28 Proceedings of the Royal Physical Society. 



oxygen. His discovery of this gas was made, it appears, sub- 

 sequent to that of Priestley, but it was made quite indepen- 

 dently. In consequence, however, of priority, the honour of 

 this discovery is always accorded to the English chemist. 

 Scheele did not content himself with investigations in inor- 

 ganic chemistry alone ; he turned his attention to the organic 

 department, and as the result of his labours in this branch, 

 he discovered, or, at least, first properly identified, the 

 foUowinoj amonsr other acids : tartaric, oxalic, citric, lactic, 

 etc., and in doing so fairly broke ground on this fertile field 

 of organic chemistry, which has since been cultivated with 

 most marvellous results. Scheele also in a manner may be 

 said to have laid the foundation of quantitative analysis, as 

 he was the first to make use of these distinctive properties of 

 substances, in order to effect their detection and separation, 

 which are now employed for the same purpose so extensively 

 by students of chemical science in our own day. 



From what has been said, it can easily be understood that the 

 science of chemistry in the time of Scheele was much further 

 advanced than it was before the onward movement given to it 

 by Boyle, Hooke, Black, Priestley, and Cavendish. But, not- 

 withstanding the valuable labours of all these chemical giants, 

 the science was still under a dense cloud. Priestley, Cavendish, 

 and Scheele, men of great genius as they certainly were, all 

 believed in the phlogistic theory — they regarded the metals 

 as being more complex substances than the oxides or calces 

 as they called them, and until this great and fatal delusion 

 was dispelled, it seems to me chemical science must always 

 have remained in a most incomplete state. In this condi- 

 tion, however, the science was not doomed to remain. In 

 the year 1743 Anthony Lavoisier was born, and ere he died 

 he gave the phlogistic theory its death-blow. Lavoisier began 

 life under very different circumstances than did poor Scheele. 

 He was liberally and carefully educated, and being possessed 

 also of a considerable fortune, he was unusually well equipped 

 for his future brilliant career. His attention having been 

 directed to the discoveries of Black, Priestley, and Cavendish, 

 he entered this new field of inquiry with all his characteristic 

 ardour and zeal, and obtained many most valuable results, 



