I have learned with the assistance of readers of these pages, that tartaric acid is found in the sediment of fermented wine along with settled yeast. It was also possibly harvested off the sides of wine kegs, formed as an encrustation. The word tartar may come from the Arabic word durd meaning dregs.

Mascarpone can be used alone or with sugar added.  Perhaps it is most famous as an ingredient in tiramisu, the Italian "rocket fuel" coffee- flavored cake. It is often used in place of butter to thicken and enrich rissoti.
 

PROCEDURE:

1) Warm 32 ounces of light cream in a stainless steel double boiler to 185 degrees Fahrenheit (85 Celsius).

2) Dissolve 1/4 teaspoon of tartaric acid in 2 Tbl of water.

3) Stir the dissolved tartaric acid into the hot cream, stir well.  It should start to thicken almost immediately. Maintain the 185 F for five minutes, stirring occasionally.

4) Refrigerate covered for 12 hours in the stainless steel inner pot (or transfer to a clean plastic container with lid).  The whey should separate somewhat in that time.

5) Transfer to a sterile handkerchief, and suspend over a bowl for 24 hours in the refrigerator to allow the whey to drain out.

6) Transfer the finished mascarpone to a smaller air tight container, store in the refrigerator, use within a week or two.