| 摘要 |
PURPOSE:To permit alum or aluminum sulfate to indicate its adsorbability of basic gas by impregnating the alum or aluminum sulfate with a substance changeable in color in response to a pH change. CONSTITUTION:When alum and aluminum sulfate are used as an adsorbing agent in combination with the other adsorbing agent, the alum and aluminum sulfate are impregnated with a substance changeable in color in response to a pH change. Natural and artificial coloring material, e.g. a pH indicator having a transition interval of at most 8 in pH value may be used as the color- changeable substance. |
