Earwax of bacteria. Cerumen has been found to reduce the viability of a wide range of bacteria, including "Haemophilus influenzae", "Staphylococcus aureus", and many variants of "Escherichia coli", sometimes by as much as 99%. The growth of two fungi commonly present in otomycosis was also significantly inhibited by human cerumen. These antimicrobial properties are due principally to the presence of saturated fatty acids, lysozyme and, especially, to the slight acidity of cerumen (pH typically around 6.1 in normal individuals). Conversely, other research has found that cerumen can support microbial growth and some cerumen samples were found to have bacterial counts as
Chemical substance them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature". In geology, substances of uniform composition are called minerals, while physical mixtures (aggregates) of several minerals (different substances) are defined as rocks. Many minerals, however, mutually