144 



TABLE 141. — THERMAL RESISTIVITIES AT 20°C EXPRESSED IN FOURIERS 



FOR A cm 3 



The fourier 48 is defined as that thermal resistance that will transfer heat energy at the 

 rate of 1 joule per sec (1 watt) for each degree (C) temperature difference between the 

 terminal surfaces (equivalent roughly to a prism of Ag or Cu 4 cm long by 1 cm 2 

 cross section). 



Silver 239 



Copper 258 



Aluminum .49 



Brass (30% Zn). .93 



Iron . . , 1.6 



Nickel 1.7 



Steel (1% C)... 2.1 



Constantan 4.4 



Mercury 12.0 



[IceatO°C] 45 



Glass* 133 



Concrete * 140 



Water 170 



Mica * ( 1 to 



laminations 200 



Firebrick * 200 



[Firebrick 25°C 



to 1000°C] 90 



Brick masonry * . . . . 250 



Leather * 600 



Hydrogen 600 



Hard rubber 610 



Helium 690 



Rubber * (over 



90%) 700 



Wood (Virginia 



pine across 



grain) 710 



Paper * 1000 



Asbestos* (wool). 1100 



Cork* 2000 



Cotton batting 



(loose) 2500 



Wool (loose) 2500 



Air 4100 



Carbon dioxide .... 6700 



4S Harper, D. R., Journ. Washington Acad. Sci., vol. 18, p. 469, 1928. 



* Substances marked with the asterisk vary widely in thermal conductivity according to composition. 

 For limits of such variation, consult International Critical Tables, vol. 2. The figure listed above for any 

 such material represents the author's estimate of the "best guess" for use in those cases where the 

 composition of the material is not specified. 



In preparing this table, the author has consulted vol. 2, I.C.T. For still other materials, grateful 

 acknowledgment is made to the staff of the National Bureau of Standards for advice in selecting most 

 probable values in the light of present information. 



SMITHSONIAN PHYSICAL TABLES 



