Foam formation of aqueous solutions of both alcohols and electrolytes are accounted under the assumption of parallelism between the foam formation and the energy required to remove the unit area of adsorption layer from the surface. The maximum observed at the concentration of about 45 % for alcohol solutions are also accounted. The relative relation between some electrolyte solutions is accounted under the assumption that the thickness of adsorption layer increases in the sequence of lyotropic series of anions: Cl−, NO3−<SO4−−<OH−.
Wettabilities of purified paraffin, crude paraffin, palmitic acid and cetyl alcohol are measured towards aqueous solutions of potassium, calcium, aluminum and thorium salts. It is pointed out that palmitic acid surface becomes remarkably wettable by the contact with aqueous solution of thorium or aluminum salt even in the extreme dilution. Such an increase in wettability can neither be explained simply by ζ-potential change of the palmitic acid surface in those solutions nor overturning of the molecule in surface layer. Alternative explanations are suggested.
Contrary to the general belief, the author confirmed the presence of iron in the filtrate from the carbonate fusion melt of brown coal ash or rock. The interference leading to lower results due to ferrous iron is more serious than that due to ferric iron as the vanadate ion is reduced to vanadyl when acidified with sulfuric acid. Consequently the oxidizing procedure with potassium permanganate is required to diminish this undesirable effect. If a considerably large amount of iron is present, it is necessary to make a preliminary separation of iron from vanadium in a slightly alkaline medium with oxine and chloroform. Hence the vanadium determination can be carried out following the directions recommended. The separation method proposed by the author was spectroscopically tested and it was shown that a larger amount of iron can be separated without any trace of vanadium being carried down. However this procedure is not always required and can be eliminated as the quality of the sample to be tested varies. The interference due to the presence of ferric iron can be reduced to some extent, even when a considerably large amount of iron is present in the solution prepared for the color comparison, by warming it and keeping it on standing for several minutes. Some experiments on the determination of the vanadium content of various samples were also conducted, with the results that the modified method can be used as well with a considerable accuracy.
The colorimetric method of determining chromium in silicate rocks with diphenylcarbazide has the defect resulting in a distinct tendency for producing slightly lower figures as recognized already. After a thorough study of the method the author pointed out the possible sources for the serious errors, especially for those which give negative results. Thus the oxidation method in an alkaline medium was proposed, which was compared with the widely used old method. The accuracy and reproducibility of this method are not entirely satisfactory but so far it will serve as the most accurate method. The content of chromium in brown coal in Japan determined by this oxidation method with sodium peroxide will be reported in a later communication.