INTENSIFICATION ey 
Mercuric chloride 20 ¢ 154 gr. 
Ammonium chloride NS OieqyZ)oz., 192 an; 
Hydrochloric acid 10 ¢g 47 St. 
Water 1000 ccm 16 oz. 
The large proportion of the ammonium chloride is said to 
facilitate the removal of the mercury salt. 
The blackening may be effected with one of the following 
reagents : 
A. Ferrous oxalate developer, using 1 part of iron sulphate 
solution to 6 of oxalate; 
B. Amidol developer. Other developing agents with sul- 
phite may be used; 
C. Sodium sulphite, 5 per cent solution of the anhydrous 
or 10 per cent solution of the hydrated salt; 
D. Ammonia, 10 per cent solution of the strongest am- 
monia water. The bromide bleach does not give such satis- 
factory results with this as the chloride; 
KE. Silver-potassio-cyanide (Monckhoven). ‘This is pre- 
pared from: 
I. Silver nitrate 20 g 154 ger. 
Water 500 ccm 8 Oz. 
II. Potassium cyanide 20g 154 gr. 
Water 500 ccm 8 oz. 
Add three-fourths of I to II and shake thoroughly; a thick 
curdy white precipitate will be thrown down, which dissolves 
on shaking. If a perfectly clear solution is obtained, add 
more [ until, after shaking and allowing to stand with occa- 
sional agitation for 10 minutes, there is a permanent white 
precipitate. The quantity of silver required depends on the 
strength of the cyanide, which varies considerably; in any 
case, a permanent deposit must be formed, even by adding 
more silver than above stated. This method of mixing is 
better than adding the cyanide to the silver. If the negatives 
