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certain substances were never discovered till the alche-mical eye had been accustomed to survey its fires, for years,with the scrutinizing glance of inquisitorial curiosity, expect-ing,—anxiously expecting, to discover that substance realized,which would repay his never-ceasing solicitude, and im-mortalize his name. He consequently watched every changeof colour; every minute circumstance he caught with thevision of an eagle. He, however, missed his ultimateobject, but, unwittingly, conferred benefits, by his labours,upon real science, which the world will ever have to ac-knowledge with unfeigned gratitude. The same compli-ment is also due to what is now viewed in European climesas another chimerical science,—judicial astrology, oncethe general pursuit of Europe as well as Asia, where it isstill in its glory, gave being to the noblest discoveries in thecelestial science of astronomy.
The name cobalt is given at the present moment to allsuch minerals as contain a semi-metal, the calx or matrixof which can be melted into blue glass, or which is foundto communicate a blue tint to common glass; and is con-sequently conducive to the purest crystal, provided it hasnot too much colour ; there being a certain slight degree ofblue in the most perfect white colour, or rather, in thepurest colourless bodies which can be discovered. Themetal itself, if metal it can be called, correctly speaking,rather the mineral itself, is fit for no particular purpose,the calx being only useful. It is first roasted and freedfrom all foreign impurities; then it is well calcined, andsold as an article of commerce, mixed or unmixed withfine white sand, under the name of zaffer (zajfera;) or itis melted with siliceous earth and potash to a certainspecies of blue glass, called smalt, which, when groundvery fine,—to an impalpable powder, is known to the com-mercial world as powder-blue. These several articles be-coming most valuable pigments; because they best with-stand fire without any injury ; also, because they aresusceptible of any degree of tint, and of every shade ofcolour, for preparation of various imitations of precious, or ascalled, artificial stones, for tinging crystal, for enamelling, forpainting porcelain and common earthenware, with potterygoods of every description; likewise, from its indispensa-ble and essential use in painting,—the polite arts are muchbenefited,—also in varnishing; but to the painter, in par-ticular, its utility is beyond every comparison, becausethere are certain natural objects which he could not imitatewithout having its assistance; such, for iustance, as those
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