600 M. BIOT ON THE APPLICATION OF CIRCULAR POLARIZATION 



which exercises some influence upon the results as they have been de- 

 scribed by M. Biot. 



CONCLUSION. 



If we admit with M. Biot : 



1st. That a substance such as grape sugar can cause a deviation in 

 the plane of polarization in one case to the right, and in another to the 

 left;— 



2nd. That two substances perfectly distinct, such as cane sugar and 

 the sugar of starch of the first formation, have sensibly the same rota- 

 tory power; — 



3rd. That two substances so approximated as are the sugars of starch of 

 the first and second formations, have perfectly distinct rotatory powers ; 

 we must conclude that there is no consequence deducible from the op- 

 tical character relative to the connection of one species with another ; 

 and that its indications relate only to diiferences of molecular arrange- 

 ments, which have but an inconsiderable influence upon the character- 

 istic properties of the species. 



On the Application of the Laws of Circular Polarization to 

 the Researches of Chemistry ; by M. Biot. 



From the NoiwcUes Annales du Museum d'Hisfoire Naturelle, vol. iii. p. 502, 



et seq. 



When a new process of observation is introduced into the sciences, 

 it is well that it should be contested and criticized by persons of repu- 

 tation, for if the discussion be conducted by each pai'ty with freedom 

 and sincerity, nothing can be more advantageous to the new invention, 

 provided it be sufficiently well established to sustain it. With a con- 

 viction of this truth, I have read the dissertation inserted by M. Che- 

 vreul in the last number of the Annales d'Hisloire Naturelle, upon 

 the phaenomena of circular polarization which I discovered in a great 

 number of solid, liquid, and even gaseous substances ; and upon the 

 employment Avhich I proposed to make of it in the most delicate re- 

 searches of organic chemistry, in which these substances almost exclu- 

 sively occur, 



M. Chevreul divides his dissertation into two parts. 



In the first (I quote his own words) he examines the objections 

 which may be urged against the optical character which I have disco- 

 vered. 



