THE WOMBAT. 24 



Hot Hypo-alum Toning for Bromide Prints. For this 

 method of toning it is not necessary that the prints should be 

 washed after fixing — a mere rinse will be quite sufficient — but I 

 think it is better that they should be dried before attempting to 

 tone them, as this tends to harden the gelatine. 



Before placing the prints in the hot hypo-alum bath, they 

 must either be put in an alum bath or placed in a cold hypo and 

 alum bath for a few minutes, and then transferred to the hot bath, 

 which is made up as follows : — 



Sodium hyposulphite ... ... 9 oz. 



Alum (common; ... ... 1 oz. 



Water ... ... ... 60 oz. 



This bath requires to be heated to about 120° before the 

 prints are put in, and then kept to about that temperature. The 

 prints take from twenty to forty minutes to tone. The quality of 

 the tones obtained by this process depends mainly upon the quality 

 of the print. Prints taken from brilliant negatives give very fine 

 tones indeed. The best paper for this purpose is a toned or tinted 

 one, such as Eastman's Royal Bromide, and some very fine effects 

 indeed may be obtained on this paper, almost approaching carbon 

 in quality. It must be remembered that this method -of toning 

 tends to slightly reduce the prints, and therefore the prints for this 

 purpose must be fully printed out. — Photography. 



SOME OF THE DEFECTS IN PLATINOTYPE 

 WORK AND THEIR CAUSES. 



1. The pictures are vigorous, but more or less fogged. 



Cause. — The paper was affected by light, either in sensitising 

 or copying, or there was too high a temperature in drying ; 

 it should not exceed 40° C. 



Spoiled ferric solution. 



The ferric solution is best preserved in hyalite flasks. If you 

 are not sure of your solution, test it before using with red 

 prussiate of potash to see that it is free from ferrite. 

 Should it contain only a trace of ferrite, it can be made fit 

 for use again by carefully adding red prussiate of potash. 

 In order to try this, mix a few cub. centims. of the norma- 

 ferric-chlorite solution with every 100 cub. centims of the 

 iron solution, and ascertain by actual experiment on papet 

 whether the restoration is complete. 



2 The prints appear weak under the developer. 

 Paper which has become damp. 



