184 History of Luminescence 



Like Priestley, Joseph Black also summarized the views of his 

 predecessors in a book of Lectures on the Elements of Chemistry 

 (1803) edited from his manuscripts by John Robinson, L. L. D. 

 and published posthumously. In an appendix headed " Pyrophore," 

 Black gave very good descriptions of the known phosphors and pyro- 

 phors, including the work of John Canton and Benjamin Wilson, 

 but with only casual mention of bioluminescences. He admitted 

 that the phenomena differed from ordinary combustion and wrote: 



But it were worth while to examine by some proper train of experi- 

 ments, whether this shining is effected by the absorption of vital air 

 [oxygen], and a subsequent decomposition by the action of fresh light. . . . 

 To us [the chemists] they are important, being nearly connected with 

 the whole doctrine of combustion,— a doctrine still full of difficulties, 

 notwithstanding the very great discoveries which have been made. The 

 separability of light and heat by a plate of glass, in the valuable observa- 

 tion of Scheele, and their seeming separability in the present instances, 

 are undoubtedly facts of great moment in philosophical chemistry, espe- 

 cially when considered along with Herschel's observations.^- The obser- 

 vation also of Mr. Goettling, that phosphorus shines bright in azote 

 and in volatile alkali, and the shining of vegetable and animal sub- 

 stances, (particularly sea fish) in a certain stage of putrescence, and 

 their shining iii vacuo and other situations incompatible with combus- 

 tion, merit a much more careful attention than has yet been given. 



As a friend of Lavoisier, Black found the new theory 



incomparably more agreeable to our general knowledge of chemical facts 

 than the ingenious [phlogiston] doctrine of Dr. Stahl, and is really sup- 

 ported by proofs which seem incontrovertible. Even though imperfect, 

 this new doctrine furnishes us with a fact, formerly unnoticed, which 

 accompanies all combustion, namely, the combination of the body called 

 combustible with vital air. 



Had Black actually studied the luminescence of animal and vege- 

 table substances he would have found the proof for his idea that 

 these luminescences are in fact connected with a type of combustion. 



Even before Priestley, Henry Cavendish had called attention to 

 variotis gases in his Experiments on Factitious Air (1766) , includ- 

 ing inflammable air (hydrogen) and fixed air (COo) , and in later 

 studies on the composition of the atmosphere (1783) . However he 

 paid scant attention to luminescence. 



Karl Scheele shares with Priestley and Lavoisier the honor of 

 " discovering " oxygen,^^ which he called " empyreal air " or " Feuer 



** On the infrared region of the spectrum. 



^^ Perhaps John Mayow (1645-1679) should be included among the discoverers 

 of oxygen because of the " spiritus nitro-aereus," described in his tract De respiratione 



