566 FOODS AND FOOD ADULTERANTS. 



A seidlitz powder contains 120 grains of this salt, but the crystallized 

 salt contains four molecules of water, and thus the actual amount of crys- 

 tallized Kochelle salt formed in the baking-powder reaction is greater 

 than the combined weight of the two salts used. That is to say, if 184 

 grains of bitartrate and 84 grains of bicarbonate are used in a bak- 

 ing there will be a residue in the dough equal to 282 grains of Kochelle 

 salt. The directions that accompany these powders generally give two 

 teaspoonfulls as the proper amount to use to the quart of flour; prob- 

 ably more is generally used. This would be at least 200 grains ; deduct- 

 ing 20 per cent, for the starch filling we have 160 grains of the mixed 

 bitartrate and bicarbonate, and this would form 165 grains of crystal- 

 lized Kochelle salt in the loaf of bread made from the quart of flour, or 

 45 grains more than is contained in a seidlitz powder. The popular idea 

 is that the chemicals used in a baking-powder mostly disappear in bak- 

 ing, and that the residue left is very slight. I doubt if many persons 

 understand that when they use tartrate powders, which are considered 

 to be the best class, or at least one of the best classes of such powders, 

 they introduce into the breadstuff very nearly an equal weight of the 

 active ingredient of seidlitz powders, and in a loaf of bread made from 

 it they consume more than the equivalent of one such powder. 



Yet the character of this residue is probably the least objectionable 

 of any of those left by baking-powder. Kochelle salt is one of the mild- 

 est of the alkaline salts. The dose as a purgative is from to 1 ounce. 

 " Given in small and repeated doses it does not purge, but is absorbed 

 and renders the urine alkaline." (United States Dispensatory.) 



Free tartaric acid, used instead of the bitartrate of potassium, would 

 give less residue. In this case the reaction would be as follows : 



150 168 230 88 



H 2 4 H 4 O 6 + 2NaHCO 3 = Na 2 C 4 H 4 O 6 .2H 2 O + 2CO 2 



Tartaric Bicarbonate Tartrate Carbonic 



acid. of sodium. of sodium. * dioxide. 



Here 150 grains of tartaric acid, with 168 grains of bicarbonate of 

 sodium, give 230 grains of residue, or 88 grains less than the combined 

 weight of the two ingredients. As to the character of this residue little 

 is said in regard to the physiological properties of tartrate of sodium 

 in the books, but probably it is essentially similar to the double tar- 

 trate. The United States Dispensatory says of it (p. 1762): 



This salt, in crystals, has been recommended by M. Delionx as an agreeable purga- 

 tive, almost without taste, and acting with power equal to that of the sulphate of 

 magnesium in the dose of 10 drachms [600 grains]. 



I do not know why this combination should be used so seldom by 

 baking-powder manufacturers. The free tartaric acid is more expen- 

 sive than the bitartrate, but less of it is required in proportion to the 

 amount of bicarbonate used. The former is more soluble, and this 

 would probably be a practical objection to its use, as it is an object in 

 baking-powders that the gas should be liberated slowly. It would per- 



