ANNALS 



OF 



PHILOSOPHY. 



SEPTEMBER, 1813. 



Article I. 



Report on a Memoir of M. Berard, relative to the Physical and 

 Chemical Properties of the different Rays ivhich compose the 

 Solar Light. By MM. BertholJet, Chaptal, and Biot* 



M. BERTHOLLET, M. Chaptal, and myself, have been 

 charged with the examination of a memoir lately presented by 

 M. Berard on the physical and chemical properties of the diffe- 

 rent rays which compose solar light. We proceed, therefore, to 

 give an account of it to the Class. 



It is a question long discussed among philosophers and che- 

 mists, whether caloric and light be modifications of the same 

 principle, or consist of principles essentially different. Many 

 systems have been constructed in favour of both hypotheses ; but 

 the only means of deciding the point is to determine by experi- 

 ment, and to fix with exactness, the properties belonging essen- 

 tially to caloric and to light, to ascertain in what respects they 

 agree, and in what they differ; and, finally, to see whether the 

 same principle, always constant in its nature, but acting diffe- 

 rently on our organs, and on bodies in different circumstances, 

 l>e capable of producing all the variety of effect which we 

 observe. 



Several skilful philosophers and chemists have already partly 

 directed their attention towards this object. Thus Mariotte 

 discovered that invisible heat radiates like light, and is reflected 



• Translated from the Anii,«I»-> if GhimM far Mar«b 181*, rol. lxixv. 

 p. 309. 



Vol. II. N° I If. h 



