The residues of the distillation are frequently used for the manufacture of bitartrate of potash, being converted for this purpose first into tartrate of lime. The hot vinasses, or after it has been cooled, is treated with milk of lime until it is neutralized, which can be recognized by the color of the liquid, or with litmus paper. The tartrate of lime which is formed is precipitated, the liquor decanted, and the precipitate cooled and dried. During the precipitation of the tartrate of lime many other bodies foreign to this substance are thrown down, which renders the whole mass impure. It is necessary to add a sufficient quantity of lime to perfectly neutralize all acids present; otherwise the precipitation of the tartrate of lime is not complete. If care is taken to carry on the precipitation in a solution which is just the least bit acid a much better tartrate of lime is secured, even being almost white. In this way the tartaric acid is fixed and separated from the other bodies which remain in the residue of the distillation. The tartrate of lime is well dried and reduced to powder or coarse consistency and preserved in bins which are kept perfectly dry. In a humid atmosphere it may undergo fermentations which practically destroy the tartaric acid which it contains. From this tartrate of lime much of the tartaric acid and bitartrate of potash of commerce are made.