Vol. X, No. 6.] Measurements with Quadrant Electrometers. 235 



[N.S.] 



Table III. 



Drying agent, calcium chloride* Teak case. August 2Qth to 



September 4th. 



Hours after 

 closing. 



Leak after insulating (volts per minute). 



4 

 12 

 24 



30 



48 



60 



Quadrants only. 



Quadrants + Condenser 



0012 

 0-016 

 0-021 

 0-020 

 019 



0-019 



0-0082 



0-0073 



0-005! » 

 0-0074 



• • 



When strong sulphuric acid was substituted for the calcium 

 chloride, the improvement of the insulation was very marked 

 at first. After about six hours the leak from the quadrants 

 fell to a minimum value of about 00025 volt per minute, or 

 only one quarter of the maximum allowed. The insulation of 

 the condenser also greatly improved. The effect, however, was 

 merely temporary. After forty hours the quadrant leak ex- 

 ceeded 0-01 volt per minute, and continued to increase until 

 after three days it reached more than double that value. 



In Table IV, which shows these results for the first sixty 

 hours, a third series of values has been added, which gives the 

 leak when the quadrants were connected to the sulphur plug 

 through which the connection with apparatus outside the case 

 was made. The outer surface of the sulphur was necessarily 

 exposed to damp air. Before the measurements were made, it 

 was lightly brushed to remove spider webs, which are frequently 

 formed on all insulators not protected. 



Table IV. 

 Drying agent , sulphuric acid. Teak case. September 6th to 11th. 



Hours after 

 closing. 



Leak after insulating (volts per minute). 



4 

 12 



24 



36 



48 

 60 



Quadrants only. 



0O026 

 0-0044 

 0-0065 

 0-0095 

 0124 

 0178 



Quadrants and 

 sulphur plug. 



Quadrants and 

 condenser. 



0-0092 

 0100 

 0-0127 

 0-0140 

 0-0156 

 0-0195 



00014 



0-0018 

 0-0032 



0*0041 

 0-0054 



0O066 



