Contact angle for mercury porosimetry

A mercury contact anglometer that measures the contact angle on powders, meets the above requirements and gives highly reproducible results is shown in Fig. 20.5. A cylindrical hole of known radius is made in a compacted bed of powder. A press is used to compact the powder around a precision bore pin, which upon removal, produces a cylindrical open-ended pore. 

After placing the housing with powder sample and mercury into the anglometer, both chambers are evacuated. Air is then allowed to bleed slowly into the upper chamber and the pressure is monitored by a sensitive transducer (not shown). A digital display, with an appropriate offset to 

Using low-pressure porosimetry, Winslow measured contact angles by determining the breakthrough pressure required to force mercury into numerous holes drilled into the surface of solid discs. 

Another method for measuring the contact angle was developed by Poynting and Thompson. When a small drop of mercury is placed on the surface of a smooth bed of powder it assumes a spherical shape except for the portion in contact with the surface. As additional mercury is added to the drop, the height increases until it reaches a maximum value. Further additions of mercury increase the drop diameter with no additional 

The relationship between contact angle 9 and the maximum drop height 

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