January 3, 1890.] 



SCIENCE. 



15 



Of the thirteen brands of powder examined, eight contained 

 large quantities of alum ; and two more, traces. Six contained 

 calcium phosphate ; two of which, however, were labelled " phos- 

 phate powders," but in the other cases it was used as an adultera- 

 tion. 



One of the phosphate powders contained a great quantity of 

 alum, although it claimed to be free from it. All contained more 

 or less starch, but the better brands use only a very small 

 quantity of it, for the purpose, they claim, of keeping the powder 

 from being decomposed by the moisture. Terra alba, or " white 

 earth," was found as a common adulterant of the cheaper powders ; 

 and, while it is claimed that it is so insoluble that it passes through 

 the body unchanged, yet, accepting that, the same thing may be 

 said of it as has been said of the use of a large quantity of starch ; 

 viz., that a larger amount of the powder must be used to produce 

 the required porosity in the bread, thus increasing the amount of 

 residue. 



It was the object of this investigation not only to find out the in- 

 fluence the residues of impure baking-powders have on digestion, 

 but also to find out to what extent, if any, the residues of the 

 purest made powders retard the digestive action of the gastric 

 juice. 



Regarding the use of alum as an adulterant. Dr. MalMt of the 

 University of Virginia has just made a careful investigation, and 

 finds that its use is very harmful, as it does not retain its form as 

 a sulphate, but, on being subjected to the process of baking, as- 

 sumes the highly insoluble form of aluminium hydroxide. 



By quantitative work with this latter compound, and also by 

 means of taking a large dose of it after a hearty meal and noting 

 the result, he has found that digestion is impaired, and proves that 

 this result is due to the fact that the aluminium unites with the 

 acid of the gastric juice, thus depreciating the effectiveness of the 

 latter secretion ; also that part of the organic matter of the food is 

 precipitated in an insoluble form by the presence of the aluminium 

 compounds. 



Accepting, then, this well-proved and universal belief that alum 

 is deleterious to the human system, a series of experiments were 

 begun to find out what other salts used in the preparation of bak- 

 ing-powders exert a harmful effect on the digestive process. 



For these experiments, an artificial gastric juice was prepared 

 by dissolving .05 of a gram of scale pepsin in a solution of .40! one 

 per cent hydrochloric acid. 



In the first series, egg-albumen was taken as the material to be 

 digested, after freeing it from globulin by precipitating the latter 

 with a few drops of hydrochloric acid. 



The first experiment was undertaken to determine what effect 

 the purest made baking-powder has on digestion ; the one which 

 stood the best tests in the previous analysis being chosen, as it 

 contained only the bicarbonate of soda and pure cream-of-tartar. 



Three digestions were carried on at the same time and under the 

 same conditions. The first was the control or normal digestion, 

 in which 10 cubic centimetres of albumen, 40 of distilled water, 

 and 50 of the artificial gastric juice, were used. In the second 



1 gram of the baking-powder was heated with the 40 cubic centi- 

 metres of water for a short time at a temperature of 100° C, to 

 give it the same conditions it would have in baking bread ; then 

 the starchy residue was filtered off, and the same amounts of gas- 

 tric juice and albumen added as were used in the control. The 

 third was treated in the same manner as the second, except that 



2 grams of the baking-powder were used. 



The three digestions were then carried on in a 40° C. water-bath, 

 thus giving the digestion normal temperature. 



After stirring well at different periods, the digestions were 

 stopped, after five hours had elapsed, by raising their temperature 

 above 70° C, and kiUing the ferment. All were neutralized with 

 a dilute solution of sodium carbonate, filtered through a weighed 

 filter, washed well with hot water, and, after drying in an oven, the 

 precipitate was weighed. 



If none of the albumen had been digested in any case, the pre- 

 cipitate sho.uld weigh I gram, for 10 cubic centimetres of egg- 

 albumen yield (with slight variations) i gram. The following fig- 

 ures, however, representing the weight of the precipitates, show 

 how far digestion had proceeded in each case : No. i, or control. 



.3065 ; No. 2, I gram of powder, .6495 ; No. 3, 2 grams of powder, 

 .7570 : in other words, the amounts digested in grams would be. 

 No. I, .6935, or 100 per cent ; No. 2, .3505, or 5oi per cent ; No. 3, 

 .2324, or 33+ per cent. 



Regarding the normal amount digested as 100 per cent, the 

 amounts digested in the other cases are thus deduced. 



While the inhibitory action of this residue seems to be very great 

 on studying these figures, it must be remembered that only a 

 small amount of albumen was used in comparison with the amount 

 of baking-powder ; but these results only go to show that even the 

 " purest " bakmg-powder retards digestion in a measure. 



To avoid the trouble with the starchy sediment that occurs with 

 the baking-powder, a second series of experiments was under- 

 taken with different amounts of the pure Rochelle salts, which is 

 the residue formed by the action of cream-of tartar on bicarbonate 

 of soda in baking. The same amount and strength of gastric juice 

 were used in this series as in the first, and also the same amount 

 of albumen. The following table shows the result obtained after 

 digestion had proceeded seventeen hours : — 



Three other series were carried through to verify the result ob- 

 tained in this experiment, and the amount digested in any case was 

 found to be fairly constant with the amount of salt used. 



A series of digestions was then carried on with the use of am- 

 monium alum to show what effect this salt has on digestion in its 

 unchanged form of a sulphate, and it is interesting to note that its 

 inhibitory action is not very much greater than the Rochelle salts. 



The following table shows the result obtained after digestion had 

 been carried on five hours : — ° 



The next residue experimented with was the one which is left in 

 the cooked food when a baking-powder adulterated with calcium 

 phosphate and alum, or an ordinary phosphatic powder containing 

 alum, is used ; i.e., aluminium phosphate. 



The results obtained in this series, when compared with those of 

 the Rochelle salts, or even with the alum, show a greater inhibi- 

 tory power than either, and go to show that the occurrence of 

 alum and calcium phosphate in the same powder forms a residue 

 which greatly retards digestion. 



The results after digestion had been carried on fifteen hours 

 were as follows : — 



In order to obtain a correct comparison between the inhibitory 

 effects of a baking-powder made from bicarbonate of soda and 



