PRINTING METHODS LANTERN SLIDES IO5 



perfect contact without the thinnest stratum 

 of air between them ; the other to devise some 

 means of effectually and certainly preventing 

 the print from sticking to the plate when 

 dry a fatal incident in the life of the former 

 always, and not infrequently so to the latter. 

 All gelatine emulsions coated on paper are 

 liable at times, especially in hot weather, to 

 softening whilst wet, usually in spots, rarely 

 all over the entire surface. Even Velox is not 

 entirely free from it, though more nearly so 

 than any other paper I have ever used. In 

 this condition it is like the most tenacious 

 glue, insoluble in water cold or hot, and sticks 

 with such pertinacity to the ferrotype plate as 

 to become inseparable from it except by de- 

 struction of the paper and practical ruin of 

 the plate for squeegeeing purposes. I have 

 now a plate to which two prints stuck in this 

 manner several years ago, and thus far they 

 have resisted every attempt at removal. I 

 keep it as a terrible example and for experi- 

 mental purposes. Fortunately I long ago dis- 

 covered a preventive remedy for this defect, 

 and the perfect contact of plate and print is 

 very easily and certainly effected. 



When the prints have been fully washed 

 and freed from all traces of hypo, they should 



