OX THE FINENESS OF THE ONE YEN SILVER COIN. 305 



Numerous double assays of individual coins by this method have 

 been made. The results do not indeed show absolute coincidence, 

 but the agreement has been in most cases quite close. 



Thus double assays made by this method on 105 coins gave 

 the following; percentage occurrences of differences : 



Difference nil = 1 Ü" 1 * 



Difference of between 0*1 and 0.5 per mille = 5!>0 ,, 



„ 0-6 and L-0 „ = 181 „ 



., ., „ 1-1 and 1-5 „ = 2*8 ., 



1-6 = 1-0 „ 



The correctness of the results obtained by this method has been 

 verified by us in many instances by the direct assay of the winde coin, 

 after taking the portions for assay by punching, the coin being cut up 

 into small parts and divided into as many assays as there are pieces of 

 metal. In other instance- the entire coin, after the removal of the 

 punchings for assay, has been dissolved in nitric acid and made up 

 with water to a certain known volume, an accurately calibrated bottle 

 of about 2 j litres capacity being used for this purpose. An aliquot 

 part of this liquid was taken up in a Stas pipette. The liquid was then 

 transferred to a shaking bottle and assayed after having been evaporat- 

 ed on the water-bath to the same degree of concentration as in ordinary 

 assays. The results have shown in all cases a close agreement be- 

 tween the assay on the punchings and the exact fineness of the coin 

 ascertained in this way. 



