B.— CHEMISTRY. 51 



Aromatic Selenium and Tellurium Compounds. — Phenol and the cresols 

 have been condensed with selenium oxychloride when two types of 

 seleniferous products have been distinguished, polar salt-like substances 

 (Formula I) and non -polar selenides (Formula II). 



I [(HO . C6H,)3Se] CI •Se(C,He.OH), II 



When the cresols are condensed with basic tellurium chloride the 

 following tjrpes were distinguished, all containing quadrivalent tellurium : 

 HO . C,H, . TeCl,, (HOC\H,),Tea, (HOC,H,),TeCl. The more soluble of 

 such selenium and tellurium compounds have been tested on trypanosomes, 

 but so far no evidence of activity has been discerned. 



Studies in the Diphenyl Series. — The o-xenylamine required in the 

 synthesis of cyclic antimonials was formerly obtained in a somewhat 

 tedious manner by the pyrolysis of diazoaminobenzene. This base has 

 now been prepared by a method practicable on a large scale from com- 

 mercially obtainable diphenyl. 



o-Xenylamine and its homologues, for example, 4': 5-dimethyl- 

 •o-xenylamine, are convenient starting-points for the synthesis of carbazole 

 and phenanthridine derivatives. 



Residual Affinity and Co-okdination. 



An experimental study of the effect of various co-ordinated addenda 

 on the valencies of copper, silver and gold has been pursued during the 

 past five years with the following results. 



Stabilisation of the cupric condition. — In the absence of suitable addenda 

 the cupric ion is unstable when in combination with less electronegative 

 anions such as iodide, sulphite, thiosulphate, thiocyanate, selenocyanate 

 and hypophosphite, but by co-ordinating this metallic ion with 

 €thylenediamine (en=NH2.[CHJ,,.NH2) stability is thereby conferred on 

 the bivalent condition, and well-defined complex salts of the following 

 types are obtained: [Cu, 2en, 2H,0]I.„ [Cu, 2en, R.OH] I,(R = CH, or 

 C.,H,), [Cu, 2en]X where X=SO„ S,0„ 8,0^, S,0, or S,0, and [Cu, 2en] Y., 

 where Y=CNS, CNSe or H^PO.,. Moreover, the following stable normal 

 salts [Cu, 2en] CO,, 2H,0, and [Cu, 2en] (NO,), are obtainable with 

 carbonate and nitrite radicals respectively. 



Stabilisation of the cuprous condition. — Even more noteworthy than the 

 preceding effect of ethylenediamine is the influence of addenda containing 

 sulphur on the stability of the cuprous ion. Cuprous sulphate, an endo- 

 thermic compound, decomposes in water with generation of heat and loss 

 of half its copper, Cu.^S04+ 5Aq =CuSOj, 5Aq -f Cu, but by co-ordinating 



CH, . NHv^ 

 the cuprous ion with ethvlenethiocarbamide, etu = | \CS the 



CH, . NH/ 



univalent condition becomes stabilised even in combination with nitrate, 

 sulphate and acetate radicals. The following colourless water-soluble 

 salts have been identified : [Cu, 4 etu] NO,., [Cu, 3 etu], SO^ and 

 tCu, 3 etu] CH,CO,. 



Co-ordination compounds of silver. — Since the silver ion is generally 

 univalent, its co-ordination with ethvlenethiocarbamide or other sulphur 



E 2 



