Career
Thanks to the grant she received in connection with her master's degree, in 1909 Leslie was able to become a research assistant in Marie Curie's Institute in Paris where she remained until 1911. In the laboratory, under the guidance of André Debierne, she worked mainly with Lucie Blanquiès, Eva Ramstedt and Ellen Gleditsch, with whom she shared accommodation in a nearby pension. She wrote several articles in French on extraction of new elements from thorium and their properties. She had many contributions on the "emanation of radioactive thorium", and her minute measurement practices allowed her to provide robust data on the half-life, atomic weight and activity of the products of the disintegration series of thorium ("the thorium series") and actinium ("the actinium series"). These contributions were the latest in the developing field of radioactivity. She collaborated with and became long term friends with Polish-Russian physicist Jadwiga Szmidt during their time at the Curie Institute.
Upon recommendation from Curie, she then moved to Manchester to work with Ernest Rutherford at the Physical Laboratory of the Victoria University (1911–1912). In particular, she undertook research on the properties of thorium and actinium, demonstrating that "products from different decay series were probably radon".
After leaving Manchester she worked as a high school teacher in West Hartlepool (1912–1913) and as an assistant lecturer and demonstrator in chemistry at the University College in Bangor, Wales (1914–1915).
During World War I Leslie was hired in 1915 by the government to work as a chemist on explosive production, concentrating on nitric acid, for WWI efforts. She was promoted to head the research lab at H.M. Explosives Factory in Litherland near Liverpool after optimising the production of nitric acid which was required for the large-scale manufacture of explosives. As women were held in low esteem in science and engineering at the time, she was the first woman to be recognised for her war work and to be given a significant promotion. Thus both her Bangor and Liverpool appointments were unusual and could be explained by the shortage of men during the war. Leslie lost her job in explosives research in 1917 as male engineers returned from the front.
In 1918 Leslie was awarded a doctoral degree by the University of Leeds for her combined work on thorium and explosives, which "contributed effectively towards the solution of urgent technical problems". As a result, she was the first woman to be awarded a doctorate by the University of Leeds. The same year she became a demonstrator in chemistry at Leeds and in 1928 a full lecturer in physical chemistry. During those years her research mostly focused on the chemistry of synthetic dyes.
She was elected a Fellow of the Chemical Society in 1920, the first year women were admitted as fellows.
In 1923 Leslie married Alfred Hamilton Burr, a chemist at the University of Salford. In 1929 she left Leeds to stay with her husband. Only after his death in 1933 did she return, continuing to work in Leeds until a month before she died.
May Sybil Leslie-Burr died in her home at Bardsey, West Yorkshire, of lung cancer on 3 July 1937, aged 49.
