350

BOOK VIII.

in order that, if there is in the cakes any alum or vitriol or saltpetre capableof injuring the metals, although it rarely does injure them, the water mayremove it and make the cakes soft. The solidified juices are nearly allharmful to the metal, when cakes or ore of this kind are smelted. The cakeswhich are to be roasted are placed on wood piled up in the form of a crate,and this pile is fired 22 .

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The cakes which are made of copper smelted from schist are first thrownupon the ground and broken, and then placed in the furnace on bundles offaggots, and these are lighted. These cakes are generally roasted seventimes and occasionally nine times. While this is being done, if they are

22 There can be no doubt that these are mattes, as will develop in Chapter ix. TheGerman term in the Glossary for fanes ex fyrite is stein, the same as the modern Germanfor matte. Orpiment and realgar are the yellow and red arsenical sulphides. The cadmiawas no doubt the cobalt-arsenic minerals (see note on p. 112). The “solidified juices” weregenerally anything that could be expelled short of smelting, i.e., roasted off or leached out,as shown in note 4, p. 1 ; they embrace the sulphates, salts, sulphur, bitumen, andarsenical sulphides, etc. For further information on leaching out the sulphates, alum, etc.,see note 10, p. 564.