, Analogues of the double atom of water, 



4% Dr. W. Odling on the Doctrine of Equivalents. 



in«' to it the equivalent notation by dashes^ to which I have 

 before referred. About the same time Gerhardt began to use 

 mult-equivalent radicals, which in the later volumes of Tj-aite 

 de Chimie Orgnnique, he employed largely to express the consti- 

 tution of bodies formed on the types chloride, oxide, and amide 

 respectively. Kekule also represented coniine with a bi-equiva- 

 lent radical; and other chemists followed in the same track. I 

 append some examples of formulse proposed by WilHamson and 

 myself, illustrating our views of mult-equivaleat radicals. 



(CO)" KH 02 

 Acid carbonate of potash* 



(C2 0^)" Et2 02 

 Oxalic aether*. 



(soyH^o^ 



Sulphuric acid*. 



(PH2)'" H 0^ 



Hvpophosphorous acidf. 



(PO)'" H 0^ 



Metaphospboric acidf. 



(C'H-^OTH^O'' ^ 



Citric acidt- 



(PO)'" H3 03 



Phosphoric acidt. 



(CO)" C^H^ N 



Cyanic aether*. 



(CS)" C^H'^ N 



Oil of mustard J. 



(Q2 02)" H N 



OximideJ. 



(C2 02)" H" W 



Oxamide*. 



(C« H^)" 114 ^i 



Senii-bcnzidine§. 



(CO)" H^ N^ 



Urea + . 



(C0)"(CMP)2H2N2 



Flavine+. 



(CS)" (C^ H-^) H3 W 



ThiosinnamineJ. } 



There is a point of considerable interest connected with the 



* Williamson. ' Chemical Gazette,' 1851. 

 t Odling, ' Journal of Chemical Society,' 1855. 



X Notes to Cavendish Society's Translation of Laurent's Methode de 

 Chimie, 1855. § Journal of Royal Institution, 1855. 



1 Analogues of the treble atom of water, 

 [ H^ H3 0'^ 



Analogues of ammonia, H^ H N. 



Analogues of the double atom 

 ammonia, H^ H^ N^. 



of 



