MAGNKTISM 



When the rotation is in the opposite direction, as in titanium 

 chloride and in salts of iron, we mav perhaps account for it bv 

 a negative sign for /3, i.e. a decrease in ,/ at \ i . or perhaps 



by assigning the opposite sign for r, which implies that positive 

 charges are revolving. 



Confirmations of the theory. Highi * showed that tin- 

 wave lengths of two oppositely circularly polarised rays \\eie 

 different when thev were made to traverse a magnetic- field along 

 the lines of force, before the electron theorv \\as elaborated to 

 account for the difference of their velocities. A pencil from a 

 source was divided into two pencils which \\ere circularly polar 

 with rotations in opposite directions and then ran alongside each 

 other through a tube containing an active liquid and surrounded by 

 a solenoid. The two pencils then P.-ISM d through a Nicol and inter- 

 fered in the focal plain- of a micrometer e\ epiecc by which the frii 

 could be seen and their positions fixed. Wh<-n the cm put 



on the position of a fring. id b\ the micrometer \\ iie. Thru 



the current Wai I6V< r-ed and t he trin^ - xhifh-d, and by an amount 

 sufficiently near to that which woi'ld be e\pc cted from t he oi.-. i \ . d 

 rotation of the- planes of polarisation in the liquid 1 ame 



current. 



Hraee 4 - made a similar experiment with a similar result. - 

 time later, by making the tuo ra\s travel in an an nt of 



5890 

 D, 



I'M. 



prisms to and fro along the lines of fosce, 1 edt-d in 

 separating them on emergence. 



Macahiso and Corbinot >ho\\i(l that the lotation is in the 



same direction on opposite ridefl -dium \apour absorption 



band, anil W)od measured the i in the neigh bourhood of 



both 1) lines, and obtained results of the kind icpn-entcd in 

 Fig. 245. Butintht i solution of praseodidymium chloride. 



* 1 1 W. JfriMiittir, ii. p. 71." (1 



Phil. Maij. i. p. n;i (inn]). II the inlnxliii-iin- 



carlior work, :ind tlit-n 



t d'Hipt. llrud. cxxvii. ]>. .MS; W,,,,l. ft/,fi,-M. L'n.l r<l. \ 

 Phil. Mtry. [it] xiv. p. IT. (1 



