In this case, as in the case of those systems where the pure components are deposited, a minimum freezing point is obtained. In the latter case, however, there are two freezing-point curves which intersect at a eutectic point; in the case where mixed crystals are formed there is only one continuous curve. On one side of the minimum point the liquid phase contains relatively more, on the other side relatively less, of the one component than does the solid phase; while at the minimum point the composition of the two phases is the same. At this point, therefore, complete solidification or complete liquefaction will occur without change of temperature, and the mixed crystals will accordingly exhibit a definite melting point. [Illustration: FIG. 52.] {188} Example.--As an example of this there may be taken the mixed crystals of mercuric bromide and iodide.[273] Mercuric bromide melts at 236.5°, and mercuric iodide at 255.4°. The mixed crystal of definite constant melting point (minimum point) contains 59 mols. per cent. of mercuric bromide, the melting point being 216.1°. The numerical data are contained in the following table, and represented graphically in Fig. 52:-- ----------------------------------------------------- Mols. per cent. of | | HgBr_{2}. | Freezing point. | Melting point. ----------------------------------------------------- 100 | 236.5° | 236° 90 | 228.8° | 226° 80 | 222.2° | 219° 70 | 217.8° | 217° 65 | 216.6° | 216° 60 | 216.1° | 215.5° 55 | 216.3° | 216° 50 | 217.3° | 216° 40 | 221.1° | 218° 30 | 227.8° | 223° 20 | 236.2° | 231° 10 | 245.5° | 242° 0 | 255.4° | 254° ----------------------------------------------------- [Illustration: FIG. 53.]