419 



also shows Ihe positixe pari of the charge of salicylas luitiiens, and 

 gives the h)garithnis of llie strengths of (lie solntions along Ihe 

 abscissa. 



Addition ot sodinin-chloridc lo these strong solnlions of salicylas 

 natricns had no more inflnence npon these positive charges than an 

 addition of sngar had. On the other hand, nnder the inflnence of 

 the same substances, changes were brought about in the negative 

 charge of weakei- solutions, as Ihe figure illustrates. 



The charge of the salicylic acid itself also first increases with the 

 rise of the concentration, afterwards it decreases (Fig. 2), to rise 

 above the zero-line a little before the point of saturation. The effect 

 of salt and sugar upon Ihe charge is very slight at this moment, 

 just as it is with salicylas natricus; after crossing the zero-line, 

 however, it comes forth again, but in a positive sense. 



The facts .just described or illusti-ated seem a chaos at first sight. 

 Some order is discovered, when we reflect that in dilute solutions, 

 which are the only solutions we have to deal with in spraying, 

 cations and anions act separately. The effects of cations and anions 

 are superposed. In spraying salicylic acid and caproic acid (fig. 2 

 and 3) only the anion is of importance. In spraying salicylas natricus 

 there is an action of salicylic acid and sodium; in the combined 

 spraying with salts and sugar there is a combination of effects of 

 all cations and anions present. 



It is not possible as yet lo account for these phenomena; they 

 belong, indeed, to the fleld of physics proper. Provisionally we are 

 able lo state only that strong solutions of salicylas natricus yield, 

 on spraying, dense nel)ulae, forming large droplets; the latter are 

 so large that sodium-chloride and sugar particles do not appai-ently 

 affect them. When the salicylas natricus solution is diluted ihe charge 

 is affected first by the sodium-chloride and only mnch later by 

 the sugai'. 



It is not clear why with sodium-chloride this influence reveals 

 itself first in a negative sense, and, with a w^eaker salicylas natricus 

 solution in a positive sense, while with sugar that influence man- 

 ifests itself later and oidy in a negative sense. This negative sodium- 

 chloride phase is altogether lacking with salicylic acid, while the 

 charge-curves of this acid with and without sugar run together for 

 some time in the neighbourhood of the zero-line (as was the case 

 with salicylas natricus) and after this yield a positive sugar-effect. 



Considering these results, it was interesting to ascertain whether 

 there are also other substances presenting charges of opposite signs 

 in different concentrations. We fixed upon the acids of the fatty 



