STUDIO AND WORKROOM 7 
Copal, powdered WAT 90 gr. 
Oil of lavender 1000 ccm 16 oz. 
Dissolve by heat and stir in, for black: 
Lampblack 12's Oar: 
Indigo 0.5¢ 4 gr, 
Or, for white: | 
Zinc white | 15g: iho: 
Apply with a fine brush. 
Mattinc GiLass.—Dissolve by heat: 
Sodium or potassium fluoride 4¢ 20 gr. 
Gelatine 4g 20 ger. 
Water 1000 ccm 1 oz. 
Coat on the glass and allow to set well and dry, then immerse 
in a 6 per cent solution of hydrochloric acid for 30 to 60 
seconds, and dry without washing. The gelatine can be dis- 
solved off with hot water and a fine matt surface is obtained. 
Or the following may be used: 
A. Sodium fluoride 60 g 60 gr. 
Potassium sulphate 12¢ 12 er. 
Water 500 ccm az: 
B. Zine chloride l4¢g 14 gr. 
Hydrochloric acid 65 ccm 65 min. 
Water 500 ccm Loz: 
Mix in equal quantities just before use and apply with a quill 
pen or fine brush. In about 30 minutes a fine matt surface is 
obtained. Another plan, which is even more convenient, is 
to paint a square or rectangle with the above solution, when 
the whole surface will be matted. Titles may easily be writ- 
ten on the surface with a soft lead pencil, and can be easily 
removed at any time with rubber or soap and water. 
SUBSTITUTES FOR GrouND GLass.—Expose a dry plate to 
the light of a match at a distance of 3 feet, then develop until 
uniformly grey, fix and wash. Immerse the plate ina solu- 
