Problems with Glass

I was building the mob spawner I wanted to use soul sand and magma block to make an elevator for going up and down quickly.

I wanted to make visible the bubbles of the soul sand and of the magma cube, so I used glass, white glass.

I made a pillar of glass, but while I was placing blocks of glass, I noticed that it showed 1 face of the block of glass, while all of the faces of the glass blocks below were not there.

(Sorry For My Bad English)