LOW-POWER WOUK 



39 



The slide is mounted by binding it against another shp of glass the same size, a 

 mask of paper of suitable shape being interposed to prevent the film touching the 

 surface of the opposing plate. 



The "printing-out" slide needs but little description. It is made with a very 

 transparent emulsion, and is placed in the frame and exposed to artificial or other 

 light like an ordinary piece of printing-out paper. One side of the frame can be 

 lifted, and owing to the transparency of the film the depth of printing can be easily 

 estimated. The subsequent processes are fully set out in the printed directions with 

 each box, and need not be narrated here. 



With respect to collodion plates, the best ready-made ones we know are sold 

 under the name of " Hill-Norris Dry Collodion Lantern -slide Plates." They require 

 about a third more exposure than the rapid Paget we have described, and they may 

 be developed with the same hydroquinone and soda solution, as it suits them very 

 well. Great care is necessary in the use of the plates by contact, as the film is so 

 dehcate the slightest touch will scratch them. They also require the most exact 

 exposure, as they flash up in development to a certain pitch which can never be 

 made deeper or more dense by any length of development. They have the advantage, 

 however, of being able to be fixed by a watery solution of any strength of cyanide of 

 potassium, which does its work immediately and only requires a few seconds' washing 

 to remove. They can be dried, too, in front of the fire or over a spirit lamp with 

 impunity in a few minutes. 



Seeing, however, so many collodion slides are made by the so called "wet-plate 

 process," we feel it would be an omission on our part if we neglected to mention how 

 these can be manufactured by the photographer himself 



It is first necessary to obtain what is called a bath and dipper, which can be 

 procured for small-sized plates very cheaply. Into this is placed a solution of re- 

 crystallised nitrate of silver from 40 to 60 grains to the ounce of distilled water. 

 The glass plate to be used should be first most scrupulously cleaned both sides, and 

 this must never be neglected, for if so the penalty paid for the mistake will be a 

 severe one — the film will float ofl" after its development, or after it is fixed in one or 

 other washings. 



To make this less likely we have always adopted the following plan in times past, 

 when we freely used the wet- plate process for negatives, even on the field. It is to 

 pour over the plate a preliminary coating of albumen in some form. There are many 

 formulae, but the one we used was always eflfectual, easy to make, and kept well. 

 The solution was made by mixing i part of white of egg in about 500 to 700 parts of 



