OF ARTS AND SCIENCES. 



315 



for the solid and the liquid state, respectively, are more nearly ripe 

 for discussion. 



This, in brief, is my method. What it thus far has yielded I will 

 now indicate. 



5. Tliermal Expansion. — In virtue of the occurrence of volume 

 lag,* or hysteresis, substances of the kind needed in § 4 are forth- 

 coming. I infer, therefore, that as regards isopiestic thermal expan- 

 sion the liquid and the solid, as well as the gas, obey certain ideal 

 laws, which may be conceived to hold good even though temperature 

 be decreased below condensation or solidifying points, indefinitely. 



I have worked with the beautifully crystalline solid thymol, which 

 melts slightly below 50° C, and when freshly distilled can be cooled 

 even below 0° C. 



TABLE I. — Expansion of Thymol, v =: 



vo 



1-kd 



* Am. Journal, Vol. XLII. p. 125 et seq., 1891. Cf. Vol. XXXVIIL p. 408, 

 1889 ; Vol. XXXIX. pp. 490-494, 1890. 



t Evaporation in the first set not allowed for ; hence the high Vq — .96369. 



} The lump unavoidably contains vacuities and fissures within. Powdered 

 thymol cannot be put under mercury, free from air. 



