[halfangstrom]

Hi I am looking for a liquid that is denser than water. It needs to be safe for kids and if possible colorless.

[curiouscat]

Depends on how safe.

Brine?

CaCl2 in H2O?

Mollasses?

Neither will burn nor explode nor give off toxic fumes or something. But if they drank a cup things wont be too pretty.

[billnotgatez]

Brine or CaCl2 in H2O or Molasses would eventually dissolve in water leaving a solution rather than layers.

Even Glycerol (or Glycerin), Corn starch solutions , Glucose, Milk, corn syrup, honey, and Sugar solutions would eventually dissolve as well.

I guess you just have to select one that does not dissolve rapidly.

Layered liquids
http://scidaho.org/wikidemo/index.php?title=Layered_liquids

[halfangstrom]

Thanks for the replies but I think I am looking for something different. I just remember seeing a youtube video of some invisible substance in a top-open glass box. The man in the video put a 'boat' on the substance and it floated. Then the man filled the 'boat' with the substance and then it capsized.

Perhaps this substance was a gas?

[Borek]

SF₆ comes to mind.

[halfangstrom]

Yes that is it. Thank you!

Here it is in action:
http://www.youtube.com/watch?v=A4hUNOpyeFY