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.
The water solubility of some iron compounds increases at lower pH values. Other iron compounds may be more water soluble than the examples mentioned above. Iron carbonate has a water solubility of 60 mg/L, iron sulphide of 6 mg/L, and iron vitriol even of 295 g/L. Many iron chelation complexes are water soluble.Usually there is a difference between water soluble Fe 2+ compounds and generally water insoluble Fe 3+ compounds. The latter are only water soluble in strongly acidic solutions, but water solubility increases when these are reduced to Fe 2+ under certain conditions.he water solubility of some iron compounds increases at lower pH values. Other iron compounds may be more water soluble than the examples mentioned above. Iron carbonate has a water solubility of 60 mg/L, iron sulphide of 6 mg/L, and iron vitriol even of 295 g/L. Many iron chelation complexes are water soluble.