SCIOPTICON MANUAL. G7 



and forefinger, without being visible upon the screen, 

 as is sometimes the case with the square slide. Then 

 again, it is easier to place in its proper position (right 

 side up), having only one chance of error instead of 

 three. 



A WRY PLATE PROCESS FOR LANTERN SLIDES. 



TANNO-OALLIC PRESERVATIVE.* 



In considering the dry process, it is but proper to 

 say that a large number of different formulas have been 

 published; in fact, scarcely half a dozen photographer;; 

 think alike on this subject. It is, therefore, impossible 

 to give a formula that will give universal satisfaction. 

 In preparing this paper for publication, it must be dis- 

 tinctly understood that nothing new in the way of pre- 

 servative or development is claimed; it is simply one of 

 the many methods for preparing dry plates that has 

 given reliable results. 



The dry-plate photographer must bo prepared for 

 many and great failures, and be possessed of the greatest 

 amount of patience and nicety of manipulation, for other- 

 wise time is wasted, and the best process voted a failure. 

 Commence with reliable chemicals, and follow up the 

 process with a lavish expenditure of water when wash- 

 ing is mentioned, not only on the collodion plate, but 

 thoroughly rinse the various glasses and dishes, and 

 particularly the fingers, between each operation. Use 

 as little light as possible when making or developing 

 dry plates, and be careful that the light is yellow. 



Probably more dry plates are ruined, and the par- 

 ticular process used condemned as worthless, by the use 



* I am greatly indebted to my friend, Mr. E. Wallace, Jr., for his kindness 

 in furnishing me with the formula, and showing, by his own experiments, the 

 valuable results to be obtained from this process. J. G. BROWNE. 



