342 MR. P. O. PEDERSEN ON THE SURFACE-TENSION OF LIQUIDS 



INTRODUCTION. 



AMONG the large number of methods available for the determination of the surface- 

 tension of liquids that proposed by Lord RAYLEIGH* stands out with great 

 fundamental advantages. The principle is as follows : A jet of liquid issuing from a 

 not circular aperture is executing transverse vibrations about its cylindrical con- 

 figuration of equilibrium. Since the phase of vibration depends upon the time 

 elapsed, it is always the same at the same point in space, and thus the motion is 

 steady and the boundary of the jet a fixed surface showing stationary waves. 



Measurements of the corresponding wave-length (X), the velocity (V), and cross- 

 section (A) of the jet, together with the density (p) of the liquid afford the necessary 

 constants for the calculation of the capillary-tension (T) according to Lord RAYLEIGH'S 

 theory of jet-vibration. 



The method is free from every supposition respecting the angle of contact. This 

 advantage, however, it has in common with several other methods, especially the 

 following : 



The method of reflection proposed by R. Eorvost and also used by D. PEKAR| and 



G. ZEMPLEN. 



The method of ripples || that has been used very much in recent times. 

 The method of maximum pressure of small air-bubbles proposed by M. CANTOR^ 



and further developed by R. FEUSTEL.*'' 



Another advantage of Lord RAYLEIGH'S method is that the surface in use is 

 continually renewed. In this manner the capillary-tension can be determined before 

 the surface is 7^5- second old. This circumstance is of very great importance, as the 



* Lord RAYLEIGH, 'Roy. Soc. Proc.,' 29, p. 71, 1879 ('Papers I.,' p. 377). 



t R. EOTVOS, ' WIED. Ann.,' 27, p. 448, 1886. 



i PEKAR, 'Zeitschr. f. phys. Chem.,' 39, p. 433, 1902. 



G. ZEMPLEN, 'Ann. d. Phys.,' 20, p. 783, 1906. 



|| See for instance: L. MATTHIESEN, 'Pogg. Ann.,' 134, p. 107, 1868; 141, p. 375, 1870; ' WIED. Ann.,' 

 32, p. 626, 1887; 38, p. 118, 1889. A. ARENDT, 'Rep. d. Phys.,' 24, p. 318, 1888. KELVIN, 'Phil. Mag.,' 

 42, p. 368, 1871 ; ' Baltimore Lectures,' App. G., London, 1904. Lord RAYLEIGH, 'Phil. Mag.,' 16, p. 50, 

 1883 ('Papers II.,' p. 212); 'Phil. Mag.,' 30, p. 386, 1890 ('Papers III.,' p. 383). J. H. VINCENT, 'Phil. 

 Mag.,' 43, p. 411, 1897. N. E. DORSEY, 'Phil. Mag.,' 44, pp. 134, 369, 1897. J. A. CRAW, in A. GRAY, 

 'A Treatise on Physics,' vol. I., p. 659, London, 1901. L. GRUNMACH, 'Verb. d. Deutsch. phys. Ges.,' I., 

 p. 13, 1889; 'Ber. d. Akad. d. Wiss.,' Berlin, p. 829, 1900, and p. 914, 1901 ; 'Ann. d. Phys.,' 3, p. 659, 

 1900; 4, p. 367, 1901; 6, p. 559, 1901; 7, p. 236, 1902; 9, p. 1261, 1902; 15, p. 401, 1904; 'Festschr.,' 

 L. BOLTZMANN, p. 460, 1904; 'Wiss. Abh. d. K. Norra.-Aich.-Komm.,' Heft III., p. 101, 1902. 

 KALAHNE, 'Ann. d. Phys.,' 7, p. 440, 1902. A. BRUMMER, 'Dissertation,' Berlin, 1902. K. LOEWENFELD, 

 'Dissertation,' Berlin, 1905. 



f M. CANTOR, ' WIED. Ann.,' 47, p. 399, 1892 ; 'Ann. d, Phys.,' 7, p. 698. 1902. 



** R. FEUSTEL, 'Ann. d. Phys.,' 16, p. 61, 1905. 



