MONCKHOVEN'S INTENSIFIER.
By this method a mixture of mercury and silver is deposited on the original image, giving an excellent black colour. Two solutions are required, both of which, it should be noted, are highly poisonous, the potassium cyanide being one of the dead liest poisons known.
No. 1.—Mercuric chloride ... 50 grs.
Potassium bromide .,. 50 grs.
Water ... ... 5 oz.
No. 2.—Silver nitrate ... 50 grs Potassium cyanide 50 grs.
Water ... ... 5 oz.
In making up No. 2, the water should be divided into equal portions, the cyanide being dissolved in one and the silver nitrate in the other. The cyanide solution is then poured into the dissolved silver nitrate, well shaking the mixture. A white pre cipitate will be formed, which will gradu ally become almost but not quite redis solved. If it should become quite redis solved, add a drop or two of silver nitrate solution, until a slight precipitate is again formed. The solution should then be fil
tered. The negative is immersed in the No. 1 solution until it is bleached, the extent of which will depend, as usual, on the amount of intensification desired. It is then washed for about a quarter of an hour, when it is placed in No. 2 solution until the image is blackened through to the back. The plate must not be left in the cyanide too long, or a gradual reduction of density will take place. The plate is then thoroughly washed. The operation may he repeated if the first intensification is in sufficient. A negative treated by this method looks slightly denser while wet than when dry, and this must be borne in mind. If the negative is found to be too dense, it may be reduced with a solution of about 1 oz. of hypo. to 20 oz. of water.