Wine, lees pressing

Calcium tartrate is produced by extracting wine lees (deposited on the bottom of vats containing 19 to 38 % of potassium bitartrate) and grape marc (the residue from pressing grapes), filtering the solution and then adding slaked lime and calcium chloride [31.18]. 

Port wine is fermented in shallow receptacles of masonry in which the grapes are trodden and, after fermentation, pressed. Fermentation in Italy, Spain, and the south of France is carried out at 15° to 24° C., and is a top fermentation, but in Germany and with the finer French wines, a bottom fermentation is made at 5° to 12° C. At the higher temperature the fermentation takes from 3 to 8 days, and the wine produced is fiery, high in alcohol, and lacking in delicate aroma. At the lower temperature the first fermentation lasts a few weeks, but yields a wine of delicate flavour. When fermentation is complete, and the wine has become clear, all the yeast aud other suspended matters are deposited oil the bottom of the cask or vat, constituting the lees. From this the young wine is racked, i.e. decanted or siphoned off, and run into a clean cask. 

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