between Metallic Masses having different Temperatures. 441 



Platinum. 



Iron. 



Tin. 



Antimony ; does not vibrate. 



Bismuth ditto. 



28. This arrangement indicates very distinctly the order in 

 which the metals possess the property or properties essential to 

 vibration with regard to lead. But a very important inquiry is 

 immediately suggested : Is the property of lead as the cold 

 metal peculiar to it ? or does it only require a certain space be- 

 tween any two metals in this scale to produce the effect ? For 

 example, lead being placed in the arrangement between tin and 

 antimony, platinum is the third metal above it ; the question is, 

 Would platinum used as the cold metal bear the same relation to 

 gold, the third metal above it, as lead does to platinum ? This 

 is the principle, though of course we are not bound to suppose 

 that the energy is proportional to the number of metals inter- 

 posed in the list ; since we have already seen that the vibrating 

 property in relation to cold lead is almost the same in several 

 consecutive metals. The observation stated by Mr FARADAY, 

 forcibly suggests the idea that a certain interval in the scale of 

 metals is alone required to produce the effect ; the lowest metal 

 being necessarily the coolest. 



29. The following are some cases of decided vibrations ob- 

 tained among numerous experiments. Upon COLD TIN, heated 

 silver, copper, gold, and iron, vibrate in the order just stated, 

 silver being the most intense. Upon COLD IRON, silver vibrates 

 decisively ; my experiments, therefore, confirm the statements 

 of Mr FARADAY. With hot copper I have likewise obtained dis- 

 tinct vibrations, though it is not possible at ah 1 times to repeat 

 the experiment in a satisfactory manner. With hot gold the vi- 

 brations were dubious. Upon COLD ZINC, no hot metal except 

 silver has been observed to vibrate. In this case, however, the 



