Effect of Heat on the Discharge of an Induction- Coil. 477 



No measurements appear to have been made on tetra- 

 valent ions, but it is easy to calculate their coagulative 

 power on this hypothesis. Equal electrical charges would 

 be obtained by the conjunction of three tetrads, four triads, 

 six diads, or twelve monads. We should thus find : 



Ci:c 2 :c 3 : c 4 =B tV : W : B* : B* 



! 1 1 111 



= 1 : B T *: B< : B* : =1 : -:--.-. 



• ( tV t-V 



if B T5 be put -x. 



The coagulative powers arc then in the ratios 



Pi ■ )>2 ' 1H : }h=l: oc : x 2 : x z . 

 Thus the first series of numbers becomes 

 1 : 32 : 1021 : 32800, 

 and the second 1 : 40 : 1600 : 64000. 



It is probable, therefore, that Linder and Picton would 

 have found the coagulative power of the sulphates of tetra- 

 valent metals to be about thirty thousand times as great as 

 that of the equivalent monovalent solution ; while under the 

 conditions of Schulze's experiments the result would probably 

 have been about sixty thousand times that value. 



My thanks are due to Mr. Gr. T. Walker for suggestions on 

 the mathematical part of the reasoning given above. 



October 6, 1899. 



L. The Effect of Ileal on the. Discharge of an Induction- Coil, in 

 which the Primary Circuit is interrupted by an Electrolytic 

 Break. ByF. J. Jervis-Smith, 31. A., E.R.S., Oxford*. 



ri^HE pointed conductors of the secondary wire of a 10-inch 

 I induction-coil by Apps were separated till a spark would 

 not pass, and only a faint brush was visible; on bringing the 

 flame of a spirit-lamp near one of the points, a torrent of 

 sparks instantly bridged over the space between the points. 

 When the flame was removed the sparks ceased, and were 

 restored each time the flame was brought back. Bat this 

 was not the case when the flame was brought into a similar 

 position with respect to the other point. The application of 

 the flame did not cause the sparking to bridge across the 

 space between the points; but on reversing the direction of the 

 primary current, the sparks crossed as before. The nature of 

 the discharge was then tested by applying an #-ray tube; the 

 point affected by the flame was found to be the kathode pole. 

 When balls instead of points were used, the above-mentioned 

 effect could not be obtained. 



* Communicated by tbe Author. 



