Proposed the existence of a fundamental unit of electrical charge in electrolysis.

Invented the Crookes Radiometer, demonstrating radiation pressure and thermal gas transpiration.

Established transverse wave optics foundation for electromagnetic field theory.

Discovered Gallium (Ga, Z=31), confirming Mendeleev's predicted Eka-Aluminum.

In 1876, German physicist Eugen Goldstein coined the term "Cathode Rays" (Kathodenstrahlen) to describe light beams emitted from negative electrodes in vacuum discharge tubes, prefiguring the discovery of the electron.

Derived the Phase Rule (F = C - P + 2) governing multi-phase chemical equilibrium.

Initiated experimental investigations into spark gap electric discharge phenomena.

Introduced discrete energy elements epsilon into combinatorics to calculate probability.

Derived S = k_B log W connecting thermodynamic entropy directly to microstate multiplicity.

In December 1878, American mathematical physicist Josiah Willard Gibbs completed his masterwork formulating Gibbs Free Energy (G = H - TS), the Phase Rule, and chemical potential.

In 1878, American astronomer Samuel Pierpont Langley invented the bolometer, an ultra-sensitive electrical sensor capable of measuring temperature variations of 1/100,000th of a degree Celsius.

Demonstrated cathode ray magnetic deflection, shadow casting, and momentum in Crookes tubes.