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.
In my research on cellulose, I had to dissolved cellulose in some solvents in order to characterize it. I prepared cellulose from cotton linters and purified it at the highest level. I needed to control the MW of cellulose for synthesis of cellulose chemical derivatives (i.e., carboxy methyl cellulose, a.k.a. CMC).