THE CHEMISTRY OF LIGHT PRODUCTION 87 



"Resemblances: 



VII. The TMngs wherein I observed a Piece of shining 

 Wood and a burning Coal to agree or resemble each other 

 are principally these five: 



1. Both of them are Luminaries, that is, give Light, as 



having it (if I may so speak) residing in them; 

 and not like Looking-glasses, or white Bodies, 

 which are conspicuous only by the incident Beams 

 of the Sun, or some other luminous Body, which 

 they reflect. . . . 



2. Both shining Wood and a burning Coal need the 



Presence of the Air (and that too of such a Den- 

 sity to make them continue shining. . . . 



3. Both shining Wood and a burning Coal, having been 



deprived, for a Time, of their Light, by the with- 

 drawing of the contiguous Air, may presently 

 recover it by letting in fresh -4ir upon them. . . . 



4. Both a quick Coal and shining Wood will be easily 



quenched by Water and many other Liquors. 



5. As a quick Coal is not to be extinguished by the 



Coldness of the Air, when it is greater than ordi- 

 nary; so neither is a Piece of shining Wood to be 

 deprived of its Light by the same Quality of 

 the Air. ... 



Differences : 



1. The first Difference I observed betwixt a live Coal 

 and a shining Wood is, that whereas the Light 

 of the former is readily extinguishable by Com- 

 pression (as is obvious in the Practice of suddenly 



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