Examples of index fossils. Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages).
Methyl cellulose. Methyl cellulose (or methylcellulose) is a chemical compound derived from cellulose. It is a hydrophilic white powder in pure form and dissolves in cold (but not in hot) water, forming a clear viscous solution or gel.
Soluble: can dissolve in a liquid called a solvent (often water) insoluble: not soluble solvent: The substance in greater amount as measured in moles of molecules per litre of solution. Example: ethanol + water. Sometimes the ethanol is dissolved in the water, and sometimes the water is dissolved in the water.