02 



Prof. 0. W. Richardson on the Positive 



confirms the preceding results and brings out one or two now 

 points as well. This set is represented in fig. 7. The curves 

 at the top (fig. 7, A), points thus : x , exhibit the effect 

 of heating the platinum by itself. In these experiments 

 V = 200 volts, H = 4700 lines per cm. 2 , and z=*556 cm. 

 The displacement 2*85 turns for the platinum ions lends to 

 the values e/m=349 ami ra = 27*7, in agreement with those 

 found previously. 



Three curves are given, fie,-. 7, B, representing observations 

 on sodium sulphate. Those with points thus : ©, were 

 obtained when the salt was tirsi heated. It will be noticed 

 thai thev are broader than and not so high as the later ones. 

 The displacement of the maximum, 2*95 turns, corresponds to 

 m = 25"9. It i^ greater than thai lor the platinum ions, and 

 less than that, 3*3 turns, obtained after the sodium sulphate 

 had been heated longer. The two remaining curves were 

 taken in succession after the salt bad been heated for about 

 fourteen hours. The curve* with points thus: x, were 

 taken first, those with points © and [x~| later. The displace- 

 ment of the n aximum is the same in both cases, and the 

 el ai;e fcer of tie eiirvos is very much ihe same. The value 

 of m calculated from the displacements is 22-0. 



The -renter value of ))) and the greater breadth of the 

 curves obtained on firsl heating is readily explained if we 

 suppose that the sodium sulphate contains a small quantity 

 of potassium sulphate which would be much more effectively 

 ionized, at the lower temperature at which the observations 

 commenced. 



The results of the measurements with the sodium sulphate 

 are eat hered together for reference in the following table. The 

 units &c. are the same as in the table for lithium sulphate. 



Sodium Sulphate — Positive Tons. 



Substance. 



Time 

 heated. 



(ions). 



V 



(volts). 



H 



(lines per 

 em. 2 ). 



.r 



(1-0635 



cm.). 



elm 

 (E.M. 

 units). 



m 

 (H=l). 



Platinum . 







•492 



200 



4650 



100 



287 



33-7 



Na 2 S0 4 ... 



o 



•497 



2U0 



4650 



115 



363 



26-6 



Na k -S0 4 ... 



8 



•497 



200 



4650 



1-225 



413 



23-4 



>XS0 4 ... 



24 



•497 



200 



4G50 



1-25 



430 



225 



Platinum . 







•556 



200 



4700 



1425 



349 



277 



>xso 4 ... 







•556 



200 



4700 



1-475 



373 



259 



j; ]\XS0 4 ... 



13 



•556 



2C0 



4700 



1-60 



439 



22 



' Na 2 S0 4 ... 



35 



•556 



210 



4700 



1-60 



439 



22-0 



■ 1 



