---------------+----------------+-----------------+----------------- Per cent. of | Per cent. of | Freezing point. | Melting point. _d_-carvoxime. | _l_-carvoxime. | | ---------------+----------------+-----------------+----------------- 100 | 0 | 72.0° | 72.0° 99 | 1 | 72.4° | -- 98 | 2 | 73.0° | -- 95 | 5 | 75.4° | 73.0° 90 | 10 | 79.0° | 75.0° 80 | 20 | 84.6° | 80.0° 70 | 30 | 88.2° | 85.0° 60 | 40 | 90.4° | -- 50 | 50 | 91.4° | 91.4° 25 | 75 | 86.4° | 82.0° 8 | 92 | 77.4° | -- 1 | 99 | 72.4° | -- 0 | 100 | 72.0° | 72.0° ---------------+----------------+-----------------+----------------- {187} In this figure, the melting-point curve, _i.e._ the temperature-concentration curve for the mixed crystals, is represented by the lower curve. Since the addition of the lævo-form to the dextro-form raises the melting point of the latter, the concentration of the lævo-form (on the right-hand branch of the curve) must, in accordance with the rule given, be greater in the solid phase than in the liquid. Similarly, since addition of the dextro-form raises the melting point of the lævo-form, the solid phase (on the left-hand branch of the curve) must be richer in dextro- than in lævo-carvoxime. At the maximum point, the melting-point and freezing-point curves touch; at this point, therefore, the composition of the solid and liquid phases must be identical. It is evident, therefore, that at the maximum point the liquid will solidify, or the solid will liquefy completely without change of temperature; and, accordingly, mixed crystals of the composition represented by the maximum point will exhibit a definite melting point, and will in this respect behave like a simple substance. (_c_) _The freezing-point curve passes through a minimum_ (Curve III., Fig. 49).