644 THE ART OF CASTING BRONZE IN JAPAN. 



Imperfectly refined copper, containing larger proportions of sulphur 

 and iron than those given above but still comparatively free from 

 arsenic, antimony, and bismuth, is sometimes used. When Japanese 

 castings are unsound from vesicular cavities, the unsoundness is gen- 

 erally due to the sulphur in such copper. The sulphur becomes oxi- 

 dized, during melting and pouring the alloy, to gaseous sulphurous 

 anhydride, and the cavities are formed by bubbles of this gas being 

 retained in the casting during solidification. In our own foundries 

 this element is also too frequently the unsuspected cause of the same 

 defects in castings. 



The tin used generally contains lead, occasionally iron and copi)er, 

 but rarely other impurities. 



The lead is tolerably pure, excej)ting that it always contains a little 

 silver. 



Zinc, which is of frequent occurrence in Japanese bronzes (karakane), 

 has never been added as metal, and its presence is due to the brass 

 articles which often form part of the "scrap" of the furnace charges. 



The presence of arsenic and antimony, both of which are often found 

 in considerable amounts in these alloys, is not due to the use of 

 impure metals, but to the addition of a i)seudospeise called " shiro-me" — 

 a by-product of the desilverization of copper by lead ' — the composition 

 of which is given in the following analysis, which I have made of a char- 

 acteristic specimen : 



Shiroine. 



Copper 72. 70 



Lead 8. 53 



Arsenic 11. 37 



Antimony 4. 27 



Tin 93 



Iron 13 99.50 



The first official record we have of the use of this pseudospeise is con- 

 tained in an edict of the Government in 1761, prescribing its addition 

 to the copper-tin -lead bronze to be used in the mints for the casting of 

 coins, but doubtless it had been similarly employed very much earlier 

 than that date, and almost certainly in the casting of the colossal 

 Buddha in Kioto in 1614 A. D. It was added to tlie alloy in order to 

 increase its hardness without diminishing its fusibility, and to obtain 

 in the castings a sharper impression of the mold than was possible with 

 the copper-tin-lead alloy alone. During later years it has been used by 

 some bronze founders because its addition to "karakane" has been 

 found to facilitate the jiroduction of the gray patina, which is preferred 

 for objects which have to be decorated with inlaid-line designs in silver. 



It is almost needless to say that silver, although mentioned in temple 

 records as having been added to the bronze used for the casting of some 

 of their famous images and bells, has never been so added, as there is 

 never more present than can be accounted for by its occurrence in the 



Shirome. 



Silver 1 . 33 



Sulphur 33 



Zinc Nil. 



Gold Trace. 



1 "A Japanese pseudospeise," by W. Gowland. Jour. Soc. Chemical Industry, Vol. 

 XIII, page 463. 



