1872.] Dr. A. W. Hofmann on the Phosphorus Bases. 227 



Dimethylphosphine. 



CH 1 

 CJI 7 P = CH 3 P. 



The method of preparing dimethylphosphine has been already stated. 

 It is a transparent colourless liquid, which, when protected from the atmo- 

 sphere, may be preserved without change. It is lighter than water, in 

 which it is insoluble ; alcohol and ether, on the other hand, dissolve it 

 with facility. Its boiling-point is 25°. 



Dimethylphosphine is remarkable for the avidity with which it attracts 

 oxygen, and which is infinitely superior to that of the monomethylated 

 base. In contact with the air, it instantaneously takes fire and burns with 

 a powerfully luminous phosphorus flame. If the hydrogen atmosphere in 

 which it is prepared contain only traces of air, the presence of which is 

 at once indicated by the formation of white fumes, violent and by no 

 means dangerless explosions are occasionally experienced in working with 

 this compound, even if great care be employed. 



Dimethylphosphine easily unites with acids ; all the salts are exceedingly 

 soluble. The solution of the chlorhydrate furnishes with platinum per- 

 chloride a fine crystalline salt. The base also unites with sulphur and 

 carbon bisulphide. The compounds thus formed are not yet investigated ; 

 but it may even now be remarked that they essentially differ from those 

 produced by trimethylphosphine ; more especially in the deportment of the 

 two bases with carbon bisulphide, a marked discrepancy is observed. Di- 

 methylphosphine in this case produces no crystalline compound similar to 

 those which are formed by the tertiary phosphines ; so that the absence of 

 trimethylphosphine among the products of the action of methyl iodide on 

 phosphonium iodide may be readily demonstrated. 



The inflammability and the low boiling-point of dimethylphosphine 

 render it difficult to work with this body except in the midst of winter. 

 The examination of its numerous products of decomposition, which pro- 

 mises to be fruitful in results, is therefore as yet but little advanced. 

 Hitherto I have studied somewhat more in detail only the products of 

 oxidation of the methyl bases, which I beg leave to describe to the 

 Society in a special paper. 



III. Products of Oxidation of the Methylated Phosphines. 

 When determining phosphorus in several substances which in the course 

 of the new researches on the phosphines had to be examined, it was found 

 that these bodies, and especially the members of the methyl series, resist 

 with remarkable energy the action of even the most powerful oxidizing 

 agents, 



If the phosphoretted bodies were heated according to the method of 

 Carius, it happened sometimes, especially when the digestion in sealed tubes 

 was conducted according to the earlier directions with nitric acid not per- 



