138 TABLE 134.— THERMAL CONDUCTIVITY, METALS AND ALLOYS 



The coefficient k is the quantity of heat in small calories which is transmitted per second 

 through a plate one centimeter thick per square centimeter of its surface when the differ- 

 ence of temperature between the two faces of the plate is 1°C. The coefficient k is found 

 to vary with the absolute temperature of the plate, and is expressed approximately by 

 the equation k t = k {\ -f a(t — to)]. ko is the conductivity at to, the lower temperature of 

 the bracketed pairs in the table, kt that at temperature t, and a is a constant. k t in g-cal 

 per degree C per sec across cm 3 = 0.239 X kt in watts per degree C per sec across cm 3 . 



Substance 

 Aluminum . . , 



Antimony 

 Bismuth . 



Brass 



, yellow. . . 



" , red 



Cadmium, pure . 



Constantan 



(60 Cu-f 40 Ni) 



Copper,* pure . . , 



German silver 

 Gold 



Graphite . 

 Iridium . . 

 Iron.f pure 



Iron, wrought . . 

 Iron, 



polycrystalline . 

 Iron, 



polycrystalline . 

 Iron, 



polycrystalline . 

 Iron, 



polycrystalline . 

 Iron, steel, 1% C. 



Lead, pure 



t°C 



-190 



30 



76.4 







100 



-186 



18 



100 



-160 



17 











-160 



18 



100 



18 



100 



-160 1 



18 



100 







-190 



17 



17 



17 



18 



100 



-160 



kt 



cgs 



.497 



.497 



.550 



.04421 



.0396/ 



.025 



.01941 



.0161 J 



.181 



.260 



.204 



.246 



.239 



.2221 



.215/ 



.05401 



.0640 J 



.079 



.9181 



.908 J 



.070 



.793 



.705 



.037 



.141 



,1611 



151J 



,152 



+.0030 

 —.00104 



—.0021 



+.0024 

 +.0015 



—.00038 

 +.00227 



—.00013 



+.0027 

 —.00007 



+ .0003 

 —.0005 



—.0008 



30 .173 

 100 .163 

 200 .147 



> —.0008 



Magnesium 



Manganin 



" (84 Cu + 4 

 Nil2Mn). 



800 .071 



18 .1081 



100 .107 J 



-160 .092 



18 .0831 



100 .081 J 



108} S" 



-160 .035 — 



18 .05191 , m ~ 



100 .0630/ + 0026 



-.0001 



-.0001 



Substance i°C 



Mercury 



50 



Molybdenum 17 



Nickel —160 



18 







100 



200 



700 



1000 



1200 



Palladium 18 



100 



Platinum 18 



100 



Pt 10% Ir 17 



Pt 10% Rh 17 



Platinoid 18 



Potassium 5.0 



57.4 



Rhodium 17 



Silver, pure — 160 



18 



100 



Sodium 5.7 



88.1 



Steel 18 



Tantalum 17 



1700 



1900 



2100 



Tin 



" 100 



" , pure — 160 



Tungsten 17 



1600 



2000 



2400 



2800 



Wood's alloy — 



Zinc, pure — 160 



Zinc, 



polycrystalline . 

 Zinc, 



polycrystalline . 

 Zinc, 



polycrystalline . 

 Zinc, liquid 



kt 



cgs 



.01481 

 .01 89 J 

 .346 

 .129 

 .1420 

 .14251 

 .1380 J 

 .13251 

 .069 J 

 .0641 

 .058 J 

 .16831 

 .182 J" 

 .16641 

 .1733/ 

 .074 

 .072 

 .060 

 2321 

 .216 J 

 .210 

 .998 

 1.0061 

 .992 J 

 .3211 

 .288 J 

 .110 

 .130 

 .174 

 .1861 

 .198/ 

 .1551 

 .145/ 

 .192 

 .476 

 .2491 

 .272/ 

 .2941 

 .313/ 

 .319 

 .278 







200 



400 

 500 



.280 



.250 



.231 

 .144 



+.0055 

 —.0001 



—.00032 

 —.00095 

 —.00047 

 +.0010 



+.00051 



+.0002 

 +.0002 



—.0013 

 -.0010 



—.00017 

 -.0012 



-.0001 



+.00032 

 —.00069 



-.0001 

 +.00023 



+ .00016 



> — 



•Copper: 100-197°C, kt = 1.043; 100-268°, 0.969; 100-370°, 931' 

 tlron: 100-727°C, kt = 0.202; 100-912°, 0.184; 100-1245°, 0.191. 



100-541°, 0.902. 



SMITHSONIAN PHYSICAL TABLES 



