3 
per cent chrome-alum solution. This results in so high a degree of hardening that the 
film will stand hot water without any detriment to the colour balance. 
d. To speed up work, the between-the-baths rinsings have been curtailed to two minutes. 
Therefore, to avoid the appearance of fog in the course of subsequent treatment, hard- 
ening is followed by an acid fixing bath after which comes bleaching. The recipe for the 
succeeding baths has been simplified. 
e. Some substances having a particular effect on the photographic properties of the image 
are introduced. When the colour balance suffers owing to the greater speed of the upper 
layer, an alcohol solution of iodine is added in amounts depending on the rate of the 
Sd Do 0 
IND 
/ Emuision 9823 
  
70 
  
  
  
  
  
  
9727 
d 
ED 709 
3 
g 
+ Sd 
eros, 
  
  
  
  
  
  
  
  
  
  
  
6 8 10 11/7 
Lime of development 6) 
Fig. 3. The variation of Fig. 4. 
speed and fog with dif- a) without iodine. 
ferent amounts of benzo- b) 0.12 gr of iodine per litre. 
triazol. 
loss of balance, but not exceeding 0.2 gr per litre. (Fig. 4). When there is underexposure 
it is advisable to add tallium salts in 1 gram per litre concentration whereby emulsion 
speed becomes doubled, and Gamma increases 11 times. Some falling off of colour 
balance occurs then but is kept well within permissible tolerances. 
f. It is advisable to perform the development using coils (spirals), for the application of 
spool winding appliances results in an undue lengthening of the negative process. In 
general the ZNIIGAiK method reduces the time of precessing to 32-35 minutes instead 
of the usual 55 minutes. 
4. Printing from aerial negatives is done with subtractive filters or with three ad- 
ditive filters [4]. Thanks to the convenient design of the additive printer (copying ap- 
paratus) (Fig. 5) which enables the desired spectral composition of the printing light to be 
obtained by means of a photocell, such devices are on the way to superceding the subtractive 
machines in spite of the latter being comparatively simpler in operation. The assessment of 
colour reproduction on spectrozonal films is based on the maximum colour gradation in