446 



Intelligence and Miscellaneous Articles. 



Inl 



d 



cubic metre there are - molecules, calling the density d, and 



the atomic weight p. If we wish to get the number of the mole- 

 cules N (that is to say, the number of molecules contained in the 

 linear unit or the edge of the cube), we have 



*=</l 



Taking a for the measured lengthening between zero and 100° C. 

 we get directly the relation 



^100 ~h 





Such is the value of the augmentation of the thermal wave- 

 length when the temperature passes from zero to 100°. 



Now, if the attraction of matter for matter obeys a general law, 

 every solid molecule will divide into two or more liquid molecules 

 when the oscillations have become equal to a certain maximum, 

 constant for all bodies. 



We have therefore to verify two physical laws which are the ne- 

 cessary consequence of these deductions : — 



1st. The higher the fusion-temperature of a solid, the shorter must 

 the molecular oscillations be. 



2nd. As the fusion-temperatures of solids correspond to equal 

 lengths of oscillation, the product of the oscillation-lengths into the 

 fusion-temperatures must be a number constant for all solids. 



These two laws are verified with as much exactness as the expe- 

 rimental determinations of the various elements entering into the 

 equations permit. 



The following Table comprises the metals of which the coefficients 

 of dilatation are known with sufficient accuracy : — 



Table of the Thermal Wave-lengths of Solids, and of the Product 

 of their Multiplication by the Fusion-temperatures*. 



Names. 



Atomic 

 weights. 



Densi- 

 ties. 



Values of 

 a. 



Wave- 

 lengths. 



Fusion- 

 tempera- 

 tures. 

 273°+ 



Products. 

 V 



Selenium . . . 

 Lead 



39-75 

 104 

 32-7 

 54 



31-75 

 98 

 28 

 98-5 



4-30 

 11-35 



7-19 

 10-60 



8-9 

 19-258 



7-79 

 21-53 



000368 



0-0028657 



0002942 



0-00193 



0001715 



0-001466 



0-0011717 



0-0008842 



0-007725 



0-005382 



0-004873 



0-003077 



0-0026215 



0-0025205 



0-0017805 



0-001467 



217 



335 



450 



977 



1050 



1100 



1600 



1700 



3-7854 



3-272 



3-523 



3-841 



3-468 



3-459 



3-34 



3-59 



Zinc 



Silver 



Copper 



Gold 



Iron 



Platinum . . . 



* The wave-lengths are in the inverse ratio of the fusion-temperatures ; 

 and the products are sensibly constant. 



