60 Dr Davy^s Observations on Phosphorus. 



Compression and rarefaction, in the instance of common air, 

 has an effect analogous to that mentioned when speaking of oxy- 

 gen. In a bent tube, under an increased pressure of 90 inches 

 of mercury, phosphorus did not shine. When the experiment 

 was reversed, it became luminous, and more so than under 

 ofdinary atmospheric pressure. The volume of atmospheric air 

 compressed in one instance and rarefied in the other, was about 

 one cubic inch. 



The same effect is displayed in a striking manner by heat- 

 ing phosphorus in a retort securely closed. The compression 

 from the intense heat produced when the phosphorus inflames, 

 presently extinguishes the flame, which may be rekindled by al- 

 lowing a portion of the confined air to escape. 



When phosphorus is placed on the plate of an air-pump, un- 

 der a receiver, and the air exhausted, the brightness of its light 

 in the dark rather increases with the exhaustion, and, in the 

 nearly |x^nlct vacuum formed by a good pump, its light was 

 not diminished. When the air has been suddenly readmitted, 

 its light has been extinguished, and for a few seconds it has 

 ceased to .slune. 



When phosphorus has been placed in distilled water under 

 thp receivei' of an air-pump, and the air dissolved in the water 

 has been exhausted, or taking it into the open air out of the 

 water by a thread attached to it, it has shone with rather increased 

 brightness. If now immersed in common water, and suddenly 

 taken into the atmosphere, it has emitted no light. Many other 

 effects similar to this might be mentioned, showing how circum- 

 stanjces, apparently very trifling, exercise an influence on phos- 

 phorus, and promote or impede, in a manner that could not have 

 been expected a priof-i, its union with oxygen, and its luminous 

 appearance depending on this union. 



In accordance with the results of Mr Graham's experiments, 

 I have found that the vapour of ether, oil of turpentine, aild 

 every other essential oil that I have tried, extinguished the light 

 of phosphorus shining iti common air. The vapour of alcohol, 

 of camphor, and even of assafcetida at ordinary temperatures, 

 has had the sdme effect. Phosphorus even fuses in the vapour of 

 camphor without becoming luminous ; arid may even be sublim- 

 ed with camphor without inflaming. The mixed sublimate of 



