A Lippmann electrometer is a device for detecting small rushes of

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The movin ...

and was invented by Gabriel Lippmann in 1873.Fritz Scholz
''Electroanalytical Methods: Guide to Experiments and Applications''
2nd ed., Springer, 2010. The device consists of a tube which is thick on one end and very thin on the other. The thin end is designed to act as a

capillary A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the body: ...

tube. The tube is half-filled with mercury with a small amount of dilute sulfuric acid above the mercury in the capillary tube. Metal wires are connected at the thick end into the mercury and at the thin end into the sulfuric acid. When the pulse of electricity arrives it changes the surface tension of the mercury and allows it to leap up a short distance in the capillary tube. This device was used in the first practical ECG machine which was invented by

Augustus Desiré Waller Augustus Desiré Waller FRS (12 July 1856 – 11 March 1922) was a British physiologist and the son of Augustus Volney Waller. He was born in Paris, France. He studied medicine at Aberdeen University, where he qualified in 1878 and obtained h ...

References

Electrophysiology Measuring instruments {{Physics-stub

See also

References