430 



Mr. S. U. Pickering on the 



There can be no question but that the method of analysing 

 results by differentiation presents many difficulties, and must 

 be used with extreme caution ; nor can it be denied that many 

 of the changes of curvature which I consider to be probable 

 are but faintly marked, and are by no means beyond question. 

 This must inevitably be the case if these changes are due to 

 changes in the unstable and partially dissociated hydrates 

 constituting the liquid. Their existence can be established only 

 by the concordance of the indications obtained from many 

 independent sources, and can scarcely be refuted by a hasty 

 criticism (such as Prof. Arrhenius's) of results which had not 

 been published. 



Figs. 1, 2, and 3 give rough illustrations of the six experi- 

 mental curves examined. They show how very different the 

 figures are in the different cases, and how improbable it would 

 be that they should all split up by mere chance into the same 

 number of sections, and exhibit changes at the same points*. 

 Illustrations of the first differentials derived from them would 

 lead to the same conclusion. 









Fig. 1. 





Den- 

 sity. 



V8 

 1-6 

 1'4 

 1-2 



IT 











































Con 

 ti. 



06 



40 00 



Per cent. EUSOj. 



* Diagrams representing on a larger scale the portions below 10 per 

 cent, would show the differences in a still more striking- manner. 



