THE ANALYST. 207 ALUM I N BAKING POWDER. IN a recent issue of the Scientgc American Supplement will be found a communication from G. E. Patrick, Professor of Chemistry in the University of Kansas, giving details of a series of practical tests to determine whether the hydrate of alumina is dissolved by the gastric juice. The question has avital bearing on the discussion as to the safety of using alum in baking powders.Professor Patrick attacks it without prejudice, by strictly scientific methods, and arrives at results which are certainly gratifying in view of the wide use of alum powders in our kitchens. Professor Patrick takes his text from the published opinion of a prominent physician who says, after stating the difficulties attending a thorough mixture of the hgredients of alum baking powders :--" But even if the exact proportions were maintained, the208 THE ANALYST.salts formed would retain their injurious properties, as they would dissolve in the gastric juice. The gastric juice contains not only lactic acid, but a large amount of hydrochloric acid, and both the sulphate and hxdrate of alumina would be dissolved. ” After testing by reference to authorities the statement that the gastric juice contains a large amount of hydrochloric acid, and finding the weight of evidence to be that the quantity is in reality extremely minute, and that little not free, Professor Patrick proceeds b describe his examination of the practical question whether the hydrate of alumina.as it exists in bread after baking, when made with alum powders, will be dissolved in the fluids of the alimentary canal.This question could be determined only by careful tests with living animals. Professor Patrick found cats to be most available. Having made biscuits with an acknowledged alum baking powder, using twelve times the proportion of powder directed on the labels, and employing for each experiment a distinct sample of powder, he fed the biscuits to cats that had fasted from one to two days.The amount eaten in each case was enough to give at least half a teaspoonful of powder to each experiment. After allowing for digestion 20 minutes, 45 minutes, 18 hours, 2 hours, and 2+ hours, respectively, the cats were killed, and the contents of the stomach and small intestines were carefully examined for dissolved alumina. In each case undissolved hydrate of alumina was found, but of dissolved alumina there was never a trace.Surprised at the uniformity of these results, and thinking that the organic matter of the flour might have interfered with the solution of the alumina or his detection of it, Professor Patrick made two crucial experiments. In each, two teaspoonfuls of the powder were mixed with water and baked at the ordinary temperature of the oven.The mass was then fed to a cat (under compulsion) and after a specified time the stomach and intestines were examined as before. In neither case was a trace of dissolved alumina discovered. Similar experiments were then tried with unbaked (gelatinous) hydrate of alumina, and in these cases a trace of dissolved alumina was found; the inference being that it is not safe to eat dough made with alum powder-it should always be baked.Another important practical point was also suggested-namely, that if bread is carelessly mixed or with insufficient water, some of the powder may remain dry and the alum not changed to the hydrate ; in which case the effect would probably be injurious.In order to test this question, and also to furnish a check on the other experiments with biscuits, Professor Patrick had a batch made in which the mixing was less thorough than usual and with less water. These were fed to cats, and subsequent tests developed in every case a trace of dissolved alumina. These experiments, while proving the reliability of those first described, go to show, Professor Patrick thinks, that to insure the entire absence of alum in the bread, the mixing must be done with plenty of water. As a simple precaution it might be well to mix the batter too thin at first, and stiffen it by the addition of pure flour.z:--New Remedies. Mr. J. Baynes has been appointed Public Analyst for the Borough of Boston. * We do not find, however, that Professor Patrick’s experiments contain any reference to the effects which might be produced by the insoluble alumina.- [Eds. ANALYST.]