BOOK IX. 355 



A wall which will be called the "second wall " is constructed of brick 

 or stone, two feet and as many palms thick, in order that it may be strong 

 enough to bear the weight. It is built fifteen feet high, and its length depends 

 on the number of furnaces which are put in the works ; there are usually 

 six furnaces, rarely more, and often less. There are three furnace walls, a 

 back one which is against the " second " wall, and two side ones, of which I 

 will speak later. These should be made of natural stone, as this is more 

 serviceable than burnt bricks, because bricks soon become defective and 

 crumble away, when the smelter or his deputy chips off the accretions which 

 adhere to the walls when the ore is smelted. Natural stone resists injury 

 by the fire and lasts a long time, especially that which is soft and devoid 

 of cracks ; but, on the contrary, that which is hard and has many cracks 

 is burst asunder by the fire and destroyed. For this reason, furnaces which 

 are made of the latter are easily weakened by the fire, and when the accretions 

 are chipped off they crumble to pieces. The front furnace wall should be 

 made of brick, and there should be in the lower part a mouth three palms 

 wide and one and a half feet high, when the hearth is completed. A hole 

 slanting upward, three palms long, is made through the back furnace wall, at 

 the height of a cubit, before the hearth has been prepared ; through this 

 hole and a hole one foot long in the " second " wall — as the back of this wall 

 has an arch — is inserted a pipe of iron or bronze, in which are fixed the nozzles 



" bronze age " prior to recorded civilization, starting with the savage who accidentally 

 built a fire on top of some easily reducible ore, and discovered metal in the ashes, etc. ; but 

 as this method has been pursued times out of number to no particular purpose, we wiU 

 confine ourselves to a summary of such facts as we can assemble. " Founders' hoards " 

 of the bronze age are scattered over Western Europe, and indicate that smelting was done 

 in shallow pits with charcoal. With the Egyptians we find occasional inscriptions showing 

 small furnaces with forced draught, in early cases with a blow-pipe, but later — about 1500 

 B.C. — with bellows also. The crucible was apparently used by the Egyptians in secondary 

 melting, such remains at Mt. Sinai probably dating before 2000 B.C. With the advent of the 

 Prophets, and the first Greek literature — gth to 7th century B.C.— we find frequent references 

 to bellows. The remains of smelting appliances at Mt. Laurion (500-300 B.C.) do not indicate 

 much advance over the primitive hearth ; however, at this locality we do find evidence of 

 the ability to separate minerals by specific gravity, by washing crushed ore over inclined 

 surfaces with a sort of huddle attachment. Stone grinding-mills were used to crush ore from 

 the earhest times of Mt. Laurion down to the Middle Ages. About the beginning of the 

 Christian era the writings of Diodorus, Strabo, Dioscorides, and Phny indicate considerable 

 advance in appliances. Strabo describes high stacks to carry off lead fumes ; Dioscorides 

 explains a furnace with a dust-chamber to catch pompholyx (zinc oxide) ; Pliny refers to the 

 upper and lower crucibles (a forehearth) and to the pillars and arches of the furnaces. From 

 all of their descriptions we may conclude that the furnaces had then reached some size, and 

 were, of course, equipped with bellows. At this time sulphide copper and lead ores were 

 smelted ; but as to fluxes, except lead for silver, and lead and soda for gold, we have practically 

 no mention. Charcoal was the universal fuel for smelting down to the i8th century. Both 

 Dioscorides and Pliny describe a distillation apparatus used to recover quicksilver. A formid- 

 able list of mineral products and metal alloys in use, indicate in themselves considerable 

 apparatus, of the details of which we have no indication ; in the main these products were 

 lead sulphide, sulphate, and oxide (red-lead and litharge) ; zinc oxide ; iron sulphide, oxide 

 and sulphate ; arsenic and antimony sulphides ; mercury sulphide, sulphur, bitumen, soda, 

 alum and potash, ; and of the alloys, bronze, brass, pewter, electrum and steel. 



From this period to the period of the awakening of learning our only light is an 

 occasional gleam from Theophilus and the Alchemists. The former gave a more detailed 

 description of metallurgical appliances than had been done before, but there is little vital 

 change apparent from the apparatus of Roman times. The Alchemists gave a great stimulus 

 to industrial chemistry in the discovery of the mineral acids, and described distillation apparatus 

 of approximately modern form. 



The next period — the Renaissance — is one in which our descriptions are for the first 

 time satisfactory, and a discussion would be but a review of De Re Metallica. 



