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. [Illustration: John Mayow.] 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 particles of two kinds of gases at least: one of these, termed “nitro-aerial particles,” is necessary for the support of life and for the combustion of inflammable bodies; while the other, left after this constituent has been removed, is incapable of supporting either life or combustion. The portion which is necessary for life enters, during respiration, into the blood. It is the chief cause of motion in animals and in plants.