JULY — SEPT. 1857.] m Photography. 
the small quantity of organic matter remaining on it tending to 
give density. The picture is then to be brought out in the usual 
way, but in this process I find that a large quantity of a 40 grain 
solution of Nitrate of silver is required before the image will appear, 
viz. about 5 or 6 drops to the drachm of the developing solution. 
The developer at this sta^e should not be applied further than is 
necessary to bring out all the details of the picture. When this 
is done I wash the plate well with common water and then treat 
with Cyanide of Potassium. The picture is now a bad positive and 
requires deepening. This is done by washing the Cyanide- well off 
the plate, and •then again carrying on the development with 
Pyrogallic Acid an^ Nitrate of silver, rocking the plate to and 
fro to make it flow evenly over its surface. The high lights im- 
mediately deepen into beautiful blacks, while the dark shadows 
should remain clear and free from any deposit of Metallic silver. 
In my first experiments with Oxymel, I developed at once before 
fixing, and invariably got a certain degree of foggyness in the dark 
shadows which whitened them to such an extent that they were 
almost opaque and required a long exposure to print on paper. Two 
of the negatives produced at the last meeting were of this charac- 
ter. 
The process is extremely easy in all its details. The following 
formulae are I find the best in this climate. 
Bath. 
Distilled Water j 1 oz. 
Crystallised Nitrate of Silver 30 grains. 
saturated with Iodide of Silver in the usual way. The proportion 
of Iodide of Potassium I have used for this purpose is 5 grains to 
20 oz. of the silver solution. After filteration I add to every 20 
oz. of the Bath 10 minims of glacial Acetic Acid. This I find 
tends to preserve the clearness of the pictures under the deve- 
loper. • 
The Collodion must of course be what is commonly used for ne- 
gatives. 
In this process many failures are due to the bad quality of Oxy- 
t 
