. De re metallica. Metallurgy; Mineral industries. 348 BOOK VIII. they throw it into a copper sieve, and separate the very small pieces which pass through the sieve from the larger ones ; of these the former are smelted in a faggot pile and the latter in the furnace. Of such a number then are the methods of A—Trough. B—Launder. C—Hoe. D—Sieve. One method of burning is principally employed, and two of roasting. The black tin is burned by a hot fire in a furnace similar to an oven^^ ; it is burned if it is a dark-blue colour, or if pyrites and the stone from which iron is made are mixe
. De re metallica. Metallurgy; Mineral industries. 348 BOOK VIII. they throw it into a copper sieve, and separate the very small pieces which pass through the sieve from the larger ones ; of these the former are smelted in a faggot pile and the latter in the furnace. Of such a number then are the methods of A—Trough. B—Launder. C—Hoe. D—Sieve. One method of burning is principally employed, and two of roasting. The black tin is burned by a hot fire in a furnace similar to an oven^^ ; it is burned if it is a dark-blue colour, or if pyrites and the stone from which iron is made are mixed with it, for the dark blue colour if not burnt, consumes the tin. If pyrites and the other stone are not volatihsed into fumes in a furnace of this kind, the tin which is made from the tin-stone is impure. The tin-stone is thrown either into the back part of the furnace, or into one side of it ; but in the former case the wood is placed in front, in the latter case alongside, in such a manner, however, that neither firebrands nor coals may fall upon the tin-stone itself or touch it. The fuel is manipulated by a poker made of wood. The tin-stone is now stirred with a rake with two '^From a metallurgical point of view all of these operations are roasting. Even to-day, however, the expression " burning " tin is in use in some parts of Cornwall, and in former times it was Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Agricola, Georg, 1494-1555; Hoover, Herbert, 1874-1964. New York, Dover Publications
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