Henry, Thomas

(b. Wrexham, Wales, 28 September 1734; d. Manchester, England, 18 June 1816)

chemistry.

Henry was the son of a dancing master. When he left Wrexham Grammar School his family lacked the means to support a hoped-for career in the church, so he was apprenticed to a local apothecary. After completing his apprenticeship at Knutsford, Cheshire, he became assistant to an apothecary at Oxford, where he attended lectures on anatomy. In 1759 he returned to Knutsford and married Mary Kinsey; in 1764 he moved to a business in a fashionable part of Manchester.

There Henry became acquainted with several men of intellectual distinction—in particular the physician Thomas Percival, to whom he attributed his initiation into experimental science. This new interest, and his commercial ventures, claimed his attention. Percival was a Unitarian; Henry became one and was drawn into the group of Dissenters from whose enterprise arose the Manchester Literary and Philosophical Society in 1781 (he was a founder-member, one of the first joint secretaries, and president from 1805 to 1816), the short-lived College of Arts and Sciences (1783), and the Manchester Academy (1786), a successor to the famous Warrington Academy. At the last two Henry lectured on chemistry and on bleaching and dyeing.

One of the first in Britain to use chlorine for bleaching textiles, Henry pioneered the use of milk of lime to absorb the gas, thus reducing the dangers of the process. In a paper on dyeing, read in 1786, he pleaded for the application of chemical knowledge to the art and gave a correct interpretation of the role of mordants.

Henry’s most profitable venture, which earned him his nickname “Magnesia,” was the manufacture and sale, for medicinal purposes, of calcined magnesia following his submission for publication of “An Account of an Improved Method of Preparing Magnesia Alba” Medical Transactions of the Royal College of Physicians,2 [1772], 226–234). The manufacture of magnesia, by a process that remained almost unchanged from its beginning in 1772, provided a comfortable income for the family until 1933.

In 1773 Henry published his Experiments and Observations, consisting mainly of articles on the properties and uses of calcined magnesia and on putrefaction. He described experiments which appeared to uphold Macbride’s observation that the putrefaction of meat and similar substances was halted by a stream of “fixed air” (carbon dioxide). Both he and Percival, Henry said, had successfully treated putrid diseases with the gas, Subsequently they questioned Priestley’s reports of the toxicity of fixed air to vegetation and satisfied themselves that, on the contrary, it provided nourishment for plants. (See Thomas Percival, “On the Pursuits of Experimental Philosophy,” in Memoirs of the Manchester Literary and Philosophical Society,2 [1785], 326–341; and Thomas Henry, “Observations on the Influence of Fixed Air on Vegetation,” ibid., 341–349. See also E. L. Scott, “The ‘Macbridean Doctrine of Air: An Eighteenth-Century Explanation of Some Biochemical Processes, Including Photosynthesis,” in Ambix, 17 [1970], 43–57.)

In 1776 Henry published the first and thus far the only complete English translation of Lavoisier’s Opuscules, taking the opportunity to correct Lavoisier’s account of some of Priestley’s work. Later he translated nine of Lavoisier’s essays but defended, in an appendix, his own and Priestley’s belief in phlogiston. Surviving correspondence shows that, unlike Priestley, he eventually abandoned it.

Henry was elected a fellow of the Royal Society in 1775 on Priestley’s recommendation. Although not a great scientist he did much to found a scientific tradition in Manchester, enhanced in his own lifetime by his son William and their mutual friend John Dalton.

BIBLIOGRAPHY

I. Original Works. Henry’s main work is Experiments and Observations on the Following Subjects: 1. On the Preparation, Calcination and Medicinal Uses of Magnesia. 2. On the Solvent Qualities of Calcined Magnesia. 3. On the Variety in the Solvent Powers of Quicklime, When Used in Different Quantities. 4. On Various Absorbents as Promoting or Retarding Putrefaction. 5. On the Comparative Antiseptic Powers of Vegetable Infusions Prepared With Lime etc. 6. On the Sweetening Properties of Fixed Air (London, 1773); the first essay is a reprint of his 1772 paper to the Royal College of Physicians. His translations are Essays, Physical and Chemical, From the French of Lavoisier (London, 1776), with notes and app.; and Essays on the Effects Produced by Various Processes on Atmospheric Air, With a Particular View to an Investigation of the Constitution of Acids (Warrington, 1783), with a pref. on the controversy between Priestley and Lavoisier. He also published a short biography of the Swiss physiologist Albrecht von Haller, Memoirs of Albert de Holler (Warrington, 1783), based on his translation of the eulogy read to the French Academy of Sciences.

Henry published a number of pamphlets, the most important being An Account of a Method of Preserving Water at Sea From Putrefaction and of Restoring to the Water Its Original Pleasantness and Purity by a Cheap and Easy Process... (Warrington, 1781). His advocacy of using quicklime, to be precipitated with carbon dioxide when the water was required for consumption, was pressed upon the Admiralty but never adopted. A paper on this subject was published in the Manchester Memoirs (see below).

Many of Henry’s papers read to the Manchester Literary and Philosophical Society were not published; -an incomplete list of those which appeared in the Memoirs is given in Royal Society, Catalogue of Scientific Papers, 111 (London, 1869), 292–293. Those mentioned above are “On the Preservation of Sea Water From Putrefaction By Means of Quicklime...” in Memoirs of the Manchester Literary and Philosophical Society, 1 (1785). 41–53 (read in 1781); and “Considerations Relative to the Nature of Wool, Silk and Cotton, as Objects of the Art of Dying; on the Various Preparations and Mordants, Requisite for These Different Substances; and on the Nature and Properties of Colouring Matter; Together With Some Observations on the Theory of Dying in General,” ibid., 3 (1790), 343–408.

II. Secondary Literature. The main biographical source is his son William’s tribute, “A Tribute to the Memory of the Late President of the Literary and Philosophical Society of Manchester,” in Memoirs of the Manchester Literary and Philosophical Society, 2nd ser.. 3 (1819), 391–429. Biographical sketches are in J. Wheeler, Manchester: Its Political, Social and Commercial History, Ancient and Modern (Manchester, 1836), pp. 488–493; and E. M. Brockbank, Sketches of the Lives and Work of the Honorary Medical Staff of the Manchester Infirmary (Manchester. 1904), pp. 72–82, with portrait. See also W. V. Farrar, K. R. Farrar, and E. L. Scott, “The Henrys of Manchester,” in Royal Institute of Chemistry Reviews, 4 (1971), 35–47.

E. L. Scott