FIXING VARNISHING. 22$ 



Both development and intensification are best performed 

 in a dish the former in an ebonite, the latter in one of 

 porcelain. 



When the plate has again become dry, warm and varnish 

 it as usual. 



Fixing. It is well to finish fixing each plate by im- 

 mersing it for about ten minutes in a perfectly fresh hypo- 

 sulphite solution after the plate has, in the ordinary sense 

 of the word, been fixed that is, after the creamy appear- 

 ance of the film has been discharged by immersion in a 

 solution perhaps not quite fresh. The temperature of the 

 hyposulphite solution should not be below 50 nor above 

 70 F. The apparent change in the strength of the image 

 which attends fixing has led some to suppose that the 

 image is greatly weakened by the action of the hyposul- 

 phite solution ; but this is not the case, and we think it 

 important to state clearly that the hyposulphite solution 

 will not injure the image, even if it be allowed to act for a 

 very much longer time than is necessary for the thorough 

 fixation of the image and the removal of instable silver 

 compounds from the film. Time must be allowed, both for 

 the action of the hyposulphite of soda solution, and also for 

 thorough washing afterwards, in order to effect the com- 

 plete removal from the plate of compounds which, if not 

 removed, will ultimately destroy the plate. 



Finishing the Plate. The plate must be dried spontane- 

 ously. On no account may artificial heat be applied. In 

 case of urgency drying may be hastened by immersion in 

 methylated spirit, and then varnished when dry. A suit- 

 able varnish for this purpose is Mawson and Swan's " dry 

 plate varnish." In every case the negative should be care- 

 fully preserved from damp. Enamel collodion is a useful 

 temporary varnish for negatives on gelatine plates. 



Q 



