The previous paper (Part I) was reported on the yellowing of tyrosine, tryptphane and their mixed solution exposed to light within the range of 20_??_80 hrs.
In the present paper, an attempt is made to study on the yelowing of each solution mentioned obove, by exposing to light for various time of 0_??_20 hri., and the following results are obtained.
By comparison with the spectral optical density of each solution, it is found that the coloring processes of the mixed solution by light may be classified into the fallowing three periods;
In the first period (0_??_5hrs.), the coloring of tryptphane are scarcely recognized under the influence of tyrosine.
In the second period (5_??_10hrs.), the sensitization with respect to the visible light absorption appears rapidly at the short wave side.
In the third period (10_??_20hrs.), it proceeds slowly at the long wave side.
Considering the above facts from the colorimetrical point of view, the dominant wavelength of the mixed solution shifts from 573.0 to 575.5mμ.
The coloring phenomena of the silk stuffs are similar with the mixed solution: both the dominant wavelengths are between those of tyrosine and tryptphane.
In regard to the relation between transmittance T(%) of the mixed solution and exposure time t(hr), the following formulae, which bear the same relation to the case of that by exposing for a longer time, are obtained.
Where the values of k; depending on the wavelength, vary 3 to 4.