STUDIO AND WORKROOM 11 
rocking the dish, and then adding the silver-potash mixtures. 
The action begins at once, and in 2 or 3 minutes a light swab 
of absorbent cotton should be lightly drawn over the surface 
so as to prevent the heavy sediment from settling down. As 
the cotton becomes dirty, it should be thrown away and fresh 
used. When to stop the action depends entirely upon experi- 
ence; if too soon, the deposit is thin, and if too prolonged, it 
is thick and requires much polishing. Wash with distilled 
water, lightly swab with cotton, and allow to dry in a vertical 
position for at least an hour. Polishers are most satisfactorily 
made of the best chamois leather stretched over a ball of 
cotton. Two polishers are necessary. First go over the 
whole surface with a plain rubber with light circular strokes, 
dusting occasionally. Then rub a little rouge into the other 
pad, and polish in the same way. 
It has been stated that celluloid can be silvered with the 
above solution; or the celluloid may be immersed in the sugar 
solution and then the others added in succession. For the 
above process the old fashioned sugar candy is the best form 
of sugar to use; if this is not procurable, the best cane sugar 
must be used. 
Rk. E. Crowther gave a modification of this process in which 
caustic soda is used and which seems not to be so dependent 
on absolute purity of the chemicals. To make 100 ccm (3 oz., 
250 min.) of solution, the following are required: I. 10 
per cent solution of silver nitrate in distilled water; II. 7.25 
per cent solution of caustic soda in distilled water; III. 28 to 
30 per cent ammonia solution (strongest ammonia water) ; 
IV. Reducing solution—equal volumes of A and B, made as 
follows: 
A. Sugar, lump or whitecrystal 9g 150 gr. 
Distilled water 50 ccm 845 min. 
Nitric acid, c. p. 0.4 ccm 6 min. 
