58 JOURNAL OF THE 



after washing with water, alcohol and ether, take fire spontaneously 

 on drying. This shows that much phosphorus is precipitated also, 

 enclosed in and carried down by the metallic phosphide. "Washing 

 with carbon disulphide did not remove this. Careful drying, with 

 exclusion of air, weighing, oxidizing and dissolving in nitric acid 

 and determining the copper, gave in three experiments as the per 

 centage of copper 10.44, 6.95 and 6.77. If this precipitate be left 

 some days in contact with an excess of the copper solution, or cov- 

 ered over with alcohol, (water might have answered the purpose, 

 but was not used), it becomes non-inflammable, and is copper phos- 

 phide. The silver precipitate acts in the same way, at first inflam- 

 mable, after long standing non-inflammable. It is black in color, 

 but usually not so homogeneous in appearance as the copper pre- 

 cipitate, having white grains in it lighter than the rest, and tending 

 to rise to the surface of the washing liquid. 



Agitation with water alone does not precipitate the phosphorus 

 from its solution in carbon disulphide, nor does water with other 

 metallic salts than those mentioned, dissolved in it. Lead salts, for 

 instance, give only a dingy scum. Agitation with alcohol will cause 

 a precipitation of the phosphorus, and so also with ether. 



If the precipitate is covered with alcohol and left a month or so 

 at ordinary temperatures, the alcohol becomes denser and strongly 

 acid, and the phosphorus disappears from the precipitate. On 

 attempting a distillation, the alcohol first comes over. This alcohol* 

 is still slightly acid and becomes milky on adding water. The tine 

 milky white precipitate cannot be caught on a filter. It smokes on 

 exposure to air as phosphorus does. For the remaining liquid the 

 thermometer rises a few degrees above 100°, then falls with rapid 

 evolution of gas. If distillation is persisted in, a few c. c. of a dense 

 syrupy liquid with a strongly acid reaction are left. There is prob- 

 ably a formation of ethyl phosphoric acid then, and this is decom- 

 posed by the distillation. Alcohol poured over any finely divided 

 phosphorus acts very similarly. 



Chemical Laboratory^ U. N. C. 



