ON THE FINENESS I »F THE ONE YEN SILVER COIN. 299 



III. Methods of Cutting Portions for Assay 

 from the Coin. 



If the figures <riven in the proceeding section be taken as re- 

 presenting the general distribution of silver in the One Yen Coin, 

 what would be the best mode of cutting portions for assay from it in 

 order to ascertain the exact fineness of the piece? 



It is almost superfluous to mention that the assay of the entire 

 piece of such a large coin as the Silver Yen, being rather cumbersome, 

 ii is usually convenient to take about one gram of it for an assay. 



It would hi- comparatively easy to cut out an exact representative 

 sample from the coin, if the direction of rolling were apparent on its 

 surface, for we should then know which was the central or richest 

 part. Such is the case with blank- before they are treated with dilute 

 acid. But in the coin, marks are obliterated, and portions must be 

 cut from such positions that they represent the entire piece as nearly 

 as possible, in whatever relation they may stand with regard to the 

 direction of rolling of the bar, from which the particular coin has 

 keen prepared. 



Four methods of cutting a coin for assay, besides our own, are 

 known to us. and we will proceed to examine each of them. 



Method a. A small portion is cut off from the rim of a coin, 

 which, in some cases, is partly laminated by means of a pair of rollers 

 previous to cutting. Since we know that the fineness at different 

 parts differ so greatly, this method of single cutting must be at once 

 rejected, as being unsuitable for large silver coins. 



Method b. In the assay laboratory of the Bureau of the Mint 

 at "Washington the standard silver dollar is first rolled out into a 

 very thin ribbon by means of a pair of small rollers ; an innumerable 

 number of small discs is then punched out of all parts of this ribbon, 



