BOOK XI. 



539 



The bellows which this master uses differ in size from the others, for the 

 boards are seven and a half feet long ; the back part is three feet wide ; 

 the front, where the head is joined on is a foot, two palms and as many digits. 

 The head is a cubit and a digit long ; the back part of it is a cubit and a 

 palm wide, and then becomes gradually narrower. The nozzles of the bellows 

 are bound together by means of an iron chain, controlled by a thick 

 bar, one end of which penetrates into the ground against the back of the long 

 wall, and the other end passes under the beam which is laid upon the 

 foremost perforated beams. These nozzles are so placed in a copper pipe 

 that they are at a distance of a palm from the mouth ; the mouth should be 

 made three digits in diameter, that the air may be violently expelled through 

 this narrow aperture. 



There now remain the hquation thorns, the ash-coloured copper, the 

 " slags," and the cadmiaP Liquation cakes are made from thorns in the 

 following manner. 28 There are taken three-quarters of a centumpondium of 

 thorns, which have their origin from the cakes of copper-lead alloy when 

 lead-silver is liquated, and as many parts of a centumpondium of the thorns 

 derived from cakes made from once re-melted thorns by the same method, 

 and to them are added a centumpondium of de-silverized lead and half a 

 centumpondium of hearth-lead. If there is in the works plenty of litharge, it 

 is substituted for the de-silverized lead. One and a half centumpondia of 

 litharge and hearth-lead is added to the same weight of primary thorns, 

 and half a centumpondium of thorns which have their origin from liquation 

 cakes composed of thorns twice re-melted by the same method (tertiary 

 thorns), and a fourth part of a centumpondium of thorns which are pro- 



" made from the cakes of copper. All these methods are carried on in the works of Cyprus ; 

 " the difference between these substances is that the squamae (copper scales) are detached from 

 " hammering the cakes, while the flower falls off spontaneously." Agricola (De Nat. Fos., 

 p. 352) notes that " flowers of copper {flos certs) have the same properties as ' roasted 

 " copper.' " 



^'It seems scarcely necessary to discuss in detail the complicated " flow scheme " of the 

 various minor bye-products. They are all re-introduced into the liquation circuit, and thereby 

 are created other bye-products of the same kind ad infinitum. Further notes are given on: — 

 Liquation thorns . . . . Note 28. 



« Slags „30- 



Ash-coloured copper . . ,, 29. 



Concentrates . . . . ,, 33. 



Cadmia . . . . .. ,,32. 



There are no data given, either by Agricola or the later authors, which allow satis- 

 factory calculation of the relative quantities of these products. A rough estimate from the 

 data given in previous notes would indicate that in one liquation only about 70% of the 

 original copper came out as refined copper, and that about 70% of the original lead would go 

 to the cupellation furnace, i.e., about 30% of the original metal sent to the blast furnace 

 would go into the " thorns," " slags," and " ash-coloured copper." The ultimate losses 

 were very great, as given before (p. 491), they probably amounted to 25% of the silver, 9% 

 copper, and 16% of the lead. 



**There were the following classes of thorns : — 



1st. From liquation. 

 2nd. From drying. 

 3rd. From cupellation. 

 In a general way, according to the later authors, they were largely lead o.xide, and 

 contained from 5% to 20% cuprous oxide. If a calculation be made backward from the 

 products given as the result of the charge described, it would appear that in this case they must 

 have contained at least one-fifth copper. The silver in these liquation cakes would run about 

 24 ozs. per ton, in the liquated lead about 36 ozs. per ton, and in the liquation thorns 24 ozs. 

 per ton. The extraction into the liquated lead would be about 80% of the silver. 



