[IK]

Dear All

I am trying to understand the method by which the maximum bubble pressure method works. All the Literature information I have read state that once a bubble is formed the bubble pressure increases until it reaches a maximum pressure from which the surface tension is measured. As I understand it a new bubble is formed continuously and for each bubble the maximum bubble pressure is measured from which the surface tension is calculated.

My question is why does the surface tension decrease for each new bubble? Most of the other surface tension measurement methods always have one new surface formed and therefore the surface tension of that surface decreases with time as more surfactants adsorb. However with this method a new surface is formed every time so why does the surface tension drop?