THE ART OF CASTING BRONZE IN JAPAN. 649 



acetates of copper (verdigris), iron sulphate, snlpliui- in fine powder, 

 alum, vinegar prepared from unripe plums, and a decoction of the roots 

 or entire plant of Calamagrostis halconensis (Kat. Ord. Grcuninca'), 

 potassium nitrate, and sodium chloride. The most important of these 

 reagents are the flrst five in the above enumeration. Various mixtures 

 of these are dissolved or suspended in j)lum vinegar and water to form 

 what are called the pickling solutions. Sometimes they are api^lied in 

 the form of pastes. Some are also used singly to obtain special effects, 

 especially the decoction of Galamagrostis. The proportions in which 

 they are mixed to form the pickling solutions are different in every art 

 foundry, even for the same patina. Hence several recipes — said to be 

 used for special patinas — which have been communicated to foreigners, 

 and in which these proportions are given in very exact weights, are not 

 strictly representative of actual practice. So far as my observations 

 go, the ingredients are never carefully weighed in making a solution, 

 and when it is made additional quantities are so often mixed with it at 

 the discretion of the craftsman, that after the flrst day of its use it is 

 impossible to say what its composition really is. Old solutions are 

 always preferred to new, and in many cases are added to the new in 

 large quantities, thus still further increasing the indeflniteness of their 

 comi)osition. In the bronze department of the imperial mint, which 

 was superintended by an old art worker of great skill, there was only 

 one pickling solution for the treatment of bronze. About equal parts 

 of copper and iron sulphates and smaller quantities of alum and sul- 

 phur mixed with varying quantities of plum vinegar, water, and old 

 solution were used in its preperation. Almost every variety of stains 

 and patinas, excepting red and green, were obtained by its use by 

 varying the mode in which it was applied and the treatment of the 

 bronze between the applications. 



The processes for producing a patina by the use of these solutions 

 are, as might be expected from what I have just stated, neither simple 

 nor easy, and the intermediate operations on which its production 

 depends, more than on the exact composition of the solution, are so 

 variously modified in different foundries that I can only give you an 

 imperfect account of their chief features within the limits of this 

 liaper. 



When the casting has been freed from any adherent portion of the 

 mold its surface, where necessary, is very carefully smoothed by lightly 

 rubbing it with a piece of soft, close-grained charcoal or with an 

 impalpable powder of silicious shale i^repared by levigation. After its 

 surface has been thus prepared it is sometimes boiled in a decoction of 

 finely ground beans {Glycine hispida), this treatment being supposed to 

 facilitate the action of the pickling solution. 



It is then immersed in the pickling solution, which is frequently 

 heated almost or quite to the boiling point, but sometimes to a much 

 lower temperature. In other cases it is allowed to remain in a cold 

 solution for many hours. After the casting has been acted on until the 



