Maganese - an element sometimes found dissolved in ground water, usually with dissolved iron but in lower concentrations; causes black stains, and other problems similar to iron.
Magnesium - one of the elements making up the earths crust, the compounds of which when dis-solved in water make the water hard. The presence of magnesium in water is a factor contributing to the formation of scale and insoluble soap curds.
Manganese Greensand - greensand which has been processed to incorporate in its pores and on its surface the higher oxides of manganese. The product has a mild oxidizing power, and is often used in the oxidization and precipitation of iron, manganese and/or hydrogen sulfide, and their removal from water.
Media - the selected materials in a filter that form the barrier to the passage of certain suspended solids or dissolved molecules.
Medium - singular form of media.
mg/l - The abbreviation for milligrams per liter.
Micron - a linear measure equal to one millionth of a meter.
Micron Rating - the term applied to a filter to indicate the particle size of suspended solids that will be removed. As used in industry standards, this is an "absolute", not "nominal" rating.
Milligram per liter - a unit concentration of matter used in reporting the results of water andwaste-water analyses. In dilute water solutions, it is practially equal to the part per million, but varies from the ppm in concentrated solutions such as brine. As most analyses are performed on measured volumes of water, the mg/l is a more accurate expression of the concentration, and is the preferred unit of measure.
Millimicron - a unit of length equal to one thousandth of a micron, often used to express the wave-length of colors of visible light in colormetric analytical procedures. The symbol for the millimicron is "mu".
Mineral - a term applied to inorganic substances, such as rocks and similar matter found in the earths strata, Minerals normally have definite chemical composition and crystal stucture. The term also applied to matter derived from minerals, such as inorganic ions found in water.
Mole - the molecular weight of a chemical compound expressed in grams.
Molecule - the simplest combination of atoms that will form a specific chemical compound; the smallest particle of a substance which will still retain the essential composition and properties of that substance, and which can be broken down only into atoms and simpler substances.
Most Probable Number - MPN - the term used to indicate the number or organisms which, according to statistical theory, would be most likely to produce the results observed in certain bacter-iological tests,; usually expressed as a number of 100 ml of water.