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T. KOGA & 0. YAMAGATA 



The exact determination of the fineness of any individual coin 

 is not so easy, since the silver-copper alloy usually employed in 

 coinage shows the property of segregation to a considerable degree, 

 the silver beino; concentrated towards the centre of the ingot made 

 from this alloy. A small portion cut from the coin in a haphazard 

 manner will not therefore be the true representative sample of the coin 

 taken as a whole. 



Although the experiments strictly refer to the silver yen coin, 

 yet the conclusions drawn from them may be applied equally well to 

 many other coins, when the conditions of manufacture are similar. 



In order to obtain a clear understanding of such conditions, it 

 may be perhaps useful to give a brief account of the process of silver 

 minting in the Imperial Mint. 



The process of minting begins with the melting of refined silver 

 with the right proportion of copper in a crucible, the metal being covered 

 with a layer of powdered charcoal. When in perfect fusion, the bath 

 is stirred up thoroughly; a small portion is dipped out and immediately 

 let fall into cold water. The small shots, or granules of the alloy 

 thus obtained are dried and reserved for assay, which determines the 

 exact proportion of silver in that melt. The metal is then poured 

 into cast iron moulds and transformed into long flat strips or " bars," 

 which are taken out of the moulds and cooled in water. The bars are 

 next rolled out by a pair of rollers, until they are reduced to the 

 thickness of the coin to be manufactured. In the course of lamination, 

 these bars, now known as " fillets," usually require to be annealed, an 

 operation which is performed in a sort of reverberatory furnace, where 

 they are heated to a low redness ; they are then taken out and 

 immediately cooled in water, so as to reduce the oxidation of the 

 metal to a minimum. 



The finished fillets are taken to the cutting machine, by which 



