SINCLAIR STAMMERS / SCIENCE PHOTO LIBRARY SINCLAIR STAMMERS / SCIENCE PHOTO LIBRARY
Comparison of the appearance of columns of water (dyed red) and mercury poured into wide diameter tubes. The reason why the meniscus (surface) of water curves upwards whilst that of mercury curves downwards may be explained by the difference between the adhesive and cohesive properties of water & mercury. Cohesive forces exist between molecules of the same substance, whereas adhesive forces bind molecules of different substances. Adhesion of water molecules to glass is stronger than their own cohesion - consequently, the meniscus (surface) curves upwards. Conversely, cohesion of mercury is greater than its adhesion to glass and its meniscus curves downwards.
Model release not required. Property release not required.