Priestley phlogiston theory

Stahl subsequently renamed the terra pingnis phlogiston, the motion of fire (or heat), the essential element of all combnstible materials. Thns the phlogiston theory was born to explain all combnstion and was widely accepted for most of the eighteenth centnry by, among others, such luminaries of chemistry as Joseph Priestley. 

M. and Mme. Lavoisier. In 1777 Lavoisier gave quantitative proof of the incorrectness of the phlogiston theory. Shortly after Priestley and Scheele discovered oxygen, Lavoisier gave the true explanation of combustion and respiration Ber-thollet, Guyton de Morveau, Fourcroy, and Klaproth were among the first to accept the new views. See also ref. (60)... 

Lavoisier s ideas met initial resistance from the established chemical community. After all, phlogiston had been used for a century to explain chemistry, and natural philosophers had explained their work based on phlogiston theory. The leading chemists of the day, including Richard Kirwan (1733-1812), Priestley, Cavendish, andTor-bern Bergman (1735-1784), not only rejected Lavoisier s ideas, but they also were antagonistic toward him. This was not to say... 

Obviously, thought Priestley, the air was peculiarly lacking in phlogiston, and was therefore especially avid to soak it up from burning substances. Priestley never swayed from his firm conviction in the phlogiston theory as long as he lived, and he called his new gas dephlogisticated air . 

In the old Phlogiston Theory, phlogiston is equivalent to minus oxygen in the later theory it was sometimes assumed to be hydrogen (Cavendish, Kirwan, Priestley), or the matter of light (Macquer). Practically every chemist adopted the theory during the eighteenth century. 

Priestley, if not Watt, was happy to implicate Watt s contribution to the Considerations, publicly as well as privately, in a rearguard defence of phlogiston theory. 

The phlogiston theory remained unrefuted for about fifty years. In 1772 Rutherford discovered nitrogen, and in 1774 Priestley isolated oxygen ( dephlogisticated air ). Between the years 1772 and 1788 Lavoisier made numerous investigations into the nature of combustion, his results leading him to the conclusion that there is no essential difference between respiration, combustion, and calcination. 

The discovery of the compound nature of water by Cavendish and Watt, and the results obtained by Lavoisier and his coadjutors in their investigations of the quantitative composition of this substance, rendered the phlogiston theory untenable. It had played a useful part as the first step to placing the science of chemistry on a rational basis, and it is interesting to note that both Priestley and Cavendish remained phlogistians to the end. 

I.e. the phlogiston theory (although Stahl himself received virtually no historical study) and the British pneumatic chemical tradition from Stephen Hales to Priestley. 

Stephen Touhnin rejected the positivist-Whig notion of instant rationality according to which, in 1775, Lavoisier used the crucial experiment on the calcination and revivification of mercury by heat alone to discredit the phlogiston theory and establish the oxygen theory. As Toulmin noted, Priesdey responded to this experiment in 1783 with a crucial experiment of his own. Priestley appealed to the reaction between minium (lead oxide) and inflammable air (hydrogen) over water as a counter demonstration , in which the phlogiston... 

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