Chapter III

_The Assay of Silver Ores._
Silver and Mercury 15
Assaying of Silver Ores 16
Crucible Assay 16
Fluxes for Crucible Assay 16
Assay of Genuine Silver Ores 16
Carbonate of Soda 16
Dimensions of Crucible 16
Litharge 17
Preparation and Charge for Assay 17
Treatment in the Furnace 18
Casting-mould 18
Scorification Process 18
Fusing Cup or Scorifier 19
Special Form of Scorifier 19
Scorification Assay the Reverse of Crucible Assay 19
Charge for Scorification Assay 20
Advantages of the Process 20
Anthracite and its Object 21
Separation of the Silver from the Slag 21
Borax, use of, in Assaying 22
Continental Method of Assaying 22
Flux and Charge for Crucible 23
Details of the Process 23, 24
Skittle-pot 25
Cupellation 26
Cupel, its Mode of Manufacture 26
Cupel-mould 27
Assayer's Muffle 28
Cupel-tongs 28
Brightening 29
Sprouting 29
Weighing of Silver Assay 30
Chief Alloy of Silver 30

CHAPTER IV.

_The Cupellation of Silver Ores._

Test-ring 31
Preparation of Bone-ash 32
Defects in Bone-ash Cupel 33
Currents of Air to the Furnace 33
Withdrawal of the Silver from the Cupel 34
Removal of the Litharge, Manner of 35
Quantity of Alloy per Cupel 35
Purity of Silver after Cupellation 37
Ancient Method of Assaying 37
Dr. Lamborn on Assaying 38
Scriptural Testimony 37, 38
English System of Assay 39