Simpson, Maxwell (1815–1902), chemist, was born 15 March 1815 in Beech Hill, Co. Armagh, youngest among nine children of Thomas Simpson, prosperous linen merchant and flour mill owner, whose wife's maiden name was Browne. He was educated at the private school of Dr Henderson, at Newry, Co. Down (the school attended also by John Mitchel (qv) and John Martin (qv)), proceeding in 1832 to TCD, where Charles Lever (qv) encouraged him to take up medicine. Simpson's taste for medicine did not improve with knowledge, and instead he graduated BA (1837). After graduation he spent a few years in London. During this period he visited Paris, where he attended a public lecture on chemistry by Jean Baptiste André Dumas, which made such an impression on him that he decided to study the subject. After his return to London, he attended the lectures of Thomas Graham at University College, London, and also worked in Graham's laboratory.
In 1845 Simpson returned to Dublin and on 12 April in Donaghmore, Co. Down, married Mary (d. 1900), second daughter of Samuel Martin of Loughorne, Co. Down, and sister of John Martin, the Young Irelander. Little is known of Simpson's political sympathies, though he remained on friendly terms with his brother-in-law, visiting him before his transportation in 1849. Several of the couple's six children were baptised in Donaghmore, even after they settled in Dublin, where he was appointed to the chair of chemistry at the Park St. medical school (1847). Every lecturer at this institution was expected to hold a medical degree, and in order to satisfy this regulation he resumed his medical studies, graduating MB (1847). In 1848 he moved to the Peter St. school of medicine, where he delivered lectures before large classes. While there he was granted three years’ leave of absence, and in 1851 travelled to Germany to study the continental system of teaching chemistry under Adolph Kolbe in Marburg and Robert Bunsen in Heidelberg. At Heidelberg he did his first original work, devising a superior method of determining nitrogen in organic compounds. In 1854 he returned to Dublin and resumed his lectures at Peter St. until 1856, when he finally gave up his lectureship. He then travelled with his family to Paris and commenced work in Adolphe Wurtz's laboratory. Returning to Dublin in 1859, he set up his own laboratory in a back kitchen of his house at 33 Wellington Road. Here he carried out the researches that made his reputation as a pioneer in the field of organic chemistry, and he was the first to synthesise succinic acid as well as other polybasic acids. He kept up contact with his continental counterparts and returned to work with Wurtz in Paris in 1867, after which he spent some time in London working as an examiner to the Indian civil service, at Woolwich. He also acted as an examiner in materia medica for the QUI.
In 1872 Simpson was appointed to the chair of chemistry in QCC. He devoted himself fully to his professorial duties and the development of the chemical department, publishing only two further research papers. He was held in high regard by his students, and was a pioneer in the use of practical demonstration experiments to illustrate lectures. He always returned class fees paid by financially poorer students, and was also remembered for refusing commercial work outside the university. Throughout his career he urged the importance of chemistry as a subject for study in secondary schools and universities.
Simpson was an FRS (1862), fellow and vice-president of the Chemical Society (1857, 1872–4), fellow of the RUI (1882–91), and an honorary fellow of the King's and Queen's College of Physicians (1868). In 1878 he was appointed president of the chemical section of the British Association's meeting in Dublin. He received the honorary degrees of MD (1864) and LLD (1878) from Dublin University and the honorary degree of D.Sc. from the QUI (1882). He retired in 1891 and lived at 7 Darnley Road, Holland Park Avenue, London, until his death on 26 February 1902. His wife and one of his daughters predeceased him.