116 C. Ba?'us — Ionization of Water Nuclei. 



distinctive definition is adopted. Both occurrences are similarly 

 reduced. The present case of river water is one in which there 

 is an excess of negative over positive nuclei. In other cases 

 (pure water) the reverse may be the case, or again there may 

 be an absence of an excess of either sign. If the nuclei were 

 without charges, however, the medium would not conduct 

 (§ 14). In a condenser positive or negative charges are soonest 

 dissipated according as there is excess of negative or positive 

 nuclei in the medium, respectively. 



12. Number of Electrons. — Assuming each nucleus to have 

 its own specific velocity, independent of the potential gradient 

 of the electric field, and to carry one electron, the number of 

 nuclei per cub. cm. was preliminarily computed as n = G 

 (dE / dt) — / 16*7 eV, where G is the capacity, dE / dt the 

 leakage of the condenser and appurtenances in practical units, 

 e the charge in coulombs on each, and "Fthe volume of nucleated 

 air, in liters, entering the condenser per minute. Attributing 

 the larger current from positive charges in the condenser to an 

 excess of negative ions, the average current was assumed to 

 represent the case of an equal number of ions of either sign, 

 i. e., when the excess of negative ions has been removed. The 

 values so obtained for this average current if each nucleus carries 

 but one electron (which cannot be the case) are 



n z= 1-0 X 10 6 

 1-3 

 1-5 



The increase is due to the gradual wear of the jet, whereby 

 fresher nuclei are conveyed into the condenser, as explained. 



13. Number of Nuclei. — With this large number of ions, 

 the number of nuclei as estimated from the coronas is in sharp 

 contrast. There being less than 10 4 and more than 10 3 original 

 nuclei, the charge of each must be greater than 100 and less 

 than 200 electrons, agreeing that the whole charge is carried 

 bv the nuclei, for which there is good reason as the currents 

 and the number of nuclei increase together with the efficiency 

 of the jet. 



If each nucleus is to carry the charge stated, its potential 

 will still be of relatively small value, as was shown in §6. 



14. Ohm's Law. — For potential differences above 10-20 

 volts or gradients of 15-30 volt/cm., the currents in the con- 

 denser are roughly constant. Below this the current begins to 

 decrease with the gradient, without, however, quite vanishing, 

 even when the potential difference is zero. In the above 

 tables, or chart No. 4, for instance, the average current for a 

 charge at 



