James Gow Black (baptised James Black) was born in Tomgarrow, Little Dunkeld, Perthshire, Scotland, on 10 May 1835, the son of David Black and his wife, Margaret Gow. As 'the son of a poor Highland crofter' (his father was a quarrier and farmer), Black supported himself by manual labour, and from the age of 14 by teaching. The nearest parish school was six miles from his home, so he set up his own school to teach neighbouring children. The money he received from this venture enabled him to attend the burgh school at Perth.
After several years as a teacher at the Liff Free Church School he studied at the Moray House Training College, then at the University of Edinburgh, graduating MA in 1864, BSc in 1867 and DSc in 1869. He married Jeannie Crichton in Edinburgh on 25 August 1869; they were to have two sons and two daughters. By 1871 Black was a joint director of collegiate classes in Edinburgh, a fellow of the Botanical Society of Edinburgh and of the Educational Institute of Scotland, and an enthusiastic member of the Edinburgh Naturalists' Field Club, which he helped found.
On 22 February 1871 Black was unanimously chosen from a list of 23 applicants for the chair of natural science at the newly established University of Otago, New Zealand. He and his family arrived at Port Chalmers on the Christian McAusland at the end of 1871. Otago's provincial superintendent, James Macandrew, had wanted provision made for a school of mines and of agricultural chemistry at the university and the chair of natural science was partly subsidised by the provincial government. It was specified that the incumbent be able to teach chemistry and mineralogy and their applications to agriculture and mining. Black was eminently well qualified in all fields; by 1877 he was professor of chemistry and mineralogy and soon afterwards, with the establishment of the School of Mines, professor of chemistry, a position he held until his retirement in 1911.
In his introductory lecture at the opening of the University of Otago's second session in May 1872, Black claimed that one of the aims of a scientific education was to enable a person 'to produce a pound of corn, or wool, or iron, or gold, at half the expenditure which it previously cost.' The practical application of science was the central focus of his career. His two books, Chemistry for the gold fields (1885), which he dedicated to 'The Diggers and Miners of New Zealand', and Lectures on agricultural chemistry (1895), were manuals as well as textbooks. He was not active in research, nor, for the most part, in the affairs of the university's professorial board, the Otago Institute or the New Zealand Institute.
James Gow Black was first and foremost a teacher and populariser of science. His style was lucid, forceful and tinged with humour; his lecture demonstrations fascinating, sometimes to the point of appearing magical; his enthusiasm contagious. He addressed numerous audiences: students, teachers – many of whom travelled considerable distances to attend his Saturday morning classes, miners and the general public. While some questioned the value of popular lectures, none doubted Black's abilities as a lecturer. Following the success of a lecture series that he gave in Lawrence in 1884, Black spent the following three long vacations touring the goldfields of New Zealand. These tours, which were supported by W. J. M. Larnach, the minister of mines, encouraged the establishment and development of many local schools of mines. Black's role in inaugurating this form of technical education received wide recognition.
In 1873 Black was appointed provincial government analyst, and, two years later, a local analyst under the Adulteration of Food Act 1866, a position that he held, under subsequent acts, until 1909. He was an analyst and consultant to mining and other industries, and a provisional director of Kempthorne, Prosser and Company's New Zealand Drug Company on its formation in 1879. It was Black's analysis of specimens from the region that led to his involvement, as a scientific expert, investor and participant, in the Pegasus Creek tin rush on Stewart Island (1888–90). Black paid many visits to Stewart Island. He settled there on retirement, and died at Halfmoon Bay on 25 December 1914; his wife survived him until 1919.
A robust and restlessly energetic man, Black charged along the streets of Dunedin, rambled through the countryside, sometimes with the Dunedin Field Naturalist Club of which he was a founding member, and travelled widely. He was president of the Otago University Football Club (1899–1902 and 1904–11) and a vice president of the Boxing Club (1909–11). Black's geniality, sincerity, kindness and childlike exuberance endeared him to his students, colleagues and the public. In the words of a colleague, 'Burns would have loved him.'