Tables 261-265 



TABLE 261. — The Unit of Thermal Resistance — the Fourier 



279 



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

 rate of one joule per sec. (one watt) for each degree (centigrade) temperature difference 

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

 cross section). (Harper, Journ. Wash. Acad. Sci., 18, 469, 1928.) 



TABLE 262. — Factors to Reduce Heat Flow in Fouriers for a cm 3 to Other Units 



To watts/cm 2 cal. /sec/cm 2 kilocal./hr./m 2 hp./ft. 2 hp./ft. 2 hp./ft. 2 watts/in. 2 



Gradient °C/cm °C/cm °C/m °C/in. °F./ft. °F./in. °C/in. 



Multiples 1 4.18 .0116 4.14 44 3.67 .394 



TABLE 263. — Conversion Factors Between Units of Current Density of Heat Flow. Quantity of Heat Energy 

 Transferred Through Unit Area per Unit Time 



The calorie is taken as 4.183 absolute joules. 



TABLE 264. — Thermal Resistivities at 20°C Expressed in Fouriers for a Centimeter Cube 



Silver 0.239 



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 



Mica* (J. to 



laminations) . 



Firebrick* 



[Firebrick 25°C 



to iooo°C]. . . 

 Brick masonry* 



Leather* 



Hydrogen 



Hard rubber. . . 

 Helium 



170 



200 

 200 



90 

 250 

 600 

 600 

 610 

 690 



Rubber* (over 

 90%)........ 



Wood (Virginia 

 pine across 

 grain) 



Paper* 



Asbestos* (wool) 



Cork* 



Cotton batting 

 (loose) 



Wool (loose) 



Air 



Carbon dioxide. . 



700 



710 

 1000 

 1 100 

 2000 



2500 

 2500 

 4100 

 6700 



* 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. and has courteously been furnished advance 

 values for some other materials by the editors of I.C.T. For still other materials, grateful acknowledgment is 

 made to the staff of the Bureau of Standards, for advice in selecting most probable values in the light of present 

 information. 



TABLE 265. — Anti-Freezing Solutions (for automobile radiators, etc.) 



(From Bur. Standards Letter Circulars No. 29, 1925.) 

 Per cent by vol. in water with freezing points and specific gravities. 



Per cent by vol 10% 



Denatured alcohol — 3°C 



(90% by vol.)* 988 



Wood alcoholf ~5°C 



(97% by vol.) 987 



Distilled glycerine§ — 2°C 



(95% by vol.) 1.029 



Ethylene glycol§ — 3°C 



(95% by vol.) 1.016 



* 90 % by vol. indicates quality of alcohol (180 proof) ; if 188 proof (that is containing only 6 % water) amount 

 required will be about 4 % less. 



t The vapor from wood alcohol is harmful. SGlycerine and ethylene glycol are oracticallv nonvolatile and 

 noncorrosive. 



Smithsonian Tables 



