348 PROCEEDINGS OF THE AMERICAN ACADEMY. 



manufactured, to reach 30,000 and even 40,000 atmos on the first ap- 

 pHcation of pressure. On subsequent applications rupture may come 

 at half the first maximum. This subsequent early rupture is due to the 

 fact that these pressures are greatly in excess of the theoretical limit 

 of the steel, so that there is a distortion of thennner parts far beyond 

 the elastic limit and consequent rapid fatigjie. The pressures reached 

 in this paper are not the greatest attainable because of the questionable 

 scientific economy of pushing pressures to a value where rupture may 

 occur at any moment and destroy valuable apparatus and time. 



The previous work in this field is wholly below 5000 kgm. The two 

 principal investigators are Amagat,i who studied the compressibility 

 and the thermal dilatation of a number of liquids up to 3000 atmos, 

 without, however, touching on the change of state liquid-solid; and 

 Tammann,2 who studied the change of state liquid-solid, without 

 determining the behavior of the liquid, over a range of pressure of usu- 

 ally about 3000 kgm., but reaching a few times to 4000 and once to 

 4800. There are no liquids common to the work of both Amagat and 

 Tammann, so that the complete data are not known for even a single 

 liquid. 



The previous work done on mercury is almost negligible for the 

 present purpose. Accurate compressibility determinations run only to 

 500 kgm. (the highest are by Kichards ^), and the effect of pressure 

 on freezing point has been observed only by Tammann, * who found 

 results up to 2000 kgm. that are inconsistent among themselves by 

 30 per cent. 



The data of this paper cover a range of 12,000 kgm., and give both 

 the changes of volume of the liquid with temperature and pressure, and 

 the thermodynamic data required on the freezing curve. The temper- 

 ature range corresponding to this wide pressure range is comparatively 

 small, since at 12,000 kgm. the freezing temperature has been raised to 

 only 20°, that is, through a range of 60°. 



In addition to the data connected more intimately with pressure, 

 several quantities relating to solid mercury at atmospheric pressure 

 have incidentally been determined. It has been a surprise to find how 

 untrustworthy the commonly accepted data for solid mercury are. 

 Thus the only determination of the latent heat of melting dates back 

 to 1838, before the value of the melting temperature itself was known 

 more accurately than within 3°. 



1 Amagat, Ann. de Chim. et Phys. (6), 29, 6S-136, 505-574 (1893). 

 ' Tammann, Kristallisieren and Sohmelzen (Barth, Leipzig, 1903). 

 3 Richards, Pub. Carnegie Inst. Wash., No. 7 (1903), and No. 76 (1907). 

 * Tammann, loc. cit., p. 248. 



