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IX. Experiments and Observations on the Light which is spon- 

 taneously emitted, with some Degree of Permanency, from 

 various Bodies. By Nathaniel Hulme, M. D. F. R. S. and A. S< 



Read February 13, 1800. 



INTRODUCTION, 



J. he discoveries which have been made with respect to light, 

 as it proceeds immediately from the sun, are many and im- 

 portant ; but the observations on that species of light which is 

 spontaneously emitted from various bodies, are not only few in 

 number, but in general very imperfect. The author is therefore 

 desirous of drawing the future attention of the philosopher more 

 particularly to this subject, and of communicating his own ex- 

 periments and observations upon it, to this learned Society. 



By the spontaneous emission of this light, the author wishes to 

 distinguish it from all kinds of artificial phosphorus ; which, as 

 he apprehends, differ essentially, in some of their properties, 

 from that light of which he means to treat. And, by its adhesion 

 to bodies with some degree of permanency, he distinguishes it 

 from that transient sort of light which is observable in electri- 

 city, in meteors, and in other lucid emanations. The light which 

 is the subject of this paper, he shall therefore beg leave to dis- 

 criminate by the name of spontaneous light. 



The substances from which such light is emitted, are princi- 

 pally the following. 



Marine animals, both in a living state, and when deprived of life. 



MDCCC. Y 



