2l6 



Tables 233-234. 



CONDUCTIVITY FOR HEAT. 



TABLE 233. — Various Substances. 



kt is the heat in gram-calories flowing in i sec. through a plate i cm. thick per sq. cm. for i°C 



drop in temperature. 



Substance. 



Asbestos fiber 



85% inagnesia asbestos . . 

 Cotton 



Eiderdown 



Lampblack, Cabot number 5 

 Quartz, mesh 200 .... 

 Poplox, popped NajSiOs . 

 Wool fibers 



Density. 



0.201 



.216 



.021 

 . 101 

 .0021 

 .109 



•iij3 

 1.05 

 0.093 



.015 

 .054 

 .192 



°C. 



500 



500 



.oooig 



.00016 



.000 1 7 



.0001 1 1 



.000071 



.00015 



.000046 



.000074 



.000107 



.00024 



.00009 1 



.000160 



.0001 18 



.0000S5 



.000054 



Substance. 



Asbestos paper 

 Blotting paper . 

 Portland cement 

 Cork, t,o°C . 

 Chalk .... 

 Ebonite, t, 49° . 

 Glass, mean 



Ice 



Leather, cow-hide 

 " chamois 

 Linen .... 

 Silk .... 

 Caen stone, limestone 

 Free stone, sandstone 



k, 



0.00043 

 .00015 

 .00071 

 .0007? 

 .0020 

 .00037 

 .002 

 .0057 

 .00042 

 .00015 

 .00021 

 .000095 

 .0043 

 .0021 



Authority. 



Lees-Chorl- 

 ton. 



Forbes. 

 I H, L, D, 

 ) see p. 205. 



Various. 



Neumann. 



) 



I Lees-Chorl- 



I ton. 



I 



I H, L, D. 



Left-hand half of table from Randolph, Tr. Am. Electroch. Soc. XXI ., p. 550, 1912; k, (Randolph's values) 

 is mean conductivity between given temperature and about io°C. Note effect of compression (density). Tlie 

 following are from Barratt Proc. Phys. Soc, London, 27, 81, 1914. 



The following values are from unpublished data furnished by C. E. Skinner of the Westinghouse Co., Pitts- 

 burgh, Penn. They give the mean conductivity in gram-calories per .sec. per cm. cube per °C. w hen the mean 



temperature of the cube is that stated in the table. Resistance in thermal ohms (watts/inchVinch/°C.) := — - 



10.6 



conductivity. 



Substance. 



Air-cell asbestos 



Cork, ground 



Diatoniit 



Infusorial earth, natural . . . 



" " h'd pressed blocks 



Magnesium carbonate .... 



Vitribestos 



Grams, 

 per cm^. 



0.232 

 .168 

 .326 

 .506 

 .321 

 •450 

 .362 



Conductivity. 



100° C. 



0.00034 

 .00015 

 .00028 

 .00034 

 .00030 

 .00023 

 .00049 



200° c. 



0.00043 

 .00019 

 .00032 

 .00032 

 .00029 

 .00025 

 .00066 



300° c. 



.00037 

 .00040 



.00033 



.00025 

 .00079 



400° c. 



0.00042 

 .00036 

 .00090 



500° c. 



0.00046 



Safe 

 temp. 



320 



1 80 

 600 



400 

 300 

 600 



TABLE 234. — Water and Salt Solutions. 



Smithsonian Tables. 



