PHENOMENA OF PYROPHORI. 95 



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The conclusion drawn from this circumstance was, " That 

 light is not only acted on by other bodies, but it is capable of 

 uniting with them, and afterwards leaving them without any 

 change." 



If we consider, from analogy, that in oyster-shell lime, 

 which is an alkaline earth, nitrogen and carbon are consti- 

 tuents, and in sulphur, hydrogen, carbon, and nitrogen, are 

 present, they, in the operation of forming the compound, may 

 absorb oxygen at a red heat. The principles of light, accord- 

 ing to the present theory, are combined in the pyrophorus 

 but imperfect in their proportions, and also in their polarity 

 of combination, yet possessing the power to attract and absorb 

 the whole of the rays of light, as it is admitted light is subject 

 to the laws of attraction, and consequently possesses gravity. 



But if the established measure of the velocity of light is 

 granted, we must presuppose a propelling power, which may 

 be repulsion, as before alluded to ; and that force must operate 

 as pressure, and in a direct line from the radiating point ; and 

 under the influence of that force, the absorption of light by an 

 opaque body so composed, and of an irregular unpolished sur- 

 face (less capable of reflection), on removal to a dark room, the 

 direct influence of the pressure of radiant light being with- 

 drawn, instead of retaining what it had absorbed, it is now 

 disposed to discharge it, and possessing in its integral parts 

 the principles which constitute light, although these principles, 

 from want of exactitude in proportion, and other necessary 

 advantages of polarity, are not in their then position capable 

 of immediately becoming radiant matter without an impetus, 

 yet possess the power to develope what they had acquired by 

 attraction, during the application of pressure, and perhaps to 

 render it perfect by supplying any deficiency. 



The discharge of light from the pyrophorus may be rendered 

 more evident by the aid of caloric, as in the instance of the 

 experiments on the glass globes, but consequently the one 



