Ml{. II. MIIKUKTOX IIAKKK ON C( iM UfSTION IN DRIED i)\\ 



587 



were passed through the cork of a large l>oiling tube containing mercury. A long 

 tube open at both ends and passing through the cork served to condense the mercury 



vapour. 



Fig. 6. 



The mercury was boiled. After a few minutes the wet phosphorus burnt, the dry 

 phosphorus showing no change. Further than that, though kept in the boiling 

 mercury for four hours, it was apparently unaltered. We should have expected that 

 it would have been, partly at all events, transformed into the ordinary modification. 

 Is it possible that the change from one modification to the other is affected by 

 dryness? 



To answer this question the following experiment was undertaken : Two tubes 

 containing pure amorphous phosphorus in (a) moist and (/>) dry nitrogen were heated 

 in the vapour of boiling mercury for four hours. The phosphorus in both tubes was 

 apparently unaltered. No sublimate of ordinary phosphorus could be seen on the cold 

 parts of either tube. When the same tubes were heated in sulphur vapour at 440, 

 the production of ordinary phosphorus was quickly noticed in both tubes. Dryness 

 does not apparently affect the temperature of the change. 



Two tubes were prepared bent at right angles. A small quantity of amorphous 

 phosphorus was placed in each, and one was filled with pure nitrogen, the other with 

 pure oxygen, both gases being saturated with aqueous vapour. The ends of the tubes 

 were then sealed. In order to heat the phosphorus contained in them, the limbs 

 containing the phosphorus were placed in an air bath, holes being cut in its sides for 

 their reception. The air bath was provided with a PAGE'S regulator and the tempera- 

 ture was kept constant at 260. The other limbs of the tubes were outside the air 

 bath and were kept cool (fig. 7). 



After six hours the tubes were removed. No perceptible change had taken place in 

 the nitrogen tube ; a small quantity of ordinary phosphorus appeared on the cold jmrt 

 of the oxygen tube. 



4 F 2 



