The Gases of the Atmosphere. William Ramsay

celestial luminaries, and causing, by their impulse, the idea of light in us. The third sort is its characteristic and essential property, I mean permanently elastic parts.”

      Boyle also relates experiments designed to “produce what appears to be air”; and he describes the production, by the action of oil-of-vitriol on steel filings, of “air” (now known as hydrogen) which possessed the property of elasticity; although he failed to notice its inflammability. He further obtained carbon dioxide by the fermentation of raisins, and probably also hydrogen chloride in the gaseous form by breaking a bulb containing “some good spirit-of-salt” in a vacuous receiver.

      The result of shrewd reasoning power, applied, however, to imperfect observations, is well illustrated by the following passages:

      “For tho’, by reason of its great thinness and of its being, in its usual state, devoid both of taste and smell, air seems wholly unfit to be a menstruum [or solvent]; yet it may have a dissolving, or at least a consuming, power on many bodies, especially such as are peculiarly disposed to admit its operations. For the air has a great advantage by the vast quantity of it that may come to work, in proportion to the bodies exposed thereto. … Thus we find a rust on copper that has been long exposed to the air.”[2]

       Boyle, shortly after, describes the production of “an efflorescence of a vitriolic nature” on marcasite (or sulphide of iron) which has been exposed to the air; and he relates that the “ore of alum, robb’d of its salt, will in tract of time recover it by being exposed to the air, as we are assured by the experienced Agricola.”

      To account for such actions, and for combustion, he proceeds (p. 81):

      “The difficulty we find in keeping flame and fire alive, tho’ but for a little time, without air, renders it suspicious that there may be dispersed thro’ the rest of the atmosphere some odd substance, either of a solar, astral, or other foreign nature; on account whereof the air is so necessary to the subsistance of flame. … It also seems by the sudden wasting or spoiling of this fine substance, whatever it be, that the bulk of it is but very small in proportion to the air it impregnates with its vertue; for after the extinction of the flame, the air in the receiver was not visibly alter’d; and for ought I could perceive by several ways of judging, the air retained either all, or at least the far greatest part, of its elasticity; which I take to be its most genuine and distinguishing property. And this undestroyed springyness of the air, with the necessity of fresh air to the life of hot animals, suggest a great suspicion of some vital substance, if I may so call it, diffused thro’ the air; whether it be a volatile nitre, or rather some anonymous substance, sidereal or subterraneal; tho’ not improbably of kin to that which seems so necessary to the maintenance of the other flames.”

      The experimental part of Boyle’s work relates to the oxidation of cuprous to cupric compounds, with the change of colour from brown to blue or green, either in ammoniacal or in hydrochloric acid solution; and he goes so far as to prove that two ounces of marcasites broken into small lumps, and kept in a room “freely accessible to the air, which was esteemed to be very pure,” for somewhat less than seven weeks, gained above twelve grains by oxidation.

      In his Memoirs for a General History of the Air, Boyle draws up a programme of research, of the carrying out of which, however, there is no record. He proposes (p. 23):

       “1. To produce air by fermentation in well clos’d receivers.

       “To produce air by fermentation in sealed glasses.

       “To separate air from liquors by boiling.

       “To separate air from liquors by the air-pump.

       “To produce air by corrosion, especially with spirit of vinegar.

       “To separate air by animal and sulphureous dissolvants.

       “To obtain air in an exhausted receiver by burning-glasses and red-hot irons.

       “To produce air out of gunpowder and other nitrous bodies.

       “2. To examine the produced aerial substances by their preserving or reviving animals, flame, fire, the light of rotten wood, and of fish.

       “To examine it by its elasticity, and the duration thereof.

       “To do the same by its weight, and its elevating the fumes of liquors.”

      We shall all agree that if Boyle had successfully carried out such experiments, our knowledge of the true nature of air would have come quite a century before it did. Some of these experiments were indeed made by John Mayow, his contemporary, whose work and speculations we shall now proceed to consider.

      John Mayow was born in the parish of St. Dunstan, London, in 1645. His family was originally Cornish, having come from Bree, in Cornwall. He entered Wadham College, Oxford, at the early age of sixteen, and was shortly afterwards made a probationer-fellow of All Souls’ College. After the usual three years of study, he took his degree in Law; but not being attracted by the legal profession, he turned his attention to medicine, and became a medical practitioner at Bath, where he lived during the fashionable season. When not more than twenty-three years of age, he wrote two essays on Respiration, ascribing the inflation of the lungs to the action of the intercostal muscles. These “Tractatus duo” were published in 1668. Some years later he produced the treatise on which his fame rests; it is entitled “Tractatus quinque medico-physici, quorum primus agit de sal-nitro et spiritu nitro-aëreo; secundus, de respiratione; tertius, de respiratione foetus in utero et ovo; quartus, de motu musculari, et spiritibus animalibus; ultimus, de rhachitide; studio Joh. Mayow, LL.D. & Medici, nec non Coll. Omn. Anim. in Univ. Oxon. Socii. Oxonii e Theatro Sheldoniano, An. Dom. mdclxxiv. ” The work was dedicated to Sir Henry Coventry. It was inserted in an abridged form in the Philosophical Transactions of the Royal Society, some time after its publication, but received only scant recognition, for the fame of Newton and Boyle overshadowed the labours of less well-known investigators. And Mayow did not live to press his discoveries on the attention of his contemporaries, for he died in 1679, five years after the publication of his tracts, in his thirty-fourth year. Little is known of Mayow’s domestic life, save that he married shortly before his death. His scientific work proves that if he had been granted the usual span of life, his extraordinary genius would have furthered the knowledge of the true explanation of the nature of air, and its function in supporting combustion and respiration, and that his views would have been accepted more than a century before Lavoisier—with fuller knowledge, and with the scientific position which at once gained a hearing—forced precisely similar doctrines upon the attention of the scientific world.

      Mayow was a contemporary of Boyle, and frequently made use of Boyle’s experiments in support of the theories which he advanced. Curiously enough, while Boyle seems to have read Mayow’s work, he does not appear to have been favourably impressed by his conclusions. Boyle, at the age of fifty-two, had doubtless formed his own opinions, and was unwilling that they should be disturbed by the speculations, well founded though they were, of so young a man. And shortly after Mayow’s death, the views of Becher, one of his contemporaries, expounded and made definite by Stahl, regarding the nature of combustion, were universally received.

      After Lavoisier’s theories had overthrown these false views, attention was again directed to Mayow’s tracts by Johann Andreas Scherer, in a work published at Vienna in 1793, and also by Dr. Yeats in 1798. Scherer gives a careful analysis of Mayow’s work, somewhat altering the order of his paragraphs, with a paraphrase in German of the Latin text, which he quotes in full. Yeats’ treatise is more especially concerned with the medical aspect of Mayow’s work, although it also deals with the purely chemical portion at considerable length. In the following account of Mayow’s researches, free use has been made of both of these works, as well as of his own “Tracts.”

      Mayow’s contributions to the chemistry of the atmosphere may be classified thus:—

      1. The atmosphere consists of