ANDREW LAMBERT PHOTOGRAPHY / SCIENCE PHOTO LIBRARY ANDREW LAMBERT PHOTOGRAPHY / SCIENCE PHOTO LIBRARY
Litmus paper test. Litmus paper changes colour in acidic or alkaline conditions. It is a mixture of lichen pigments. It turns red in acids (left) and blue in alkalis (right). Distilled water (H2O, centre) is neutral and does not cause a colour change.
Model release not required. Property release not required.