SCIOPTICON MANUAL. 69 



The preservative must be fresh. Three ounces of this 

 mixture will prepare half a dozen 6x8 plates. 



If the preservative is poured over the plate, apply 

 twice, working it well into the film; throw the first dose 

 away, and use the second flowing for the first applica- 

 tion to the next plate. 



The plates must be carefully dried, either by natural 

 or by artificial heat.; a hot-water bottle will be found 

 useful for that purpose should artificial heat be thought 

 best. 



THE EXPOSURE 



Will depend upon the strength of the negative, and 

 the nature of the light; a few seconds will generally be 

 enough. Close contact is absolutely required to produce 

 sharp positives. An ordinary printing-frame can be 

 used. 



TO DEVELOP 



In a dark-room, remove the dry plate from the frame, 

 place it in a dish, and flow over it 



Alcohol 



coo, ........ . i 



Water, ........... } equal parts. 



Then wash in running water. 



DEVELOPING SOLUTIONS. 



Pyrogallic Acid, ......... 2 grains. 



Water, ............ 1 ounce. 



Made from a stock-bottle of 



Alcohol, ............ 1 ounce. 



Pyrogallic Acid, ......... 96 grains. 



Five minims of this solutions contains one grain of 

 pyro. 



