It's a question which come into my mind after reading related notes now and again and I can't think of plausible response to it. Given Statements: We have a container filled with mercury and a glass capillary tube placed in it . As tube's diameter become smaller mercury's height in tube will get shorter and shorter.The reason said to be due to strong cohesion mercury has which makes it reluctant to stick to capillary walls and go higher unlike water. My Question: If mercury has such strong cohesion why it's seen to rise,although small, in our glass tube? I'll appreciate any help !