C hap. 3 8 . ] Luminous Appearance cf Fife . 253 



a degree of combuftion takes place, but fo extremely- 

 faint, that light only is produced, without the leaft ap- 

 pearance of fenfible heat. 



This fhort explanation of the caufe will, I flatter 

 myfelf, correfpond with moft of the phenomena of this 

 kind noticed by philofophers. Mr. Boyle found that 

 the light of rotten wood was in moft refpects analogous 

 to that of putrefcent fubftances. The light of the 

 former, however, differed in fome refpe6i:s; it was 

 prefently quenched with water, fpirit of wine, and 

 ieveral other fluids ; but the light of fome fliining 

 veal was not entirely quenched by water, though its 

 virtue was inftantly deftroyed by fpirit of wine *. The 

 fame philofopher was fometimes difappointed in his 

 experiments on Ihining fifties; particularly he ob- 

 ferved, that they failed to become luminous in cold 

 and frofty weather, which is perfe6tly agreeable to the 

 nature of phofphorus, fince its combuftion is exactly 

 in proportion to the heat which is applied to it. He 

 remarks alfo in another place, that the light of film- 

 ing wood was completely extinguifhed by extreme 

 cold. 



Some bodies have a much greater tendency to pro- 

 duce this light than others. A foreign philofpher re- 

 marked, that on opening a fea polypus it was fo lumi- 

 nous as to ftartle moft of the perfons who faw it ; the 

 nails and the fingers of thofe who touched it became 

 luminous alfo. The light of the glow worm, and other 

 luminous infects, muft depend upon fome flimy or fluid 

 matter which they emit, and which is probably a com- 

 bination of phofphorus with oil. There is a remarkable 

 fhell-fifh, called phoks, which forms for itfelf holes in dif- 

 ferent kinds of flone. This fifti illuminates the mouth of 



* 'Prieft. Op. 565. 



the 



