Mayow, John

, a very learned and ingenious physician of the seventeenth century, appears to have been born in Cornwall, in 1645, was a scholar of Wadham college, Oxford, and a probationary fellow of All Souls’ college. He took his degrees in civil law, but studied and practised physic; and principally at Bath, in the summer. He died at the house of an apothecary in York-street, Covent-garden, in September 1679, and was buried in the church of that parish. He published, “Tractatus quinque medicophysici, 1. de sale nitro, et spiritu nitro-aerio; 2. de re spiratione; 3. de respiratione foetus in utero, et ovo; 4. de motu musculari et spiritibus animalibus; 5. de Rachitide.” These were published together at Oxford, in 1674, 8vo; but there is an edition of two of them, “de respiratione,” and “de Rachitide,” published together at Leyden, in 1671. The fame of this author has been lately renewed and extended by Dr. Beddoes, who published in 179O, “Chemical Experiments and Opinions, extracted from a work published in the last century,” 8vo, in which he gives to Mayow the highest credit as a chemist, and ascribes to him some of the greatest modern discoveries respecting air; giving many extracts from the three first of his treatises. | His chief discovery was, that dephlogisticated air (or as he called it, with Scheele) fire-air, exists in the nitrous acid, and in the atmosphere; which he proved by such decisive experiments, as to render it impossible to explain how Boyle and Hales could avoid availing themselves, in their researches into air, of so capital a discovery. Mayow also relates his manner of passing aeriform fluids under water, from vessel to vessel, which is generally believed to be a new art. He did not collect dephlogisticated air in vessels, and transfer it from one jar to another, but he proved its existence by finding substances that would burn in vacuo, and in water when mixed with nitre; and after animals had breathed and died in vessels filled with atmospheric air, or after fire had been extinguished in them, there was a residuum, which was the part of the air unfit for respiration, and for supporting fire; and he further shewed, that nitrous acid cannot be formed, but by exposing the substances that generate it to the atmosphere. Mayow was undoubtedly no common man, especially since, if the above dates are right, he was only thirty-four at the time of his death. But he was not so unknown* as Dr. Beddoes supposed, for, since the repetition of the same discovery by Priestley and Scheele, reference has frequently been made by chemists to Mayow, as the original inventor; though no other person appears so closely to have examined his work as that writer. At the same time it appears, that with the partiality of a commentator, he has exalted his author unwarrantably at the expence of other chemists, and to a height, which, without the aid of strained interpretations, cannot be justified by the text. 1


Ath. Ox. Tol. II. Month. Rev. vol. II. and vol. XIII. N. British Critic, vol. XII. p. 345.