570 FOODS AND FOOD ADULTERANTS. 



more acrid taste and is more irritating than potassium bromide. Its unpleasant taste 

 and irritating qualities render it less convenient for administration than the bromide 

 of potassium. 



We all know how mild a substance is chloride of sodium (common table salt) ; but 

 of ammonium chloride Stille" and Maisch write : " The direct effects of doses of 5 to '20 

 grains of this salt, repeated at intervals of several hours, are a sense of oppression, 

 warmth, and uneasiness in the stomach, some fullness in the head. If it is used for 

 many days together in full doses, it disturbs the digestion, coats the tongue, and im- 

 pairs the appetite." We have already seen how active a drug carbonate of ammonia 

 is, and -while, in the absence of proof, it would be rash to assert that sulphate of 

 ammonia in five-grain doses is certainly injurious, yet there is abundant ground for 

 further investigating its effect before asserting that it is milder in its effects than 

 Rochelle salt. It may be that this question of the presence of ammonium salts in 

 any considerable quantities in the residues of baking-powders deserves more at- 

 tention than it has hitherto received. 



It would seem from the above that there would be considerable differ- 

 ence between the physiological effects of potash and ammonia alums 

 themselves. Yet the medical authorities make no such distinction. 

 Ammonia alum is officinal in the British Pharmacopoeia, and while the 

 United States Pharmacopoeia specifies potash alum, the particular form 

 met with in trad6 is entirely determined by the comparative cheapness 

 of manufacture. 



The question of the relative harmfulness of these different salts in the 

 residues of baking-powders is really one for the physiologist or hygienist 

 to decide, not the chemist. Physiological experiments alone can decide 

 them positively. 



The consideration of the residue of hydrate of aluminium will be 

 taken up later on. 



POWDERS CONTAINING MORE THAN ONE ACID INGREDIENT. 



As might be expected, some powders are met with which have been 

 made up with various proportions of different acid ingredients, and 

 which belong therefore to more than one of the above-mentioned classes. 

 Professor Cornwall speaks as follows concerning some of these mixed 

 powders : 



The makers of alum baking-powders sometimes add tartaric acid or bitartrate 

 to their powders, either with or without the addition of acid phosphate of lime. 

 This is doubtless done with the best intentions, either to secure a more rapid escape 

 of carbonic-acid gas at the outset, or otherwise improve the powder. We have found 

 such additions in the case of several of our samples, but the presence of tartaric acid 

 or tartrates in alum powders is very objectionable. If added in sufficient quantity 

 to otherwise pure alum powders, they prevent the precipitation of the insoluble hy- 

 drate of aluminium entirely when the powder is boiled with water, and they may ren- 

 der much of the alumina soluble iu water even after the bread is baked. Without 

 doubt it would then be readily soluble in the digestive organs, producing there the 

 effects due to alum or any other soluble aluminium compound. With one of our sam- 

 ples wo found that the simple water solution seemed to contain as much alumina as a 

 nitric-acid solution. In neither of these solutions could any of the alumina In- thrown 

 down by u slight excess of ammonia water, although it was readily precipitated from 

 the solution first rendered alkaline with caustic soda, then slightly acidified with 

 acetic acid and boiled with excess of phosphate of soda. 



