The Bulletin. 47 



The residue left in bread from an alum powder is more complex 

 than the residue from any of the other classes mentioned, and depend 

 on the kind of alum used. Sodium sulphate and aluminium hy- 

 droxid are necessarily present, and if potash and ammonium alum 

 are used their respective sulphates would be present also. 



There is a class of powders that contain two, and sometimes even 

 more, acid-furnishing material ; of these the alum-phosphate powders 

 are the most important. They are mixtures of alum and phosphate 

 powders, and the residue left in the bread by them would be a mixture 

 of the residues already referred to under alum and phosphate powders, 

 with a small amount of aluminium phosphate in addition. 



All baking powders, without exceptions, leave in the bread certain 

 salts, above mentioned, which are foreign to flour and objectionable, 

 and most of which are used in medicine, though some of them not 

 internally. 



EXAMINATION OF SAMPLES. 



Thirty-nine samples have been examined and classified as follows: 



Phosphate Powders 10 



Tartrate Powders 8 



Alum Powders 20 



Alum-phosphate Powders 1 



No adulteration was found and only one sample (JSTo. 6604) was 

 not properly labeled. The acid ingredient was not stated on the 

 label, as is required. 



In the examination of these powders quantitative determinations 

 were made of the carbon-dioxide gas (the active leavening constituent 

 to which powders owe their value) and the insoluble ash, though 

 qualitative tests were made to ascertain the materials from which 

 the powders were made, as well as any impurities or adulterants. 



On standing, baking powders, unless put up practically air-tight, 

 gradually lose their leavening power; and the longer a powder 

 stands, other things being equal, the lower its leavening power will 

 be. If a powder is not put up dry and kept so, there will be a gradual 

 decomposition or loss in leavening power. While no actual adultera- 

 tion was found in the samples examined, several of them had prac- 

 tically lost their strength or leavening power, and a few of them were 

 almost worthless because of it. Whether a powder has lost its leaven- 

 ing power or whether it never had any makes little difference to the 

 consumer, fur one is as worthless as the other. 



As baking powders deteriorate on standing, merchants should never 

 keep them in stock to be very old. 



