490 Messrs Jones and Millington, The Spatial 



on the change of sulphur and selenium from quadri- to sexa- 

 valency), the conclusions drawn from the above experiments are 

 invalidated by this possibility. It has not been found necessary, 

 however, to assume that this change of ' valency-direction ' does 

 occur in the nitrogen atom during the change from tri- to quinque- 

 valency in order to explain the observed phenomena (see Trans. 

 Chem. Soc, 1903, Lxxxm. 1403). 



Kipping and Salway (Trans. Chem. Soc, 1904, lxxxv. 438) 

 have attacked the problem in a new way by investigating the 

 reaction of various primary and secondary amines with an 

 optically active acid chloride. In all the cases examined no 

 isomerism was detected which could be assigned to the asym- 

 metry of the nitrogen atom, so that they definitely conclude that 

 the configuration of the trivalent nitrogen atom is plane. 



Before the publication of the last-mentioned paper the authors 

 had made some experiments in the hope of obtaining evidence 

 which should not be open to the objection raised by Pope and 

 Harvey to previous attempts to resolve trivalent nitrogen com- 

 pounds, and so bringing the matter to some definite conclusion. 

 The above work of Kipping and Salway affords such strong 

 evidence in favour of the plane configuration, which is supported 

 by the authors' experiments in so far as they have been carried 

 out, that it was thought unnecessary to continue the work and 

 to publish the results already obtained. 



The object was to make the experiments with compounds in 

 which there should be no change in the valency of the nitrogen 

 atom during the processes involved. Two such sets of compounds 



"R \ 



are available; namely, hydrazines of the type „, /N— NH 2 , in 



which the salt formation will almost certainly take place with the 

 unsubstituted amine group, particularly if R and R/ be aryl groups, 



and the acids of the type C 6 H 4 \ „ \ R' 



-COOH or -S0 3 H. 



Up to the present one compound of each class has been in- 

 vestigated, namely, benzyl-phenyl-hydrazine by fractional crystal- 

 lisation of the dextro-camphorsulphonate and methyl-ethyl-aniline- 

 sulphonic acid by fractional crystallisation of its brucine salt. 



Benzyl-phenyl-hydrazine dextro-camphorsulphonate was pre- 

 pared by mixing together molecular quantities of the acid and 

 base dissolved in hot ethyl acetate. The solvent was evaporated 

 off; the solid which was left soon crystallised, and was then re- 

 peatedly recrystallised from a mixture of ethyl acetate and ether, 

 when it was obtained in long prisms melting at 156° — 157 c C. 



The salt is very sparingly soluble in water, so that determinations 



