ARTICLES 

 THE VISCOSITY OF PURE LIQUIDS 



By SIR EDWARD THORPE, C.B., LL.D., F.R.S., 

 Emeritus Professor of Chemistry, Imperial College of Science and Technology, London 



Under this title, Prof. Svante Arrhenius, the Director of the 

 Nobel Institute, Stockholm, has published recently an important 

 communication dealing with the viscosity, or internal friction, 

 of homogeneous liquids 1 in which he discusses this property 

 in relation to other physical characteristics, and incidentally 

 throws additional light upon the question which has exercised 

 many minds since the time of Poiseuille, who first experiment- 

 ally established the principles of a convenient and accurate 

 method of measuring the viscosity of liquids, namely, What is 

 the connection between this particular physical property and 

 the chemical nature (using that phrase in its most compre- 

 hensive sense) of the liquids ? 



It has already been pointed out by the writer of this article 

 in memoirs published in the Philosophical Transactions of the 

 Royal Society in conjunction with the late Mr. J. W. Rodger 2 

 that the viscosity-values of the paraffin hydrocarbons and of 

 the ethers at their normal boiling-points, when they are pre- 

 sumably under comparable conditions of temperature, are 

 identical in each class respectively. This regularity was not 

 observed under similar circumstances in the case of other 

 homologous series : in general an increment of CH 2 brings 

 about a diminution of the viscosity-coefficient. 



Starting from the fact that, as a rule, the specific weight at 

 the boiling-point in these homologous series decreases with the 

 increasing number of CH. groups, and from the assumption 



1 Meddelanden /ran K. Vetenskaps Akademiens Nobelinstitut, Band 3, No. 20. 

 Stockholm : Almquist & Wiksells Boktryckeri, A.E. ; London : William Wesley 

 & Son, 28, Essex Street, Strand. 



* Phil. Trans. A. 185, 397 (1894), and 189, y\ (1897). 



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