the residues left by alum baking powders in bread baked with them, and that the solutions of the aluminum compounds thus formed will pass through animal membranes by osmosis.' (638.)

When aluminum hydroxide and aluminum phosphate are heated they give off water, and become less soluble. For the purpose of determining the degree in which the water may be driven off and insolubility produced in the process of baking, Professor MALLET made experiments as to the temperature of the interior of bread in the oven. Experiments were made with a large public baking oven of brick, 12 feet by 14 feet, heated by a coke fire; with a small brick oven in family use; and with the ovens of ordinary cast-iron cooking stoves, burning both wood and coal. The results were substantially uniform. The temperature of the oven atmosphere varied from 472° to 496 F. The maximum temperature shown by the registering thermometer with its bulb in the center of a loaf of bread, large or small, never exceeded 212° F., and at that temperature not all the water is removed. The lowest temperature recorded was 197° F. In that case the bread was not quite sufficiently baked through. (561,562,565.) Professor Mallet concludes that part of the aluminum is probably taken into solution. (566.) I. Physiological effects of alum baking powder.-1. Harmless.-Professor AUSTEN states that the residuum left in bread when alum baking powder is used consists of sulphate of soda and hydrate of alumina. The amount of sulphate of soda is so small that it may be overlooked. Indeed, it is asserted that the presence of it is rather advantageous. The manufacturers of the well-known "grape nuts" state that one of the most advantageous features of this food is the presence of a certain amount of sulphate of soda. As to the hydrate of alumina, Dr. Austen asserts that several authorities have pronounced it perfectly harmless under practical conditions. Some experiments from which a contrary inference has been drawn do not seem to Dr. Austen to warrant the inference. Professor Mallet ate quite large quantities of hydrate of alumina, prepared from alum baking powder, and noted the effect produced upon himself. He thought it gave him indigestion. Professor Mallet is an eminent man, but Dr. Austen does not think that he considers himself a physiological chemist. He is not accustomed to experimenting on himself, and it is therefore questionable whether he is able to observe accurately the effects upon himself of a given substance. If a man unaccustomed to such experiments eats any substance, and devotes his thoughts to the effects which it may have upon him, violent effects due to suggestion may appear. Violent diarrhea has been produced by a glass of water with the suggestion that diarrhea would follow. Moreover, even if such an experiment were conducted by a person whose experience fitted him to conduct it, it would still be inconclusive as to the question at issue the effect of small amounts of baking-powder products as taken in actual practice. Experiments with the chemical residuum of baking-powders may be inferential, but they can not fairly be considered proofs. (535, 536.)

Professor Austen states that, being empowered to undertake an experimental investigation of the effect of food prepared with alum baking powder upon the human system, he engaged Prof. Austin Flint, one of the most distinguished living physiologists, and Dr. E. E. Smith, a former assistant of Professor Chittenden, of Yale College, to conduct the actual experiments. As a standard of comparison, normal or control bread, a bread made with hydrochloric acid and bicarbonate of soda, carefully weighed out in their proper proportions, was fixed upon. Such a bread contains no residuum from the leavening substance except common salt. This bread and also a bread made with a common brand of alum baking powder bought in the market were very carefully made by Dr. Smith himself and reduced to crumbs and sampled, so that the material might show an even composition. The first experiment was made with artificial digestion, by means of a solution of hydrochloric acid and pepsin. The result showed practically no difference between the action of the control bread and that of the alum baking-powder bread.

The next experiment was made upon human beings. Persons were got into a proper normal condition and were then fed with a diet of determined composition, consisting of the breads under consideration and meat, milk, butter, and water. The feces and urine were collected and analyzed. No appreciable difference was found between the effects of the alum bread and those of the control bread. The per cent of available nitrogen in the feces from the alum bread was 90.8 per cent; from the control bread, 90 per cent.

The next set of experiments was to ascertain the influence of the bread made with alum baking powder upon the secretion of the gastric juice. Several men, young doctors or medical students, were given each 60 grains of one bread or the other and a certain amount of water in the morning, without any other food. Exactly an hour afterwards their stomach contents were pumped out and analyzed. There was no appreciable difference between the influence of the control bread and the influence of the alum baking powder bread on the secretion of the gastric

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juice. Dr. Smith summed up the results of these experiments as follows: 'In the experiments, the results of which are here briefly outlined, no difference was manifest in the influence on the digestive process of the Layton (alum) bread and the control bread. So far as has been observed, then, the residue resulting from the use of Layton alum powder has not diminished the digestibility of the food product or interfered with the digestive process.”

Dr. Austen mentions as a matter of importance that the persons upon whom these experiments were made did not know what bread they were eating. In this way the influence of suggestion was avoided. (539,540.)

Professor Austen says that he and Prof. Austin Flint and Dr. Smith "have been absolutely unable to find, by the most carefully and exactly conducted chemicophysiological experiments, the slightest difference between control bread free from residuum except salt and the bread made with alum baking powder." His conclusion is, therefore, that the use of alum baking powder in the preparation of food is absolutely uninjurious and wholesome. It is true that bread, like any food product, may be improperly prepared; but bread and similar products are, as a rule, fairly well made, and if they were not, any evil results which might follow defective preparation should not be attributed to the materials. (541, 543.) Dr. Austen states that he has submitted to many eminent physicians the questions whether they have ever had a patient whose diseased condition of the digestive system could be attributed, either wholly or in part, to the use of alum baking powder in food, and whether they have ever been led to attribute any functional disorders or diseased conditions to the use of alum baking powder in food. He has not been able to get from the most eminent physicians in New York and several other cities an opinion that anyone has ever observed any functional disturbance which could be traced to the use of alum baking powders. (538,541.)

Mr. DELAFONTAINE has examined bread and cakes made with baking powder, and never detected any residuum injurious to health, unless the sodium sulphate resulting from the decomposition of the alum products or the product resulting from decomposition of the cream of tartar products be injurious; and there is so little that it does not amount to anything. Alum is sometimes prescribed as an astringent in doses of from 10 to 20 grains. If in a baking powder containing 40 per cent of crystallized alum 1 per cent should escape decomposition, there would be less than 1 grain in the loaf of bread. The smoking of a cigar sometimes is worse than the amount of alum or cream of tartar which may escape decomposition in baking. The great outery against this or that baking powder is more for advertising purposes than in the interest of public health. Mr. Delafontaine thinks that as the two kinds are manufactured now the honors are even between them as regards healthfulness. He admits that cream of tartar occurs in grapes, while alum does not occur in any natural food, but says cream of tartar has some poisonous properties, potassium salts being poisonous. Tartaric acid in cream of tartar is a poison, but it takes a very large dose of cream of tartar or tartaric acid to kill a person. (230,232.)

Mr. MURRAY uses alum in making baking powders, and thinks it just as good and healthful as cream of tartar if properly neutralized. (67.)

Mr. PETRAENS, a chemist, says that he is convinced after an investigation of alum baking powder that it is not deleterious to the public health, and that it is really the most perfect baking powder in the market, because its residuum is smaller than that of any other. The baking powders of commerce are generally a mixture of, say, 75 per cent of an alum powder and 25 per cent of a phosphate powder. The alum part, or 75 per cent of the baking powder, will produce about 22 per cent of sodium sulphate and about 3 per cent of alumina oxid. There is no danger that any alum will remain in the bread after baking, because the alum will rapidly be decomposed by the soda under heat of the oven. Mr. Petraens says that alum baking powder is an excellent leavener, because the burnt alum is insoluble in cold water, and the powder therefore generates gas very slightly before it is heated. The baker is enabled to do his kneading slowly and thoroughly, and a more wholesome food is produced than when it is necessary to hurry the dough into the oven. (292, 293.)

2. Wholesomeness doubtful.-Professor DE SCHWEINITZ, a chemist and bacteriologist of the Department of Agriculture, says that so far as physiological experiments go there has been practically no evidence to show that alum in baking powder does any harm. The case is perhaps parallel to that of borax and boracic acid. The work done from the physiological standpoint has proved as conclusively as such work can prove that borax and boracic acid are perfectly harmless. Yet one would not recommend their use. Theoretically alum in baking powder may be said to be injurious. The burden of proof lies on the side of those who favor the use of it. (614.)

Professor MUNROE says the salts of alum are well known to be poisonous in large doses. If a substance which is poisonous in large amounts is proposed as an article of food, those who introduce it should be subject to the burden of proof that it is not injurious in moderate and repeated doses. (608, 609.)

Dr. MEW says sodium sulphate in very small quantities retards artificial digestion in the test tubes in the laboratory. It may possibly produce injurious effects in the stomach. Since there are possibilities, perhaps probabilities, of some harm being done, it is better to use the tartrate powders. The discussion of the subject is largely hypothetical. The physiological test is the ultimate analysis, and there has been very little physiological work done on the problem. In the Army no alum baking powder has ever been used. (612,613.)

Dr. WOODWARD, health officer of the District of Columbia and former coroner, has never seen or heard of any specific case in which injurious effects have been traced to the use of alum in bread or in baking powder. Any astringent, like alum, diminishes the secretion of any mucous membrane, such as the lining of the stomach, and therefore interferes with digestion. The use of alum itself as an ingredient of food should be forbidden.

The purpose of the manufacturers of alum baking powder is that no alum as such shall exist in the bread. Statements about the effects of alum do not, therefore, necessarily apply, although through the careless manufacture of such baking powders alum may possibly appear in the bread. The statement that substances which are not natural constituents of organic bodies are injurious is, of course, a matter of theoretical reasoning. The most that can be said is that the burden of proof should be on the advocate of the use of such substances. But since there are materials for baking powder that are free from this objection, it would seem that steps should be taken either to secure evidence of the harmlessness of alum powders or to forbid the use of them. (610,611.)

Professor HALLBERG says the question whether or not alum is an irritant poison has not yet been entirely settled. (81.)

Dr. CRAMPTON, chief of the division of chemistry in the office of the Commissioner of Internal Revenue, states his conclusions as follows:

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 aluminum 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 containing it is used.

(3) Whether the absorption of small quantities of alum into the human system would be productive of serious effects is still an open question and one that careful physiological experiment alone can decide." (624.)

3. Injurious effects affirmed.-Dr. WILEY says alum is an irritant and to some extent an antiseptic, tending to paralyze the ferments of digestion. It is poison in the sense of being an irritant, but not to so great an extent as many irritants. Its presence in food is very reprehensible, even in small quantities. Many stomachs can take a little alum without harm, but its presence should always be marked and known. He would not use alum in bread if he knew it. (46, 588.)

Professor VAUGHAN, dean of the medical faculty of the University of Michigan, says the question regarding baking powder is not altogether whether it is a poisonous substance or not, but also whether the bread made from it is good bread. He is quite positive that the alum baking powders should be condemned for the following reasons: (1) The action of the alum on the bicarbonate of soda is irregular and uncertain. No chemist can mix these substances in such proportions that they will give off a definite amount of carbonic-acid gas under all conditions, and consequently the bread will vary with the conditions of temperature, amount of water, kind of dough, etc., and is liable to be inferior. (2) The alum works upon the bicarbonate of soda so slowly and imperfectly that in a great many cases a residue of alum is left unchanged. Alum in large doses is seriously harmful, and even in small quantities it is an astringent and interferes with the secretion of the gastric juices, and is therefore injurious, especially when taken two or three times a day for a long period. (3) Even when the alum undergoes decomposition it forms either phosphate of aluminum or hydrate of aluminum, or both, and both of these are soluble to some extent in the gastric juices and are soluble in albuminous substances. They are harmful even in small quantities. (202, 205, 206.)

Professor FAIRHURST thinks the occurrence of hydrate of alumina in bread injurious to health. Alumina is not a constituent of the body, and its compounds, when taken in the blood, are simply foreign substances which must be

1

eliminated by the kidneys. Extra work is thus thrown upon the kidneys, and disease of them may possibly result. (620.)

Dr. JOHN C. WISE, medical inspector, United States Navy, writes the chairman of the committee (1) that alum baking powders produce a heavier and more indigestible bread than those made of tartrate of potash; (2) that the injurious effect of alum on the mucous coat of the stomach is not disputed, alum being both an irritant and an astringent, interfering seriously with the secretion of the digestive juices. (627.)

Dr. WILLIAM W. JOHNSTON, of Washington, says alum is used in medical practice to contract the blood vessels of the alimentary canal and to diminish the secretions. This effect necessarily interferes with digestion when produced in a man in health, and its long continuance would undoubtedly produce disease. The chemists assert that when alum is used in bread making its action is uncertain, and that a certain amount of it often remains unchanged. If this is a fact, Dr. Johnston says there can be no question of its deleterious influence. (225, 226.) Professor MOTT prefaces the account of his experiments in the use of alum baking powders with this remark: "It hardly seems necessary for any experiments on animals to decide a question of this nature so that the use of alum baking powders can be condemned, for a thorough scientific investigation of the subject can lead to no other conclusion." Though fully believing that experiments were unnecessary to determine this question in a sense hostile to the use of alum baking powder, Professor Mott thought it advisable to perform some experiments, in view of the fact that Professor Patrick, of Missouri, had conducted some experiments which he thought sustained the opposite opinion.

Professor Mott's first experiment consisted in the feeding of dogs with biscuits containing very large amounts of alum baking powder, in some cases 20 teaspoonfuls to the quart of flour, and in some cases 10 teaspoonfuls to the quart. These doses were followed by nausea and vomiting, extreme constipation, and a condition of general sickness and debility. Dogs fed with biscuits containing 20 teaspoonfuls of cream-of-tartar baking powder to the quart of flour showed no signs of sickness, though in one case the administration of the food was continued four days. Professor Mott's conclusion is that these experiments clearly demonstrate that the salts left in biscuits when a cream of tartar baking powder is used are perfectly harmless, but when an alum baking powder is used are very dangerous. (628–630.)

Professor Mott administered to dogs hydrate of alumina, mixed with meat, in doses of from 1 ounce to 4 ounces of precipitated hydrate, containing seven-eighths of its weight of abnormal water. Nausea, vomiting, and constipation followed, with weakness of the limbs, loss of ambition, and dulling of the eyes. Phosphate of alumina, containing three-fourths of its weight of abnormal water, administered in a dose of 3 ounces, followed by a dose of 2 ounces the next morning, produced a diminution of activity, dimming of the eyes, and an appearance of sickness, but no vomiting. Alum mixed with meat produced the same results as the

hydrate of alumina.

After feeding dogs with hydrate of alumina mixed with meat, and after also injecting a solution of hydrate of alumina directly into the stomach, Professor Mott found alumina in the blood, kidney, heart, spleen, and liver. The stomach and the duodenum were found congested.

One dog was fed with phosphate of alumina in quantities not stated. The stomach and the duodenum were found much congested after death, and considerable amounts of alumina were found in the spleen, liver, and heart.

In the only case in which the details of the administration of the hydrate of alumina are given, the dog was fed with 5 ounces of precipitated hydrate of alumina mixed with 2 ounces of meat. He ate only one-third of the mixture. This was followed up with five injections of hydrate of alumina directly into the stomach, the first dose being one-twentieth of an ounce, the last one-fourth of an ounce, and each of the other doses 1 ounce. The dog which took phosphate of alumina received 5 ounces of the precipitated phosphate (containing much water) mixed with meat.

From these experiments Professor Mott concludes that both hydrate of alumina and phosphate of alumina, when introduced into the stomach, are "sure to produce accute inflammation." (630-635.)

Professor Mott performed experiments in artificial digestion with gastric juice obtained from dogs, from which he concludes that both hydrate of alumina and alum check the digestive operation of the gastric juice, rendering it incapable of dissolving even the most digestible substances and entirely destroying its power of dissolving the more indigestible substances, such as boiled white of egg. Though the experiments of which he gives detailed reports were all made with

alum or with hydrate of alumina, he states in general terms that experiments were made with phosphate of alumina and basic sulphate of alumina, and that his experiments show that all alumina salts render the pepsin inactive and interfere with the powers of digestion. (632,633.)

Professor Mott presented a letter from Dr. E. S. Wayne, of Cincinnati, Ohio, dated April 10, 1879, in which Dr. Wayne states that a Mr. Edwards and his wife and children were all made sick by eating cakes made with alum baking powder. They thought they had been poisoned with arsenic. Dr. Wayne examined the cakes and the powder and found nothing but alum. Dr. Wayne states that he has also known of another similar case. (636.)

Professor Mott expresses the opinion that a person who eats 1 biscuit made with alum baking powder will suffer from the alumina salts present in it. He adds: “It is certain that persons continually eating biscuits made with an alum baking powder will suffer from its poisonous effects, as the alumina salts, instead of passing out of the system, accumulate in the various organs, interfering with their proper functions." (636.)

Assistant Surgeon FREEMAN, of the United States Navy, believes that the continued use of alum baking powder will produce chronic indigestion. (619, 620.) Dr. STRINGFIELD, a specialist in diseases of the digestive tract, testifies that alum, a double sulphate of aluminum and soda, is an irritant poison, cumulative in its effects. It impairs nutrition, retards digestion both in the stomach and in the intestines, and produces dyspepsia, indigestion, and constipation. It is also a positive irritant of the kidneys, through which it is excreted. It undergoes change in the stomach, liberating carbonic-acid gas and forming a phosphate or hydrate of aluminum. The hydrates or phosphates formed are moderately soluble in the gastric juice.

Dr. Stringfield has concluded from his observation that the great majority of cases of difficulty with the digestive tract may be traced to the white bread and the quick hot breads that are made with baking powder. The daily and continuous use of alum is not only harmful, but positively poisonous. (548,549.)

Dr. WEBER says that the unpalatable taste of food prepared with alum baking powder is due to sodium sulphate or Glauber's salts, which is extremely bitter. Besides the matter of taste, this has the disadvantage that all unpalatable food interferes with digestion by checking the secretion of the gastric fluids. (606.) Upon treating aluminum hydroxide and aluminum phosphate with an artificial gastric juice prepared with hydrochloric acid and pepsin, Professor MALLET found that a part of the aluminum was dissolved by the acid liquid and a part of the organic matter used as pepsin was rendered insoluble. Both of these effects are regarded by Professor Mallet as tending to indicate and to explain an interference with natural digestion by aluminum compounds taken into the stomach. The hydrochloric acid of the gastric juice, being partly charged with the aluminum, would have less power of dissolving the nutritious substances of food, and the precipitation of pepsin in an insoluble form would also interfere with the digestive process. Professor Mallet believes that soluble organic matters contained in food might also be rendered insoluble in the same manner as the pepsin. (564,565.)

Professor Mallet gives an account of a series of experiments upon his own person to determine the physiological effects of hydroxide and phosphate of aluminum, which are the principal residual substances left in bread by the use of alum baking powders. A weighed quantity of one or the other was taken, either with or a few minutes before a regular meal. The experiments were made with intervals of three or four days between them. There was no preexisting digestive derangement, and as much care as possible was taken to avoid any mere fancying of expected symptoms. The quantity of aluminum hydroxide taken at one time varied from 10 to 50 grains, and the average was about 28 grains. The quantity of aluminum phosphate taken at a time varied from 10 to 100 grains, and the average was 45 grains. These doses were intentionally made larger than quantities of the aluminum compounds which might probably be received at once in eating bread made with alum baking powder. The object was to determine with what doses distinct effects were noticeable. Distinct effects seemed generally to appear when the dose was not less than 20 grains of the hydroxide or not less than 30 or 40 grains of the phosphate. Bread made of the ordinary alum baking powders might be expected to contain about 13 or 14 grains of aluminum hydroxide to the pound of bread if alum alone were used in making the powder, or about 20 or 21 grains of aluminum phosphate to the pound of bread if alum and calcium acid phosphate were used together and all the aluminum were left in the bread as phosphate.

On two or three occasions, particularly with the smallest doses, there was no clearly observable effect. The general tenor of the experiments, however, con