DEVELOPMENT 81 
the water used. In the case of rodinal it was found that a 
plate which required 3 minutes development with a 1:20 
solution, when the latter was diluted to 1: 200, did not require 
30 minutes, but 42, with air-free distilled water; with ordi- 
nary distilled water 46 minutes, and with tap water 52 min- 
utes. Pyro-soda and glycin seem to be the only developers 
that are not affected by the water, but a pyro developer 
diluted ten times requires fifteen times normal to obtain the 
same results. Stand development is not economical, as most 
~ commercial tanks require a large amount of solution, which 
is, as a rule, so oxidised at the end of development as to be 
useless for a second time. The following are some of the 
developers recommended for this method. 
Pyro-soda (Wratten & Wainwright) — 
A. Sodium sulphite, dry 5) 3 oz. 
Pyrogallol 1.66 g 1 oz. 
Sulphuric acid 0.21 ccm 1 dr. 
Water 1000 ccm 600 oz. 
B. Sodium carbonate, cryst. 10g 6 oz. 
Water 1000 ccm 600 oz. 
Mix in equal parts. 
Glycin (Wratten & Wainwright ).— 
Glycin 0.833 g Y, oz. 
Sodium sulphite, dry 125\2 34 OZ. 
Potassium carbonate 4.16 ¢ 2Y4 oz. 
Water 1000 ccm 600 oz. 
Glycin (Bothamley) — 
Glycin 3¢g 46 gr. 
Sodium sulphite, dry js) 23 gr. 
Water 2000 ccm 70 oz. 
Time 1 hour at 18° C. (65° F.). 
