METALS AND METALLOIDS 709 



Some of these aromatic amino-derivatives of antimony may 

 find therapeutic application, and already triphenylstibine sulphide, 

 (C 6 H 6 ) 3 SbS (" sulphoform "), has been used in the treatment of 

 skin diseases. 



3. Influence of Valency on the Stability of Organo- 

 metallic and metalloidal compounds 



Reference has already been made to the influence of valency 

 in the formation of organic compounds of metals and metalloids. 

 There is no well-authenticated case where a univalent metal 

 furnishes an organic derivative capable of existence as an 

 individual compound. Sodium ethyl is only known in com- 

 bination with zinc ethyl. When a metal has several valencies 

 the tendency is for the organic compound to contain the metal 

 in its highest state of valency. Mercury, thallium, gold, and lead 

 exhibit this tendency, as is shown by their organic derivatives 

 already cited. A series of comparative experiments with 

 camphor and the elements of the arsenic family show the same 

 tendency at work. Sodium camphor was condensed with the 

 trichlorides of phosphorus, arsenic, and antimony containing 

 the non-metal or metalloid in the tervalent condition, the 

 products as shown by the following table, contained these 

 elements in the quinquevalent state : 



Condensation Products from Sodium Camphor and the Trichlorides of 



the Phosphorus Group 



Products. Phosphorus trichloride. Arsenic trichloride. Antimony trichloride. 



Dicamphoryl (C l0 H l5 O) 2 PO . OH, di- (C l0 H, s O),2AsO . OH, di- 



derivatives. camphorylphosphinic camphorylarsinic acid, 



acid, stable in concen- stable in hot dilute 



trated aqueous alkali aqueous alkali hydrox- 



hydroxides ; decom- ides ; decomposed by 



posed by fused alkali very strong solutions of 



hydroxides. these alkalis. 



Tricamphoryl (C| H 15 O) 3 As(OH) 2 , tri- (Ci H ls O) 3 SbCl 2 , tricam- 



derivatives. camphorylarsinic acid, phorylstibinic chloride, 



is as stable towards slowly resolved by water 

 alkalis as the above di- into 

 camphoryl derivative. (C l0 H 15 O) 3 Sb(OH) 2 , 



trie am phorylstibinic 

 acid, very unstable, de- 

 composed by dilute 

 aqueous sodium hydrox- 

 ide and even by boiling 

 water. 



This very general tendency affords confirmation for the 

 view that valency is largely a question of arrangement in space. 



