Adjective : a soluble powder. ,a soluble problem.    From Dictionary.com. 

I would have made the seams unsoluble and only the fabric soluble.    From Wordnik.com.  [AnimeBlogger.net Antenna] Reference

The longer the case was probed, the deeper became its unsoluble aspects.    From Wordnik.com.  [The Traitor: A Story of the Fall of the Invisible Empire] Reference

The antiquated view of Du Bois-Reymond (1872) -- that human consciousness is an unsoluble "world-riddle," a transcendent phenomenon in essential antithesis to all other natural phenomena -- continues to be upheld in numerous writings.    From Wordnik.com.  [Monism as Connecting Religion and Science A Man of Science] Reference