(1) The influence of the temperature of preparation on the forma？ion of platinum-carbonyl sol from the chloroplatinic acid solution by the action of carbon monoxide were investigated at various temperatures between 5° and 80°C., together with the influence of the concentration of solution ranging from 0.01 to 0.1% with respect to H2PtCl6·6H2O. (2) Stable sols having a tinge of red with a dash of purple may be produced from the solutions of concentrations between 0.01 and 0.08% in a wide range of temperature; sols of various colours such as brownish red, brown as well as dark brown may be formed in the same limits of concentration as the above at the elevated temperatures. (3) Sols tinged with red slightly inclining to purple may be obtained, though unstable, from the 0.1% acid solutions only at lower temperatures. (4) The colouration effects above-mentioned were spectroscopically analyzed with the Nutting’s spectrophotometer, and it was found that the extinction curves for the sols tinged with red reach a maximum at about 540 mμ, while those for the sols with a tinge varying from brown to black decrease monotonously with the increasing wave-length.
The molecular compounds of various nitrobenenes with naphthylamines, naphthols, and naphthalene were systematically compared and the compound formations discussed by means of solid—liquid phase diagrams.