BOOK X. 459 



libra of sulphur (not exposed to the fire), half a libra of refined salt, a quarter of 

 a libra of sal-ammoniac, and one uncia of red-lead. The fourth compound 

 consists of one libra each of refined salt, sulphur (not exposed to the fire) and 

 argol, and half a libra of chrysocolla which the Moors call borax. The fifth 

 compound has equal proportions of sulphur (not exposed to the fire), sal- 

 ammoniac, saltpetre, and verdigris. 



The silver which contains some portion of gold is first melted with 

 lead in an earthen crucible, and they are heated together until the silver 

 exhales the lead. If there was a libra of silver, there must be six drachmae of 

 lead. Then the silver is sprinkled with two unciae of that powdered com- 



interest and obscurity, but also because of differences of view as to its translation ; jwe have 

 given that of Mr. H. C. Hamilton (London, 1903). A review of this discussion will be found 

 in Percy's Metallurgy of Gold and Silver, p, 399. That it refers to cementation at all hangs 

 by a slender thread, but it seems more nearly this than anything else. 



Pliny (xx.Kiii, 25) is a little more ample ; " (The gold) is heated with double its 

 " weight of salt and thrice its weight of misy, and again with two portions of salt and one of a 

 " stone which they call schisios. The virus is drawn out when these things are burnt together 

 " in an earthen crucible, itself remaining pure and incorrupt, the remaining ash being 

 " preserved in an earthen pot and mixed with water as a lotion for lichen (ring-worm) on the 

 " face." Percy, (Metallurgy Silver and Gold, p. 398) rightly considers that this undoubtedly 

 refers to the parting of silver and gold by cementation with common salt. Especially as 

 Pliny further on states that with regard to misy, " In purifying gold they mix it with this 

 " substance." There can be no doubt from the explanations of Pliny and Dioscorides that 

 misy was an oxidized pyrite, mostly iron sulphate. Assuming the latter case, then all of the 

 necessary elements of cementation, i.e., vitriol, salt, and an aluminous or silicious element, are 

 present. 



The first entirely satisfactory evidence on parting is to be found in Theophilus (12th 

 Century), and we quote the following from Hendrie's translation (p. 245) ; " Of Heating the 

 " Gold. Take gold, of whatsoever sort it may be, and beat it until thin leaves are made in 

 " breadth three fingers, and as long as you can. Then cut out pieces that are equally long 

 " and wide and join them together equally, and perforate through all with a fine cutting 

 " iron. Afterwards take two earthen pots proved in the fire, of such size that the gold can 

 " lie flat in them, and break a tile very small, or clay of the furnace burned and red, weigh 

 " it, powdered, into two equal parts, and add to it a third part salt for the same weight ; 

 " which things being slightly sprinkled with urine, are mixed together so that they may not 

 " adhere together, but are scarcely wetted, and put a little of it upon a pot about the 

 " breadth of the gold, then a piece of the gold itself, and again the composition, and 

 " again the gold, which in the digestion is thus always covered, that gold may not be in 

 " contact with gold ; and thus fill the pot to the top and cover it above with another pot, 

 " which you carefully lute round with clay, mixed and beaten, and you place it over the fire, 

 " that it may be dried. In the meantime compose a furnace from stones and clay, two feet 

 " in height, and a foot and a half in breadth, wide at the bottom, but narrow at the top, 

 " where there is an opening in the middle, in which project three long and hard stones, which 

 " may be able to sustain the flame for a long time, upon which you place the pots with the 

 " gold, and cover them with other tiles in abundance. Then supply fire and wood, and take 

 " care that a copious fire is not wanting for the space of a day and night. In the morning 

 " taking out the gold, again melt, beat and place it in the furnace as before. Again also, 

 " after a day and night, take it away and mixing a little copper with it, melt it as before, and 

 " replace it upon the furnace. And when you have taken it away a third time, wash and dry 

 " it carefully', and so weighing it, see how much is wanting, then fold it up and keep it." 



The next mention is by Geber, of whose date and authenticity there is great 



doubt, but, in any event, the work bearing his name is generally considered 



to be prior to the 14th, although he has been placed as early as the 8th 



Century. We quote from Russell's translation, pp. 17 and 224, which we have 



checked with the Latin edition of 1542 : " Sol, or gold, is beaten into thin plates 



and with them and common salt very well prepared lay upon lay in a vessel of 



calcination which set into the furnace and calcine well for three days until the whole is 



subtily calcined. Then take it out, grind well and wash it with vinegar, and dry it in the 



sun. Afterwards grind it well with half its weight of cleansed sal-armoniac ; then set it 



to be dissolved until the whole be dissolved into most clear water." Further on : " Now 



we will declare the way of cementing. Seeing it is known to us that cement is very necessary 



in the examen of perfection, we say it is compounded of inflammable things. Of this 



