on the Diffusion of Gases, Sfc. 83 



the shallow jar. The difference, however, was altogether in- 

 sufficient to enable us to account for the well known experi- 

 ment of the concentration of alcohol in a bladder, by referring 

 it to the superior diffusiveness of water-vapour. But it is 

 conceivable, and the subject is at present under investigation, 

 that imperceptible pores, or orifices of excessive minuteness, 

 may be altogether impassable (by diffusion) by gases of low 

 diffusive power, that is, by dense gases, and passable only by 

 gases of a certain diffusive energy. Hydrogen gas certainly 

 escapes from a bladder more rapidly than any other gas, and 

 probably from diffusion, as the place of the hydrogen is found 

 occupied by common air. But to these investigations, and to 

 certain theoretic considerations, I hope again to recur in a 

 future paper. 



Observations on the Oxidation of Phosphorus, By Thomas 

 Graham, A.M., F.R.S.E., Lecturer on Chemistry, Glasgow. 



We are at present in possession of several curious facts re- 

 specting the insensible combustion of phosphorus at low 

 temperatures. 



1. In pure oxygen gas, under the atmospheric pressure, and 

 at temperatures below 64°, the usual white smoke is not seen 

 around phosphorus in day-light, and it is not luminous in the 

 dark. No absorption of oxygen takes place. 



2. A slight expansion of the oxygen gas, produced by dimi- 

 nishing the pressure upon it two or three inches below the 

 usual pressure of the atmosphere, occasions phosphorus to be 

 acted upon by pure oxygen, and to undergo slow combustion. 



3. By diluting oxygen with certain gases, such as hydrogen, 

 azote, protoxide of azote, carbonic oxide, carbonic acid, &c, 

 the oxygen becomes capable of supporting the slow combus- 

 tion of phosphorus even under the atmospheric pressure, as 

 well as when rarefied by reduced pressure. Hence phosphorus 

 is luminous in common air. The proportion of foreign gas 

 necessarily varies according to the nature of the gas. 



G 2 



