Journal . n of sulphurousacid. The iodine is not, however, liberated, but in pre-sence of the water at once oxidises a further portion ofsulphurous acid to sulphuric acid. The final result ofthe reaction is therefore a conversion of the sulphurousacid into sulphur and sulphuric acid:—3St i 2HsO 4HI=2SO«H S+4HL The ratio of sulphur, as sulphuricacid, to free sulphur was proved quantitatively. Wehere have a very neat example of so-called catalyticaction. Now when iodine and sulphurous acid solutionare mixed, hydriodic acid is formed, and this may causea further reduction of a further portion of
Journal . n of sulphurousacid. The iodine is not, however, liberated, but in pre-sence of the water at once oxidises a further portion ofsulphurous acid to sulphuric acid. The final result ofthe reaction is therefore a conversion of the sulphurousacid into sulphur and sulphuric acid:—3St i 2HsO 4HI=2SO«H S+4HL The ratio of sulphur, as sulphuricacid, to free sulphur was proved quantitatively. Wehere have a very neat example of so-called catalyticaction. Now when iodine and sulphurous acid solutionare mixed, hydriodic acid is formed, and this may causea further reduction of a further portion of the sulphurousacid. This is of course more liable to occur, even whendilute solutions are used, when the iodine solution is runinto the sulphurous acid solution than when the reversetakes place. It is interesting to note here that the pro-longed action of alkaline sulphites exerts a similar actionon sulphurous acid ; sulphur and sulphuric acid beingformed, hydro-sulphurous acid being formed as an inter-. together with the drying tubes, connections, etc., beingweighed before and after the determination. The authorsfind as a mean of 1G results 0398 per cent, of CO„, thequantities varying from 0219 per cent, to 0629 per authorities give an average of 01 to 02 per cent, ofCO, in beer. —C. A. K. On Sulphurous Arid and Iodomeiry. J. , 242, 93—113. BTJNSBS explains the well-known tact, that in his iodo-metric method the sulphurous acid is not completelyoxidised to sulphuric acid unless the sulphurous acid solu-tion is very dilute—(, 003—004 per cent, sulphurdioxide), by the supposition that in a more concentratedsolution the sulphuric acid first formed is again reduced bythe hydriodic acid. Now- this explanation, though it hasnever been experimentally proved, has been universallyaccepted and is often cited as an instance of a reversablereaction. The author has carried out numerous experi-ments on the subject, with the following results:—(1.)
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