[1] He graduated with honors from the Faculty of Physics and Mathematics at the Imperial University of Warsaw (1882) and continued his education at the St. Petersburg Institute of Communication Engineers.

During his career as a professor, he supervised some of the first diploma theses on the subjects of electric power systems (tramway, railway, and hydropower) and electrification of rolling stock repair plants.

He also conducted comprehensive experiments in the field of optics and light waves (concerning mainly diffraction, wavelengths, and dispersion).

[2][8] His works on the Polish Reformation movement are valued mainly due to the large number of primary sources employed, many of which are now lost or no longer available.

[2] Among his most important publications are: "Zbory i senatorowie protestanccy w dawnej Polsce" (1904)[2] (Protestant churches and senators in old Poland) and "Zbiór pomników reformacji kościoła polskiego i litewskiego" (Monumenta Reformationis Polonicae et Lithuanicae) (1911).

Merczyng, in cooperation with Jan Jakubowski, mathematically analyzed the Radziwiłł map of the Grand Duchy of Lithuania.