Displayed in the applet window is the asymmetric unit of the crystal structure of the organic molecule:

That two atom fragment is actually a water molecule - the oxygen atom lies on a crystallographic 2-fold axis. To add the 2nd H-atom, click "Add H". The water molecule is hydrogen bonded to the hydroxyl group of the above molecule.

In fact, there are four molecules hydrogen bonded to the water. Click "More".

There is a second water molecule in the unit cell - click "2nd water".

This second water molecule is, of course, hydrogen bonded to four of the organic molecules - click "More".

Now things are getting complicated: one of the "new" H-bonded molecules is translated one unit cell length along the b-axis (the short cell axis) from one of the first four molecules, beginning a "layering" effect along b. This second water molecule also occurs on the "other side" of the unit cell - click "More".

If we add one of these layers along the positive b-axis, Things get really messy. This second water molecule also occurs on the "other side" of the unit cell - click "Even More".

And if we add a layer along the negative b-axis! - click "Many More".

Compound 9178