220 



Domestic Science 



It will be evident that copper does not unite with 

 oxygen so readily as magnesium, but the blackish 

 appearance of its surface is nevertheless due to the 

 production of a thin film of copper oxide. 



149. EXPERIMENT 86. Fit up carefully the appara- 

 tus shown in Fig. 71, leaving the jar, /, however, 

 inverted and filled with water, on the bottom of the 

 trough. Weigh the roll of copper gauze, before inser- 

 tion in the tube, on a balance which weighs correctly to 

 1 centigram. 



Fig. 71. 



G = gas-holder filled with air. 



R = reservoir of gas-holder. 



P, P = well-greased glass stopcocks. 



D = glass delivery tube. 



A, A = square shields of asbestos millboard 



H = piece of hard combustion tubing about I ft. long and f inch 



in diameter. 



C = roll of bright copper gauze about 5 in. long. 

 B = Ramsay burner (a row of Bunsen burners may be substituted 



for this). 



N = stout rubber connection. 

 J = large gas- jar. 

 T = earthenware pneumatic trough. 

 V = beehive cell. 

 S = tight-fitting hollow glass stopper. 



