OIL AND BROMOIL 305 
colour, and either the special inks, or lithographic, or photo- 
gravure inks may be used. Artist’s powder colours may also 
be used, and worked up on a slab with a palette knife with 
medium, boiled linseed oil, or raw oil with a little japanner’s 
gold size. The inks dry very slowly, and it has been sug- 
gested to treat the completed print with certain solvents for 
the medium, such as benzol, benzol and alcohol, petroleum 
ether, gasoline, etc. These are dangerous, and the best is 
carbon tetrachloride. The print is rinsed once or twice with 
the solvent, and then dried. This treatment gives a somewhat 
dead appearance in the shadows; then ordinary celluloid 
varnish, diluted with 2 to 3 parts of amyl acetate may be used, 
the prints immersed therein for a minute, and dried. 
Oit Printinc.—This is a process worked out by G. H. 
Rawlins, which is practically based on the older processes of 
Poitevin and Mariot. Gelatinised paper is sensitised with a 
bichromate, exposed under a negative, thoroughly washed, 
soaked in water for an hour, and then inked up, either with 
a roller or brushes, charged with greasy ink, which only takes 
on the exposed parts. 
Special papers, pigmoil or oil printing, can be obtained 
commercially; or paper may be floated on a 6 per cent solu- 
tion of soft collotype gelatine for a few minutes and hung up 
to dry. It should be sensitised with the following: 
Ammonium bichromate 60 g 460 gr. 
Water 1000 ccm 16 oz. 
For use mix 1 part stock solution with 2 parts denatured 
alcohol. Place the paper face up on a flat board or sheet of 
glass, and apply the sensitiser freely with a pad of absorbent 
cotton or soft linen, a flat brush or a Blanchard brush. The 
alcoholic solution will not keep. The paper may also be 
immersed in a 5 per cent solution of ammonium bichromate 
