﻿THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



MARCH 1869. 



XXII. Historical Notes on some Phenomena connected with the 

 Boiling of Liquids. By Charles Tomlinson, F.R.S* 



1. TljTHEN water is heated to that temperature at which its 

 ™ " tension equals the whole pressure of both air and va- 

 pour on its surface, and it begins to emit steam not only from 

 its surface (as it did before), but from all parts of its depth, it is 

 said to be boiling. The boiling-point of any liquid means, 

 therefore, the temperature at which its evaporating tendency 

 equals the pressure of the atmosphere at the time — or the lowest 

 temperature at which its vapour can have the elasticity of com- 

 mon air. 



2. During many years after the invention of the barometer, 

 and the consequent discovery of atmospheric pressure, it was 

 supposed that the above statements contained a sufficient account 

 of boiling. It was not until the irregular shifting of the boil- 

 ing-point hi thermometers under a constant pressure had been 

 insisted on by such men as De Luc, Shuckburg, Horsley, and 

 Cavendish, that steps were taken to determine the conditions 

 on which that instrument should be constructed. The Royal 



* Communicated by the Author. 



[In preparing' the paper " On Boiling Liquids " recently read before the 

 Royal Society, 1 was led to consult a good many books and memoirs, and 

 to accumulate a number of historical details which, though not adapted to 

 the ' Proceedings ' of a Society whose chief object is to assist the progress 

 of living science, may yet, if briefly stated, be acceptable in the Philosophical 

 Magazine, which performs the useful functions both of critic and of observer. 

 The insertion of these historical details may serve to correct some errors 

 that have crept into our text-books.] 



Phil. Mag. S. 4. Vol 37. No. 248. Mar. 18C9. M 



