374 Means of obtaining pure y&>. [Book V, 



metallic properties, and lofes the weight which it had 

 acquired in becoming oxidated *. 



There is, however, a method by which oxygen gas 

 may be obtained with lefs heat and greater facility, 

 and it is as follows ; put fome red lead into a bottle, 

 together with fome good ftrong oil of vitriol, but with- 

 out any water. Let the red lead fill about a quarter 

 of the bottle, and the vitriolic acid be about the fame 

 quantity, or very little lefs ; then apply the bent tube 

 to the bottle by inferting it through a cork, and hav- 

 ing inverted another bottle filled with water in a bafon 

 about half- filled alfo with water, direct the other enc| 

 of the crooked tube into the bottle inverted in the 

 water. In this ftage of the procefs we mud obfervc, 

 that without heat this mixture of red lead and vitriolic 

 acid will not afford any oxygen air, or a very incon- 

 fiderable quantity ; it is necefTary, therefore, to apply 

 the flame of a candle or wax taper to the bottle con- 

 taining the ingredients, while the crooked tube opens 

 a communication between this bottle and that inverted 

 in the water. In this manner the red lead will yield 

 a quantity of elaftic fluid, which will pafs through the 

 crooked tube into the inverted bottle, and as the quan- 

 tity of dephlogifticated air increales in the inverted 

 bottle, the water in it will be feen to fubfide j this air 

 will not be ail pure, becaufe a confiderable quantity of 

 fixed air enters with it. In order to feparate the fixeci 

 from the pure air, the inverted bottle, when filled with 

 the compound pf both, muft be agitated in a bafon of 

 lime water, by which means the lime water will abforbj 

 the whole of the fixed air, and leave the dephlo? 

 gifticated air or oxygen gas by itfelf. 



.Oxygen gas may alfo be obtained in confiderabls 



* Briflbn, torn. ii. p. 25. 



