BOOK VII. 



239 



are equal portions of very minuto lead granules, melted salt, stibium and 

 iron slag Or else take equal portions of gold ore, vitriol, argol, and of salt. 

 So much for the fluxes. 



In the assay furnace, when it has been prepared in the way in which I 

 have described, is first placed a muffle. Then selected pieces of live charcoals 

 are laid on it, for, from pieces of inferior quality, a great quantity of ash collects 

 around the muffle and hinders the action of the fire. Then the scorifiers are 

 placed under the muffle with tongs, and glowing coals are placed under the 

 fore part of the muffle to warm the scorifiers more quickly ; and when the lead 

 or ore is to be placed in the scorifiers, they are taken out again with the 

 tongs. When the scorifiers glow in the heat, first of all the ash or small 

 charcoals, if any have fallen into them, should be blown away with an iron 

 pipe two feet long and a digit in diameter ; this same thing must be done 

 if ash or small coal has fallen into the cupels. Next, put in a small ball of lead 

 with the tongs, and when this lead has begun to be turned into fumes and 

 consumed, add to it the prepared ore wrapped in paper. It is preferable that 

 the assayer should wrap it in paper, and in this way put it in the scorifier, 

 than that he should drop it in with a copper ladle ; for when the 

 scorifiers are small, if he uses a ladle he frequently spills some part of the 

 ore. When the paper is burnt, he stirs the ore with a small charcoal held in 

 the tongs, so that the lead may absorb the metal which is mixed in the ore ; 

 when this mixture has taken place, the slag partly adheres by its cir- 

 cumference to the scorifier and makes a kind of black ring, and partly 

 floats on the lead in which is mixed the gold or silver ; then the slag must 

 be removed from it. 



The lead used must be entirely free from every trace of silver, as is that 

 which is known as VUlacense.^^ But if this kind is not obtainable, the lead 

 must be assayed separately, to determine with certainty that proportion of 

 silver it contains, so that it may be deducted from the calculation of the 

 ore, and the result be exact ; for unless such lead be used, the assay will be 

 false and misleading. The lead balls are made with a pair of iron tongs, 

 about one foot long ; its iron claws are so formed that when pressed 

 together they are egg-shaped ; each claw contains a hollow cup, and when 

 the claws are closed there extends upward from the cup a passage, so there 

 are two openings, one of which leads to each hollow cup. And so when the 

 molten lead is poured in through the openings, it flows down into the hollow 

 cup, and two balls are formed by one pouring. 



In this place I ought not to omit mention of another method of assa5^ng 

 employed by some assayers. They first of all place prepared ore in the 

 scorifiers and heat it, and afterward they add the lead. Of this method I 

 cannot approve, for in this way the ore frequently becomes cemented, and 

 for this reason it does not stir easily afterward, and is very slow in mixing 

 with the lead. 



^'The lead free from silver, called villacense, was probably from Bleyberg, not far from 

 Villach in Upper Austria, this locality having been for centuries celebrated for its pure lead. 

 These mines were worked prior to, and long after, Agricola's time. 



