MR. H. BREHETON BAKER ON COMBUSTION IN DRIED OXYGEN. 583 



peutoxide was introduced at one end and sealed bulbs of purified carbon bisulphide 

 at the other. A stream of dried oxygen WHS passed through the tubes and the ends 

 sealed. The bulbs of carbon bisulphide were then broken, and the vapour, mixed 

 with oxygen, was allowed to dry over phosphorus pentoxide for two weeks. Each 

 tube was then heated over an Argand burner with a comparison tube containing 

 the same gases in a moist state. Though the wet tubes exploded first in every case, 

 the dry ones did so a few seconds later, and apparently with equal force. 



Combustion of Ordinary Phosphorus in Oxygen. 



Commercial stick phosphorus was melted under a solution of potassium bichromate 

 in dilute sulphuric acid, dried and heated to 60 in a sealed tube with phosphorus 

 trichloride. The tube was allowed to project some 15 centimetres out of the air bath, 

 so that the sublimed phosphorus could condense in the cool part, but it was so inclined 

 that any chloride which distilled over should run back into the heated part, which 

 contained the melted phosphorus, mixed with phosphorus pentoxide. In three weeks 

 the greater part of the phosphorus was deposited in the cold part of the tube. The 

 iridescent crystals were melted and allowed to run into the cooler end of the tube, 

 which was drawn out to a diameter of about 5 mm. This part was then sealed off. 



The tube of purified phosphorus was placed with some phosphorus pentoxide in a 

 tube of hard glass bent at right angles, and previously heated to redness. One end 

 of this was connected with the stoppered neck of a Bunsen's gas pipette by a joint of 

 dried india-rubber. The pipette contained oxygen which had been drying for eight 

 days over phosphorus pentoxide. The tube was exhausted as completely as possible 

 by a Sprengel pump with two fall tubes, and the end connected with the pump 

 sealed. The tubulure at the bottom of the pipette was connected with a flexible 

 india-rubber tube, dried as far as possible, which was connected with a resei-voir of 

 dried mercury. The mercury reservoir could be raised or lowered according as a high or 

 low pressure was desired (fig. 5). After the whole apparatus had been allowed to stand 

 for a week to allow the small residue of air in the vacuous tube to dry, the following 

 experiment was carried on in a dark room. The oxygen was admitted to the vacuous 

 tube, and the tube containing the phosphorus was broken. On the pressure being 

 diminished, a very faint luminosity was seen on the phosphorus, which flickered for 

 several hours, the interval between the extinguishing and the reappearance of the 

 light being about a second and a half. This flickering was not due to variations of 

 pressure caused by the shaking of the mercury in the reservoir, as the experiment 

 was carried on in a cellar with a stone floor, on a solid wooden bench screwed to the 

 ground. The tap was then turned off and the tube allowed to dry for three days 

 more. At the end of this time the luminosity had disappeared, nor did it show itself 

 though the pressure was varied in every possible way. The phosphorus was then 

 melted by heating the tube with a spirit lamp, and still no luminosity appeared. It 



