| 摘要 |
PURPOSE:To provide a pH indicator which is free from secular change in coloration, can be preserved for a long time and permits simple and accurate measurement for pH of roughly neutral fertilizers and soil as well by mixing a mixture of 1 or >=2 kinds of general pH indicators with >=1 kind of polyhydric alcohols. CONSTITUTION:An indicator prepd. by mixing >=1 kind of general pH indicators with 1 kind of polyhydric alcohols, for example, by mixing 15pts.vol. 0.2% methyl orange, 15pts.vol. 0.4% methyl red. 60pts.vol. 0.2% bromothymol blue and 60pts.vol. propylene glycol uniformly to prepare a pH indicator is used. Since the solvent is hard to evaporate, there is no secular change in coloration, and accurate measurement by easy colorimetry with color gradiation charts is made possible. If the indicator prepd. by dissolving a suitable amt. of KCl further in said indicator is used for measuring the pH of soil, the H ions adsorbed in viscouse minerals are extracted and the pH is measured easily. |
