the Oxidation of Phosphorus. 87 



sure possible for a particular mixture, a slight inclination of 

 the tube from its vertical position, which has the effect of con- 

 densing the gas, extinguishes the light; while, on bringing 

 back the tube to its vertical position, the phosphorus again 

 becomes luminous. 



The influence of other vapour on the oxidation of phos- 

 phorus at various pressures did not present any material dif- 

 ferences from that of defiant gas just detailed. 



Naphtha and turpentine vapours appeared to lose their 

 negative influence very rapidly as the pressure was reduced. 



Carburetted hydrogen of marshes impedes to a certain 

 degree, but does not altogether prevent, the oxidation of phos- 

 phorus. Its effect vanishes over a mercurial column of a few 

 inches, a circumstance which will be attended to with advan- 

 tage in removing, by means of phosphorus, the small portion 

 of oxygen generally found in that gas. 



The sulphuret of phosphorus and phosphuretted hydrogen 

 gas are likewise protected from oxidation, to a certain extent, 

 by olefiant gas, sulphuric ether, &c, although less powerfully 

 than phosphorus, in proportion to their higher accendibility. 



The oxidation of potassium appears likewise, from several 

 comparative experiments, to be considerably retarded in dry 

 air, containing a fourth or a fifth of its bulk of ether-vapour or 

 olefiant gas, particularly of the latter. A piece of potassium, 

 about the size of a pea, confined for a month in dry air, con- 

 taining a fifth of its bulk of olefiant gas, was merely covered by 

 a thin coating of grey oxide ; while another piece of potassium, 

 in similar circumstances, with the exception of the olefiant gas, 

 was deeply penetrated with fissures of a kernel white. 



The interference of those gases in preventing the oxidation 

 of phosphorus, &c, is probably allied to the influence of the 

 same and several other gases in preventing the accension of 

 the explosive mixture of oxygen and hydrogen by the electric 

 spark, first observed by Sir H. Davy (Essay on Flame), and 

 since confirmed and investigated by Dr. Henry (Phil. Trans. 

 1824), and Dr. Turner (Edin. Phil. Journal, vol. xi.) Ole- 

 fiant gas was found to act most powerfully, half a volume pre- 

 venting the combustion of the explosive mixture, that is, 

 defending the hydrogen from oxidation ; and here, as in the 



