1872.] Dr. A. W. Hofmann on the Phosphorus Bases. 233 



and arsenic, already traced in so many directions. I hope that the conti- 

 nuation of these researches will still further elucidate this similarity. There 

 can be no doubt that the several members of the kakodyl series from which 

 arsenmonomethylic and kakodylic acids have been produced will soon be 

 represented amongst the derivatives of phosphorus. The discovery, too, 

 of the primary and secondary arsines, the oxidation of which, as is obvious 

 from the results described in this note, must yield the same acids, will pro- 

 bably not have long to be waited for. 



IV. Primary and Secondary Ethylic Derivatives of Phosphoretted 



Hydrogen. 



Afterwhat has been elicited by the investigation of the methyl compounds, 

 there could be but little doubt as to the phenomena to be observed by re- 

 peating the experiments in the ethyl series. Nevertheless the study of the 

 ethyl compounds presented an interest of its own. In the first place, it 

 was desirable experimentally to generalize the new method by applying it 

 to different groups ; again the properties likely to be possessed by the ethyl- 

 phosphines, and more particularly their higher boiling-points, appeared to 

 promise that the experimental difficulties of this inquiry would be materially 

 diminished by working in the ethyl series. 



The formation of the ethylphosphines by means of ethyl iodide, phospho- 

 nium iodide, and zinc oxide takes place with the same facility and precision 

 as that of the methylated compounds. The reaction, however, proceeds 

 but slowly at the temperature of boiling water. Exposure of the tubes to 

 a temperature between 140° and 150° C. for six or eight hours is sufficient 

 for the transformation. The product of the reaction in this case, exactly as 

 in that of the methyl series, contains the primary and secondary bases only. 

 Their separation and preparation in a state of purity is carried out in exactly 

 the same manner as that of the corresponding methyl compounds. 



Ethylphosphine. 



C„H 7 P= H }¥. 

 Hj 



Colourless, transparent, mobile liquid, powerfully refractive, lighter than 

 water, in which it is insoluble. It is easily soluble in alcohol and ether. 

 These solutions are without any action on vegetal colours. Ethylphos- 

 phine boils constantly at 25°, and is thus seen to possess exactly the same 

 boiling-point as dimethylphosphine (p. 227), with which it is isomeric. 



CH,] C 2 H 5 1 

 CH 3 P = II } P = C a H 7 P. 

 H J II J 



The odour of this compound is overwhelming ; it strongly recalls that 

 of the foimonitriles, producing more especially the same sensation of bitter- 

 ness on the tongue and to the very depth of the throat, Odour aud taste 



