120 THE BOOK OF THE LANTERN. 



cent, solution of sodic citrate, poured on and off, and gently 

 rubbed upon the gelatine surface with a plug of cotton 

 wool. This treatment is not necessary if rainwater is 

 available. Messrs. Mawson and Swan supply an admirable 

 plate for lantern-slide work. It can be used for reducing 

 in the camera, or for contact printing, and is amenable to 

 more than one method of development. 



At one of the exhibitions this firm showed a specimen 

 frame of four transparencies from one negative, each 

 developed by a different formula, and showing a difference 

 of tint for each. I was so pleased with their appearance 

 that I asked for particulars, and the firm kindly supplied 

 me with the four formulae in question. Here they are : 



A. Meta Bisulphite Developer. 

 B. Carbonate Soda 

 C. Ammon. Sulphite 

 D. Ferrous Oxalate 



A. 



I. 



Pyrogallic Acid ... ... ... ... 40 grs. 



Meta-bisnlphite Potass 120 



Bromide Ammonium ... ... ... ... 40 ,, 



Distilled Water 20 ozs. 



II. 

 Liquor Ammonia ... .. t ... ... 2 drms. 



Distilled Water 20 ozs. 



Mix equal parts of A and B just before using. 

 B. 



Equal parts. 



