422 



If we take a weak ^) concentralioii of salicylic acid, the inliibilory 

 iiifhieiice of alkali-earl lis far exceeds that of sodium, and, if we 

 except magiiesiiun, which is now farther removed from the alkalis 

 than calcium, strontium and barium, they form together the lyotrope 

 series more distinctly than in a higher salicylic acid concenlration '), 

 so that the series Ca, Sr <^ Ba is more distinct. (Jhlorides of zinc, 

 cadmium and lead, all bivalent in this combination, form a progressive 

 series Zn <^ Cd <^ Pb. Still strongei' is the inhibition of bismuth and 

 aluminium-compounds, both trivalent. 



The study of the influence of the chloriiies of alkali-earths becomes, 

 however, somewhat complicated, because, in a certain concentration, 

 these salts are of themselves able to impai-t a very weak charge to 

 the nebula. 



Still more than by the caliou, the action of neulral sails on the 

 electrifying |)<)wcr of salicylic acid is determined by the nature of 

 the anion. This influence has been obser>ed in a series of polassium 

 salts (Table 2). In case no potassium salt was at our disposal, as 

 with tarlaric acid, we look sodium-chloride and its action was com- 

 pared with thai of NaCl, a<'elas Na aiul KNa tartrate and interpolated 

 in the potassium-series. In this way a distinct lyotiope series is 

 obtained: CNS. N(\ < Id, CI, Hr < (J,H,(), < Tartr. < Pliosph. < 

 Citr. <Sulph. 



The univalent acids of this series present inter se smaller differences 

 than the bivalent tartrates, the neutral phosphates, the citrates, and 

 the sulphates. Still we can observe in conceuti-atious of 0,001 n, 

 0,002 u, and 0,005 n more marked dilFei-ences between the univalent 

 anions themselves. Sulphohydrocyanic acid causes the least inhibition 

 of the charge of .salicylic acid; sulphate and citrate act most strongly ; 

 the differences between these two extremes arc great. 



In spraying solutions of salicylic acid, containing neulral salts, 

 the anion is the principal agent in inhibiting the charge of this 

 acid, so that the lyotrope series are miudi more pronounced for 

 the anion than for the cation; in those of the cations the terms of 

 every group of metals are distinguishable, but there is no regular 

 succession of those groups. In order to estimate the natuie of these 

 differences, obtained with a negative sign, we ascertained whether 

 acids, giving a positive sign, such as acetic acid, behave in a similar 

 way. The charge of acetic acid was increased by the addition of 

 neutral salts, so that here, not the factor of inhibition, as was the 

 case with the negative phase of salicylic acid, but that of the increase 



1) At 0.0005 n. 



2) 0.00 1 n. 



