1912 Ammonium Cyanate into Urea 147 



I have used this explanation in my own lectures since that time. 

 Essentially the same explanation is given by Willstatter in his 

 lectures in Ziirich. By introducing the idea of partial valence 

 the mechanism is more readily conceived. The reaction is for- 

 mulated thus: 



H— N++C=0 H— N— C-0 



': ■: II 



H — NHi H NH2 



The partial valences of the nitrogen and carbon atoms are rep- 

 resented by a number of very short lines, not dots, which should 

 be reserved for ordinary valences. (The practise of writers in 

 this matter is not uniform, but uniformity would be very desir- 

 able.) When the partial valences come into play in the pres- 

 ence of H.NH2, one of the double bonds between nitrogen and 

 carbon is broken, as represented in lecture practise by a double 

 stroke across the bond and the partial valences resolve them- 

 selves into ordinary valences. 



Alvin S. Wheeler. 



University of North Carolina. 



