Subject: How does a lotion pump works?

I want to know the construction of a household lotion pump and how it 
works.  On an ocassion, I found some lotion pumps are better for more 
watery liquid, and some are designed for more gel-like mixture.  I wondered 
how will the size of the tube attached to the pump, or the density of the 
contained substence will affect how well the pump work.  I also found out 
that some not well designed pump cause the contained liquid (watery kind)to 
keep dripping after using.  How can I modify it to minimise the waste?

Re: How does a lotion pump works?