448 BOOK X. 



As great expense is incurred in parting the metals by the methods that 

 I have explained, as night vigils are necessary when aqua valens is made, 

 and as generally much labour and great pains have to be expended on this 

 matter, other methods for parting have been invented by clever men, which 

 are less costly, less laborious, and in which there is less loss if through care- 

 lessness an error is made. There are three methods, the first performed with 

 sulphur, the second with antimony, the third by means of some compound 

 which consists of these or other ingredients. 



In the first method,^® the silver containing some gold is melted in a 

 crucible and made into granules. For every libra of granules, there is taken 

 a sixth of a libra and a sicilicus of sulphur (not exposed to the fire) ; this, 

 when crushed, is sprinkled over the moistened granules, and then they are put 

 into a new earthen pot of the capacity of four sextarii, or into several of them 

 if there is an abundance of granules. The pot, having been fiUed, is covered 

 with an earthen hd and smeared over, and placed within a circle of fire set one 

 and a half feet distant from the pot on all sides, in order that the sulphur 

 added to the silver should not be distilled when melted. The pot is opened, 



^*The object of this treatment with sulphur and copper is to separate a considerable 

 portion of silver from low-grade bullion (i.e., silver containing some gold), in preparation 

 for final treatment of the richer gold-silver alloy with nitric acid. Silver sulphide is created 

 by adding sulphur, and is drawn off in a silver-copper regulus. After the first sentence, the 

 author uses silver alone where he obviously means silver " containing some gold," and further 

 he speaks of the " gold lump " (massula) where he likewise means a button containing a great 

 deal of silver. For clarity we introduced the term " regulus " for the Latin mistura. The 

 operation falls into six stages : a, granulation ; b, sulphurization of the granulated bullion ; 

 c, melting to form a combination of the silver sulphide with copper into a regulus, an alloy 

 of gold and silver settling out ; d, repetition of the treatment to abstract further silver from 

 the " lump ; " e, refining the " lump " with nitric acid ; /, recovery of the silver from the 

 regulus by addition of lead, Uquation and cupellation. | 



The use of a " circle of fire " secures a low temperature that would neither volatilize 

 the sulphur nor melt the bullion. The amount of sulphur given is equal to a ratio of 48 parts 

 bullion and 9 parts sulphur. We are not certain about the translation of the paragraph in 

 relation to the proportion of copper added to the granulated bulhon ; because in giving 

 definite quantities of copper to be added in the contingencies of various original copper 

 contents in the bullion, it would be expected that they were intended to produce some 

 positive ratio of copper and silver. However, the ratio as we understand the text in various 

 cases works out to irregular amounts, i.e., 48 parts of silver to 16, 12.6, 24, 20.5, 20.8, 17.8, or 

 18 parts of copper. In order to obtain complete separation there should be sufficient sulphur 

 to have formed a sulphide of the copper as well as of the silver, or else some of the copper 

 I nd silver would come down metalhc with the " lump ". The above ratio of copper added to 

 the sulphurized silver, in the first instance would give about 18 parts of copper and 9 parts 

 of sulphur to 48 parts of silver. The copper would require 4.5 parts of sulphur to convert 

 it into sulphide, and the silver about 7 parts, or a total of 11. 5 parts required against 9 parts 

 furnished. It is plain, therefore, that insufficient sulphur is given. Further, the litharge 

 would probably take up some sulphur and throw down metallic lead into the " lump ". 

 However, it is necessary that there should be some free metallics to collect the gold, and, 

 therefore, the separation could not be complete in one operation. In any event, on the above 

 ratios the " gold lump " from the first operation was pretty coppery, and contained some 

 lead and probably a good deal of silver, because the copper would tend to desulphurize the 

 latter. The " powder " of glass-galls, salt, and litharge would render the mass more liquid 

 and assist the " gold lump " to .separate out. 



The Roman silver sesterce, worth about 2^ pence or 4.2 American cents, was no doubt 

 used by Agricola merely to indicate an infinitesimal quantity. The test to be applied to the 

 regulus by way of cupellation and parting of a sample with nitric acid, requires no explanation. 

 The truth of the description as to determining whether the gold had settled out, by using a 

 chalked iron rod, can only be tested by actual experiment. It is probable, however, that the 

 sulphur in the regulus would attack the iron and make it black. The re-melting of the regulus, 

 if some gold remains in it, with copper and " powder " without more sulphur, would provide 

 again free metallics to gather the remaining gold, and by desulphurizing some silver this 

 button would probably not be very pure. 



