639 



basicity ot" tlie anions but according to their ljotfO|)ic strength. 

 Ljotropieally SO^ and PO^ are nearly eqnai, l)nt CI has a sliarply 

 different position, contrarj- to the sequence of basicity. Operating 

 with neutral salts we thei-efore seem to have missed the parallelism 

 Reinders found with acids and alcalies. 



One is inclined to consider the transition of the dye from the 

 water to the alcohol layer as the process of salting out, so common 

 to the emuisoids. Indeed the CNS ion. the extreme term of the series, 

 caused precipitation after 24 hours, ^) when brought to the dye 

 solution in water to an amount of 4 millimol p. L., (the same 

 concentration as the electrolytes had in the water-layer before the 

 alcohol was added). It is evident that dyes, showing in many 

 respects the properties of lyophylic colloids, are salted out by 

 electrolytes in the sequence of the lyotropic series ; and it is therefore 

 easy to understand that lyotropic influences (it would be preferable 

 to say liydrotropic here) cause a distribution of the dye in such a 

 way, that the most active ion causes the greatest transition of the 

 dye to the alcoholic layer. 



4. Our knowledge about the influence of neutral salts on dyeing 

 is however small. The dissertation of Baccio Beccari '), a pupil of 

 Pelet, is the only systematical investigation we know, and even 

 in this methylene blue is the only basic dj^e and Na,SO^ and 

 Na,HPO^ are the only neutral salts considered. The sequence in 

 which that dye is taken up is this: solution in water — solution 

 containing Na,SO^ — solution with Na^HPO^, all according to 

 Pelet's theory '). 



As we thought it interesting to know whether lyotropic phenomena 

 had any influence on the process of dyeing, we have made investi- 

 gations about the quantity of dye adsorbed in the presence of the 

 sodium salts of PO,, SO,. CI. Br or NO,. 



For dyes we took methylene blue, crystal violet and auramine ; 

 bloodcoal was the adsorbens. In each series the initial concentration 

 and the amount of coal were exactly equal. The concentration at 

 the end of the process was estimated by Pelet and Garuti's volume- 



1) When in contact with isobutylic alcohol, a precipitate could only be seen 

 after some weeks at the boundary of the layers. 



'^) Diss. Lausanne: Etude des relations des phenomènes de teinture et d'adsorb- 

 tion. (Florence 1908;. 



^) Investigations of A. Wild, mentioned in Pelet Julivet's book p. 98, show 

 the following sequence in the case of methyleneblue : HoO — Gl — SO4— PO4. 



