THE 



AMERICAN JOURNAL OF SCIENCE 



[THIRD SERIES.] 



Aet. I. — The Change of Heat Conductivity* on Passing 

 Isothermally from Solid to Liquid ; by C. Baeus. 



1. Preliminary. — To fully investigate a problem like the 

 present, the application of pressures is obviously necessary. 

 In my workf on the continuity of solid and liquid I showed, 

 however, that hysteresis rarely if ever fails to accompany 

 change of state. Since therefore undercooling is not avoided, 

 even when pressure changes the state of a body from solid to 

 liquid at the same temperature, it seemed permissible to facili- 

 tate the experiments by selecting an undercooled liquid at the 

 outset. In other words, thymol — and with this substance the 

 following measurements were made — which can be kept either 

 liquid or solid between 0° and 50° C, merely exhibits under 

 atmospheric pressures and temperatures the same volume lag, 

 that in more or less pronounced degree is common to most if 

 not all crystalline bodies, at pressures and temperatures as a 

 rule enormously higher. Apart from this it seems idle to 

 ascribe to the molten liquid a more intimate relation to the 

 solid than that possessed by the undercooled liquid, without 

 distinctly specifying just what the relation is ; and this at the 

 present state of our knowledge of the solid and liquid mole- 

 cule, is impossible. Yague notions about polymerism are little 

 to the point. Without evidence to the contrary, I am at 

 liberty to suppose that the liquid as well as the solid obey cer- 

 tain ideal physical laws ; and these I may conceive to be pro- 



* This investigation was suggested by Mr. Clarence KiDg. 

 fThis Journal, xlii, p. 125, 1891 ; cf. p. 140. 



Am. Jour. Sci— Thibd Series, Vol. XL1V, No. 259.— July, 1892. 

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