- 6 - 



Each cup was supplied at first by a calibrated dropper and later 

 on by the outlet of a proportioning funnel, both of which in turn 

 being fed by a 100 cc hypodermic syringe acting as a positive 

 displacement pump closed by a motor-driven screw. Thus, it was 

 possible to know and control the quantities of industrial waste 

 being introduced into the model either by counting drops delivered 

 per minute from calibrated dropper tips or by timing the revolu- 

 tions of the motor-driven screw. The industrial waste was simu- 

 lated by an acid. The acid concentration chosen was such that 

 when it mixed with a given number of volumes of ambient model 

 water, containing an indicator solution of brom cresol green, it 

 changed color from yellow to blue. The model water was set chemi- 

 cally to a known alkaline state (blue) such that for a given acid 

 strength the color change (yellow-blue) would occur at a predeter- 

 mined dilution. In this way the industrial waste, more concen- 

 trated than any specified dilution figure was represented by yellow 

 water, and further dilutions in excess of those specified by a 

 pleasing blue color which pervaded the whole model and varied in 

 intensity with the depth of water. 



Under certain conditions, continued discharge of industrial 

 waste eventually extended unneutralized acid boundaries into the 

 Gulf portion of the model. If routine titration of samples of 

 water drawn from the Gulf showed it necessary, as the unneutralized 

 acid reached and mixed away in the Gulf, a base of identical 

 strength was introduced volume for volume into the Gulf at the 



