538 



PROF. LETTS AND MR R. F. BLAKE ON 



poly-haloid compounds is, however, more marked. They give the following table, contain- 

 ing a list of the new substances, the methods of forming them, and their chief properties : — 



No. 



Substance. 



Method of Formation. 



Temperature of 

 Formation. 



Chief Properties. 



1 



PEt 4 IBr 4 ? 



Br 2 on iodide. 



cold. 



Bright red crystals, solid ; unstable. 



2 



PEtJBr 



Alcohol on I. 





Orange crystals ; stable. 



3 



PEt 4 ICl 4 



Cl 2 on iodide. 



70° 



Yellow crystal mass ; unstable. 



4 



PEt 4 ICl 2 



Alcohol on 3. 





Yellow crystals ; stable. 



5 



PEt 4 Br 7 



Br 2 on bromide. 



110 



Yellow crystal mass ; unstable. 



6 



PEt 4 Br 3 



Alcohol on 5 or 9. 





Red crystals ; stable. 



7 



PEt 4 Cl 3 



Cl 2 on chloride. 



110 



Yellow crystal mass ; unstable. 



8 



(PEt 4 ) 2 S0 4 Br.„ ? 



Br 2 on sulphate. 



cold. 



Red, liquid ; unstable. 



9 



(PEt 4 ) 2 S0 4 Br 12 



Br 2 on sulphate. 



110 



Red, solid ; unstable. 



10 



(PEt 4 ) 2 S0 4 Cl 4 



Cl 2 on sulphate. 



130 



Yellow, solid ; unstable. 



Organic Phosphorus Compounds which cannot be placed in any of the above Groups. 



A phosphorised kakodyl (CH 3 ) 4 P 2 (the methyl analogue of liquid phosphuretted 

 hydrogen) was obtained by Thenard # by the action of chloride of methyl on phosphide 

 of calcium, and is interesting not alone as being the sole representative (as yet prepared) 

 of its class, but also as having been probably the first phosphine obtained. Thenard 

 describes it as a colourless, highly refractive liquid, of an odour recalling that of kakodyl 

 itself, insoluble in water, and boiling at about 250°. It inflames spontaneously in 

 contact with air, but if oxidised slowly, gives a crystalline acid (CH 3 ) 4 P 2 H 2 4 := 

 (CH 3 ) 2 PH0 2 (dimethyl phosphinic acid), analogous to kakodylic acid. Treated with an 

 excess of hydrochloric acid, it is converted into trimethyl phosphine, and a solid yellow 

 substance (CH 3 ) 2 P 4 (which is also formed in the original reaction), and which Thenard 

 regarded as the methyl analogue of solid phosphide of hydrogen. 



Michaelis t obtained a substance, which he named diphosphenyl, or phospho-benzol, 

 C 6 H 5 — P = P — C 6 H 5 (corresponding to azobenzol), by the action of phenyl phosphorous 

 chloride on monophenyl phosphine, 



C 6 H 5 PC1 2 +C 6 H 5 PH 2 = (C 6 H 5 ) 2 P 2 + 2HC1. 

 It is a pale yellow powder, insoluble in water, alcohol, and ether, but readily soluble in 

 hot benzol, and is slowly oxidised by the air to (C 6 H 5 ) 2 P 2 0. Treated with chlorine, 

 phenyl phosphorous chloride is regenerated. With nitric acid it is oxidised to phenyl 

 phosphinous acid C 6 H 5 PH 2 2 , if the acid is dilute, but to phenyl phosphinic acid, 

 C 6 H 5 PH 2 3 , if the acid is strong. Treated with hydrochloric acid, it reacts so as to 

 regenerate the substances from which it is formed. 



Michaelis | also obtained a substance, which he called di-phospho-benzene hydrate, 

 C 6 H 5 — P = P — OH, by the action of spontaneously inflammable phosphuretted hydrogen 

 on phenyl phosphorous chloride. It is a yellow powder, soluble with ease in bisulphide of 

 carbon, taking fire on exposure to air, and oxidised by nitric acid to phenyl phosphinic 



* Thenard, Comptes Rendus, xxi. p. 144, and xxv. p. 829. 



t Michaelis, Berichte, x. p. 807. J Michaelis, Berichte, vii. (1875) p. 499. 



