158 THE PRODUCTION OF POSITIVES. 



quantity of ferrous oxalate developer, in the propor- 

 tion of four parts of a saturated solution of oxalate of 

 potash to one of ferrous sulphate (care being taken 

 to add tho latter to the former, not vice versa, else 

 a precipitate is formed which weakens the developer), 

 and one or two drops of Bromide of Ammonium are 

 placed in a glass measure. The mixed solutions are 

 then poured over the paper, previously placed in a 

 developing tray after its removal from the water. We 

 may now utilise all the ruby light at our command to 

 watch the process of development, as the colour of 

 the solution covering the paper is sufficiently non- 

 actinic to prevent the image being injured by too 

 strong a light. In about half a minute the picture 

 will begin to appear and in about three minutes the 

 process will be complete. It must not be carried too 

 far, in fact not so far as would be desirable in the 

 finished picture, as the intensity is considerably in- 

 creased by the fixing solution. After a slight rinse in 

 water it is immersed in the alum bath for one minute, 

 and after another rinse placed in the hyposulphite 

 solution for three minutes. It is then washed in fre- 

 quent changes of water and finally dried and mounted 

 in the manner described when treating of ordinary 

 silver prints, with this exception, that the picture 

 when pasted on cardboard must be allowed to dry 

 perfectly before the application of the hot iron, or the 

 gelatinised surface will be certain to adhere to any- 

 thing placed over it during the process. We wish 

 here again to impress on the operator the necessity of 

 using the developing solution perfectly fresh, as the 



