Anhydrous ferric chloride is a covalent compound FeCl 3 that dissolves in organic solvents as well as in water. It forms bright-yellow crystals as the hexahydrate. Anhydrous ferric sulphate is colorless, but crystals of Fe 2 (SO 4 ) 3 ·9h 2 O are yellow. Ferric ammonium alum, FeNH 4 (SO 4 ) 2 ·12H 2 O is pale violet, the typical ferric color in solution. This is an "alum" without aluminium, the iron standing it for it. It is a mordant because of the gelatinous ferric hydroxide formed when a solution is make alkaline. There are also ferric potassium alum, also colorless or violet, and ferrous ammonium sulphate, which forms blue-green crystals of the hexahydrate.
Page Object is a Design Pattern which has become popular in test automation for enhancing test maintenance and reducing code duplication. A page object is an object-oriented class that serves as an interface to a page of your AUT. The tests then use the methods of this page object class whenever they need to interact with the UI of that page. The benefit is that if the UI changes for the page, the tests themselves don’t need to change, only the code within the page object needs to change. Subsequently all changes to support that new UI are located in one place.