THE BOOK OF THE LANTERN. 199 



the first case, the film is so thick that we can see nothing 

 through it, but in the case of the chloride plate the flame of 

 the red lamp can easily be seen through the glass ; indeed, 

 upon first using such plates, photographers are apt to 

 wonder whether so thin a film can ever yield a picture. As 

 a matter of fact, the film is as thick as that upon a bromide 

 plate, only the emulsion of which it is composed is of a 

 far more transparent quality. 



Having then a chloride plate at hand, and having if ne- 

 cessary cut it down to a size which will enable it to slip 

 with ease into a chemical tank, the course of operations 

 will be as follows: 1, Exposure; 2, development; and 

 3, fixation. 



Provide a good negative (if it be a portrait of some one 

 well known to the spectators, so much the better), and place 

 it in a printing frame, with the chloride plate against it, 

 film to film. Expose to the light of an inch of magnesium 

 wire held two feet away from the printing frame, or to the 

 rays of the lime light for about ten seconds. Now place 

 the little tank on the stage of the lantern, and against the 

 inner side of it, that is, next the light place a sheet 

 of ruby glass. The effect upon the screen will now be 

 simply that of a blank red disc. The exposed plate may 

 now be taken from the printing frame and placed in the 

 tank. Take good care that it is placed there upside down, 

 so that the image when developed will appear the right way 

 up. The developing fluid, ferrous oxalate (see page 121), 

 may now be mixed. This should be at hand in two solu- 

 tions, so that by mixing the one with the other the de- 

 veloper is ready without any delay. As it is poured into 



