r 7 4 HEE OES OF INVENTION AND DISCO VER Y. 



editions, was translated into foreign languages, and procured 

 him the honour of being elected a Fellow of the Royal Society, 

 as one of his biographers says ; but his election took place the 

 year before, and about the same time the University of Edin- 

 burgh conferred on him the degree of Doctor of Laws, 



His attention was now turned to the properties of fixed air 

 He commenced his experiments on this subject in 1768, and the 

 first of his publications appeared in 1772, in which he announced 

 a method of impregnating water with fixed air. In the paper 

 read to the Royal Society in 1772, which obtained the Copley 

 medal, he gave an account of his discoveries ; and at the same 

 time announced the discovery of nitrous gas, and its appli- 

 cation as a test of the purity and fitness for respiration of gases 

 generally. 



About this time also he showed the use of the burning lens 

 in pneumatic experiments ; he related the discovery and 

 properties of muriatic acid gas; added much to what was 

 known of the gas generated by putrefactive processes, and 

 by vegetable fermentation ; and he determined many facts 

 relative to the diminution and deterioration of air, by the 

 combustion of charcoal and the calcination of metal. 



In 1774 he made a full discovery of dephlogisticated gas, 

 which he produced from the oxides of silver and lead. This 

 hitherto secret source of animal life and animal heat, of which 

 Mayon had a faint glimpse, was unquestionably first exhibited 

 l)y Dr, Priestley, though it was discovered about the same time 

 by Scheele of Sweden. 



In 1776 his observations on respiration were read before the 

 Royal Society, in which he discovered that the common air 

 inspired was diminished in quantity and deteriorated in quality 

 by the action of the blood upon it, through the blood-vessels 



