574 FOODS AND FOOD ADULTERANTS. 



From the various evidence that has been produced on both sides of 

 the question, I think the following conclusions may be safely drawn : 



(1) That form of alum powder in which sufficient phosphate is added 

 to combine with all the aluminium present is a better form, and less apt 

 to bring alum into the system than where alum alone is used. 



(2) It must be expected that small quantities, at least, of alum will 

 be absorbed by the digestive fluids where any form of powder contain- 

 ing it is used. 



(3) Whether the absorption of small quantities of alum into the hu- 

 man system would be productive of serious effects is still an open ques- 

 tion, and one that careful physiological experiment alone can decide. 



As the experiments made by Professor Mallet are the most recent on 

 this subject, I quote here his conclusions. I may say that most of those 

 based upon purely chemical work I can indorse, having confirmed many 

 in my own work, but I think the evidence furnished by his physiological 

 work is hardly sufficient to justify his conclusion as to the harmfulness 

 of such powders. 



GENERAL SUMMARY OF THE CONCLUSIONS REACHED. 1 



The main points which seein to be established by the experiments under discussion 

 are, briefly stated, the following : 



(a) The greater part of the alum baking-powders in the American market are 

 made with alum, the acid phosphate of calcium, bicarbonate of sodium, and starch. 



(&) These powders, as found in retail trade, give off very different proportions of 

 carbonic-acid gas, and therefore require to be used in different proportion with the 

 same quantity of flour, some of the iuferior powders in largely increased amount to 

 produce the requisite porosity in bread. 



(c) In these powders there is generally present an excess of the alkaline ingredient, 

 but this excess varies in amount, and there is sometimes found on the contrary an 

 excess of acid material. 



(d) On moistening with water these powders, even when containing an excess of 

 alkaline material, yield small quantities of aluminium and calcium in a soluble con- 

 dition. 



(e) As a consequence of the common employment of calcinm-acid phosphate along 

 with alum in the manufacture of baking-powders, these, after use in bread-making, 

 leave, at any rate, most of their aluminium in the form of phosphate. When alum 

 alone is used the phosphate is replaced by hydroxide. 



(/") The temperature to which the interior of bread is exposed in bakmg does not 

 exceed 212 F. 



(g) At the temperature of 212 F. neither the " water of combination " of 

 aluminium hydroxide nor the whole of the associated water of either this or the phos- 

 phate is removed in baking bread containing these substances as residues from bak- 

 ing-powder. 



(ft) In doses not very greatly exceeding such quantities as may be derived from 

 bread as commonly used, aluminium hydroxide and phosphate produce, or produced 

 in experiments upon myself, an inhibitory effect upon gastric digestion. 



(i) This effect is probably a consequence of the fact that a part of the aluminium 

 unites with the acid of the gastric juice and is taken up into solution, while at the 

 same time the remainder of the aluminium hydroxide or phosphate throws down in 

 insoluble form the organic substance constituting the peptic ferment. 



Chemical News, 58, 276; also published in pamphlet form, 



