or spools are made by the Eastman and other 
companies, and may be used successfully in their proper roll-holders 
when they can be kept perfectly dry. Elat films made by Eitch, Edwards 
and others have many advantages for travellers. The celluloid of which 
they are made is very much lighter than glass, and in exposure and 
development may be treated in the same way as a glass plate. When 
plates can be carried, the extra weight is compensated for by greater 
certainty of success, and general excellence in the photographs. The 
latest novelty has just been put on the market, the Secco Film. It is 
described as a preparation of the surface of paper in such a manner that 
the sensitive emulsion adheres closely to it during exposure, so that the 
finished negative can be readily stripped at any time after drying. The 
great advantage claimed is that the film has no chemical effect on the 
emulsion, and is in no way more liable to failure than when the glass 
plate is used. 
How to keep plates and films dry .—When the traveller has along journey 
before him, aud the prospect of storing his plates and films for months 
both before and after exposure, it is of the greatest importance that pre¬ 
cautions should be taken against the inroads of damp. This applies 
with full force when the country to be explored has a hot, humid climate. 
Plates and films that have absorbed moisture, causing decomposition in 
the sensitive gelatine coating, are frequently brought back to this country 
to be developed, and are the most fruitful cause of failure. The remedy 
is simple, but can only be applied when packing and repacking the plates. 
Some guarantee should be sought from makers of plates and films that 
they are packed perfectly dry, and that the packing used is also dry. 
Assuming that work has to be done in a damp climate and that the plates 
have been exposed in the camera and require to be repacked, they should 
be dried in a box containing a small quantity of chloride of calcium. The 
box used for drying may be also designed to carry the camera and outfit. 
It should have a lid with a rim of rubber padding, so that by putting the 
lid on and a weight on it, the box would be fairly air-tight. Stack the 
exposed plates, or films, in the bottom of box, so separated as to permit 
the passage of air between. Place a cup or saucer on the bottom of box 
containing chloride of calcium. (The chloride should be first dried on 
