"2. There existed no trace of oxidation from the 

 metal. The binding-in wire which connected the longi- 

 tudinal rods was absolutely free from oxidation. 



" 3. The adherence between the metal and the cement 

 concrete constituting the body of the pipe was such 

 that, despite the thinness of the concrete (if in.), they 

 could only be separated by heavy blows from a sledge- 

 hammer. 



"4. When struck with the hammer, these pipes 

 evinced remarkable sonority, such as might be ob- 

 tained from a sound cast-iron pipe. 



"5. The detached fragments of the cement concrete 

 showed very sharp angles. 



"6. The Water Committee of the City Council 

 declared that this line of pipes had required no repairs 

 since it was set in place in 1886." 



From these, and similar exhaustive tests, it appears 

 that reinforced-concrete pipes are ideal for drainage 

 purposes, and are likely to replace iron ones in many 

 places in structures where the pipes are built into the 

 walls. In Thomas Edison's " one-piece concrete 

 house" most of the piping of all kinds is of concrete. 

 This material should not, however, be used for hot- 

 water conveyors. 



STRENGTH AND DURABILITY OF CONCRETE 



Frameworks of steel or iron are lighter than those 

 made of reinforced concrete for supporting the same 

 load. This greater weight of the concrete is an ad- 

 vantage in most places, but not so wherever long spans 

 are required, such as in bridges. For short bridges, 



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