The main treatment objects in coagulation stage are suspended organisms and colloidal impurities in water. The perfection of coagulation process has a great influence on subsequent treatment, such as sedimentation, filtration and chlorination, so it is a very important link in Water Treatment process. Polyaluminum chloride and polyferric sulfate are often used in most waterworks.
Tint reducing power, compared with standard samples
This article discusses the discovery of phosphorescent lithopone on watercolor drawings by American artist John La Farge dated between 1890 and 1905 and the history of lithopone in the pigment industry in the late 19th and early 20th centuries. Despite having many desirable qualities for use in white watercolor or oil paints, the development of lithopone as an artists’ pigment was hampered by its tendency to darken in sunlight. Its availability to, and adoption by, artists remain unclear, as colormen's trade catalogs were generally not explicit in describing white pigments as containing lithopone. Further, lithopone may be mistaken for lead white during visual examination and its short-lived phosphorescence can be easily missed by the uninformed observer. Phosphorescent lithopone has been documented on only one other work-to-date: a watercolor by Van Gogh. In addition to the history of lithopone's manufacture, the article details the mechanism for its phosphorescence and its identification aided by Raman spectroscopy and spectrofluorimetry.
4.3 g/Cm3
