Dr. Hofmann and M. Cahours on the Phosphorus-bases. 395 



ceding abstract, a comparison of these substances 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 ])roperties, 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 

 presence of elements so dissimilar as nitrogen, phosphorus, arsenic, 

 and antimony ; they might, moreover, be confounded with potassa 

 and soda, by which they are scarcely surpassed in alkaline power. 



Only the deportment of the hydratcd oxides, under the influence 

 of heat, distinguishes the derivatives of nitrogen from the corre- 

 sponding terms of the phosphorus-, arsenic-, and antimony-series. 



If we regard, on the other hand, the compounds belonging to the 

 ammo7na-type, we observe that the electro-positive character of the 

 substances gradually rises in intensity from the nitrogen- to the 

 antimony-compounds. Thus, trimethylamine and triethylamine are 

 not capable of unituig with oxygen, chlorine, bromine, and iodine ; 

 a power which the corresponding terms of the phosphorus-, arsenic-, 

 and antimony-series possess in a high degree. 



Triethylamine unites with the acids, producing compounds of the 

 ammonium-type, and containing 



E3N,HC1 



E3N,HS04 



EgN.HNOfi 



The corresponding compounds in the arsenic- and antimony-series 

 do not exist ; at all events chemists have not yet succeeded in pre- 

 paring them. Triethylarsine and triethylstibine combine only directly 

 with oxygen, chlorine, sulphur, &c., producing saline bodies which 

 have the composition respectively, — 



E3ASO2 EgSbOj 



EgAsCl.^ EgSbCla 



E.jAsS2 E.,SbS2 



In the phosphorus-series, lastly, the two classes are represented. 

 Triethylphosphinc not only forms compounds analogous to the salts 

 of triethylamine, but also the terms corresponding to the binoxides of 

 triethylarsine and triethylstibine. We have in the first place the 

 terms 



E,P,IIC1 

 EjlMISO^ 



e", p, UNO., 



2D2 



