Text-book of medical and pharmaceutical chemistry . of sodiumhydroxide, having care to keep the mixture cool by immersion incold water. 2NaOH 4- Br, = NaOBr -f NaBr + 159. Iodine and Oxygen.—There are three or four unim-portant and unstable oxides of iodine known. , I2O5, andpossibly I2O7. Two oxygen acids are known, iodic, HIO3, andperiodic, HIO4. The first is obtained by treating iodine withnit-ric acid, and the second by passing chlorine through an alka-line solution of sodium iodate. The first, when pure, appears as a white crystalline solid, andthe second as colorless crystals.
Text-book of medical and pharmaceutical chemistry . of sodiumhydroxide, having care to keep the mixture cool by immersion incold water. 2NaOH 4- Br, = NaOBr -f NaBr + 159. Iodine and Oxygen.—There are three or four unim-portant and unstable oxides of iodine known. , I2O5, andpossibly I2O7. Two oxygen acids are known, iodic, HIO3, andperiodic, HIO4. The first is obtained by treating iodine withnit-ric acid, and the second by passing chlorine through an alka-line solution of sodium iodate. The first, when pure, appears as a white crystalline solid, andthe second as colorless crystals. Both are very soluble in water,are easily decomposed, and form corresponding salts. SULPHUR. 149 SULPHUR. S = 32. Sp. gr., 2. Density of vapor, 32. Melts at 115° C. (239° F.) Den-sity of vapor at 500° C. (932° F.) = = Sg. At 1000° C.(1832° F.)= = 8.,. 160. Occurrence.—Sulphur was known to the ancients. Itoccurs in volcanic regions, and is brought mostly from Sicily andIceland. The sulphur occurs native, mixed with clay, from. KEFIMNG OF SULPHUK. which it is separated by distillation. This element also occursas sulphates in the minerals, gypsum, CaSO^.aAq, Barite, BaS04,and as sulphides of iron, copper, nickel, and in fact, with manyof the metals; also as a precipitate from sulphur waters. Thefollowing reaction explains its deposition from such waters: 2H,S + O, = 2H,0 + S,. 161. Preparation.—It is prepared from the native sulphurmixed with more or less earth, found in volcanic regions 150 MEDICAL CHEMISTRY. of Sicily, by distilling it from the non-volatile impurities. Asecond distillation is necessary to prepare the refined sulphur ofthe market. The second distillation is conducted in a retort,the vapor being carried into a large chamber (Fig. 48), where,if the process is conducted slowly, it collects in the form of acrystalline powder called flowers of sulphur, or sulphursublimatum U. S. P. If the process is conducted morerapidly the chamber becomes hot
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