96 GENERAL SCIENCE 



TABLE 



Thormnl Transmission in Btu. per Hr., per 



Material. Conductivity Sq " Ft ' P er in ' Thickness for Each 



Degree F. Difference in Temp. 



1. Silver 100 2900.0 



2. Copper 90 2600 . 



3. Aluminum 50 1950 . 



4. Brass 27 



5. Zinc 26 



6. Tin ,. 14.7 



7. Iron 14 460.0 



8. German silver 8.4 



9. Mercury silver .... 1.7 



10. Rock .25-. 9 0.7to26.0 



11. Granite .53 



12. Limestone .52 



13. Ice .5 



14. Porcelain .25 7.2 



15. Brick .2-. 5 6.0 to 15.0 



16. Glass (ordinary). .. .16 4.6 



17. Water .14 4.0 



18. Plaster (ordinary) . . 1-. 15 2 . 9 to 4 . 3 



19. Wood (hard) .06 1.7 



20. Asbestos paper .... . 045 1 . 3 

 Asbestos felt .025 .7 



21. Sawdust .018 .52 



22. Wood (very soft) ., .015 .43 



23. Paper .013 .38 



24. Cork board . .012 .34 



25. Wool .010 .29 



26. Hair felt .010 .24 



27. Cotton wool .009 .26 



28. Feathers . 0057 . 16 



29. Air .005 



30. Silk .000095 



31. Snow .00051 



32. Leather . .00037 



