8S Apparatus for the Combiifllon of Phofpborus. 



\ycv, my experiments on the combuftion of phofphorus In the 

 fd called vacuum of an air pump. Had profeiror Gottling, 

 and other German chemifts who have obferved phofphorus 

 to (hine in azotic gas, paid more attention to what thefe ex- 

 periments clearly eftablifh, they would not have made fp 

 much noife refpefting a phenomenon which is fo like the 

 Ihining of phofphorus before it inflames in air highly rare- 

 fied. This {hining of phofphorus in an imperfect vacuum, 

 fliews that the fmall quantity of oxygen gas contained 

 in atmofpheric air fo highly rarefied, is ftill fufHcient tq 

 occafion that luminous appearance ; and as it is well known 

 ihat it is abfolutely impoflfible to produce azotic gas whicl^ 

 does not contain fome oxygen gas, they might have feen by 

 my experiments, that the fmall quantity of oxygen which 

 jnuft have been contained in their azptic gas was fufficicnt 

 to produce that light which they obferved. 



I (hall here only add, that phofphorus will not fliine 

 at all in azotic gas which contains no oxygen gas. This I 

 {hewed, on the i8th of January 1794, in my lectures at the 

 Teylerian Inftitute. I introduced azotic gas over mercury, 

 and freed it totally from oxygen gas by introducing 

 phofphorus into it on the point of a bent iron wire, which 

 I paffed up through the mercury, fo as to bring the phof- 

 phorus in contaft with a piece of ignited iron previoufly in- 

 troduced into the receiver. All the oxygen gas united itfelf 

 in a moment with the volatilized phofphorus ; and another 

 bit of phofphorus, which after the cooling of the apparatus 

 I made to rife through the quickfilver into the azotic gas, 

 ■which in that manner was freed from all oxygen, did not 

 fhine. A fmall bubble of atmofpheric air was fufficicnt to 

 reproduce the fhining. It was then feen diftufed throughout 

 the whole gas, in the fame manner as when atmofpheric air 

 is admitted into an exhaufted receiver in which phofphorus 

 has ceafed to be luminous. I fhewed, in the courfe of the 

 fame lefture, that phofphorus does not ihine in a perfeft 



vacuum. 



