At home Rochelle's salt synthesis I tried to make Rochelle's salt. It didn't work!


7 oz cream of tartar 
1 cup distilled water
heat to 180 F and keep there
add 1/2 tsp sodium carbonate at a time until there is no fizzing
filter and let cool


The solution ended with a strong yellow/brown tint. It took at least an hour of adding sodium carbonate. While cooling it rapidly formed a crystallized honey look and that was it. I reheated and added more distilled water to lighten it up a bit thinking it needed to evaporate slower. This time when it cooled nothing happened.

The sodium carbonate was 100%, and the cream of tartar was McCormick. It's possible that came with some impurities hence the brown/yellow grossness. 

Is there as way to save this batch? Should I just try again? Is there a better recipe?  

My first instinct is that it didn't work because you don't science with Imperial units.
Tried again with 365 brand (whole foods) Cream of Tartar. Worked much better.


39g Cream of Tartar 
50ml distilled water
Sodium Carbonate added slowly until stirring produces clear liquid