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Similarly to the carrot-carotin, the carotin from cow’s serum and 
human serum, and the xanthophyll from fowl’s serum and egg-yolk 
ean be obtained in an aqueous, colloidal solution. The latter are 
more opalescent than the carotin solution from carrots, the egg-yolk 
solution most of all. Nevertheless they pass through the filter 
unaltered, and the opalescence may be largely diminished by removal 
of the fats and of the cholesterin. t 
When extracting these aqueous colloidal solutions with ether, no 
trace of pigment passes over to the ether — as has been described 
for the carotin from Daucus carota. After the addition of a small 
amount of alcohol, the pigment will again pass over quantitatively 
into the ether layer. 
It appears, therefore, that also in aqueous colloidal protein-free 
solutions alcohol plays a liberating influence upon lipochrome. 
Precisely the same influence is exerted by a small quantity of 
alkali: if to an aqueous carotin-solution ether is added, (which by 
itself does not extract any pigment from it) and subsequently some 
drops of 10 pere. NaOH, and this solution is shaken rapidly, all 
the pigment will pass over into the ether. We feel greatly indebted 
to Prof. Krurr for investigating for us these colloidal solutions and 
for discussing the problem with us. He stated that the solutions 
presented TynDALL’s phenomenon, while under the ultramicroscope 
small particles are visible performing the Brownian movements. He 
also found that, besides by alcohol and 10 pere. NaOH, also all 
sorts of other salts, especially the bivalent and the trivalent metals 
exert the same liberating influence on lipochrome. For instance when 
we add to the colloidal carotin-solution some drops of aluminium-sol, 
and subsequently shake with ether, the lowermost layer will 
immediately be completely decolourized. 
After having searched in vain for a similar phenomenon in the 
literature to which we had access, we learnt that Wirrsrärrer had 
observed the same in aqueous colloidal solutions of chtorophyl. He 
prepared them — as we did the analogous lipochrome-solutions — 
by adding a large quantity of water to an alcoholic chlorophyl- 
solution and subsequently evaporating the alcohol in vacuo. He did 
not succeed now in extracting the chlorophyl from the aqueous 
solution with ether. Still the green pigment passed directly over into 
the ether, when he had added a small quantum of an electrolyte 
to the aqueous solution. WitisrArrer did not ascertain whether 
some drops of alcohol had any “liberating” effect. He accounts for 
the action of the salt by assuming that the dispersed chlorophy|- 
particles cannot be reached by the ether. The addition of the 
