TABLE 139.— DIFFUSIVITI ES 



143 



The diffusivity of a substance = h 2 = k/cp, where k is the conductivity for heat, c the 

 specific heat and p the density (Kelvin). The values are mostly for room temperatures, 

 about 18° C. 



Material Diffusivity 



Aluminum 860 



Antimony 135 



Bismuth 069 



Brass (yellow) 339 



Cadmium 467 



Copper 1.140 



Gold 1.209 



Iron (wrought, also mild steel) 173 



lion (cast, also 1% carbon steel) 121 



Lead 245 



Magnesium 932 



Mercury 45 



Nickel 155 



Palladium 261 



Platinum 243 



Silver 1.700 



Tin 407 



Zinc 413 



Air 1 atm 179 



Asbestos (loose) 0025 



Brick (average fire) 0052 



Brick (average building) 0044 



Material Diffusivity 



Coal 002 



Concrete (cinder) 0032 



Concrete (stone) 0048 



Concrete (light slag) 006 



Cork (ground) 0017 



Ebonite 0010 



Glass (ordinary) 0057 



Granite 0127 



Ice 0112 



Limestone 0081 



Marble (white) 0097 



Paraffin 00098 



Rock material (earth aver.) 0118 



Rock material (crustal rocks) 0064 



Sandstone 0113 



Snow (fresh) 0033 



Soil (clay or sand, slightly damp) 005 



Soil (very dry) 0031 



Water 0017 



Wood (pine, cross grain) 00068 



Wood (pine with grain) 0023 



TABLE 140.— THERMAL CONDUCTIVITY— LIQUIDS, PRESSURE EFFECT 47 



Conduc- 

 tivity at 

 kg/cm 2 



No.* Liquid °C (cgs) 



1 Methyl 30 .000505 



alcohol .... 75 .000493 



2 Ethyl 30 .000430 



alcohol .... 75 .000416 



3 Isopropyl 30 .000367 



alcohol .... 75 .000363 



4 Normal butyl 30 .000400 



alcohol .... 75 .000391 



5 Isoamyl 30 .000354 



alcohol .... 75 .000348 



6 Ether 30 .000329 



75 .000322 



7 Acetone 30 .000429 



75 .000403 



8 Carbon 30 .000382 



bisulphide . . 75 .000362 



9 Ethyl 30 .000286 



bromide ... 75 .000273 



10 Ethyl 30 .000265 



iodide 75 .000261 



11 Water 30 .00144 



75 .00154 



12 Toluol 30 .000364 



75 .000339 



13 Normal 30 .000322 



pentane ... 75 .000307 



14 Petroleum 30 .000312 



ether 75 .000302 



15 Kerosene .... 75 .000333 



Conductivity relative to unity (0 kg/cm 2 ) as function of 

 pressure in kg/cm 2 



47 Bridgman, P. W., Proc. Ainer. Acad. Arts and Sci., vol. 59, p. 158, 1923. 



* 1. 2, 6, 8, 12, 13, extreme purity; 3, 4, 5, 7, 9, 10, 11, very pure; 14, 15, commercial. 



t Toluol freezes at 9900 kg/cm 2 at 30°. The figure at 11000 is for the solid. 



SMITHSONIAN PHYSICAL TABLES 



