The London, Edinburgh and Dublin philosophical magazine and journal of science . and Attached Water. Ill Infinite Solubility. § 249. An examination of curves of solubility of salts inwater, drawn so that the ordinates are temperatures and theabscissae are percentages, reveals two types of curves, whichdiffer only essentially in their right-hand or salt-saturatedbranches. Iodide and bromide and, perhaps, chloride ofsodium may be taken as the type of a, fig. 3, and nitre of bffig. 3 (see § 126). The curvature of the right-hand branchesof both curves must diminish as we travel from the cryohy-dra
The London, Edinburgh and Dublin philosophical magazine and journal of science . and Attached Water. Ill Infinite Solubility. § 249. An examination of curves of solubility of salts inwater, drawn so that the ordinates are temperatures and theabscissae are percentages, reveals two types of curves, whichdiffer only essentially in their right-hand or salt-saturatedbranches. Iodide and bromide and, perhaps, chloride ofsodium may be taken as the type of a, fig. 3, and nitre of bffig. 3 (see § 126). The curvature of the right-hand branchesof both curves must diminish as we travel from the cryohy-drate in the direction of the arrows, otherwise there would betwo temperatures at which there is the same solubility (a, , dotted lines) for every solubility between certain limits ;or (b, fig. 3, dotted lines) there would be two solubilities forevery temperature between certain limits. If we concede the Fig. impossibility of these conditions, there appear to be three alter-natives—the curve loses curvature either parabolically orhyperbolically, or there must be contrariflexure. The firstwould carry the conditions into the region of critical state anddecomposition. The second might mean, in the case of atype, if such asymptote be also parallel to the ordinates, thata certain per cent, ratio of salt is soluble in water at a certaintemperature, and at all higher temperatures; in the case of btype, if such asymptote be parallel to the abscissae, that ata certain temperature a finite mass of water will dissolve aninfinite mass of salt. 112 Frederick Guthrie on Salt-Solutions For the experimental examination of this curious questionthe salt-alloy of nitrate of lead and nitrate of potash, describedin § 215, is excellently well adapted. Its composition is46-86 nitrate of lead +53*14 nitrate of potash, and its fusing-point, being 207°, is well within the range of the mercurialthermometer. Its
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