420 



PHOSPHORUS. 



(o.) The same thing is less perfectly done by simply melting the 

 phosphorus in the vial and then corking and rolling it around, that the 

 phosphorus may adhere to every part. 



(p.) A sulphur match is to be introduced and rapidly withdrawn, 

 rubbing at the same time against the side ; if it does not fire, a little 

 friction on a board or a cork will generally make it burn.* 



(q.) Eudiometry is performed by phosphorus, by rapid combustion 

 and by slow, in various ways.f 



ATMOSPHERIC EUDIOMETER, BY PHOSPHORUS. Dr. Hare. 



" If a cylinder of phosphorus be support- 

 ed upon a wire (as here represented) within 

 a glass matrass, inverted in a jar of water, 

 the oxygen of the included air is gradually 

 absorbed. In order to determine the quan- 

 tity of oxygen in the air, we have only to 

 ascertain the ratio between the quantity ab- 

 sorbed, and the quantity included. 



" This object may be attained by weigh- 

 ing the matrass, when full of water, and 

 when containing that portion only which 

 rises into it in consequence of the absorp- 

 tion. As the weight in the first case is to 

 the weight in the last, deducting the weight 

 of the glass in both cases, so will 100 be to 

 the number of parts, in 100 of atmospheric 

 3ir, which consist of oxygen gas. 



* A spontaneous light is formed, by inserting a taper with a bit of phosporus on the 

 wick, into a tube sealed and drawn thin at the end next the phosphorus; the other 

 end maybe sealed or not; the phosphoric end is heated in the mouth or otherwise, 

 and withdrawn suddenly, or the tube is broken when the phosphorus fires it is a toy. 



J Eudiometer of Seguin. Fill with and invert in mercury, a glass tube one inch 

 in diameter and ten inches long; throw up a small piece of phosphorus; it is then 

 melted by a live coal or hot iron, and small portions of a measured quantity of air 

 are separately introduced ; the phosphorus is inflamed each time ; heat the top of 

 the tube at finishing, and measure the residuum which is nitrogen. 



Huniboldfs. Introduce phosphorus, 1 grain to 12 cubic inches of air, into a grad- 

 uated tube, hermetically sealed at one end, and carefully corked at the other. In- 

 flame it by a coal, and after all is cool the cork is withdrawn under water; the 

 space unoccupied by the water is nitrogen gas. 



JBerthollefs. In this there is a slow combustion, in a graduated glass tube. A 

 measured quantity of air is thrown up, and a slick of phosphorus, supported on a 

 glass rod, is made to pervade it. In a few days the oxygen gas will be absorbed, 

 and an acid formed which will be absorbed by the water, while the nitrogen is left. 

 Nitrogen gas dissolves a little phosphorus, and is thereby augmented in bulk 

 bout one fortieth, which must be in each case subtracted. 



