For total alkalinity testing, N/10 HSO is used by hydrologists along with phenolphthalein indicator. The phenolphthalein molecule is colorless, and the phenolphthalein ion is pink. Such applications have largely been replaced by methods using phenolphthalein/hydrogen peroxide and luminol. The oxides exhibit basic character&colon; they turn phenolphthalein red and litmus, blue. Ferroxyl indicator is a solution containing potassium hexacyanoferrate(III) and phenolphthalein. They exhibit basic character&colon; they turn phenolphthalein pink and litmus, blue. It can be found by means of an indicator, for example phenolphthalein or methyl orange. It is closely related to bisacodyl, sodium picosulfate, and phenolphthalein. Bromophenol blue is structurally related to phenolphthalein (a popular indicator). When a 1% phenolphthalein solution is applied to normal concrete, it turns bright pink. This method is used to synthesize phenolphthalein and thymolphthalein. Another common presumptive test is the Kastle-Meyer or Phenolphthalein test. Phenolphthalein is used to monitor deliming pelt cross-sectional progress. In a similar application, some spackling used to repair holes in drywall contains phenolphthalein.