BAKING POWDERS. 571 



A case in which the character of the powder appears to be improved 

 by such mixing, however, is furnished by the 



ALUM AND PHOSPHATE POWDERS. 



This combination seems to be a favorite one with manufacturers. In 

 fact there are now comparatively few u straight" alum powders in the 

 market, most of the cheaper grades being made of mixtures in various 

 proportions of the alum with acid phosphate of lime. The reaction it 

 is intended to obtain is probably the following : 



475 234 336 245 



(NH 4 ) 2 A1 2 (SO 4 ) 4 + CaH 4 (PO 4 ) 2 + 4NaHCO 3 = A1 2 (PO 4 ) 2 + 



Ammonia alum. Acid phosphate Bicarbonate of Phosphate of 



of lime. soda. aluminium. 



13C 132 284 176 72 



CaSO 4 + (NH 4 ) 2 SO 4 + 2Na 2 SO 4 + 4CO 2 + 4H 2 O 



Sulphate Sulphate of Sulphate of Carbonic- Water, 



of lime. aluminium. soda. dioxide. 



If this equation be compared with the one representing the reaction 

 in a powder made with alum alone, on page 569, it will be seen that in 

 the former the alum goes into the residue as pho'sphate instead of 

 hydrate, and the insoluble sulphate of lime takes the place of one mole- 

 cule of sulphate of soda. Otherwise the reactions are similar. This 

 reaction will only take place, of course, when the different ingredients 

 are mixed in just the proper proportions to produce it. A number of 

 variations may be produced by changing the relative proportions of the 

 different ingredients. 



THE "ALUM QUESTION." 



The literature upon the subject of the use of alum in baking-powders, 

 and upon the question as to its injurious effect upon the health of those 

 who consume the bread made from it, is already quite extensive, and if 

 quoted entire would fill a fair-sized volume. For the benefit of those 

 who may desire to make an exhaustive study of it, I will make refer- 

 ence to all of the articles bearing upon the subject that have come un- 

 der my observation as follows : 



Alum in baking-powder, by Prof. E. G. Patrick. Scientific American Supplement No. 

 185, 7, p. 2940. 



Report of proceedings in the Norfolk baking-powder case (first trial). Analyst, 4, p. 

 231. 



Norfolk baking-powder case (second trial). Ibid. ,5, p. 21. 



Editorial comment on the case. Ibid., 5. pp. 13 and 34. 



On the action of alurn in bread making, by J. West Knights. Ibid., 5, p. 67. 



Cereals and the products and accessories of flour and bread foods, by E. G. Love, 

 Ph. D. Second Annual Report State Board of Health of New York, 1882, p. 567. 



On the solubility of alumina residues from baking-powders, by Lucius Pitkin. 

 Journal American Chemical Society, 9, p. 27. 



Experiments upon alum baking-powders and the effects upon digestion of the resi- 

 dues left therefrom in bread, by Prof. J, W, Mallet, Chemical Neu>8, 58, pp. 276 ami, 

 284. 



0300 pt. 5 2 



