208 



WATER. 



to burn under a jar of common air, or better of oxygen gas, 

 standing over mercury, there will be a rapid rise of the metal, and 

 water will appear, first in vapor, and then in minute drops, lining the 

 interior of the jar. 



(e.) I find it perfectly easy to fill a large glass globe with oxygen 

 gas, by allowing it to flow from a reservoir through a tube descend- 

 ing to the bottom of the globe, and it is known when the latter is full 

 by applying a taper, blown out, and having a little fire on the wick, 

 which is then rekindled at the mouth of the globe. This arrangement 

 saves air-pump exhaustion. The hydrogen gas is then lighted in a 

 jet, and allowed to flow from a gasometer as long as it is needed. 

 As I employ the compound blow-pipe in this experiment, it is easy 

 to let in either oxygen or hydrogen as it is needed, and thus the com- 

 bustion is continued at pleasure. The production of water in this 

 mode is immediate and palpable. I subjoin a figure of a beautiful but 

 more complicated apparatus. 



Lavoisier's apparatus for the recomposition of water. 



" This apparatus con- 

 sists of a glass globe, 

 with a neck cemented 

 into a brass cap, from 

 which three tubes pro- 

 ceed, severally com- 

 municating with an air 

 pump, and with reser- 

 voirs of oxygen and hy- 

 drogen. It has also an 

 isulated wire, for pro- 

 ducing the inflamma- 

 tion of a jet of hydrogen, 

 by means of an electric 

 spark. In order to put 

 the apparatus into op- 

 eration, the globe must 

 be exhausted of air, and 

 then supplied with oxy- 

 gen to a certain extent. 

 In the next place, hy- 

 drogen is to be allowed 

 to enter it in a jet, which 

 is to be inflamed by an 

 electric spark. As the 

 oxygen is consumed, 

 more is to be admitted." 



