7 8 RAREFACTION AND CONDENSATION OF AIR. 



Broom Hill to Oakfield, Whalley Range, where he had 

 built Joule a laboratory, affording him greatly increased 

 facilities for his work. 



In August, 1843, ne na -d already engaged in experiments 

 for determining the mechanical equivalent of heat by the 

 friction of water. These he continues, with various 

 apparatus, as fast as the time occupied in adapting his 

 apparatus will allow. 



In the meantime, he proceeds to carry his experiments 

 into other regions with the same object, and to collect, 

 complete and publish notes concerning incidental 

 phenomena that he has observed during his research. On 

 December 26th, 1843, he read before this Society a paper 

 " On the Intermittent Character of the Voltaic Current in 

 Certain Cases of Electrolysis ; and On the Intensity of 

 Various Voltaic Arrangements." This, although a very 

 important paper on the subject of electrolysis, containing 

 definite measurements and explanations new at the time, 

 refers chiefly to matter collected during his previous 

 electrical researches. 



His next paper, " On the Changes of Temperature 

 Produced by the Rarefaction and Condensation of Air," 

 read before the Royal Society, June 20th, 1844, contains an 

 account of one of the most important, as well as most 

 remarkable, researches Joule made for proof of the 

 generality of the mechanical equivalent of heat and its 

 accurate determination. It also contains the first definite 

 development of the dynamical theory of matter and heat. 

 This paper was rejected for publication by the Royal 

 Society, and was published in the Philosophical Magazine^ 

 in May, 1845. 



The relations between the heat and work in the expan- 



