90 Mr Graham on Phosphuretted Hydrogen. 



I find, however, that if a small quantity of phosphuretted hydro- 

 gen, when not self-accendible, be added to a confined portion of 

 air, sticks of phosphorus introduced into that air do not smoke, 

 that phosphorus has no disposition to combine with oxygen when 

 phosphuretted hydrogen is present. In a transparent mixture of 

 one volume phosphuretted hydrogen with one thousand volumes, 

 or any smaller proportion of air, sticks of phosphorus remain un- 

 affected, but the phosphuretted hydrogen itself always undergoes 

 a slow oxidation. In a mixture of one volume phosphuretted 

 hydrogen and two thousand volumes air, phosphorus smoked 

 strongly for some time ; but at a certain period the action ceased, 

 long before the oxygen of the air was exhausted. A minute pro- 

 portion of phosphuretted hydrogen is, therefore, sufficient to pro- 

 tect phosphorus from oxidation, in which respect this gas resem- 

 bles the hydrocarburets and essential oils, which have been shown 

 to be equally efficacious in protecting phosphorus from oxidation. 

 All these bodies appear to act in this respect in one way, name- 

 ly, by taking the precedence of phosphorus in the process of oxy- 

 genation. Phosphorus therefore being less oxidable than phos- 

 phuretted hydrogen itself, cannot be supposed to take fire and 

 to inflame the gas, or to be the cause of the ascendibility of the 

 gas at low temperatures. 



On sending electric sparks through non-accendible phosphu- 

 retted hydrogen itself, phosphorus is deposited, but the gas when 

 still cloudy from the phosphorus suspended in it, proved to be 

 non-inflammable on passing it into air. 



The loss of accendibility in the case of gas confined over water, 

 is certainly wholly unconnected with the deposition of any free 

 phosphorus from the gas, which may occur, but is due to the rise 

 of oxygen from the water into the gas. It was observed that 

 water which had been boiled to deprive it of all air, and which 

 was then passed up to self-accendible gas confined over mercury, 

 did not affect the gas in the course of forty-eight hours. In this 

 case, moreover, the gas was agitated with the water. The gas 



