118 
DR. WALTER WAHL; PHYSICO-CHEMICAL DETERMINATIONS 
two small glass windows fitted to his high-pressure bomb (“ m^thode des regards ”),* * * § 
and he also twice made an attempt to use a similar arrangement for the determination 
of melting and crystallization at high pressures. His first paper on these subjects 
deals with the melting and with the formation of two different kinds of crystals of 
carbon tetrachloride.t The highest pressure employed was 1,160 atmospheres. The 
second paper, in which a somewhat different arrangement of the glass windows was 
used, deals with the crystallization of ice at temperatures below zero under the 
influence of high pressures.| In a summarizing paper Amagat§ states that he 
occasionally was able to reach pressures of about 1,600 atmospheres before the glass 
windows were broken, but oliservations were not actually made at higher pressures 
than 1,000 atmospheres. In this paper a sketch of the apparatus is also given. 
Amagat states that he met with severe difficulties during these investigations, and 
he has not pursued the subject further. 
Later melting-points and transition-points of some “ liquo-crystalline ” substances 
have been measured in Jena glass tubes up to 300 atmospheres by Hullett,|| and 
other optical observations at pressures above that of the atmosphere have been 
made by Rothmund (maximum 500 atmospheres), H Rontgen and Zehnder,** * * §§ 
SiERSTEMA,tt Liveing and Dewar,Hutton and Petavel,§§ and DurFiELD,|||l 
but in these investigations the pressures have, as a rule, not exceeded 100 
atmospheres. 
By a volumetric method melting-points were first determined at comparatively 
high pressures by Barus in 1891.111I. Barus, who undertook these measurements in 
connection with an extensive series of measurements of compressibilities,*** deter¬ 
mined the melting-point of naphthalene up to pressures of 1,435 atmospheres. In 
1898, Mack measured the melting-point of naphthalene at pressures between that of 
the atmosphere and 2,140 kg./cm.^, by observing the volume change as indicated by 
the manometer when melting occurred.ftt But our chief knowledge about equilibrium 
* E. H. Amagat, ‘ Journ. d. Chem. Phys.,’ 1893, 6 ser., XXIX., p. 68, 96, 505. 
t E. II. Amagat, ‘Compt. Rend.,’ CV. (1887), p. 165. 
+ E. H. Amagat, ‘Compt. Rend.,’ CXVII. (1893), p. 507. 
§ ‘Notice sur les Travaux Scientifiques de M. E. H. Amagat,’ Paris, 1896. 
II G. A. lIuLLETT, ‘Zeitschr. f. Phys. Chem.,’ 28, p. 622 (1899). 
^ V. Rothmund, ‘Zeitschr. f. Phys. Chem.,’ 20, p. 168 (1896). 
** Rontgen and Zehndeh, ‘Wiedemann’s Annal.,’ 44 (1891), p. 280. 
tt L. H. SlERSTEMA, ‘Communications from the Phys. Lah., University of Leyden,’ No. 35, No. 39, 
No. 49, and Suppl. 1. 
11 Liveing and Dewar, ‘Phil. Mag.,’ 26, p. 286 (1888); ‘Roy. Soc. Proc.,’ 46, p. 226 (1889). 
§§ Hutton and Petavel, ‘Phil. Mag.,’ p. 569 (1903). 
III! G. Dufeiei.d, ‘Phil. Trans.,’ A, vol. 208, p. Ill (1908). 
C. Barus, ‘ Amer. Journ. of Sc.,’ 3 ser., XLIL, p. 125 (1891); ‘Bull, of the United States Geological 
Survey,’ 96 (1892). 
*** C. Barus, ‘Bull, of the United States Geological Survey,’ Nos. 92 and 97, Washington, 1892. 
ttt E. Mack, ‘Compt. Rend.,’ 127, p. 361 (1898). 
