219

COBALT, SMALT, AND ZAFFER.

to the mode of those in Holland . Even at present, it issaid, many of the Dutch grind German cobalt with muchadvantage.

It should seem that Agricola was not acquainted with blueglass; hut it is, perhaps, strange that neither he or Malhe-sius, mention zaffera. Albin, who derived his chief intelli-gence from these two authors, is also silent on this subject;but observes of bismuth, when put in vessels it grew toge-ther again. It should seem, however, he alludes to roastedcobalt when mixed with sand, as it assumes a compact ap-pearance. For bismuth, when it is purified by roasting,can never attain that state. Vannuccio Biringoccio, whoflourished in 1725, describes zaffera as a material used forpainting glass; he calls it a heavy mineral without any fur-ther definition. Cardan gives the name zaffera to an earthwhich colours glass blue. Julius Scaliger , in his Exercita-tions on Cardan, mentions nothing of moment concerning it.Porta, who employed great diligence to obtain this speciesof knowledge, often mentions zaphara figlinorum, withoutsaying what it is; but he describes it as being useful ingiving the tint to artificial stones, after being reduced toline powder, sifted, washed, &c.

It appears, the first writer who properly described cobalt,and furnished a correct idea of its preparation, according toBeckmaun’s opinion, was Kunkel, in his Glasmaclierkunst,Nuremberg , 1743, being annotations on what Neri andMerret had said before him; he describes zaffer thus; say-ing the miners call it zafloer, and that sand was mixed onlyfor the purpose that the powder-blue used by women, forlinon, and smalt used by painters, might not be spuriouslyimitated in other countries. Rossler also says, the Bohemiancobalt is not so good as that of Misnia , its colour beingmore like ashes. Also Brandt, a member of the Councilof Mines in Sweden , first asserted that cobalt containeda semi-metal of a peculiar description. About the endof the fifteenth century, cohalt was first discovered by theminers on the confines of Saxony and Bohemia . But ithad been found in Spain previous to that period, as we haveseen. But in Germany , it is said to have obtained its namefrom Cobalus, the name of the evil genii of mines, for thereason before given: it was, besides, prejudicial to theirhealth, from the particles of arsenic contained therein. Itis observed, that so much were the clergy slaves to thepopular superstition of the times, that they offered up aform of prayer for the protection of the miners againstkobolts, spirits, &c.