66 KANSAS ACADEMY OF SCIENCE. 



THE QUALITY OF COMMERCIAL CREAM OF TARTAR. 



By L. D. Havenhill, University of Kansas, Lawrence. 

 Read before the Academy, at Topeka, December 30, 1904. 



CREAM OF TARTAR, or potassium bitartrate, as it is scientific- 

 ally termed, is derived wholly from the vegetable kingdom, and 

 almost entirely from grapes. In this fruit it abounds, particularly in 

 the vicinity of the seeds, and is the principal cause of the tart taste 

 noticeable in that region. When the juice of the grape is expressed 

 in wine-making, it carries with it the potassium bitartrate. This lat- 

 ter, since it is very much more soluble in the "must" than it is in the 

 wine, is slowly precipitated, as the fermentation proceeds, along with 

 large quantities of coloring matter and other substances. 



From these precipitates, which are known, according to whether 

 they collect on the sides or the bottoms of the fermenting tanks, as 

 "argols" and "lees," respectively, the tartar is extracted with boiling 

 water and purified by recrystallization. The chief natural impurity is 

 calcium tartrate, which is present in the argols to the extent of from 

 two per cent, to twenty per cent., but, owing to its very sparing solu- 

 bility in water, should be practically all removed during the puri- 

 fication. Sometimes traces of the heavy metals are found, due to 

 contamination from the vessels in which the argols are purified, but 

 these are rigidly excluded by the tests of the United States Pharma- 

 copcEia, so that one per cent, of impurity which is allowed is practi- 

 cally calcium tartrate and moisture. According to the food and drug 

 laws of Kansas (Gen. Stat. 1901, ch. 31, art. 11, page 487), the pure 

 article of the United States Pharmacopoeia is the only grade of cream 

 of tartar that can be legally sold in the state. 



As a drug, potassium bitartrate is classed with the saline cathartics 

 and, owing to its hydragogue properties, is much used in dropsy. 

 Aside from this, large quantities are used in combination with sodium 

 bicarbonate as a leavening agent, or baking-powder. Its acid proper- 

 ties and sparing solubility in water render it peculiarly fitted for this 

 purpose. The only drawback which, perhaps more than any other, 

 keeps it from coming into universal use is that of price — a good cream 

 of tartar baking-powder has for many years retailed at the uniform 

 price of fifty cents per pound. It is, however, possible*, with pure 



* The following simple formula will be found to give satisfactory results, when pure chemicals 

 are used: 



Cream of tartar 2 parts. 



Sodium bicarbonate 1 part. 



Corn-starch or flour 1 part. 



These ingredients must be dry, finely powdered, and free from lumps. Intimately mix, and 

 pass several times through a fine sieve. Keep in a tightly closed can. 



