Robertson. — Latent Heats of Fusion. 501 



Thus it is noticed that the amount of association decreases 

 with rising molecular weight, which fact is of universal 

 occurrence for homologous bodies in the liquid state (Ramsay 

 and Shields ; Traube) as well as for substances in solution 

 (Biltz). 



In this case, however, it happens that the amount of 

 association is inversely as the square of the molecular 

 weight : — 



Per Cent. Amount of N f u ^ bers Proportional 



Association. t °^ v , er8e 1 ° f ^ u " e f 



of Molecular Weight. 



Acetic acid ... 54 52 



Propionic acid ... 38 36 



Butyric acid ... 25 26 



Further experiments are in progress with the object of 

 ascertaining whether the same law holds for the higher mem- 

 bers of the series. 



Art. XLIX. — The Latent Heats of Fusion of the Elements 



and Compounds. 



By P. W. Robertson, Junior Scholar in the University of 



New Zealand. 



Communicated by Professor Easterfield. 

 [Read before the Wellington Philosophical Society, 11th February, 1902.] 



Abstract. 

 Crompton states that ^ = K, where A is atomic weight, w latent heat 



of fusion, T melting point on absolute scale, and v the valency of the 

 element. Now, the valency of an element is known to vary, and as the 

 results were not very concordant the author, from theoretical grounds, 



replaced this by the relation — 5 — where d is density and V ^_ 



d 



tents the space between the atoms. Just as the atomic heat of the 

 elements is only constant f r elem-nts with atomic weights over about 

 40, s.) in this relation only true under the same conditions. In the case 

 of ttie fourteen elements with atomic weighos over 40 the value varies 

 between 1 and 13, witn the exception of the three, gallium, lead, and 

 bismuth. But applying this rule to the compounds, and ohanging the 

 atomic weight into molecular weight, still more concordant results are 

 obtained. Out of thirteen inorganic compounds, with the exception of 

 t^o the re-tults vary from 19 to 2 3, being mostly near the mean 2-1. 

 There is al-o good agreement among the organic bodies examined, the 

 mean being ab >ut 2-4. The author intends to calculate more results, 

 and to present fuller tables to the Society. 



Various attempts have been made to arrive at a definite 



repre- 



