Per Teodor Cleve

Per Teodor Cleve, born on February 10, 1840, in Stockholm, was a distinguished Swedish chemist, biologist, mineralogist, and oceanographer. He made significant contributions to the field of chemistry, most notably through his discovery of the chemical elements holmium and thulium. Cleve's academic journey began at Uppsala University, where he earned his Bachelor of Science in 1863 and his PhD in 1868.

After completing his doctorate, Cleve took on the role of assistant professor of chemistry at Uppsala University, eventually rising to the position of professor of general and agricultural chemistry. His groundbreaking work in 1874 proposed that didymium was actually composed of two distinct elements, a theory that was later validated in 1885 by Carl Auer von Welsbach's discovery of neodymium and praseodymium.

In 1879, Cleve's research led to the identification of holmium and thulium, further solidifying his reputation in the scientific community. He also contributed to the understanding of aminonaphthalenesulfonic acids, which are now commonly referred to as Cleve's acids. His focus shifted towards biological studies in 1890, where he developed a method for determining the age and order of late glacial and postglacial deposits based on diatom fossils.

Cleve's influence extended into oceanography, where he authored a seminal text that has been referenced by many in the field. His life came to a close in 1905 at the age of sixty-five, leaving behind a legacy of scientific inquiry and discovery.