Appendix 3 



Relative activities (A^) and water potentials of KC £ and NaC£ solutions at 25°C. 







KCZ 









XaC£ 





Molal 

 (m) 



A 1/ 

 w 



ln A 



w 



Bars 



2 3/ 



A 



w 



ln A 



w 



Bars 



0.1 



0.996668 



-0.0033375 



- 4. 



.59 



0.996646 



-0.0033596 



- 4.62 



.3 



.99025 



- .0097978 



-13. 



.48 



.99009 



- .0099594 



-13.70 



.5 



.98394 



- .016190 



-22 



.28 



.98355 



- .16587 



-22.82 



.7 



.97763 



- .022624 



-31 



.13 



.97692 



- .023351 



-32.13 



1.0 



.96818 



- .032337 



-44 



.49 



.96686 



- .033702 



-46.37 



1.2 



.9619 



- .038845 



-53. 



.45 



.9601 



- .0407178 



-56.03 



1.4 



.9556 



- .045416 



-62 



.49 



.9532 



- .047931 



-65.95 



1.6 



.9492 



- .052136 



-71 



.74 



.9461 



- .0554070 



-76.24 



Data for A taken from Robinson and Stokes (1959) . 



o W 



Under normal atmospheric conditions the of a solution is equal to i>u because 

 there are no other components affecting the free energy status of water in solution 

 other than the solutes. 



The calculations of water potential were made using equation (2) : 



RT ln e 



= (8 .3143 X 10 7 ergs mole' 1 "K' 1 ) (298.16 e K ) (ln 0.996668) 



18. 016 cm. 3 mole-l 



= (137.5994 X 10 7 ergs cm." 3 ) (-0.0033375) 



= -4.59 X 10 6 ergs cm. -3 = -4.59 bars. 



Appendix 4 



Some of the manufacturers supplying instrumentation and equipment for application 

 in constructing and using thermocouple psychrometers : 



Thermocouple wire 



Omega Engineering Inc. Thermo-Electric Co., Inc. 



Box 4047, Springdale Station Saddle Brook 



Stamford, Conn. 06907 New Jersey 07662 



Leeds and Northrup Co. 

 4907 Stenton Avenue 

 Philadelphia, Pa. 19144 



24 



