, Lantern Slides. 35 



parency in the shadows, and the fineness of the silver deposit com- 

 posing the image. 



The wet-plate process requires perhaps a little more care and 

 experience to attain success, but it is quite simple, being briefly as 

 follows : The first requisite for making any kind of photographic 

 plates is to have the glass perfectly clean. This is accomplished 

 by putting it in any of half a dozen acid or alkaline solutions 

 easily prepared for the purpose, and leaving it there several hours, 

 after which it is removed, scrubbed, and rinsed well in several 

 changes of water. Then follows the abluminizing which consists 

 of flowing over the plate, after the final rinsing, a dilute solution 

 made by shaking up a teaspoonful of white of egg with 8 oz. 

 water and filtering it. The best way is to clean and albuminize a 

 quantity of plates, storing them for use, as they will keep indefin- 

 itely. The sensitizing bath is made by dissolving pure nitrate of 

 silver in distilled water, a proper strength being from 35 to 40 

 grains to the ounce. In the solution is dissolved iodide potassium, 

 one grain to each 8 oz., after which it is acidified by adding nitric 

 acid (c. p.) in the proportion of about i minim, of the concentrated 

 acid to 16 ozs. of the bath, which must afterwards be filtered care- 

 fully before using. The bath may be kept in a bottle, and poured 

 into a flat glass pan when required for use. To prepare a plate 

 for exposure, dust it carefully, and coat it with collodion by pour- 

 ing on it a pool near the center, and then by tilting the plate, low- 

 ering the corners consecutively, allow the collodion to flow evenly 

 over it, and drain back into the bottle. Any good collodion will 

 answer. I have found that a mixture, equal parts, of Anthony's 

 "New Negative" and "Copying" collodions gives very fine re- 

 sults. After the collodion has set. the plate is placed in the sen- 

 sitizing bath, where it is allowed to remain until on its being lifted 

 out the solution flows evenly from the surface, without the greasy 

 appearance which it will have if taken out too soon, From two 

 to five minutes is required for sensitizing. The operation is short- 

 ened by keeping the bath in motion. As soon as ready the plate 

 is taken out of the bath, drained and placed in the dark slide, 

 after which the exposure should be made as promptly as possiqle. 



The usual developer is a solution of protosulphate of iron, made 

 as follows: Sulph. iron 2 oz., acetic acid 2 to 4 oz., water 40 

 ozs. Care must be taken to cover the plate with a single sweep 

 of the developer, because if it is allowed to flow unevenly streaks 



