Wilhelmy

Wilhelmy is a German surname derived from the given name Wilhelm (William). It is found in German-speaking regions and has appeared in historical and contemporary contexts, including among scientists and engineers who contributed to chemistry, physics, and related fields.

In science and instrumentation, the name Wilhelmy is most widely associated with the Wilhelmy plate method and the Wilhelmy balance, both used to measure surface tension and related interfacial properties. The plate method involves a plate of known surface area and wetted perimeter that is suspended from a microbalance and dipped into a liquid. The force measured by the balance relates to the liquid’s surface tension γ through the relation F = γ P cos θ, where P is the wetted perimeter and θ is the contact angle at the liquid–solid interface. When the liquid wets the plate well (small θ), γ can be estimated from the measured force and the known perimeter. The method is applicable to liquid–gas, liquid–solid, and some liquid–liquid interfaces, and it can be used to study dynamic surface tension with time.

The Wilhelmy balance apparatus is used in laboratories to implement the plate method, providing a sensitive means of detecting small changes in surface tension and interfacial properties. The term Wilhelmy also appears in biographical and historical records as a family name.

See also: Wilhelmy plate, Wilhelmy balance.