18 Proceedings of the Royal Physical Society. 



think that there is no such thing as an element of fire, but 

 that what we call flame is nothing more than air mixed 

 with the volatile sulphurous parts of combustible substances. 

 Although these explanations of natural phenomena given by 

 Hooke are quaintly and imperfectly, and even in some cases 

 erroneously, given, still we cannot fail to be struck with the 

 clear indications which they afford, that he was certainly on 

 the right road, and also by the amount of real information 

 which he had acquired, as the result of his valuable and 

 remarkable investigations. Hooke expressed his intention, 

 if opportunity and life were given him, of prosecuting, im- 

 proving, and publishing his theory. This intention, however, 

 he did not fulfil; but an Oxford physician, named John 

 Mayow, who was born about ten years after Hooke, eagerly 

 took up the work, and by means of many well-contrived 

 experiments, elaborated and supported Hooke's theory. 

 Mayow was among the first who made experiments with 

 gases over water ; and his book, in which he treats of what 

 he calls spiritus nitro cereus, contains the description of many 

 experiments in what is now called pneumatic chemistry. 

 The date of the discovery of oxygen gas, which discovery 

 is justly reckoned one of the most brilliant ever made in 

 chemical science, is engraven on all our minds; in fact, 

 August 1, 1774, has been called the birthday of chemistry. 

 The more, however, which I read of and ponder on John 

 Mayow's experiments, and the conclusions which he deduced 

 therefrom, I am the more inclined to think that oxygen was 

 almost discovered a hundred years before Priestley's famous 

 chef-d'oeuvre; and any one who reads carefully what Mayow 

 has done in connection with this subject will, I imagine, be 

 much of the same opinion. 



The " dissolving part," as he terms it, of the air and of nitre, 

 he calls nitre-air or fire-air. The air, he says, is not com- 

 posed solely of nitre-air, for when a combustible substance, 

 such as a candle, is burned in a confined space, only a portion 

 of the air is consumed. Further, he says, this nitre-air or 

 fire-air is contained in nitre, so that substances will burn 

 even under water, or in a vacuum, if supplied with a suffi- 

 ciency of nitre. Although it was thus known that this fire- 



