268 PHOTOMICROGRAPHY 



NARCOTISING SOLUTION FOR ROTIFERS (C. F. Rousselet, 



F.R.M.S.). 



2% solution hydrochlorate of cocaine ... 3 parts 



Alcohol (or methylated spirit) 1 part 



Water 6 parts 



PHOTOGRAPHIC FORMULAE 



FORMULA for almost every photographic process are to be 

 found in the British Journal Photographic Almanac, which is 

 an almost indispensable book of reference for photographers. 

 Several of the following formulae are from that source. 



DEVELOPERS 

 METOL-QUINOL (R. L. Boyd). Concentrated stock solution : 



Metol 24 grains or 14 grammes. 



Quinol (hydroquinone) ...96 56 



Potassium bromide 20 12 



Warm water 4 ozs. ,, 1000 c.c. 



When dissolved add sodium sulphite (crystals crushed 

 small) 1J ozs. (400 grammes). To the white pasty mass add 

 sodium hydrate (caustic soda) 64 grains (40 grammes). 



For Plates and Gaslight Papers. Take 1 part of the stock 

 solution and add 7 parts of water. 



For Bromide Papers and Lantern Slides. Add 15 parts of 

 water to 1 part stock solution. Add 2 drops per oz. of 

 10% potassium bromide solution for papers and lantern 

 slides. 



Watkins Factor, 16. 



Time of Development. At 55 F., 3| minutes ; at 60, 

 3 minutes; at 65, 2J minutes. One oz. of the developer 

 contains metol ,75 grains, quinol 3 grains, sodium sulphite 

 (cryst.) 20 grains, caustic soda 2 grains, potassium bromide 

 0-6 grains. 



HYDROQUINONE. 



A. Hydroquinone 160 grains or 20 grammes 



Sodium sulphite 2 ozs. 100 ,, 



Citric acid 60 grains 8 



Potassium bromide . . 40 

 Water to 20 ozs. 



B. Caustic soda 160 grains 



Water to.. ..20 ozs. 



5 

 1000 c.c. 



20 grammes. 

 1000 c.c. 



