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specific gravity, which in this case were more significant than 

 specific gravity ratios, permission was obtained to average the 

 specified specific gravities of the simulated bleed waters and 

 to maintain this average difference above that of the ambient 

 water of specific gravity 1,000 at 60°F rather than lr012. Since 

 specific gravity is more easily measured than density and is 

 numerically equivalent to density if comparisons are made at a 

 convenient standard temperature, usually 60°F or 20°C, the result- 

 ing error in the equivalent density ratio was 1.2^, The average 

 difference in specific gravity of the simulated bleed water and 

 ambient water at 60°F was taken as 1.045 - 1.012 = 1.033 corres- 

 ponding closely to that of a 5fo NaCl solution at the same tempera- 

 ture. Thus the kinematic density difference 0,033 gn/cc, meas- 

 ured in terras of specific gravity under homogeneous temperature 

 conditions equivalent to 60°F, was adjusted by adding the nec- 

 essary quantities of Na2S0i to the bleed vrater tracer. 



A positive displacement pump had been designed and built to 

 handle the sum of both the simulated bleed water volumes and the 

 dilution volumes, but later it was thought better practice to 

 actually withdraw the dilution volumes from the model since these 

 volumes form a small but possibly significant part of the local 

 circulation. Relieved of this relatively major burden the bleed 

 water pump had to be run at very slow speeds, and during Test B 

 it was found that accurate proportional delivery of the scaled 

 volumes could not be detected and controlled quickly enough to 



