139 



TABLE 135.— THERMAL CONDUCTIVITY OF INSULATING MATERIALS* 



Conductivity 



joule/ cal/ 



Density (cm 2 sec "C/ (cm 2 sec °C/ 



Material g/cm 3 r°C cm) cm) 



Air, 76 cmHg 00129 .00023 .000055 



Asbestos wool 40 —100 .00068 .000162 



" 40 .00090 .000215 



" 40 +100 .00101 .00024 



" with 85 percent MgO 3 30 .00075 .000179 



Brick, very porous, dry 71 20 .00174 .00042 



machine-made, dry 1.54 .00038 .000091 



moist, 1.2% 



vol 50 .00096 .00023 



Calorox, fluffy mineral matter 064 30 .00032 .000076 



Celluloid, white 1 .4 30 .00021 .000050 



Cement mortar 2.0 90 .0055 .0013 



Chalk .0092 .0022 



Charcoal 18 20 .00055 .00013 



Coke dust 1.0 20 .0015 .00036 



Concrete 1.6 .008 .002 



Cork 05 .00032 .000076 



" 05 100 .00041 .000098 



" 35 .00061 .000146 



" 35 100 .00079 .000189 



Cotton, tightly packed 08 —150 .00038 .000091 



08 .00056 .000133 



08 +150 .00076 .00018 



Cotton wool tightly packed 08 30 .00042 .00010 



Diatomite (binders may increase 



100%) 20 .00052 .00012 



Diatomite, ditto 20 400 .00094 .00022 



" 50 .00086 .00021 



" 50 400 .00157 .00037 



Ebonite 1.19 — 190 .00138 .00033 



1.19 — 78 .00157 .00038 



1.19 .00160 .00038 



Felt, flax fibers 18 30 .00047 .00011 



" hair 27 30 .00036 .000086 



" wool 15 40 .00063 .000151 



" 33 30 .00052 .000124 



Flannel .000023 



Fuller's earth 53 30 .00101 .00024 



Glass, lead 15 .0060 .00143 



soda 2.59 20 .0072 .00172 



2.59 100 .0076 .00182 



wool 22 50 .00042 .000100 



" 22 100 .00050 .000120 



" 22 200 .00065 .000155 



" 22 300 .00081 .000195 



Graphite, 100 mesh 48 40 .0018 .00044 



40 " 42 40 .0038 .00093 



20 to 40 mesh 70 40 .0129 .0031 



Horsehair, compressed 17 20 .00051 .000122 



Ice 92 .022 .0053 



Leather, chamois 85 .00063 .000151 



cowhide 85 .00176 .000421 



sole 1.0 30 .0016 .00038 



Linen 20 .00086 .00021 



Linoleum, cork 54 20 .00080 .000191 



Mica, average 50 .0050 .0012 



* Compiled from the International Critical Tables, which see for more complete data. 



(continued) 



SMITHSONIAN PHYSICAL TABLES 



