Degree of acid found in a given paper measured by the pH factor. pH is measured from 0-14. From 0-6 is considered acid, 7 representing neutral, from 8-14 alkaline.
The quality, state or degree of being acid. In lubricating oils, acidity denotes the presence of constituents whose concentration is usually defined in terms of a neutralisation number. The constituents vary in nature and may or may not markedly influence the behaviour of the fluid.
The level of hydrogen ion concentration in a solution. Acidity is measured on the pH scale. The pH scale is a logarithmic scale. The majority of readings go from 1 (very high acidity) to 14 (very high alkalinity).