BOOK X. 



silver ; but if it should weigh a sesterce or more, then the regulus is thrown 

 back again into the earthen crucible, and it is not advantageous to add sulphur, 

 but only a little copper and powder, by which method a gold lump is again 

 made to settle at the bottom ; and this one is added to the other button which 

 is not rich in gold. 



When gold is parted from sixty-six librae of silver, the silver, copper, 

 and sulphur regulus weighs one hundred and thirty-two librae. To separate 

 the copper from the silver we require five hundred librae of lead, more or 

 less, with which the regulus is melted in the second furnace. In this 

 manner litharge and hearth-lead are made, which are re-smelted in the first 

 furnace. The cakes that are made from these are placed in the third furnace, 

 so that the lead may be separated from the copper and used again, for it 

 contains very little silver. The crucibles and their covers are crushed, washed, 

 and the sediment is melted together with litharge and hearth-lead. 



Those who wish to separate all the silver from the gold by this method 

 leave one part of gold to three of silver, and then reduce the alloy to 

 granules. Then they place it in an ampulla, and by pouring aqua valens over 

 it, part the gold from the silver, which process I explained in Book VII. 



If sulphur from the lye with which sal artificiosus is made, is strong 

 enough to float an egg thrown into it, and is boiled until it no longer emits 

 fumes, and melts when placed upon glowing coals, then, if such sulphur is 

 thrown into the melted silver, it parts the gold from it. 



Silver is also parted from gold by means of stibium 1 ' 3 . If in a bes of 

 gold there are seven, or six, or five double sextulae of silver, then three parts 

 of stibium are added to one part of gold ; but in order that the stibium should 

 not consume the gold, it is melted with copper in a red hot earthern crucible. 

 If the gold contains some portion of copper, then to eight undue of stibium 



17 There can be no doubt that in most instances Agricola's stibium is antimony sulphide, 

 but it does not follow that it was the mineral stibnite, nor have we considered it desirable to 

 introduce the precision of either of these modern terms, and have therefore retained the 

 Latin term where the sulphide is apparently intended. The use of antimony sulphide to 

 part silver from gold is based upon the greater affinity of silver than antimony for sulphur. 

 Thus the silver, as in the last process, is converted into a sulphide, and is absorbed in the 

 regulus, while the metallic antimony alloys with the gold and settles to the bottom of the pot. 

 This process has several advantages over the sulphurization with crude sulphur ; antimony 

 is a more convenient vehicle of sulphur, for it saves the preliminary sulphurization with its 

 attendant difficulties of volatilization of the sulphur ; it also saves the granulation necessary 

 in the former method ; and the treatment of the subsequent products is simpler. However, 

 it is possible that the sulphur-copper process was better adapted to bullion where the pro- 

 portion of gold was low, because the fineness of the bullion mentioned in connection with the 

 antimonial process was apparently much higher than the previous process. For instance, 

 a bes of gold, containing 5, 6, or 7 double sextulae of silver would be .792, .750. or .708 fine. 

 The antimonial method would have an advantage over nitric acid separation, in that high- 

 grade bullion could be treated direct without artificial decrease of fineness required by 

 inquartation to about .250 fine, with the consequent incidental losses of silver involved. 



The process in this description falls into six operations : a, sulphurization of the silver 

 by melting with antimony sulphide ; b, separation of the gold " lump " (massula) by jogging ; 

 c, re-melting the regulus (mistura) three or four times for recovery of further " lumps " ; d, 

 re-melting of the " lump " four times, with further additions of antimony sulphide ; e, cupel- 

 lation of the regulus to recover the silver ; /, cupellation of the antimony from the " lump " to 

 recover the gold. Percy seems to think it difficult to understand the insistence upon the 

 addition of copper. Biringuccio (iv, 6) states, among other things, that copper makes the 

 ingredients more liquid. The later metallurgists, however, such as Ercker, Lohneys, 

 and Schluter, do not mention this addition ; they do mention the " swelling and 



