THE WOMBAT. 



removing the acid which exists in the emulsion and which 

 acts as a preservative. Some papers become brick red under 

 this treatment, and when this occurs the toning action is easily 

 perceived : it is sometimes recommended that they be rendered 

 red by passing them through a bath of salt and water before 

 toning, a process which will usually have this effect. It was 

 noticed many years ago that proofs printed in the sun were of 

 a warmer colour than those printed in the shade ; the moisture 

 present in the paper and the atmosphere has also a modifying 

 effect upon the colour. 



The formula generally advised for the toning of gelatino- 

 chloride papers, and these are now almost universally employed 

 by amateurs, is one in which sulphocyanide of ammonia is 

 combined with the gold, and in all probability ninety-nine per 

 cent of practitioners use this chemical. In my opinion it is 

 not an unmixed blessing. It answers the purpose perfectly 

 when everything is favourable, and when its use is regularly 

 indulged in and properly understood, but for the average 

 amateur who is not toning prints every day and who some- 

 times allows weeks or even months to elapse between the toning 

 of two batches, it does not always work so satisfactorily. Its 

 advantages are said to be : — (i) It tones rapidly. (2) It keeps 

 fairly well. (3) It gives tones and a quality of image such as 

 no other toning agent will give. 



With regard to the first point, I admit that it will tone 

 rapidly, so rapidly, indeed, that when it is fresh there is little 

 or no control over the colour. Its energy, however, quickly 

 falls off, and by the time a few prints have been toned it is a 

 bit slower, not to say lethargic. 



The second point is advantageous to a certain extent, but 

 only to one who is too lazy to make up a fresh bath for each 

 batch of prints, and it has the disadvantage that after the first 

 toning operation the photographer never knows what he is 

 using, as the bath is contaminated to a greater or less extent, 

 and when the fresh gold is added to it there is no means of 

 ascertaining (except by analysis) what its precise strength in 

 gold is. 



The third advantage attributed to the bath is not very 

 evident to my mind. I hold the opinion that as good results 

 can be obtained with any of the ordinary toning baths as with 

 that in which sulphocyanide is used, for I have seen this 

 demonstrated as far as two or three of the usually employed 

 baths are concerned. I will admit that when alum is used 

 previous to toning, the sulphocyanide, from the softening action 

 which it exerts on gelatine, will perhaps aid the toning operation, 

 but in my own practice I never use alum ; the use of this 

 agent is not advisable if it can be avoided, and there are papers 



