The subjection of liquids to tension using the Berthelot tube method has been carried out by Temperley and Chambers (1946) and a number of subsequent workers. A common feature in all this work is the wide scatter obtained in the breaking tensions for a given specimen of the test liquid. A new type of investigation is described in which various thermal and mechanical variations were introduced into the method in order to study the effect on the measured breaking tensions, but the results still show a large scatter. Secondly, the role of surface nucleation sites in this matter is considered and a possible mechanism to explain this larger scatter is proposed.