116 BRIDGMAN. 



of sensitiveness of the pressure measurements. We conclude, there- 

 fore, that the transition Hne rises to the triple point with no percepti- 

 ble change of direction, and that the curvature found by Tammann 

 must have been an effect of the impurity. 



Tammann determined the phase diagram with two specimens, one 

 somewhat purer than the other. In the following comparison of 

 his results with those found here only the data of his pure sample 

 will be used. His L-I curve is 0.3° lower than mine at atmospheric 

 pressure, and 1.2° lower at 2000. At 20° his I-II line is 50 kgm. 

 higher than mine, and 4 kgm. lower at 60°; this is an effect of the 

 curA'ature found by Tammann. Above the triple point, his L-II 

 curve runs lower than mine and with a smaller slope; at 2600 it is 

 about 3° lower. He finds as the coordinates of the triple point 2196, 

 kgm. and 62.8° against 2085 and 64.0° of mine. The discrepancies 

 are at least in part due to impurity. Tammann's value for AT at 

 atmospheric pressure, 0.0163, is much lower than mine; he recognizes 

 that his value is too low, due to impurity. His value for AV, I-II, 

 is also very much lower than that found here, 0.0315 against 0.0568 at 

 40°. Curiously, however, his value for AT, L-I, at the triple point is 

 almost exactly that found here, 0.0273 against 0.0270. 



Besides Tammann's values at low pressures there are also a number 

 of other values for comparison. Hulett ^^ has measured the effect 

 of pressure on the melting point up to 300 kgm. He finds for the 

 melting point 40.75° against 40.87° above, and for the initial slope 

 0.0149° per kgm. against 0.0140 above. It should be remarked that 

 the value of Hulett for the melting point is sometimes misquoted as 

 41.11°, because of a misprint in the original paper by which the 

 melting point under 25 kgm. is given twice, once as that at atmospheric 

 pressure. Other values for the melting point are 40 to 41° by Calvert, 

 quoted by Schiff,^^ and 42.5° to 43° by Behal and Choay ^^ for a 

 specimen of phenol s>Tithesized by a new method. For the change 

 of volume we have 0.054 to 0.051 by Heydweiller ^8 and 0.0532 by 

 Block ^^ against 0.0567 above. For the latent heat, there is 24.93 

 cal. by Pettersson and Widman,^° and 26.9 cal. by Eykmann,^^ 

 against 29.7 above. 



25 G. A. Hulett, ZS. phys. Chem. 28, 629-762 (1899). 



26 R. Schiff, Lieb. Ann. 223, 247-268 (1SS4). 



27 A. Behal and E. Choay, Bull. Soc. Chim. Paris, (3) 11, 602-603 (1894). 



28 A. Heydweiller, Ann. Phys. 61, 527-540 (1897). 



29 H. Block, ZS. phys. Chem. 78, 384-426 (1912). 



30 O. Pettersson and O. Widnian, Forh. Stock. (3) 36, 75-79 (1879^. 



31 J. F. Eykman, ZS. phys. Chem. 4, 497-519 (1889). 



