Hartley, Sir Walter Noel (1846–1913), scientist, was born 3 February 1846 at Lichfield, Staffordshire, son of Thomas Hartley, portrait painter, who exhibited (1820–60) at the Royal Academy in London, and Caroline Hartley (née Lockwood). Walter Hartley appears to have been an only child, and to have been educated at home owing to delicate health. In 1863 he went to Edinburgh University to study medicine, but after a year there was advised to devote himself to chemistry instead, and so went to Germany, where he spent a year in Kolbe's laboratory at the University of Marburg. Returning to England in 1865, he worked as scientific assistant to Drs Angus Smith and Thudicum in Manchester on problems relating to ventilation, sanitation, and the investigation of wines. Then Hartley worked for some years at the Royal Institution in London, headed by Professor John Tyndall (qv). With Dr Odling he submitted an important paper to the Royal Society: ‘Experiments concerning the evolution of life from lifeless matter’ (1872). This paper refuted one by C. Bastian, purporting to show that organisms could be generated by heating a mixture of sodium phosphate and ammonium tartrate. Submission of the paper was apparently delayed for a year by Hartley's severe illness.
In 1871 Hartley was appointed senior demonstrator in the laboratory at King's College, London, under Prof. Bloxham. There he became interested in spectroscopy, a speciality in which he was a pioneer, showing great ingenuity in making his own equipment and designing experiments. In 1879 he was appointed professor of chemistry in the Royal College of Science for Ireland. At this period when scientific education was expanding, Hartley's appointment was an important and prestigious one. The Royal College of Science, founded in 1865, occupied the premises of the former Museum of Irish Industry in Dublin at 51 St Stephen's Green East, and was affiliated to the newly founded Royal University of Ireland, an examining body only. It was administered by the department of science and art until 1900, and existed mainly to supply scientific training to graduates and students of TCD and other colleges. In addition it provided science courses for secondary‐school teachers. Hartley remained for thirty‐two years, the rest of his working life, at the Royal College of Science and from 1902 to 1911 was dean of faculty.
On taking up his Irish appointment Hartley, already a fellow of King's College, London, received an honorary D.Sc. from Dublin University. He was later to receive many honours, including fellowship of the Royal Society (1884); vice‐presidency of the Institute of Chemistry of Great Britain and Ireland; the gold medal at the St Louis Exposition (1904) for scientific applications of photography; the Longstaff medal of the Chemical Society (1906) for research into spectro‐chemistry; and the Grand Prix for spectrographic research at the Franco–British Exhibition (1908). Overall, his main scientific achievement was probably to establish by spectrographic analysis the relationship between molecular structure and absorption spectra.
Hartley published over 150 papers, of most of which he was sole author. The following list of subjects gives some idea of the range of his research interests: emission spectra of atoms, gases in mineral cavities, the analysis of minerals and meteorites, the position of beryllium among the elements, the spectrum of chlorophyll, black marble from Kilkenny, beryls from Glencullen, films produced by vaporised metals, the fading of watercolours, and the colouring matter used in the Book of Kells. Hartley also published A course of quantitative analysis for students (Dublin, 1887).
Throughout his life Hartley suffered from severe asthma, as well as partial deafness and visual problems which he seems to have feared would lead to loss of sight. His wife May had some mental disturbance which led in 1910 to her admission, at his request, to a private psychiatric hospital where she died six years later. Considering all this, it seems remarkable that Hartley was able to complete so much work and to such a high standard. As teacher and dean, he was considerate and encouraging towards his students, especially to the women among them. However, he demanded from both students and subordinates the very high standards he set for himself, and was critical of any shortcomings.
In 1911 Hartley retired early owing to ill health and was knighted. He died in his sleep on 13 September 1913 while visiting friends at Braemar, Scotland, and is buried there. His obituary by an anonymous friend, also a fellow of the Royal Society, describes him as shy and reserved, though responsive to those who knew him. Hartley confided to this friend that he would have preferred to be a bacteriologist rather than a chemist, but for the need to make a living.
On 4 July 1882 Hartley married May, daughter of Michael Laffan of 4 Cross Ave., Blackrock, Co. Dublin, and the late Ellen Sarah Laffan (née Fitzgibbon). May Laffan Hartley (qv) was a successful novelist, but gave up writing on marriage. The couple went to live at 36 Waterloo Rd, Ballsbridge, Dublin. They had one child, John Walter (1889–1915), who studied in Dublin, qualified as a bacteriologist, and held a lectureship in agricultural bacteriology at the University of Wales (1913–14). Commissioned in the Royal Irish Fusiliers, he was killed in action at Gallipoli on 16 September 1915. W. N. Hartley's personal papers, presumably inherited by his son, are missing. His only known photograph appears in the article in Irish Chemical News referred to below. A portrait sketch by M. J. Healy is in the National Gallery of Ireland.