Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. SULPHUR, SELENIUM, TELLURIUM, AND THEIR COMPOUNDS WITH OXYGEN AND HYDROGEN. I. Sulphur, . . S = 16. Specific gravity of vapour at 814,. . . . 6.617 Specific gravity of vapour at 1800, . . . 2.219 Atomic volume at 824, J Atomic volume at 1800, i Native sulphur is a substance widely distributed in nature, occurring chiefly in volcanic districts, and in the strata with which gypsum is associated. It is also abundant as a constituent of various sulphates, such as the sulphates of calcium, barium, and strontium, and of numerous native sulphides, in which it occurs combined with iron, copper, lead, antimony, silver, and other metals. It is a component also of certain essential oils, of the pro- teinic compounds of animal and vegetable bodies, of taurine, a principle existing in bile, and of cystic oxide, a rare variety of urinary calculus. In the valleys of Noto and Mazzaro, in Sicily, it is found in great quantity, intermixed with clays containing gypsum, and it is from this locality that the greater part of the sulphur found in commerce is still derived. From the metallic sulphides, particularly iron pyrites, FeS,, it admits of being extracted; but thus obtained, it is of inferior value, in consequence of containing arsenic, an impurity neverfound in the Sicilian sulphur. The bisulphide is heated in conical clay tubes, set with a slope towards the smaller ends, which project some distance from the furnace, and arc furnished with eduction gutters which allow the liberated sulphur to flow off" in the melted state into water. The pyrites in 100 parts includes 53.33 of sulphur, and of this one- fourth is expelled, which corresponds to half an atom of sulphur. By raising the heat the product might be doubled; but the residual sulphide, FeS, would melt, and...