STUDIO AND WORKROOM 19 
Glacial acetic acid 16 drops 8 drops 
Gelatine, 6% sol. 1000 ccm 16 oz. 
Allow the same quantity as above, and bind up with one of 
the bright red screens. Or: 
Tartrazine 7.52 57'4 gr. 
Crystal violet 1515 2 120 gr. 
Cupric sulphate Lie 59D St: 
Glacial acetic acid 15 drops 8 drops 
Gelatine, 8% sol. — 1000 ccm 16 oz. 
Use the same quantity as above. This cuts out to 630 and is 
safe for orthochromatic plates. 
GREEN SAFELIGHTS.—These are used for panchromatic 
plates, and are occasionally adopted instead of the red, for 
with a green light it is possible to see better than with a faint 
red. Hiibl recommended a combination of filter blue with 
naphthol green, which is the only green dye that cuts out the 
extreme red. The blue was made into a stock solution of : 
Filter blue OMe 0.77 gr. 
Water 1000 ccm 16 oz. 
Ammonia 1 ccm LA or, 
For the screen use: 
Naphthol green 8g 61 gr. 
Blue solution as above 32 ccm YA oz. 
Gelatine, 8% sol. 1000 ccm 16 oz. 
Allow 7 ccm per 100 qcem, or 750 minims per 100 sq. in. 
Or (Lowy): 
New Bordeaux R BWVAS) (es 25/or: 
Tartrazine 6g 46 er. 
Light green S 9¢g 69 gr. 
Glycerine 50 ccm 384 min. 
Gelatine, 8% sol. 1000 ccm 16 oz. 
Allow about 10 ccm per 100 qcm, or 1000 minims per 100 
sq. in. 
