Teaching

At the time of the founding of Belgrade University in 1905, he was elected as an associate professor. He was deeply offended by this decision and on his own request retired early, on May 26 of 1905.^{[citation needed]}

In 1895, Sima Lozanić, a fellow chemist, drafted a secondary textbook for chemistry, which Leko was asked to review. Leko put forward 36 objections to the draft. Leko and Lozanić argued the points for 2 years through correspondence to The Educational Gazette, at which point the Gazette refused to publish any more argument on the matter. One of the major issues was Lozanić's classification of N3 as an allotropic modification of Nitrogen.^[2]

His teaching posts included:

• 1880-1884: Professor of Chemistry in Belgrade's secondary schools
• 1881-1894: Professor of Chemistry at the Military Academy of Belgrade^[1]
• 1894-1905: Professor of Chemistry at the University of Belgrade (then Belgrade Higher School)^[3] (part-time from 1894, made full Professor 1899)^[4]
• 1884 became a member of Serbian Academic Society
• 1892 became a member of Serbian Royal Academy
• 1902/3 and 1903/4 was the Dean of then Great School
• 1904-1920 state chemist and superintendent of State's Chemical Laboratory in Belgrade

Serbian Chemical Society

In 1897, Leko was the Manager of the Government Chemical Laboratory in Belgrade.^[5] The 3rd International Congress on Applied Chemistry was scheduled to be held in 1898, so the Main Committee for that Congress wrote to Leko suggesting a Serbian committee be organised to stimulate interest in the Serbian academic community.^[5]

The first meeting of the Serbian Chemical Society was held on 15 November 1897 in Belgrade. The society did not create the office of President until 1904, at which time Leko was appointed as President of the Serbian Chemical Society. He was replaced in approximately 1907 at his own request, given he would be absent from the country while performing the role of President and Chief Manager of the Balkan Exhibition in London.^[5]

During the period he was president, Dr Leko wrote 68 papers for the Society. Leko also authored a report on the Society's activities: 'A Contribution to the Development of Applied Chemistry in the Kingdom of Serbia' (1906).^[5]