Sec. X3.6 



MECHANICAL PROPERTIES OF AIR AND WATER 



921 



TABLE X3.j — Mechanical Properties op Fresh Water at Atmospheric Pressure 

 The data in this table, expressed in English engineering units, are taken from H. Rouse [EMF, 1946, p. 364]. 



Table X3.j lists these and other data, for fresh 

 water, to a smaller number of significant figures 

 but over a much larger range of temperature. 

 The p and v data are supplemented by data on 

 specific weight w, dynamic viscosity ;u(mu), and 

 surface tension o-(sigma), taken from the refer- 

 ence cited in the table. 



Because of the lack of complete information, 

 the data on salt water in Table X3.k are some- 

 what sketchy, although derived from various 

 sources. The dynamic-viscosity values were taken 

 from the book "The Oceans: Their Physics, 

 Chemistry, and General Biology," by H. U. 

 Sverdrup, M. W. Johnson, and R. H. Fleming, 

 Prentice-Hall, Inc., New York, 1942, page 69. 

 These authors do not give tables for the variation 



of surface tension with temperature but they 

 state, on page 70, that it "is slightly greater 

 than that of pure (fresh) water at the same 

 temperature." 



X3.6 Data on Change of State of Fresh and 

 Salt Water. Table X3.1 lists vapor-pressure or 

 change-of-state data for fresh water for the full 

 range of temperature from freezing to boiling. 

 These vapor-pressure data vary slightly from 

 those listed in Table 47.a of Sec. 47.3, but since 

 the change-of-state pressures appear to change 

 with air content and other factors, the data for 

 pure water serve only as a sort of engineering 

 reference. 



The freezing point of pure fresh water is 32 

 deg F, deg C. The effect of impurities and the 



TABLE X3.k — Mechanical Properties of Salt Water at Sea Level and Atmospheric Pressure 

 In general, the water whose characteristics are listed here is of 3.5 per cent salinity. 



