BOOK IX. 413 



down some of the powdered charcoal into it from the wall, so that the slags 

 may be separated from the hot metal, and so that it may be covered, lest 

 any part of it, being very hot, should fly away with the fumes. If after 

 the slag has been skimmed off, the powder does not cover up the whole of the 

 tin, the smelter draws a little more charcoal off the wall with a scraper. After 

 he has opened the tap-hole of the forehearth with a tapping-bar, in order 

 that the tin can flow into the tapping-pot, likewise smeared with lute, he 

 again closes the tap-hole with pure lute or lute mixed with powdered charcoal. 

 The smelter, if he be diligent and experienced, has brooms at hand with which 

 he sweeps down the walls above the furnace ; to these walls and to the 

 dust chamber minute tin-stones sometimes adhere with part of the fumes. 

 If he be not sufficiently experienced in these matters and has melted at the 

 same time all of the tin-stone, — which is commonly of three sizes, large, 

 medium, and very small, — not a little waste of the proprietor's tin results ; 

 because, before the large or the medium sizes have melted, the small have either 

 been burnt up in the furnace, or else, flying up from it, they not only adhere to 

 the walls but also fall in the dust chamber. The owner of the works has 

 the sweepings by right from the owner of the ore. For the above reasons 

 the most experienced smelter melts them down separately ; indeed, he 

 melts the very small size in a wider furnace, the medium in a medium-sized 

 furnace, and the largest size in the narrowest furnace. When he melts down 

 the small size he uses a gentle blast from the bellows, with the medium-sized 

 a moderate one, with the large size a violent blast ; and when he smelts 

 the first size he needs a slow fire, for the second a medium one, and for the 

 third a fierce one ; yet he uses a much less fierce fire than when he smelts 

 the ores of gold, silver, or copper. When the workmen have spent three 

 consecutive days and nights in this work, as is usual, they have finished 

 their labours ; in this time they are able to melt out a large weight of smaU 



" the dried beds of torrents. The miners wash these sands, and that which settles they heat 

 " in the furnace. It is also found in gold mines, which are called altttiae. A stream of water 

 " passing through detaches small black pebbles variegated with white spots, the weight of 

 " which is the same as gold. Hence it is that they remain in the baskets of the gold collectors 

 " with the gold ; afterward, they are separated in a camillum and when melted become white 

 " lead." 



There is practically no reference to the methods of Cornish tin-working over the whole 

 period of 2,000 years that mining operations were carried on there prior to the Norman 

 occupation. From then until Agricola's time, a period of some four centuries, there are 

 occasional references in Stannary Court proceedings. Charters, and such-like official documents 

 which give little metallurgical insight. From a letter of William de Wrotham, Lord Warden 

 of the Stannaries, in 1198, setting out the regulations for the impost on tin, it is evident that 

 the black tin was smelted once at the mines and that a second smelting or refining was carried 

 out in specified towns under the observation of the Crown Officials. In many other official 

 documents there are repeated references to the right to dig turfs and cut wood for smelting 

 the tin. Under note 8, p. 282, we give some further information on tin concentration, and 

 the relation of Cornish and German tin miners. Biringuccio (1540) gives very little informa- 

 tion on tin metallurgy, and we are brought to De Re Metallica for the first clear exposition. 



As to the description on these pages it must be remembered that the tin-stone has been 

 already roasted, thus removing some volatile impurities and oxidizing others, as described 

 on page 348. The furnaces and the methods of working the tin, here described, are almost 

 identical with those in use in Saxony to-day. In general, since Agricola's time tin has not seen 

 the mechanical and metallurgical development of the other metals. The comparatively 

 small quantities to be dealt with ; the necessity of maintaining a strong reducing atmosphere, 

 and consequently a mild cold blast ; and the comparatively low temperature demanded, 

 gave little impetus to other than crude appliances until very modern times. 



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