659 
The negative charge must be ascribed to another cause. The 
slight, but distinct, negative charges of the concentrated anorganic 
salt-solutions cannot be correlated to the volatility of these salts, *) 
as the latter, though not totally absent, is extremely insignificant. 
The existence of a transition from positive to negative charges in 
the solutions of some organic salts, naturally compels us to assume 
two components of opposite sign, whose influence on the transmission 
of electricity to the receiving disc is different. When considering the 
ions, generated by dissociation, as the carriers of the electricity of 
positive and negative sign, the droplets which strike on the disc 
may be responsible. It is possible that this new charge is superposed 
on the charge given by the electricity of condensation drops. 
That the presence of electrolytical ions in the droplets must 
occasion a complication of spray-electricity is obvious, since Lenarp’s 
experience with regard to waterfall-electricity has thrown light upon 
the significance of the electric double-layer, present in the surface 
of the drops. The outmost layer is negative, the inmost layer is 
positive. We may be sure that the influence of the former is greater 
than that of the latter, at least when the droplets impinge on the 
disc without great force. *) Still, the number of ions in the droplets 
cannot be small. When the ions of the superficial Jayers impart a 
charge to the dise when impinging upon it, the effect will probably 
be as great for the positive as for the negative sign. 
So far as we could judge, the solutions of anorganic bases and 
acids did not vield a charge in a single concentration. We examined 
the bases: potassiumhydroxid, sodiumhydroxide, ammonia liquida and 
bariumhydroxide; the acids: hydrochloric acid, sulphuric acid, nitric 
acid, phosphoric acid, hypophosphoric acid and hydrobromic acid; 
only hydrochloric acid formed an exception’). Of hydrochloric acid 
the complete molecules are volatile, but take up such a low place 
in the homologous series that they cannot be expected to produce 
a charge. Possibly, when in a gaseous form, they can yield an 
extremely weak positive charge, which may compensate the nega- 
tive charge of the faintly impinging droplets. 
1) CG. ZENGHELIS: ‘‘Ueber die Verdampfung fester Körper bei gewöhnlicher 
Temperatur’’. Zeitschr. f. Physik. Gh. 50, 219 (1904); 57, 9 and 109 (1907). — 
Ca-sulphate, Ca-phosphate, and Ca-sulphite proved slightly volatile. 
2) H. ZWAARDEMAKER and F. Hoerwinp: “On Spray-Electricity and Waterfall- 
Electricity”. Proceedings Vol. XXII. p. 429. 
3) This acid gave a strong positive charge and possessed a rather penetrating 
odour; in contradistinction to HCl and HBr it is not caustic when inhaled, even 
in a concentrated solution. 
