28 Prof. Forbes on the Vibration of Metallic Masses. 



The analogy is exceedingly striking, more especially when It 

 is stated that each arrangement has been compiled alone solely 

 upon the evidence of experiment, and the ground upon which 

 each metal has its place assigned to it, is fully stated in the 

 paper alluded to for the two first columns, and in the present 

 paper for the third. It is also worthy of remark, that the 

 same metals seem to be most allied to one another in each of 

 the three series. The various observers agree in treating of 

 their respective subjects, that gold, silver and copper are 

 nearly allied in all : and it is probable that platinum and iron 

 are in equally close connexion*. The observations on all 

 three points are at one in proving that there is a decided breach 

 of continuity between lead and antimony, so marked is the 

 change of property of the two lowest metals in the list. 



36. We may now venture to enunciate a third and most 

 important law of these phenomena; That the vibrations take 

 place with an intensity proportional (within certain limits) to 

 the difference of conducting power of the two metals employed 

 for heat (or electricity), — the metal havi?ig the least conducting 

 power being necessarily the coldest. I have stated that the dif- 

 ference of conducting power must be within certain limits, 

 because the anomaly of antimony and bismuth seems to be 

 caused by this exception ; and it is on the same account pro- 

 bably that the class of bodies which possess the vibrating pro- 

 perty is confined to the metals ; other matter being destitute 

 of the requisite conducting power. Here antimony and bis- 

 muth almost want this characteristic property of the other 

 metals examined. My experiments with the thermometer of 

 contact prove their very low rank as conductors of heat, as 

 Mr. Harris of Plymouth, in reporting to me some experiments 

 which he had kindly undertaken at my request, with regard 

 to their power as electrical conductors, states in regard to 

 bismuth, that nothing in " the form of a metal can be much 

 worse." [To be continued.] 



strikingly confirms the arrangement of conductors which I have given in 



the text. 



Transient Magnetic Energy of the Metals. 



Rolled Silver 39 



Copper 29 



Cast Copper 20 



Rolled Gold 16 



Cast Zinc 10 



Tin 6-9 



Lead 3-7 



Antimony 1*3 



Bismuth 045 



* It is moft probably from the great specific heat of iron that it stands so 



high in the first column. 



