144 THE BOOK OF THE LANTERN. 



be left if preferred until the tissue is quite dry. The glass 

 and its print is placed in a dish containing water at 

 the temperature of about 110 degrees if the print is wet; 

 but should the print have been allowed to dry, the water 

 must be some 10 degrees hotter. After allowing it to soak 

 for a couple of minutes or so, the paper is raised at one 

 corner, taking every precaution not to injure the sur- 

 face; when it will readily separate from the film. The 

 plate bearing the picture is then put into a solution of alum 

 for a minute, and is placed in a rack to dry. Upon ex- 

 amining a lantern slide so made, a slight granular appear- 

 ance is observable in the high lights and the sky ; but this 

 is not apparent when the image is projected on the lantern 

 screen. The picture will have the usual grey tone, which 

 is associated with f errous-oxalate development ; but it can 

 be turned to a rich brown by the following treatment : 



. ( Potassium ferricyanide ... ... ... 100 grs. 



(Water 24 ozs. 



T, (" Uranium nitrate 100 grs. 



15 (Water 24 ozs. 



Take equal parts of A and B and immerse the print in 

 the mixture until the tone changes to the tint required. 

 Then wash thoroughly and immerse for five minutes in a 

 freshly made-up solution hypo, three ounces ; water, six- 

 teen ounces, wash. The prints that will best yield to this 

 after-treatment are those in which the image is from any 

 cause rather weak ; for this final bath not only alters the 

 tone, but acts as an intensifier. 



