WATER 
of sea water that (on the basis of omic strength) a 
salinity of 32 parts per thousand is equivalent 
to an NaCl solution having a molality of 0.675 
or a weight percentage of 3.79 percent NaCl. 
Table I was computed for an initial tempera- 
ture of 15°C because this temperature is a rough 
average of conditions normally encountered in 
experimental work. Table I] was computed for 
an initial temperature of 25°C because this was 
the temperature quoted for the available com- 
pressibility data.8 Table III shows that the 
results are not sensitive to small variations in 
temperature and salinity. 
2. Specific Volume and Coefficient and 
Thermal Expansion 
The best sources of data seem to be the 
oceanographical tables of Knudsen.® Second 
power equations in ¢(°C) were fitted to the data 
tabulated for s=32: 
For Table I: 
v(t) = 0.977094 2.05 x 10-4(t— 15) 
+4 X 10-8(t—15)2. 
For Table II: 
v(t) =0.97956+2.85 K 10-4(t— 25) 
+4 xX 10-§(t—25)?. 
3. Heat Capacity 
The heat capacity data used in computing 
Tables I and II are those quoted by S. Kuwa- 
hara :!° 
Cp = Cp —0.0004226¢-+0.0000063212 cal./gm°C, 
TaBLE VII. Comparison of experimentally measured 
sound velocity with calculations based on the Ekman 
Compressibility Equation. (Salinity=31.7 parts per 
thousand.) 
Temperature Velocity of sound (ft/sec) Deviation 
(3G). Measured Calculated (%) 
10.9 4887.7 4875.6 0.26 
11.6 4885.8 4883.8 0.04 
11.6 4893.1 4883.8 0.19 
11.5 4902.4 4882.5 0.41 
11.1 4888.3 4878.5 0.20 
8 Adams, J. Am. Chem. Soc. 53, 3769 (1931). 
° Oceanographical Tables, Comissariat of Agriculture, 
USSR, Moscow, 1931. (A general compilation of oceano- 
graphic data by N. N. Zubov.) 
10S. Kuwahara, Velocity of Sound in Sea Water and 
Calculation of the Velocity for Use in Sonic Sounding 
(Hydrographic Dept. I.J.N. Tokyo, 1938). 
Aiea VnEE,  ERIOIN Ty OR ASSO .Ci& 
379 
WAVE 791 
TaBLE VIII. Comparison of Adams’s experimental 
compressibilities and the empirical fit given by the Ekman 
and Tait equations. 
(v0 —v) /vo 
Adams Ekman Tait* equation 
(experimental) equation n =7.800 
je Pure 3.79% S =32 B=3.012 n =7.445 
(kbar) H20 NaCl (Table 1) (Table II) B=3.156 
0.0 0.0000 0.0000 0.0000 0.0000 0.0000 
0.5 -0212 .0196 -0198 .0197 -0198 
1.0 -0393 .0368 -0370 -0368 -0370 
1.5 -0555 -0522 -0522 -0518 -0522 
2.0 -0699 -0658 -0655 0653 0659 
3.0 0945 -0894 0871 .0887 .0897 
4.0 1152 -1091 = -1083 -1095 
5.0 -1330 1265 a= 1254 SPAS) 
6.0 -1485 1417 — .1405 1431 
7.0 -1622 1552 = -1540 © -1569 
8.0 .1746 .1670 —= -1662 -1695 
9.0 1858 1781 = 1775 .1812 
10.0 1964 -1886 a -1876 -1917 
11.0 .2059 .1980 — .1972 -2017 
* (vo —v) /vo =(1/n) log(1+p/B). 
where 
Cy = 1.005 — 0.004136s +9.0001098s? 
—0.000001324s°. 
In the above equations, ¢ is temperature in °C 
and s is salinity in parts per 1000. These data 
are in good agreement with those used by Kirk- 
wood and Richardson, quote in Appendix II. 
4. Compressibility Data for Low Pressure Region 
(Table I) 
The following equation was used in computing 
Table I: 
10°u = —[227-+28.33t—0.551¢? 
1+0.183p 
+0.004t°]+ [105.5 +9.50¢—0.158/2] 
y—28 
—1.5p74— (7) c147.s—2.100 
+0.04t2—p(32.4—0.87/+0.022) ] 
y—28\? 
+( ‘3 ) (45-0.11—p(1.8-0.060), 
where p is pressure in kilobars, ¢ is temperature 
in degrees centigrade, and y is defined by: 
v=vo(1—pp), 
y is defined by: 
7 = —0.069+ 1.4708 Cl—0.001570 Cl? 
+0.0000398 Cl#. 
