Freezing point: line, 49 with respect

The liquid mixture remains readily in surfusion with respect to the mixed crystals of the second knd it may then furnish mixed crystals of the first kind the corresponding freezing-points are located on the line Py, extension of the line PE. 

The curve C, formed necessarily by two branches both S3mi-metrical with respect to the line X, has, for the abscissa a point of maximum ordinate. From the first theorem of Gibbs and Konovalow (Art. I94 which may be applied to the double mixture formed by the mixed crystals and the mixed liquid, this point belongs also o the line c, for which it is also a point of maximum or minimum ordinate. At this indifferent point I the mixed hquid, which is inactive by compensation, must give, on freezing, mixed holoedral crystals of composition x=i. 

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