224 Dr. A. W. Hofmann on the Phosphorus Bases. [Mar. 21, 



flame ; explosions, however, are but rarely met with. The proportions of 

 the charge are so selected, that supposing the reaction to be complete, no 

 other products except methylphosphonium iodide and zinc iodide should be 

 produced . But the presence of some unchanged phosphonium iodide together 

 with the escape of its constituents, more especially of phosphoretted hy- 

 drogen, prove at once that compounds more highly methylated must be 

 formed. Experiment shows, however, that monomethyl- and dimethyl- 

 phosphine exclusively are generated. These two substances are easily 

 separated from the crude product of the reaction, which, by means of a 

 bent wire, may be removed in one piece from the tube. 



The separation of monomethylphosphine and dimethylphosphine and 

 the preparation of the two bodies in a state of purity are based upon 

 the observation that the salts of the former base are easily and thoroughly 

 decomposed by water, whilst those of dimethylphosphine, more especially 

 in the presence of free acid, may be considerably diluted without undergoing 

 any change, but are immediately decomposed by addition of a fixed alkali. 

 The crude product of the reaction is therefore consecutively treated with 

 water and strong alkali, the former disengaging the methylphosphine, 

 which, being gaseous, is collected in concentrated hydriodic acid, the latter 

 liberating the dimethylated phosphine, which, being liquid at the common 

 temperature, may be readily condensed by an appropriate cooler. The 

 two bodies being powerfully acted upon by the oxygen of the air, the 

 whole process is to be conducted in an apparatus filled with hydrogen. 



Me thy I phosphine, 



CH 3 | 

 CH 5 P= H I P. 

 H J 



Methylphosphine is a colourless transparent gas of a most overwhelming 

 odour. 



Both by cooling and by pressure the gas may be condensed into a colour- 

 less liquid floating upon water, and boiling from platinum at —14° under 

 a pressure of 0*7585 metre. The experiment was made with from 60 to 

 70 grms. of methylphosphine condensed in one operation, the boiling-point 

 remaining constant till the last drop had distilled. In studying the be- 

 haviour of the new gas under the influence of increased pressure, I have 

 availed myself of the beautiful compression- apparatus constructed by 

 Gustav Magnus. At 0° If atmosphere was sufficient to start the lique- 

 faction ; under a pressure of atmospheres the gas was perfectly liquid, 

 its purity being thus satisfactorily established. At 10° liquefaction com- 

 menced, and was completed under a pressure of 2\ and 4 atmospheres 

 respectively ; at 20°, lastly, under a pressure of 4 and 4J atmospheres. 



The volume-weight of methylphosphine gas was easily determined by 

 allowing a small tube with a weighed quantity of the iodbydrate to rise 

 into a graduated cylinder filled with mercury and inverted over the mercu- 

 rial trough and subsequently introducing some concentrated solution of 



