MacBride, David (1726–78), doctor and scientist, was born 26 April 1726 in Ballymoney, Co. Antrim, son of Robert MacBride (1687–1759), presbyterian minister at Ballymoney, and his wife, a Miss Boyd from Killaghy, Co. Down, whose father may have been David Boyd. Robert McBride was a son of John MacBride of Belfast, and published a pamphlet in 1726, attacking the position on the subscription controversy taken by Robert Higinbotham, a minister nearby in Coleraine, Co. Londonderry. Robert MacBride's other son, John MacBride (c.1735–1800), went into the Royal Navy and, in the course of a distinguished career, became an admiral. There was also a daughter, who was ancestor of the American writer Edgar Allen Poe.
David MacBride was educated at a school in Ballymoney, was apprenticed to a local surgeon, and then became a surgeon on a navy hospital ship. When the war of the Austrian succession ended with the peace of Aix-la-Chapelle (1748), he attended anatomy and midwifery lectures by the leading doctors in Edinburgh and London, and spent two years in Ballymoney (1749–51), then moved to Dublin to set up in practice. He was at first somewhat shy and was unsuccessful; he thus had leisure to undertake chemical experiments, which he described at meetings of the Medico-Philosophical Society, of which he was a founder member in 1756 and secretary from 1762. In 1762 MacBride's suggestion in a letter to his friend George Cleghorn (qv) that wort, an infusion or decoction of malt, could be used in treating scurvy, was recommended to the admiralty, and a trial was initiated in the naval hospitals of Plymouth and Portsmouth, but was abandoned before any conclusion was reached. However, in 1765–7 Commander John MacBride made trial of his brother's theories during a voyage of his ship Jason; the ship's surgeon's journal was published by MacBride in a second edition of his Essays and in a pamphlet, both in 1767. It suggested that the use of wort had helped prevent or alleviate scurvy, and perhaps also beri-beri. Capt. James Cook, who used wort on Endeavour on his first voyage in 1768, recommended it to the admiralty as an anti-scorbutic, but its use declined when the superior efficacy of citrus juices became known.
MacBride's Experimental essays (first published 1764; further editions 1767, 1776) brought him some celebrity, both in Dublin, where his practice soon greatly increased, and also in Britain and abroad, and he was awarded the degree of doctor of physic in November 1764 by the University of Glasgow. The essays were translated into French and German, and helped make the theories of Joseph Black (qv) known to a wider audience, especially to medical men. MacBride dealt with such apparently disparate subjects as scurvy, quicklime, and digestive fermentation, but his experiments and hypotheses were all concerned with the nature of what was known as ‘fixed air’, or carbon dioxide, and he ranks as one of the pioneers of pneumatic chemistry. He adopted an earlier theory put forward by Stephen Hales, but emphasised in particular the apparent ability of ‘fixed air’ to act as a bond within organic matter. At the time, the newly discovered gases were exciting great interest amongst doctors seeking therapeutic uses for them, and MacBride believed that ‘fixed air’, which was associated with fermentation, was in fact combatting putrefaction. It would thus, he reasoned, cure diseases or conditions, such as scurvy, which were associated with putrefaction. He believed that green vegetables, which were known to prevent scurvy, fermented in the stomach, producing fixed air, and that a similar result would be obtained by the use of wort.
MacBride was in contact with many distinguished scientists and physicians of the day, notably Sir John Pringle, president of the Royal Society, who was an expert on military medicine and was an enthusiastic supporter of his theories. The Dublin Society awarded MacBride (April 1768) a silver medal for discovering an improved method of tanning leather, in which limewater was used instead of ordinary water, and he was later awarded a gold medal by the Society of Arts of London.
In 1766–7, and for some years afterwards, MacBride gave a lecture course on various aspects of medicine at his house in Jervis St., Dublin, and in 1772 he published in London a quarto volume of medical essays based on his lectures, entitled A methodical introduction to the theory and practice of medicine; the essays were republished in Latin at Utrecht, and appeared in an enlarged edition at Dublin in 1777, and in a French translation in 1787. The work was regarded as a useful compilation, and is of interest to medical historians chiefly because MacBride set out to classify diseases according to a logical system based on observation of symptoms; an approach to the subject characteristic of the period. Not all the sections of the proposed nosology of diseases were completed in the published volumes.
Shortly after he arrived in Dublin, MacBride was refused permission to marry Dorcas Evory – a relative of Thomas Evory (qv), master of the Rotunda Hospital – and both married others; on 20 November 1753 MacBride married Margaret Armstrong at St Audeon's church. When his former sweetheart's first husband died after a few years, MacBride tried unsuccessfully to persuade George Cleghorn to marry her; after his own wife died, MacBride was able to marry Dorcas (Evory) Cumming on 5 June 1762 at St Audeon's. Several children died in infancy. MacBride died of a fever 28 December 1778 at his house in Cavendish Row, Dublin; insomnia and stress resulting from overwork were held to have contributed to his condition. His patients, particularly women, greatly respected him; at least one of several published elegies lamenting his death was written by a woman.