The phase rule and its applications . temperature of the melting point, thestability limits would be the points G and H, Fig. Cameron, Journ. Physical CAem., 1898, 2. 409. EG l If. TBRIl rM BETWEEN D YNA MIC ISOME RIDE Grams of the a modificationin ioo gm. of mixture. Freezing point. 26-2 49-2 737917 95o96*0 IOI°79°46°26-2° 28-6° 30-0° The eutectic point C was found to lie at 25-26°, and thenatural freezing point D wasfound to be 27*7°. The equi-librium curve DE was deter-mined by heating the liquidmixtures at different tempera-tures until equilibrium wasattained, and then rapidly cool-in
The phase rule and its applications . temperature of the melting point, thestability limits would be the points G and H, Fig. Cameron, Journ. Physical CAem., 1898, 2. 409. EG l If. TBRIl rM BETWEEN D YNA MIC ISOME RIDE Grams of the a modificationin ioo gm. of mixture. Freezing point. 26-2 49-2 737917 95o96*0 IOI°79°46°26-2° 28-6° 30-0° The eutectic point C was found to lie at 25-26°, and thenatural freezing point D wasfound to be 27*7°. The equi-librium curve DE was deter-mined by heating the liquidmixtures at different tempera-tures until equilibrium wasattained, and then rapidly cool-ing the liquid. In all casesthe freezing point was practic-ally that of the point D. Fromthis it is seen that the equi-librium curve must be a straightline parallel to the temperatureaxis; and, therefore, isomerictransformation in the case ofthe two benzaldoximes is notaccompanied by any heat effect (p. 200). This behaviour has also been found in the case The isomeric benzaldoximes are also of interest from the. Fig. 61, fact that the stable modification has the lower meltim point (v. p. 205). Acetaldehyde and Paraldehyde.—As a second example ofthe equilibria between two isomerides, we shall take the twoisomeric (polymeric) forms of acetaldehyde, which have recentlybeen exhaustively 1 Carveth, Journ. Phys. C/iem., 1S98, 2. 159. See also Dutoit and Fath,Journ. chim. p/iys., 1903, 1. 358; Findlay, Trans. Chem. Soc, 1904, 85. 403. 2 Hollmann, Zeitschr. physikal. Chem., 1903, 43. 129. :o8 THE PHASE RULE In the case of these two substances the $()3takes place at the ordinary temperature with very great slow-ness. For this reason it is possible to determine the freezingpoint curves of acetaldehyde and paraldehyde. The threechief points on these curves, represented graphically in Fig. 62,are;— of acetaldehyde — n 8*45° of paraldehyde + 12*55° eutectic point — 119-9° In order to determine the position of the n
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