462 BOOK X. 



fallen together from the silver article, and puts them into a cloth made of woven 

 cotton or into a soft leather ; the quicksilver is squeezed through one or the 

 other into another dish.^^ The gold remains in the cloth or the leather, and 

 when collected is placed in a piece of charcoal hollowed out, and is heated 

 until it melts, and a httle button is made from it. This button is heated with 

 a little stibium in an earthen crucible and poured out into another little 

 vessel, by which method the gold settles at the bottom, and the stibium is 

 seen to be on the top ; then the work is completed. Finally, the gold 

 button is put in a hollowed-out brick and placed in the fire, and by this 

 method the gold is made pure. By means of the above methods gold is parted 

 from silver and also silver from gold. 



Now I will explain the methods used to separate copper from gold^*. 



" from foreign matter, but it also ameliorates all other metals, but it does the same for animal 

 " bodies." There are most specific descriptions of this process in the other works attributed 

 to Valentine, but their authenticity is so very doubtful that we do not quote. The 

 Probierbiichlein gives several recipes for this process, all to the same metallurgical effect, of 

 which we quote two : " How to separate silver from gold. Take i part of golden silver, i 

 " part of spiesglass, i part copper, i part lead ; melt them together in a crucible. 

 " When melted pour into the crucible pounded sulphur and directly you have poured it in 

 " cover it up with soft lime so that the fumes cannot escape, and let it get cold and you will 

 " find your gold in a button. Put that same in a pot and blow on it." " How to part gold 

 " and silver by melting or fire. Take as much gold-silver as you please and granulate it ; 

 " take I mark of these grains, i mark of powder ; put them together in a crucible. Cover it 

 " with a small cover, put it in the fire, and let it slowly heat ; blow on it gently until it melts ; 

 " stir it all well together with a stick, pour it out into a mould, strike the mould gently with 

 " a knife so that the button may settle better, let it cool, then turn the mould over, strike off 

 " the button and twice as much spiesglas as the button weighs, put them in a 

 " crucible, blow on it tiU it melts, then pour it again into a mould and break away the button 

 " as at first. If you want the gold to be good always add to the button twice as much 

 " spiesglass. It is usually good gold in three meltings. Afterward take the button, place 

 " it on a cupel, blow on it till it melts. And if it should happen that the gold is covered 

 " with a membrane, then add a very little lead, then it shines (plickt) and becomes 

 " clearer." Biringuccio (1540) also gives a fairly clear exposition of this method. All the 

 old refiners varied the process by using 'mixtures of salt, antimony sulphide, and sulphur, in 

 different proportions, with and without lead or copper ; the net effect was the same. 

 Later than Agricola these methods of parting bullion by converting the silver into a sulphide 

 and carrying it off in a regulus took other forms. For instance, Schliiter (Hiitte-Werken, 

 Braunschweig, 1738) describes a method by which, after the granulated bullion had been 

 sulphurized by cementation with sulphur in pots, it was melted with metallic iron. 

 Lampadius {Grundriss Einer Allgemeinen Hiittenkunde, Gottingen, 1827) describes a treat- 

 ment of the bullion, sulphurized as above, with litharge, thus creating a lead-silver regulus 

 and a lead-silver-gold buUion which had to be repeatedly put through the same cycle. The 

 principal object of these processes was to reduce silver bullion running low in gold to a ratio 

 acceptable for nitric acid treatment. 



Before closing the note on the separation of gold and silver, we may add that with 

 regard to the three processes largely used to-day, the separation by solution of the silver 

 from the bullion by concentrated sulphuric acid where silver sulphate is forro.ed, was first 

 described by D'Arcet, Paris, in 1802 ; the separation by introducing chlorine gas into the 

 molten bullion and thus forming silver chlorides was first described by Lewis Thompson in 

 a communication to the Society of Arts, 1833, and was first applied on a large scale by F. B. 

 Miller at the Sydney Mint in 1867-70 ; we do not propose to enter into the discussion as to 

 who is the inventor of electrolytic separation. 



^^See note 12, p. 297, for complete discussion of amalgamation. 



2*These nine methods of separating gold from copper are based fundamentally upon 

 the sulphur introduced in each case, whereby the copper is converted into sulphides and 

 separated off as a matte. The various methods are much befogged by the introduction of 

 extraneous ingredients, some of which serve as fluxes, while others would provide metallics in 

 the shape of lead or antimony for collection of the gold, but others would be of no effect, 

 except to increase the matte or slag. Inspection will show that the amount of sulphur 

 introduced in many instances is in so large ratio that unless a good deal of volatilization 

 took place there would be insufficient metallics to collect the gold, if it happened to be in 

 small quantities. In a genercd way the auriferous button is gradually impoverished in copper 



