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Ordinary Meeting, February 19th, 1861. 

 Dr. J. P. Joule, President, in the Chair. 



A Paper was read by J. C. Dyer, Esq., entitled, " Brief 

 Notes on the Freezing, Thawing, and Evaporation of Water, 

 and on the Condensation of Steam, with a View to Enquire 

 into the Cause of those Changes." 



In these Notes the Author merely aimed to place before 

 the Society the apparent agency of heat^ in the changes that 

 water undergoes in passing alternately from one to the other 

 of its conditions of ice, water, and steam, and vice versa ; and 

 that these mutations are caused, by the taking up and giving 

 out of heat, in its sensible or latent state, by the transitions 

 reciprocally from one to the other of those states. The 

 actual amount of the thermoraetric heat so passing from the 

 latent to the sensible state was given, as taken from the 

 common tables. On referring to the two ancient theories of 

 heat, the one defining it to be, "a material element, sui 

 generis, and pervading matter," &c. ; the other holding it to 

 be "no other than the motions, mechanically excited in the 

 minute particles of bodies," &c. — it w^as contended that, by 

 this latter or the " force heat theory," the melting of ice by 

 the action of the sun's rays could not be explained, since it 

 is not by their force, but by the matter of heat that enters 

 and becomes latent in the w^ater. The Author then sub- 

 mitted that the only solution, hitherto offered of the absorption 

 of sensible heat, in water and steam, as latent in these, and 

 the re-appearance of the same measure of heat, in a sensible 

 state, by the acts of condensation and freezing, is to be found 

 in the application of Dr. Black's " Latent Heat Theory." 

 Considering the force heat theory, as directly conflicting 

 with that of latent heat ; they cannot both be sustained, and 

 as the latter stands in elementary works as an established law 

 in physics, and as it affords a clear explanation of the 

 aqueous changes adduced ; it seems incumbent on those who 

 Proceedings— Lit. & Phil. Society— No. 10.— Session, 1860-61, 



