67 



The Surface Tension of Liquids. By Arthur L. Foley. 



Altliough many methods of measuring the surface tension of rKjuids have 

 been proposed and used, its absolute value is not known in a single instance. 

 Various experimenters by various methods have obtained various results ; these 

 results differing from one another in many cases by as much as fifty per cent. 

 For instance, Quincke, for the surface tension of water at 0"C, has obtained the 

 following results by the methods named : 



1. By measuring the rise of water at a vertical wall he obtained 8.7 mgm. 

 per mm. 



2. By measuring the axis of a bubble of air in the interior of a liquid, 8.2 

 mgm. 



3. By the rise of water in capillary tubes, 7.6 mgm. 



4. By measuring the size of falling drops, 6.5 mgm. 



These results show an average variation of about ten per cent., and a differ- 

 ence between the first and last of thirty-four per cent. Many other methods have 

 been used, but the results obtained are not more consistent than those given above. 

 The method generally used, and that which probably gives as consistent results 

 as any yet proposed, is the method of capillary tubes. But even if we restrict 

 ourselves to this one method, and to the results obtained by a single experimenter, 

 we find that they differ considerably. Let us again note the results obtained by 

 Quincke — than whom there is no better authority upon this subject. In Wiede- 

 man's Annalen, April, 1894, Quincke gives values ranging from 7.69 to 8.16 mgm. 

 per mm. for difi'erent sizes of tubes made from the same specimen of Jena glass; 

 and values from 7.8 to 8.1 for English fiiut glass. In the October number of the 

 Annalen, 1894, Volkmann gives as widely different results for various specimens 

 of glass. The age of the tube is found to influence the height to which the water 

 rises in it. So it would seem that a better method of measuring the surface ten- 

 sion of liquids is greatly to be desired. 



In the "Philosophical Magazine" of November, 1893, Mr. T. Proctor Hall 

 describes some "New Methods of Measuring the Surface Tension of Liquids." 

 Two years ago at the suggestion of Professor Michelson of the Chicago University, 

 I undertook to repeat and to extend the investigation. In the present article, I 

 shall confine myself to a brief statement of the results obtained by using Mr. 

 Hall's method c, the maximum-weight method.^ 



' Philof ophical Magf zine, November, 1893, p. 402. 



