The commonest type of this pottery is a red polished ware vase with black top, due to its having been baked mouth downward in a fire, the ashes of which, according to Prof. Petrie, deoxidized the hæmatite burnishing, and so turned the red colour to black. “In good examples the hæmatite has not only been reduced to black magnetic oxide, but the black has the highest polish, as seen on fine Greek vases. This is probably due to the formation of carbonyl gas in the smothered fire. This gas acts as a solvent of magnetic oxide, and hence allows it to assume a new surface, like the glassy surface of some marbles subjected to solution in water.” This black and red ware appears to be the most ancient prehistoric Egyptian pottery known. Later in date are a red ware and a black ware with rude geometrical incised designs, imitating basketwork, and with the incised lines filled in with white. Later again is a buff ware, either plain or decorated with wavy lines, concentric circles, and elaborate drawings of boats sailing on the Nile, ostriches, fish, men and women, and so on. [Illustration: 017.jpg (right) BUFF WARE VASE, Predynastic period, before 4000 B.C.] These designs are in deep red. With this elaborate pottery the Neolithic ceramic art of Egypt reached its highest point; in the succeeding period (the beginning of the historic age) there was a decline in workmanship, exhibiting clumsy forms and bad colour, and it is not until the time of the IVth Dynasty that good pottery (a fine polished red) is once more found. Meanwhile the invention of glazed pottery, which was unknown to the prehistoric Egyptians, had been made (before the beginning of the Ist Dynasty). The unglazed ware of the first three dynasties was bad, but the new invention of light blue glazed faience (not porcelain properly so called) seems to have made great progress, and we possess fine specimens at the beginning of the Ist Dynasty. The prehistoric Egyptians were also proficient in other arts. They carved ivory and they worked gold, which is known to have been almost the first metal worked by man; certainly in Egypt it was utilized for ornament even before copper was used for work. We may refer to the illustration of a flint knife with gold handle, already given.[2] [2] See illustration.