1G8 REPORT— 1900. 



and of the melting-point curves of mixtures of the moi'photroplcally 

 related compounds. 



Morp/iotrojnc JRelations/iijjs bctircen Funnanilide and its Substitution Derivatives. 



In order to determine the morphotropic effect of substitution upon 

 the crystalline form of formaniUde the simple anilides of the composi- 

 tion C,-,H,.NH (CO.X) (X=H, Me, Et, Pr, &c.) as well as several of 

 their alkyl derivatives, and also a number of the mono- and di-halogen 

 derivatives, have been crystallographically examined by Mr. L. P. Wilson ; 

 a list of the compounds measured is given in the accompanying table, in 

 which the geometrical constants are also indicated. It is evident that a 

 jDrogressive change in the structural dimensions occurs as each series is 

 traversed, although in most cases this only becomes obvious on rearranging 

 the axial ratios, and sometimes on taking simple multiples of the ratios. 

 The form in which the axial ratios are compared is indicated in the 

 second column. 



I. 0. 



In series 1, although the first memlier is monosymmetric, whilst the 

 others are orthorliombic, a well-marked morphotropic similarity in the 

 magnitudes of the ratio n/b is observed to follow the displacement of the 

 hydrogen atom in the acidic group by Me, Et or Pr. The effect of dis- 

 placing the aminic liydrt)gcn atom by Me, Et or Pr is less, as is shown by 



