Peterson 
crease in size by coalescence or further adsorption and eventually 
become indistinguishable from natural aggregates. The longest di- 
mension of typical newly formed aggregates was on the order of 
2 Drapes 
Wallace and Wilson [36] have shown the effectiveness of 
concentrating dissolved organic compounds as particulates through 
aeration. They found that for their test protein solution of 5 parts per 
billion, aeration gave almost 100 percent recovery of the compound 
in the form of particulate. 
This is typical of the concentration of dissolved organic com- 
pounds in seawater: The sum of these compounds, however, can 
reach the part per million range, 
Similar results have been found by other investigators not 
specifically studying the de novo particulate production in water. For 
example, Liebermann [26] found in the course of studies on the so- 
lubility of air bubbles in water that the contamination at the interfac- 
ial boundary between the air and water had no effect on the diffusion 
of air into the water. After the addition of many organic compounds 
and surfactants to the water, he stated that ... ''no laboratory con- 
dition could be found in which the rate of bubble diffusion was signifi- 
cantly altered.'' Lieberman also showed that when a bubble in multi- 
ple distilled water collapsed on a chemically clean surface, a micro- 
scopic amount of residue remained. When the pressure was reduced 
to 1/4 bar, the residue quite frequently nucleated another bubble. 
In another series of experiments on the diffusion of gas out of 
a bubble, Manley [37] found results similar to Liebermann, In this 
work, also, bubbles collapsing in distilled water left a small deposit 
of impurity. 
From the above discussion, it is apparent that in the typical 
cavitation test facilities, there should be no difficulty in producing 
particulate capable of cavitation nucleation. These can remain suspen- 
ded in quiescent water and can readily be produced whenever at least 
some degree of aeration of the water takes place. 
CONCLUSIONS 
The general objective of this work was to develop a better un- 
derstanding of the role of the free and dissolved gas content in water 
on the nucleation of hydrodynamic cavitation. The means by which 
this was accomplished was to use only one type of body, a headform, 
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