28 



A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



TABLE 9. CHARGES OF WATER NUCLEI. dV/dt=2 LIT./MIN. CAPACITY 409 cm. 



ELECTROMETER DEFLECTIONS, s. 



Corona on immediate condensation: white, crimson, green, being No. 9 with about 

 150,000 nuclei per cm 3 . 



* Smaller electrometer factor. 



The average number of ions in those cases where positive and negative 

 charges were observed are again found to be slightly larger than the preceding, 

 due to further enlargement of the holes of the jet, whereby fresher nuclei are 

 put into the condenser. 



The table states that the most advanced corona obtainable did not exceed 

 the middle green-blue-purple type of my series, 1 throughout the whole of the 

 work. It makes little difference whether the corona is taken instantly or a 

 few minutes after the jet is shut oft. The number of nuclei therefore is constant 

 throughout the experiments, being about io s . 



13. Jets self -shattering or impinging on water. To make sure preliminarily 

 that no induced radioactivity is demonstrable within the limiting potentials to 

 be employed, the experiments of the following table 10 were devised. Here the 

 large vertical jet (No. 9, with 18 needle holes, discharging about 8 liters per 

 minute into the water below and violently churning it) was put in action, and 

 the air above the water in the aspirator discharged into the condenser by the 

 rise of level due to the jet. The table shows the insulation before and after the 

 passage of nucleated air, for different potentials in the condenser. The data 

 are given in centimeters of deflection per minute (ds/dt). Hence the currents 

 are i=ds/dtX2.4X^o' 11 amperes. 



1 Phil. Mag. (6), in, pp. 8091, 1902, corrected in Am. J., xvi, 1903, p. 325, and in 

 Boltzmann's Jubelband, p. 204, 1904. Cf. Chap. VI. 



