80 PHOTOGRAPHIC FACTS AND FORMULAS 
following are a few temperature co-efficients that have been 
determined (Watkins) : 
Pyro-soda, without bromide (Watkins) 1.5 
Pyro-soda, with bromide (Watkins) 1.9 
Pyro-soda (H. & D.) without bromide 1.48 
Pyro-soda, Kodak powders .......... 12 
Pyro-soda tabloid (B. & W.) ........ 245 
Pyro-soda tabloid, ford formula .... 2.04 
Rodinal, Azol, Victol, Certinal ....... 1.9 
Metol-hydrochinion) .).05 6.) ieee aides 19 
Metol-hydrochinon tabloid ........... 1.86 
C5 [fest o RARER HO MOTTE PEE MTSE 8 rN 
12705) OMEN ORD MAME DU EATING 1 8 1.84 
EAC MRONT, 1 /2S010 Cho tae La a Una a 2.20 
Paramidaphenol 3) inl Cue ss eieiaua eae 2.4 
aU GV (8 6, DUAR O Ra ADHERE a ALO AOR) 2.06 
Fg 5) (A RTI re DMI SRN EG 2.06 
STAND DEVELOPMENT.—This is a method of development 
in which a dilute developer is used in an upright grooved tank, 
in which the plates are placed and left for a given time. In 
the early days, it was put forward as a cure for every error 
in exposure, and the solutions used were so dilute that from 
12 to 24 hours were required to obtain normal negatives. 
The only advantages of stand development are that the grain 
of the negatives is fine and the results uniform, if the devel- 
oper be frequently agitated, and no visual examination is re- 
quired or possible. It has been stated that the duration of 
development with the diluted solutions can be calculated from 
their dilution, that is to say, a developer that is diluted 5 times 
will require 5 times as long in the tank, but this is only true of 
one or two developers. Wratten & Wainwright found by 
careful photometric measurements, that the increase in time 
depends to a great extent on the quantity of air dissolved in 
