13S AMALGAMS. 



The sensations consequent on having discovered and 

 accurately determined a physical constant of fundamental 

 importance have been experienced by few, and Joule was 

 probably the first who, in addition to these sensations, ex- 

 perienced those which must have arisen in finding that his 

 contemporaries who were carrying on his work (Clausius 

 and Rankine) eagerly agreed in the suggestion of Sir 

 William Thomson to use J as the mathematical symbol to 

 signify the Mechanical Equivalent of Heat, and so to 

 associate for all time Joule's name with his discover}'. 



Although Joule seems to have done little more than 

 amuse himself during 1S50 and 1S51, he was not idle. 

 Having reached the terminus of the main line of his inquiry* 

 and finding the immediate branches occupied by those 

 better qualified than himself to prosecute them, he appears 

 to have taken up, for one thing, a new line of molecular 

 study requiring experimental investigation, that of "Amal- 

 gams," on which he made researches at his house, Acton 

 Square, in 1850, publishing the results partly at the British 

 Association in that year, and subsequently in 1S62 in 

 Memoirs of this Society*. At the same time, however, he 

 was continuing in his laboratory- at Oakfield his investiga- 

 tions on Electro- Magnets, which he published in two papers 

 in the Philosophical Magazine, 1852. 



At the same time Joule, having proved the impossibility 

 of exceeding the economy of the steam engine by means of 

 electro-magnetic engines, showed that he retained his early 

 ambition to accomplish a useful practical application of his 



-searches, by undertaking the invention of a hot air engine 

 which should work under conditions allowing of greater 



ranges of temperature than are obtainable in the steam 

 and so, according to the new development of 



engine 



