I9I4.] NITROGEN IN AMMONIUM SALTS. 23 



structure, is to the left. The free acid is also left handed, indicating 

 a cyclic structure similar to that of the anhydride. The sodium salt 

 and hydrochloride of aminodihydrocampholytic acid are right 

 handed. The free acid and anhydride are also right handed, but with 

 a considerably increased rotation. The sodium salt and free a-amino- 

 campholic acid are both right handed with rotations closely alike, 

 indicating that each has an open structure, but the anhydride, which 

 certainly has a cyclic structure, is left handed and has a rotation 

 very closely like that of the aminocamphonanic acid, indicating 

 again very clearly that the latter has a cyclic structure and that each 

 compound contains a cycle of six atoms. The sodium salt of /?- 

 aminocampholic acid and the free acid also correspond closely in 

 rotation, indicating an open structure for both, while the hydro- 

 chloride and anhydride have a considerably greater rotation, as is the 

 case with both the free aminodihydrocampholytic acid and its an- 

 hydride. 



All of these observations are consistent with the hypothesis that 

 aminodihydrocampholytic and aminocamphonanic acid form cyclic 

 salts containing cycles of six atoms, while the aminocampholic acids 

 do not form such salts because, if formed, they would contain cycles 

 of seven atoms. It seems difficult to find any other simple explana- 

 tion for the observations. 



The results also point very strongly to the formula for am- 

 monium salts whic'h represents them as containing quinquivalent 

 nitrogen and against Werner's formula. According to Werner's 

 formula the free aminocamphonanic and aminodihydrocampholytic 

 acids would contain cycles of seven atoms, 



CH,— C ( CH3 ) — CO— O 



C(CH,)2 H 



CHo— CH NH. 



Such a formula is quite inconsistent with all that we know about 

 the ease with which rings of five and six atoms are formed and the 

 comparative rarity of seven-atom rings. It is also inconsistent with 

 the close agreement between the rotation of the aminocamphonanic 



