INGENUITY AND LUXURY 



water caused very little disintegration, although such 

 cooling is disastrous to unprotected steel work, or plain 

 concrete. For concrete is a poor conductor of heat, 

 and the rate of expansion of iron and concrete under 

 the action of heat is practically the same. As a re- 

 sult, reinforced-concrete buildings are habitable almost 

 immediately after a conflagration. During the con- 

 flagration the temperature of rooms adjoining those 

 actually in flame is usually low enough for the firemen 

 to work in without inconvenience or danger. The 

 exalted opinion of reinforced-concrete buildings held 

 by the professional fire-fighter is a significant tribute 

 to this kind of building material. 



Many interesting experiments have been made to 

 test the protection afforded metal when embedded in 

 concrete. These all seem to show that such protec- 

 tion is all but absolute; and this has been confirmed 

 by a discovery, made by Von Empergner, of rods that 

 had been embedded in concrete under water for some 

 four hundred years and showed no signs of rust. 



In embedding the rods no special precaution is 

 necessary for their preservation save that of making 

 certain that every portion is surrounded by the concrete. 

 Even if the iron is somewhat rusty no harm seems to 

 come from it. Indeed a little rust appears to aid rather 

 than interfere with the preserving. "It is sometimes 

 stated," says Marsh, "that the metal must be thor- 

 oughly clean before being embedded in the concrete, 

 but this does not appear to be borne out by facts. In 

 some tests made to elucidate this point, the curious 

 fact presented itself that not only does rusty iron be- 



