THE WOMBAT. 



in the market with which it is unnecessary, as they are free 

 from frilhng propensities under ordinary and rational treat- 

 ment ; this being the case there is no occasion to use it. 



The disadvantages of sulphocyanide are: — (i) Its 

 deliquescent nature ; it absorbs water from the atmosphere so 

 readily that unless the bottle has been very tightly corked, 

 there is no guarantee that the quantity weighed out contains 

 the full proportion of sulphocyanide. (2) the manner in which 

 (when used at the strength recommended by the makers of 

 the papers) the bath runs away at the commencement of the 

 toning operation, rendering it almost impossible to deal with 

 more than two or three prints at one time when the bath is in 

 its most active condition. Its energy departs very rapidly, 

 and the last prints of a batch require long treatment in order 

 to obtain the tone desired. (3) The fact that in order to tone 

 one sheet of paper it is recommended to use two grains of gold 

 chloride, or, in other words, twice the quantity of gold that is 

 demanded by some other baths. If this gold were all reduced 

 and used up on the print, there would perhaps not be so much 

 to complain of, but there is no evidence that this is the case. 

 Why then use an agent which we have good reason to believe 

 wastes so large a proportion of gold ? It may be true that the 

 gold can be recovered, but working on the scale practised by 

 the amateur, this is scarcely worth the trouble, as it cannot 

 be economically done on a small scale. (4) The care needed, 

 especially in the hands of beginners, to avoid what are termed 

 " double tones." Double toning is the overtoning of the 

 lighter halftones, which become blue before the correct tone 

 has been obtained in the shadows. 



Soon after the introduction of the gelatino-chloride papers 

 I began to consider the question as stated above, and being 

 dissatisfied with the working of sulphocyanide, I set to work 

 to try and find an efficient substitute. I tried carbonate, 

 acetate, and tungstate of soda, also borax, and finally adopted 

 the acetate, compounding my toning bath at first exactly as 

 recommended for albuminised paper (acetate of soda 30 grains 

 chloride of gold 1 grain, water 8 oz., made up twenty-four 

 hours before use). This bath I found to work admirably with 

 every make of paper that I tried, but those that contained a 

 somewhat thick film of gelatine held so much of the toning 

 solution that when the prints were thrown into the washing 

 water after the desired tone had been obtained they would go 

 on toning, with the result that, when finished, they appeared 

 somewhat darker than was desired. To avoid this I made up 

 the bath with ten ounces of water instead of eight, and found 

 that it met the case. 



With the acetate of soda bath there is no double toning) 

 the bath works more slowly, and is well under control at the 



