On the Colorimetric Characteristic of Colority Standard Solutions Used in the Determination of Colority of Water

A comparative study on the absorption spectra and the colorimetric characteristic of Pt(Ⅵ)-Co(Ⅱ) solution and Cr(Ⅵ)-Co(Ⅱ) solution was made to prove the feasibility and rationality of the use of the later instead of the former solution as standard in the determination of colority of water. It was found that in spite of the presence of difference in colorimetric factors and of the metamerism character, the difference of color between the 2 standard solutions was hardly be distinguished by naked human eyes, and that the errors due to the use Cr(Ⅵ)-Co(Ⅱ) solution as standard were within the tolerable values. However, it was also found that the Cr(Ⅵ)-Co(Ⅱ) standard solution was less stable than the Pt(Ⅳ)-Co(Ⅱ) standard solution against illumination and temperature, hence attention should be paid to the storage and time of expiration of the Cr(Ⅵ)-Co(Ⅱ) solution in use.