LECTURE II.] HISTORY OF CHEMISTRY. 17 



experiments were independent of and nearly simultaneous with 

 those of Priestley. 2 Both chemists employed almost similar 

 methods for its preparation. They obtained it from mercuric 

 oxide, pyrolusite, minium, nitre, etc. Lavoisier also wrote a 

 treatise on oxygen, but Priestley states that he had previously 

 informed Lavoisier of his discovery, although the latter makes 

 no mention of this. 3 It is to be deplored, but unfortunately 

 it seems to be established, that Lavoisier repeatedly tried to 

 appropriate to himself the merits of others. I do not enter 

 further into this matter here, because I regard it as inessential 

 in the history of the development of chemistry. A man's own 

 period is concerned with his personal qualities, and history with 

 his works. Lavoisier paid with his life both for faults which 

 he committed and for faults which he did not commit. His 

 own time judged him. Posterity may regard him with admira- 

 tion and indulgence. 



The different views which were held with respect to oxygen 

 by its discoverers are of interest to us. 



Priestley, the worshipper of chance, who asserts that his 

 greatest discoveries are due to the latter only, and for whom 

 every new experiment is a source of new surprises, 4 describes in 

 detail how he discovered oxygen and studied its properties. 

 He recognises that combustion proceeds better in this gas than 

 in any other, and assumes, further, that atmospheric air owes 

 its property of supporting combustion and respiration, to the 

 presence in it of the gas which he has discovered. He finds, 

 moreover, that it is absorbed by nitric oxide, whence he derives 

 a method of determining the quantities of oxygen in mixed 

 gases. What does he conclude from all this, however; how 

 does he explain these phenomena ? According to him, when a 

 substance burns its phlogiston must be able to separate from 



2 Nordenskjold (see Carl Wilhelm Scheele, Nachgelassene Briefe und 

 Aufzeichnungen, Stockholm (1892), xxi.) even endeavours to prove that the 

 priority belongs to Scheele rather than to Priestley, but with this I do not 

 agree. 3 Priestley, The Doctrine of Phlogiston established and that of the 

 Composition of Water refuted. Northumberland (1800), 88. 4 Priestley, 

 Experiments, etc., 2, 29, 39, 42, etc.; A.C.R. 7, 5, 12, 15, etc. 



B 



