12S Miscellaneous Intelligence. 



4. Relation between the Coefficient of Elasticity of Metals, and 

 their latent heat of fusion; by C. C. Person, (Comptes Rendus, Sept. 

 4, 1848, p. 258. — The expenditure of heat by which molecules are sep- 

 arated in fusion, equals the latent heat of the substance. The author 

 conceived that the work accomplished in this separation should have a 

 simple relation to the work necessary for separating to a less amount. 

 It is already obvious that there is a remarkable relation between the 



coefficients of elasticity of metals and their latent heat. It requires 



double the force to elongate zinc as tin; and it takes an expenditure 

 of twice the heat to melt it. Lead requires five times less force for 

 the same elongation than zinc; and its fusion requires five times less 

 of heat. A similar relation exists between zinc and bismuth, if the 

 zinc be well crystallized. 



Designating by q, q f , the coefficients of elasticity of two metals, by 

 Z, V, their latent heats of fusion, we have approximately q: q' ::l:l. 

 It is natural that the proportion should not be exact : — l:l' is the relation 

 between the quantities of heat expended in melting the same quantity 

 of two metals ; q : q' is the relation between the forces necessary to 

 produce the same elongation in two pieces of metal of the same size 

 and consequently of unequal weights. It is obvious that the latent heat 

 of fusion should be proportioned not to the coefficient of elasticity, 

 but to a function of this coefficient representing the work required to 

 destroy the cohesion of molecules comprised in a unity of weights, or 

 at least to reduce this cohesion to what it is in the liquid state. The 

 formula thence becomes 



1 



V 



q 

 The formula is verified by experiment. For zinc and lead, -7=4'80 ; 



the correction, dependent on their densities (p,^,) being made, we have 

 5-28 ; but ^7=5-23, which is a close approximation. For tin and lead 



1 q 



jjz=z265] 7 = 2*20, and the correction applied gives 2-42. For zinc 

 and tin, the densities being the same, the correction becomes nothing; 



q I I 



the relations -and j, are equal or nearly so ; for y,— 1*97 ; and then, 

 according to the specimens of metals and different modes of vibration, 



we have for -, the values 2-00, 2*09, 2-11. which differ little from 1-97. 



?. ... , 



If we apply it to platinum and iron, taking zinc for a term of com- 

 parison, we find las 88 for platinum, and I =r 60 for iron ; iron bein 

 the most resistant and demanding not the highest temperature, but the 

 greatest amount of latent heat for fusion. Reciprocally, mercury 



whose latent heat of fusion is so small, offers still less tenacity than lead 



By experiments on cadmium and silver, the author finds the latent 



heat of the two 13*66 and 21-7 ; and by the formula 13-52 and 20-38. 







