CHAPTER IV. 



Second Research. — -Communicates Results to the Royal 

 Society. — Joule's Motive. — Attributes Proportionality of 

 CJiemical and Mechanical Effects to their Respective 

 Quantitative Relations to the Electric Action. — Heat in 

 Metallic Conductors. — Proportional to the Square of 

 the Current. — Absolute Measures of Heat, Current, and 

 Electromotive Force. — Heat Equivalent of Electrical 

 Effect. — Heat Developed During Electrolysis. — Electric 

 Origin of Heat. — Heats of Combustion and Electrolysis. 

 — Intensity of Chemical Affinity of Combustibles.— 

 Permanent and Transitory Voltaic Intensity. — Depen- 

 dence of Affinity on Gaseous or Liquid States. — First 

 Paper Before This Society. — The British Association. — 

 Joint Research with Scoresby. — Heat Evolved During 

 Electrolysis of Water. — Summary of Results. — Ap- 

 proaches Generalization. — Commences Third Research. 



Towards the end of 1840 Joule presented a paper to the 

 Royal Society " On the Production of Heat by Voltaic 

 Electricity," which was read in abstract December the 17th, 

 1840. This paper, from whatever point it is now viewed, 

 shows throughout the hand of a master ; but the matter it 

 contained was so far in advance of the knowledge of the 

 time, that the Royal Society declined to publish it in full 

 in the Philosophical Transactions — a circumstance which 

 not only takes a principal place in Joules' career, but has 



