Half of the third case, and cases 4, 5, and 6 in this room, are covered with various electro-negative metals and metalloids, classed according to the system laid down by Berzelius. In the third case are Tellurium and Tellurets. In the fourth are samples of native Arsenic, and its combinations with nickel and cobalt; Carbon in its various forms, pure as in the diamonds, which the visitor will notice attentively, some imbedded in the earth in which they were discovered, and models of celebrated diamonds; Black Lead in porcelain earth, for which Cumberland is celebrated; Selenium in its combinations with lead, mercury, sulphur, and other metals; and a medallion, in selenium, of Berzelius, who discovered this metal in 1818. The sixth case is covered with Sulphurets, chiefly of iron, these being commonly known as iron pyrites. These specimens of the commonest of metallic ores are from various parts of the world. Upon this table also are deposited Lord Greenock's sulphuret of cadmium, commonly called greenockite; and sulphurets of nickel. Having examined the first six cases of the series ranged along the southern side of the room, the visitor should turn to the six last cases of the series (55-60). The first northern case (55) is covered with various Sulphates, or metals in combination with sulphuric acid, exhibiting beautiful crystals and colours, including sulphate of magnesia from Oregon; sulphate of zinc, or white vitriol; sulphate of iron, or green vitriol; and the splendid blue sulphates of copper from Hungary; beautiful sulphates of lead from Anglesea; sulphates of alumina; common alum; and the splendid specimens of lazurite, or lapis-lazuli,-- "Blue as the veins o'er the Madonna's breast," from which the beautiful pigment called ultramarine is extracted. In 1828 M. Guimet succeeded in making an artificial ultramarine, known now extensively as French ultramarine, which is little, if at all, inferior in beauty to lazurite. The next case (56) contains the Arseniates, including arseniate of lime, crystallised; arseniates of copper; arseniate of nickel; and red cobalt, or arseniate of cobalt. The next case is devoted to the Phosphates, or metals mixed with phosphoric acid, including crystals of the phosphate of iron from Fernando Po, Bavaria, and Cornwall; phosphates of manganese; phosphate of copper; yellow and green uranite; phosphates of alumina, including the blue spar, which has been mistaken for lapis-lazuli, and the phosphate of alumina known as turquois, found only in Persia, and esteemed as an ornament. In the two supplemental table cases, 57 A and B, the visitor may notice specimens of Pyromorphite, a combination of phosphate and chloride of lead, and a combination of chloride of calcium with phosphate of lime. These combinations, however, cannot interest the general visitor.