1895.] Mr E. H. Griffiths, On the ' Volume Heat' of Aniline. 308 



Monday, 13 May, 1895. 

 Professor J. J. Thomson, President, in the Chair. 

 The following Communications were made to the Society : 



(1) Exhibition of some recent Photographs of the Moon. By 

 H. F. Newall, M.A., Trinity College. 



The following photographs were exhibited, (i) a print by Dr 

 Weinek from an original negative taken by MM. Loewy and 

 Puiseux with the coude equatorial of the Paris Observatory ; 

 (ii) an enlargement made by Dr Weinek from the same negative, 

 showing the crater Linn^ and the surrounding region ; (iii) a trans- 

 parent enlargement from the same negative, sent from the Paris 

 Observatory, of the region near Archimedes, on such scale that the 

 diameter of the Moon would be 3'9 metres; (iv) some direct 

 enlargements made by Mr Newall with a camera attached to the 

 25-inch visual refractor of the Cambridge Observatory. 



(2) On the 'Volume Heat' of Aniline. By E. H. Griffiths, 

 M.A., Sidney Sussex College. 



We know little as to the influence of temperature upon the 

 specific heat of bodies. It is true that books of reference occa- 

 sionally give (to four significant figures) the values of the specific 

 heat of mercury over the temperature range 0° to 100° C, as well 

 as a large number of imposing formulae by means of which the 

 specific heat of various metals at any temperature may be calcu- 

 lated by the student to as many " significant" figures as he pleases. 

 The accuracy is, however, more apparent than real. Observers 

 have been so dependent on the method of mixtures or some other 

 mode of comparison with water that our present values are almost 

 entirely relative and depend upon the experiments of Regnaulfc. 



It is generally assumed that our knowledge of the changes in 

 the capacity for heat of water is sufficiently exact, but I think that 

 this assumption is untenable. The evidence of recent observers 

 (for example Rowland, Bartoli and Stracciati, Joly, and Griffiths), 

 is in direct conflict with Regnault over ranges of temperature 

 below 34°, and I have now in the press an account of some 

 experiments which lead to the conclusion that Regnault's values 

 at higher temperatures are also inexact. 



True, that determinations made by methods similar to those 



