248 



If M!, m ?i , m 3 and w 4 be the masses of the four substitutes, Guye's 

 formula may be reduced also to the form: 

 P = (m 1 ~ m 2 ) (m^ m 3 ) (m^ w 4 ) (m 2 m 3 ) (m ? w 4 ) (m 3 mj. 



The same considerations can be used here: thus, if two of the 

 masses become equal, P becomes zero, etc. 



However, it is just in this respect that the weak point of Guye's 

 suggestive theory lies : for if the asymmetric carbon-atom be linked 

 to two isomeric radicals A and A', which accidentally possess equal 

 masses, the molecule can yet have optical activity, as has been 

 shown by direct experiments. 



Thus Fischer and Flatau 1 ) succeeded in performing the fission 

 of propyl-isopropyl-cyano-acetic acid'. 



C 



into its antipodes, and demonstrated that these have a rather large 

 specific rotation (11), notwithstanding the equality of mass of 

 the propyl-, and isopropyl-groups. 



Indeed, the mass-differences of the substitutes appear to have 

 quite a secondary importance for the magnitude of the specific 

 rotatory power of the molecules, as may be seen from the following 

 examples 2 ). 



Werner 3 ) in his beautiful investigations on complex inorganic 

 salts exhibiting optical activity, has first demonstrated, that deriva- 

 tives of the atoms of trivalent Co, Cr, Rho, Fe, etc., which all have 

 the coordinative number six, and which belong to the type: 

 Me {(X") 3 ] R 3 , in which X" is a bivalent acid radical or a base, can 

 be resolved by suitable means and under favorable circumstances, 

 into two enantiomorphously related antipodes which, although all 

 substitutes X" are here equal and thus have the same mass, exhibit 

 an enormous rotatory power, surpassing all that has been observed 

 up till now in carbon-compounds. These optically active salts belong 

 to the most interesting and remarkable objects chemistry offers, 



!) E. Fischer and E. Flatau, Ber. d. d. Chem. Ges., 42, 981, (1909). 



Numerous instances of this were mentioned already by Walden in 1895; cf. : 

 Zeits. liir phys. Chemie, 17, 712, (1895), and P. Freundler, Bull, de la Soc. chim. 

 (4), 18, 6, (1894). 



2 ) A. Werner, Ber. d. d. Chem. Ges., 45, 121, (1912); 47, 1960, 3093, 

 (1914); etc. 



