From my knowlegde:

t-butyl alcohol is a tertiary alcohol. It does not react with chromic acid in room temperature ( no reflux). Cr^+6 ions in the chromic acid are red-brown in colour. If reduction occur, the Cr^+6 ions will be reduced to Cr^+3 ions which are green in colour.

 

I have done the above test ( no reflux) using a test tube, what i can observed is two distinct layers with colourless on the upper layer and dark green solution (precipitate?) on the lower layer. Theoretically, t-butyl does not react with chromic acid, but why the colour of Chromic acid changes from red brown to green??

Are u sure ur t-butyl alcohol is pure ??

 

Or maybe your Chromic acid is not pure ??

Or perhaps the alcohol isnt pure? I was browsing wikipedia and stumbled on this Linkie It says its used to test for the presence of primary/secondary alcohols because of that selectivity so perhaps the chromium isnt the problem.