july — sept. 1857.] in Photography. 271 



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 stage 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 and 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 * 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- 



