ELlbHA MITCHELL SCIENTIFIC SOCIETY. 57 



CERTAIN REACTIONS OF PHOSPHORUS. 



F. P. VENABLE. 



I wish to gather, under this heading, some scattered observations 

 which I have made in working with phosphorus during the past 

 year. No great claims to originahty are made. Some are but new 

 applications of old principles. 



Sidot (Compt. Rend., 84, 1454) has described the action of phos- 

 phorus upon a solution of copper sulphate. My own observations 

 agreeing with his, show that the solution is decomposed with the 

 formation of copper phosphide, metallic copper, sulphuric acid and 

 phosphoric acid. The stick of phosphorus first becomes black and 

 then speedily coats itself with metallic copper (often crystalline). 

 This crust is easily removed with a sharp wire or knife, the phos- 

 phorus may be dissolved away with carbon disulphide, leaving the 

 black phosphide. Traces of copper sulphate are capable of thus 

 blackening the phosphorus, affording a delicate test for copper. The 

 oxidation of the phosphorus thus coated with copper is very slow. 

 It can be left exposed to the air for months without danger. The 

 rapidity with which the coating takes place, and the phosphorus is 

 rendered harmless, suggests the use of a copper sulphate solution 

 where small pieces of phosphorus escape into cracks of a table or 

 floor, or get beneath the finger-nail. A little of the comparatively 

 dilute solution removes the danger of fire and prevents the serious 

 injury which comes from a phosphorus burn. 



Blyth (Poisons ; Effects and Detection, p. 667) recommends copper 

 sulphate as an antidote for phosphorus poisoning, giving it as an 

 emetic. Very probably its beneficial action is also due to the insol- 

 uble copper phosphide which immediately covers the phosphorus. 

 Else why not use some safer emetic? Why is copper sulphate the 

 best, as stated by Blyth. 



W. Schneid (Zeit, Chem. IV, 161, quoted by Watts) mentions the 

 precipitates given with certain metallic solutions by phosphorus dis- 

 colved in carbon disulphide. Only a few metallic solutions can be 

 decomposed in this way. The best precipitates are gotten with 

 copper, silver and mercury. An examination of these precipitates 

 showed that they were not the phosphides alone. The precipitate 

 gotten by shaking the solution of phosphorus with a solution of 

 copper sulphate is made up of small brownish black grains which, 



