The phenomenon of cavitation occurs when a tension, applied to a liquid, exceeds a certain critical value known as the breaking tension or cavitation threshold. The present review article considers various ways in which liquids have been subjected to tension and how the accompanying cavitation has been studied. The importance of these matters in medicine and botany is also discussed.

This paper contains an account of various experiments associated with the propagation of a pressure pulse up a vertical column of liquid. When such a pulse reaches the upper free surface of the liquid it is reflected downwards as a pulse of tension. This method therefore provides a means of subjecting the liquid to tension under dynamic conditions of stressing. If the value of the tension at any depth exceeds a certain critical value the liquid will cavitate. Values of this critical tension T were measured for liquids of varying viscosities η and it was found that the empirical relation T=kη0.1 holds. Secondly, pulse propagation across the interface between two immiscible liquids was studied, and it was found that the maximum tension which could be sustained by an interface separating silicone oil and water is less than the tension which produces cavitation in either of these two liquids. Thirdly, it has been found that the cavitation produced shows several cycles of growth and collapse, a phenomenon which has been observed photographically by previous workers.

Two different methods of subjecting a liquid to tension under dynamic conditions are described. In the first method a tension pulse is created ab initio in a column of water and the resulting pressure-tension cycles are monitored by a pressure transducer. These cyclic pressure variations have been observed by earlier workers but no adequate explanation of their occurrence has been previously given; such an explanation is proposed in the present paper. Secondly, a development of the bullet-piston method used by Couzens and Trevena (1974) is described in which a new way of obtaining and presenting the experimental results is reported.

The authors describe experiments concerned with the limiting negative pressure (that is, tension) which water can sustain when stressed dynamically by propagating a pulse of tension through a vertical column of the liquid. The effect of boiling and deionization increased the ability of the water to withstand tension. A single sample of water was subjected to repeated tensile failure at regular time intervals and it was found that the breaking tension that could be sustained tended progressively to an upper limit of about 11.0 atm as this type of stressing proceeded. The breaking tension is a maximum at around the temperature corresponding to the maximum density of water.

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