692 KANSAS CITY REVIEW OE SCIENCE. 



reserved gold coins are placed in a black-lead crucible and covered with borax, to 

 assist the fluxing and to prevent the oxidation of the copper alloy. They are thus 

 melted down and stirred, by which a complete mixture is effected, so that an assay 

 piece may be taken from any part of the bar cast out. The piece taken for this 

 purpose is rolled out for convenience of cutting. It is then taken to an assay 

 balance (sensible to the io,oooth of a half-gramme or less), and from it is weighed 

 a half-gramme, which is the normal assay weight for gold, being about 7.7 grains 

 Troy. This weight is stamped 1,000, and all the lesser weights (afterward brought 

 into requisition) are decimal divisions of this weight, down to one ten-thousandth 

 part. 



Next, silver is weighed out per the quartation, and as the assay piece, if 

 standard, should contain 900 thousandths, of gold, there must be three times this 

 weight, or 2,700 thousandths of silver, and this is accordingly the quantity used. 

 Thin sheets of lead for cupellation are cut into square pieces and rolled into the 

 form of a hollow cone, and into this are introduced the assay gold and the quar- 

 tation silver. The lead is then closed around them and pressed into a ball. In 

 the furnace are placed the cupels, and into one of them is deposited the leaden 

 ball with its contents, after which the furnace is closed. When the cupellation 

 has been finished, the metal is allowed to cool slowly, and the disk or button 

 which it forms is detached from the cupel. With a hammer the button is flattened 

 and afterward annealed by bringing it to a red heat. It is then laminated by pass- 

 ing it between rollers, is again annealed, and is rolled loosely into a spiral, or coil, 

 called a cornet. It being ready for the process of quartation, it is placed in a 

 matrass containing about 1^ ounces of nitric acid, and in that it is boiled ten 

 minutes, as indicated by an electric monitor. The acid is then poured off, and 

 three-fourths of an ounce of stronger acid at thirty-two degrees is substituted for 

 it, in which the gold is boiled ten minutes more. Again the acid is poured off 

 and another boiling in equally strong acid is had. The silver having thus been 

 removed, the gold is taken out, washed in pure water and exposed in a crucible 

 to a red heat for the purpose of drying, strengthening, and annealing. The 

 cornet of gold is placed in the assay balance, and the number of thousandths which 

 it weighs expresses the fineness of the gold assayed in thousandths. 



The method employed for testing the accuracy of the process is as. follows: 

 A roll of gold of absolute purity, which has been kept under the seal of the Chair- 

 man of the Assay Commissioners, is opened in their presence, and from it is taken 

 the weight of 900 parts. To this are added 100 of copper, to make up 1,000 

 parts of the exact legal standard. The same process is employed as with the other 

 gold, and at the same time after the assay is finished, the pure gold remaining 

 ought to weigh exactly 900. The law allows a deviation one-thousandth for gold 

 coin ; that is, from 899 to 901. 



In assaying the silver, the reserved coins are melted together in a black-lead 

 crucible, to prevent oxidation and to allow of dipping out. A small portion is 

 poured into water, producing granulation, from which portion the assay is taken. 



