272 PHOTOMICROGRAPHY 



As soon as negative is sufficiently reduced immerse in 5% 

 sodium sulphite solution, then wash. 



GOLD TONING SOLUTION 



Gold chloride 2 J grains or -3 grammes 



Ammonium sulphocyanide ...30 ,, ,, 3-5 ,, 



Water 20 ozs. ,, 1000 c.c. 



Dissolve the gold and ammonium sulphocyanide separately 

 in half the quantity of boiling water. Then slowly add the 

 gold solution to the other, stirring meanwhile. 



If the solutions are made in cold water, allow to stand 12 

 hours before use. 



2J grains of gold will tone 30 quarter-plate prints. 



Wash prints for J hour in running water before toning, 

 keep moving in toning bath until the desired colour is ob- 

 tained, wash again, fix and wash for one hour at least. Prints 

 become warmer in tone during fixation, and some experience 

 is required to know when to stop toning to get a desired final 

 colour. 



PLATINOTYPE DEVELOPER 



Stock solution. Potassium oxalate ... 2 ozs. or 140 grms. 

 ,, phosphate. | oz. ,, 35 ,, 



Water 14 ozs. 1000 c.c. 



Make acid, if necessary, by adding 



Oxalic acid 60 grains or 10 grms. 



For use take 1 part stock solution and 1 part water. 

 Fixing. Hydrochloric acid . . . . 1 oz. or 12 c.c. 



Water ..80 ozs. 1000 



Immerse prints for 5 minutes in three separate baths. 

 Wash for 15 minutes and dry. 



THREE-COLOUR PHOTOGRAPHY 

 Sensitising Solution. 

 Potassium bichromate . . . . 1 oz. or 50 grammes 



Water 20 ozs. 1000 c.c. 



Liquor ammonia (-880) ... .60 minims,, 6 



Blue Toning Solution for Lantern Plates. 



10% solution ferric ammonium citrate . . 2 ozs. or 10 c.c. 



,, ,, potassium ferricyanide ... 2 ,, ,, 10 ,, 



acetic acid 20 ,, ,, 100 ,, 





