300 



Mr. C. S. Wright on Variations in the 



From the following calculations it will be seen how tne 

 different constants of the instrument were used in making a 

 determination of the value of " q " for the air contained in a 

 certain lead receiver. 



Reading of 

 Compensator distance. 



Time. 



Remarks. 



Scale Divisions (cms.). 



min. 



sec. 





•254 



•508 



1 

 1 



02 

 45 



Date of Experiment, Mar. 

 19th, 3 p.m.. 



•762 

 1-016 



o 



3 



29 

 15 



Locality. — Basement of 

 Physics Laboratory. 



1-270 

 1-524 



4 

 4 



05 



48 



Potential applied to Cylin- 

 der =+85 volts, 



1-778 

 2-032 



5 

 6 



33 



17 



Potential applied to Com- 

 pensator — -j-13'0 volts. 



2-286 



7 



05 



Vol. of Cylinder =26700 ccs. 



3-302 



8 



C9 





From Table II. the charge annulled per volt on the com- 

 pensator" tube = '00501. 



Therefore total charge annulled in 489 sec. was 



•06513 e.s. units. 



Thus -06513 = 3-4 x 10~ 10 x q x 489 x 26700, 



or 2 = 14*67, assuming the charge on an ion to be 



3-4 x 10- 10 e.s.u/s. 



As a check on the values for " q " obtained for the ioni- 

 zation in the metallic receivers with this instrument, deter- 

 minations were alternately made in the laboratory with the 

 Wilson electroscope and with a sensitive Dolazelek electro- 

 meter. The method of using the latter is shown in fig; 4. 

 With this arrangement it was possible, by simply removing 

 the receiver, unscrewing the electrode, and slipping a metal 

 cap over the earthed tube E, to allow for any charge acquired 

 by the electrodes and the free quadrants through possible 

 defective insulation of supports or by conduction through 

 the air in any part of the apparatus, other than through that 

 in the metal receiver. 



The capacity of the instrument was found by measuring 

 in each determination of the conductivity, the rate of motion 

 of the needle both with an auxiliary condenser of known 

 capacity attached to the electrode, and without. 



