233 



TABLE 220.— REAL AND APPARENT DENSITIES OF LEATHER (70°F AND 

 65 PERCENT, RELATIVE HUMIDITY) 00 



Kind of leather Apparent density Real density 



Raw bated skin 41- .45 1.43 



Formaldehyde tanned buckskin 56 1.52 



Chrome-tanned shoe upper 88 1.34 



Vegetable-tanned sole 1.03-1.15 1.46-1.49 



Chrome-tanned sole 1.17 1.46 



Formaldehyde-tanned suede 50- .58 1.55-1.62 



Vegetable-tanned goatskin 65 1.52 



00 Kanagy, J. R., and Wallace, E. L., Journ. Amer. Leather Chem. Assoc, vol. 38, p. 314, 1943; 

 Rose, H., ibid., p. 107. 



TABLE 221.— COEFFICIENT OF CUBICAL EXPANSION OF LEATHER 



(Measured in water between 25° and 75°C) 70 



Chrome Chrome-vegetable Vegetable Alum-vegetable 



496-565 X 10' n 339-298 X 10"" 502-543 X 10"° 590-599 X 10" e 



Iron Formaldehyde Tendon collagen 



592 X 10 ° 532 X 10"° 538 X 10"° 



Compressibility. 11 — The lower limit of the coefficient of compressibility of vegetable- 

 tanned sole leather has been estimated at 33 X 10"° bar" 1 . Commercial sole leathers sub- 

 jected to 3000 lb/in. 2 pressure for 3 minutes were compressed from 4 to 17 percent. 



70 Weir, C. E., Journ. Amer. Leather Chem. Assoc, vol. 44, p. 79, 1949. 



71 Weir, C. E., Journ. Amer. Leather Chem. Assoc, vol. 40, p. 404, 1945. 



TABLE 222.— EFFECT OF RELATIVE HUMIDITY OF ATMOSPHERE AT 

 21°C ON PROPERTIES OF LEATHER 72 



72 Evans, W. D., and Critchfield, C. L., Nat. Bur. Standards Journ. Res., vol. 11, p. 147, 1933. 



TABLE 223.— THERMAL CONDUCTIVITY OF LEATHER* 



cal cm" 1 sec" 1 °C -1 



Vegetable sole leather Calfskin upper Kid suede Hide bellies 



4.2 X lO" 4 2.0 X 10" 4 1.5 X 10" 4 2.3 X 10" 4 



* For reference, see footnote 68, p. 232. 

 SMITHSONIAN PHYSICAL TABLES 



