Bernd 



• - Tensile strength of the Deep Towing Basin 

 water of the David Taylor Model Basin 



along with the existence of plant and animal life in the water, have resulted in 

 surface films that delay dissolving. 



Extensive Cavitation Removes Film -Forming Materials — It is of consid- 

 erable interest to note that extended cavitation of the Deep Water Towing Basin 

 water made it similar to the tunnel water and drinking water (Fig. 9). A simi- 

 lar effect was obtained when using a protein surface film (egg albumin) to retard 

 dissolving (Fig. 10). That is, cavitation removed the materials causing surface 

 films. 



This substantiates the expectation that protein films are largely responsi- 

 ble for surface film formation. A protetin film becomes insoluble when com- 

 pressed, or agitated mechanically (11-13). The action is not reversible. Hence, 

 a protein by becoming insoluble cannot form a film from solution, and so is 

 gradually removed from action. Thus, unless the dissolved materials making 

 surface fibns are replenished, water that is normally slow dissolving should 

 eventually change its characteristics to become a fast dissolver. 



PRODUCTION OF SURFACE FILMS 

 ABOUT GAS NUCLEI 



It is rather difficult to analyze trace materials if structural details of the 

 molecules are desired. Also nuclei are too small to be observed readily in 

 their habitat. Hence an understanding of surface film action can most readily 

 be achieved if known materials are used to form surface films and the gross 

 results are observed. Furthermore, the type of materials necessary for film 

 formation can be fairly well delineated in advance by considering the essential 

 properties required to obtain the characteristics nuclei films must possess. In 

 addition, this approach leads to acquiring a means of controlling surface film 

 effects by using additives in water to produce the surface film desired. 



94 



