720 Mr. J. H. Jeans on the 



These results are in agreement with the admittedly rough 

 calculation of the inductance from the dimensions of the coil. 

 The sensitiveness was such that two microhenries could be 

 detected with certainty. 



By thus comparing a standard air-condenser with an 

 inductance whose dimensions are sufficiently large and accu- 

 rately measurable, we believe that " v " could be determined 

 with considerable accuracy. 



We can also use a slight modification of the method 

 described for the measurement of coefficients of mutual 

 induction. The results obtained by the method we hope to 

 publish shortly. 



We had hoped that the method would have been applicable 

 to the accurate determination of electrolytic conductivities ; 

 but though we can get consistent results up to jL per cent., 

 anything much beyond that seems at present hopeless owing 

 to the apparently erratic motion of the coil. The fact is, we 

 presume, that the capacity of the electrodes is not constant, 

 and the apparatus being so good for measuring capacities 

 becomes correspondingly inefficient for resistances involving 

 variable capacities. This explanation is confirmed by reducing 

 the area of the electrodes ; but even with electrodes of only 

 •02 cm.2 area or so, the results are only two or three times as 

 consistent. Even with a balancing-cell * the results are not 

 much better. Possibly, however, by making the ohmic 

 resistance of the electrolyte used a negligible quantity the 

 capacity of the electrodes might be measured instead. 



Co7iclusion. — The apparatus and methods described will^ we 

 think, prove very useful for the calibration and adjustment 

 of large and small capacities, and for the measurement of 

 self-induction. 



The Yorkshire College, Leeds. 

 Sept. 28th, 1903. 



XC. The Kinetic Theory of Gases. 



To the Editors of the Philosophical Magazine, 

 Gentlemen, 



MR. BURBURY'S note on my "Kinetic Theory of 

 Gases developed from a new standpoint ^^ seems to 

 call for a reply, although his criticisms are so numerous and 

 far reaching that I cannot ask for space in which to attempt 

 to answer them at all fully. 



* Phil. Ma^. Jan. 1897, 



