I shall further remark, on this subject, that the _abstrich_, as it is called, which in many respects has a resemblance to _stannum_, and contains also lead and silver, but at the same time metals difficult of fusion, is employed in the arts, and collected for the use of the letter-founders[518]. For this purpose it is well-adapted, on account of its hardness and durability; and in want of it lead must be mixed with regulus of antimony. At the Lower Harze the workmen began so early as 1688 to revive this _abstrich_ in particular; and as the lead thence obtained, on account of its hardness, could not be disposed of like common lead, it was sold to the letter-founders at Brunswick, at first at the rate of a hundred weight for two and a half dollars, and in the year 1689 for three dollars. But in Schlüter’s time a small quantity of it only was made annually, because the _abstrich_ could be used with more advantage for other purposes. This lead, says Schlüter, had the appearance of bronze, and was so brittle, that a piece of it broke into fragments when struck[519]. _Speise_ also, which is obtained at the blue colour-works, can be employed in the same manner. Under this term is understood a metallic mixture deposited during the preparation of blue glass, and which is composed of various metals combined with cobalt, but particularly nickel, iron, copper, arsenic, and perhaps also bismuth. It is hard, brittle, sonorous, and assumes a good polish, though it is not always of the same quality in all manufactories. As it contains some colouring particles, it is in general again added to the glass residuum. But when I lately paid a visit to the colour-mill at Carlshafen, M. Birnstein the inspector told me, that the _speise_ was manufactured at Halle into buttons of every kind. This probably is the case there in those button-manufactories established by G. H. Schier, in which buttons of all patterns are made annually to the value of 30,000 dollars[520]. The ancients, in my opinion, employed in a similar manner the _werk_ of their silver smelting-houses. I shall now proceed to examine that metal which the Greeks named κασσίτερος, or, as Pliny says, _Cassiteron_, and which he expressly adds was called by the Latins _plumbum candidum_ (white lead). I have no new hypothesis to recommend; my sole object is truth. I wish for certainty, and, when that is not to be obtained, probability; at the same time, however, I cannot rest satisfied with the judgement given by the compilers of dictionaries, and the translators and commentators of ancient authors, because I firmly believe that they never made any researches themselves on the subject.