1898.] Becent Besults of FhysicO'Cliemical Inquiry. 64:1 



WEEKLY EVENING MEETIN 



Friday, March 4, 1898. 

 Sm William Crookes, F.K.S. Vice-President, 

 Professor T. E. Thorpe, LL.D, F.Pt.S. 



Some Recent Results of Physico- Chemical Inquiry. 



The lecturer gave an account of the main results of an investigation 

 on the relations between the viscosity (internal friction) of liquids and 

 their chemical nature which had occupied the late Mr. J. W. Eodger 

 and himself during several years. He pointed out, in the first 

 place, that the many attempts which had been made since Hermann 

 Kopp directed attention to the connection which exists between the 

 molecular weights of substances and their densities, to establish 

 similar relationships between the magnitudes of other physical 

 constants and chemical composition, had rendered it highly probable 

 that all physical constants are to be regarded as functions of the 

 chemical nature of molecules, and that the variations in their mag- 

 nitude observed in passing from substance to substance are to be 

 attributed to changes in chemical composition. As yet, however, all 

 endeavours to connect the chemical nature of liquids with their 

 viscosity have been only partially successful, although it is obvious 

 from the work of Graham, Rellstab, Pribram and Haudl, and Garten- 

 meister, that such a connection ought to be discoverable. 



Thus it was known that an increment of CH2 in a homologous, 

 series is in general accompanied by an increase in viscosity, and 

 that the increase is greater when the increment of CH2 takes place 

 in an alcohol radicle than when it takes place in an acid radicle, 

 Metameric bodies have, in general, different viscosity values, and 

 these are nearer together the nearer the boiling points of the liquids. 

 Substances containing double-linked carbon are more viscous than 

 those of equal molecular weight containing single-linked carbon. 

 The substitution in a molecule of CI, Br, I and NO2 for H in all 

 cases increases the viscosity of the substance. This increase is 

 smallest on the introduction of CI, and increases on the introduction 

 of Br, I, and NO2 and in the order given. The absolute amount of 

 the increase depends not only upon the nature of the substituting 

 radicle but also upon its position in the molecule. Of two isomeric 

 esters that possesses the greater viscosity which contains the higher 

 alcoholic radicle. The ester containing the normal radicle has always, 

 a greater viscosity than the iso-compound, and this obtains no matter 



