525 



Iodide of phosphomethylium Me 4 P I 



Platinochloride of ditto Me 4 P Cl, PtCl. 2 



Aurochloride of ditto Me 4 P Cl, AuCl 3 



Iodide of phosph'ethyltrimethylium . . (Me 3 E) P I 



Platinochloride of ditto .. (Me 3 E) P Cl, PtCl 2 



Iodide of phosph'amyltrimethylium . . (Me 3 Ayl) P I 



Platinochloride of ditto .. (Me s Ayl) P Cl, PC1 2 



Ethyl-series. 



Triethylphosphine E 3 P 



Platinochloride of triethylphosphine. . E 3 P, HC1, PtCl 2 



Binoxide of ditto . . E 3 P O 2 



Bisulphide of triethylphosphine .... E 3 PS 2 



Biselenide of ditto E 3 P Se 2 



Iodide of phosphethylium E 4 PI 



Platinochloride of ditto E 4 P Cl, PtCl 2 



Aurochloride of ditto E 4 PC1, AuCl 3 



Iodide of phosphomethyl-triethylimn . (MeE 3 ) P I 



Platinochloride of ditto . . (MeE 3 ) PCI, PtCl 2 



Iodide of phosph'amyltriethylium. . . . (Ayl E 3 ) P I 



Platinochloride of ditto (Ayl E 3 ) PCI, PtCl 2 



On glancing at the phosphorus-compounds noticed in the pre- 

 ceding abstract, a comparison of these suhstances with the corre- 

 sponding terms of the nitrogen-, arsenic-, and antimony-series 

 is unavoidably forced upon us. Whether we consider the compo- 

 sition, or whether we review the properties of these groups, the 

 most striking analogies, indeed an almost perfect parallelism, cannot 

 be mistaken ; similar formulae, similar modes of combination, similar 

 decompositions. 



This analogy is particularly manifest in the compounds belonging 

 to the ammonium-type. In these remarkable bodies, nitrogen, 

 phosphorus, arsenic, and antimony appear to play absolutely the 

 same part. It is more especially in the oxides of these compound 

 metals that the analogy of composition induces a perfect identity of 

 properties, and, indeed, of very salient properties, which may be 

 traced in almost every direction. If we were satisfied with the 

 study of the reactions of these bodies, we should never suspect, in 

 compounds possessing such a close similarity of properties, the 



2 Q2 



