Abstract: A harness indicator is highly reactive to a trace amount of Ca2+, and is slow to degrade in a high temperature environment of greater than 50° C. In one embodiment, the hardness indicator contains EBT, a pH buffer, and a masking agent as main components, and an admixture of Mg-EDTA. In another embodiment, the hardness indicator contains EBT, a pH buffer, and a masking agent as main components, and an admixture of anhydrous Mg-EDTA. In another embodiment, the hardness indicator contains EBT, a pH buffer, and a masking agent as main components, and an admixture of anhydrous Mg-EDTA and potassium sorbate. In a further embodiment, the hardness indicator contains EBT, a pH buffer, and a masking agent as main components, and an admixture of Mg-EDTA and potassium sorbate. In a further embodiment, the hardness indicator contains EBT, a pH buffer, and a masking agent as main components, and an admixture of potassium sorbate.

Abstract: A liquid feeding apparatus quantitatively feeds a liquid by pressing and clogging an elastic tube between a press roller and an arc-shaped guide portion through rotational motion of the press roller. The liquid feeding apparatus includes a main unit in which the press roller is provided, and a liquid cassette which accommodates a liquid cartridge. One end of the elastic tube is connected to a reservoir for the liquid to be fed, and the other end is connected to a check valve. The liquid cassette is removably fitted to the liquid feeding apparatus so that the elastic tube is subject to pressing action of the press roller.