THE PRODUCTION OF POSITIVES. 151 



brown verging on purple gives the most artistic ap- 

 pearance when finished. If an engraving tone 

 be required the process must be continued until a 

 decided purple tint is produced. Overtoning is to 

 be avoided as a cold grey picture is the result. 



After toning the washings are repeated, and the 

 prints finally fixed in a solution containing : 

 Sodium Hyposulphite, 1J ounces. 

 Liq. Ammon. Fort., 3 drops. 

 Water, 9 ounces. 



This solution should not be above 85 or below 75 

 Far. and always freshly made. 



After ten or fifteen minutes immersion, with con- 

 tinual motion, the unaltered silver will be dissolved 

 away. The prints are then immediately removed to 

 a large tub of water, and kept in continual motion 

 for a quarter of an hour. The water is then 

 changed ; at the end of an hour the change re- 

 peated ; at two hours again repeated, and so on for 

 eight hours. At the expiration of this time all 

 traces of hypo will have disappeared ; the prints are 

 then hung up to dry. 



All operations, except the final washings must be 

 conducted in a subdued light, coloured light will not 

 answer, white light alone enabling us to distinguish 

 the proper tint when toning. The prints when dry 

 are cut to the required shape, with a sharp knife, not 

 scissors, and mounted on cardboard with thick starch 

 or glue, to which a few drops of carbolic acid have 

 been added. When perfectly dry their appearance 

 may be much improved, by passing through a rolling 



