Molecular Surface-Energy 

 // in Erg pro cm^. 



283 



-^O'-ZO" 



20° 40° 60 



Temp. 



100° 120° 140° 160° '60° 200° 220° 

 Fig. 5. 



^ 3. Tlie results reviewed in Tables 1 — 19 and graphically repro- 

 duced in Fig. 1 — 5, give rise to the following general remarks. 



In general the shape of the (i-/-curves, as determined by the values 

 of the temperatiire-coefiicients of it. appears to be quite analogous 

 in the case of derivatives of similar constitution : it is so in tlie 

 case of all halogen-derivatives of the hydrocarbons (Fig. 1), in the 

 case of the alcohols and water (Fig. 2), and in that of the neutral 

 elliers of two-basic acids (Fig. 5). 



In the case of ethylene-, and of ellnjUdene-chlorkle (Fig. 1), the 

 ditferent situation of the two ciilorine-atoms in their molecules, 

 ajipears in these cases to cause an appreciable diflerence of the \'alues 

 of [i at corresponding temperatures : thus such isomerides evidently 

 do not possess the same surface-energy, as has been occasionally 

 susjjected by previous authors (Feustei.). With the increase of the 

 atomic weight of the halogen (cf. ncetylenc-letrahroinide and -tetra- 



