BAKING POWDERS. 605 



PROBABLE PERCENTAGE COMBINATION. 



Sodium bicarbonate, NaHCO 3 ......................................... ----- 25.71 



(Residual sodium oxide, NasO) ............................................ 3. 17 



Acid phosphate of lime, anhydrous : 



H 3 PO 4 ........................................................ IB. 15 



-- 37. 10 



Starch .................................................................... 26.41 



Water of association (phosphate) .. ........................................ 7.<>1 



100. 00 



5509. Horsford's Self-raising Bread Preparation. 

 [Made by Rumford Chemical "Works, Providence, R. I.] 



THE ACID POWDER. 

 PERCENTAGE COMPOSITION. 



Calcium oxide, CaO ....................................................... 16.78 



Phosphoric acid, P 2 O 5 ..................................................... 2;J.97 



Sulphuric acid, SO 3 .............................................. ........ 6.00 



Starch ............................................................... .... 20.81 



Water of combination and association by difference ........................ 32. 44 



100. 00 



PROBABLE PERCENTAGE COMBINATION. 



Acid phosphate of lime : 



Ca 3 (P0 4 ) 2 21.00 



H 3 PO 4 19.80 



40. 80 



Calcium sulphate, CaSO 4 11.40 



Starch 20.81 



Water of association 26.99 



100. 00 



This sample was different from all the others in being put up in two 

 separate packages. One of these contained the acid ingredient, with 

 starch to keep it from becoming dry, and the other, bicarbonate of soda. 

 The directions are to mix the contents of both papers, if the whole is to 

 be made use of at once, or to use two equal measures of the acid part to 

 one of the soda. For analysis the contents of the papers were taken 

 separately, and the results obtained from the acid part are given above. 

 The other paper contained simply bicarbonate of soda of good strength. 



For the determination of the available carbonic acid another sample 

 was purchased, the entire contents of both papers thoroughly mixed, 

 and a portion of the mixed powders weighed out and submitted to an- 

 alysis. The first estimation made gave 13.56 per cent, available car- 

 bonic acid. By the time a duplicate estimation was made, perhaps an 

 hour after the first, the per cent, had fallen to 12.03, showing a very 

 rapid deterioration, or loss of available gas. Two subsequent estima- 

 tions made the same day gave, respectively, 9.50 per cent, and 9. per 



