Can I Save the Cerulean?

I'm finally going through all the old tubes of watercolors I've collected over the years, including many inherited from my mother, and seeing what I have and what condition it's in. The chemical data sheets for cerulean state that it ' tends to granulate or become chalky in watercolors' and indeed what's in the tube is not the usual sticky mass of dried paint but rather a crumbly powder. It is a fabulous color, and a tube runs about $12 so I'm trying to figure out if I can reconstitute it. I used it here for the 'sky' but it did not apply evenly nor in a proper watercolory manner.