Text-book of hygiene : a comprehensive treatise on the principles and practice of preventive medicine from an American standpoint
Rohé, George H. (George Henry), 1851-1899
44 TKXT-r.OOK OF JlY<iIENK on the third vessel, the Argo^ 18 died during the pas- sage, and 98 of the 107 survivoi's suffered from palu- dal fevers of all forms. IN'one of the crew of the Argo were sick however. The two vessels exempt from sickness, and the crew of the Argo had been supplied with pure water, while the soldiers on the latter vessel had been furnislied with water from a marsh. This water was said to have a disagi'eeable odor and taste. The testimony of a large number of East Indian physicians is also quoted by Parkes in support of the view that malarial fevers are often caused by impure drinking water. The observations of Dr. Charles Smart upon the production of the ' mount- ain fever' of the Western territories, have alreadj^ been referred to. The author ventures to state it as his opinion however,, that the instances in which malarial fevers are due to impure drinking water are very rare. The causation of typhoid fever and cholera by impure drinking water will be presently referred to. Recently the opinion has been expressed by some that yellow fever and diphtheria are also spread by polluted drinking water, but no strong evidence has yet been adduced in its support. There can be very little doubt that diarrhcea and dysentery are frequently caused by water which has been contaminated with decaying organic matter. The evidence in favor of this amounts practically to demon- stration. It must not be forgotten that the ova of certain animal parasites, as distoma hematobium, filaria san- guinis hominis, and medinensis, anchylostoma duode- nale, and possibly of round and tape worms, are taken into the system with the drinking water. Organic detritus of various kinds, sewage, decom- posing animal and vegetable matter, refuse from manufacturing establishments, maybe a source of x)ol- W ATE It. 45 lution of water and render it unlit for drinking or other domestic purposes. It is, however, not certain that water thus rendered unclean is prejudicial to health ; in fact Dr. Emmerich, of Munich has recently put his skepticism on this point to a practical test. For two weeks he drank daily from one to two pints of very filthy water; in fact, nothing less than sewage. The water was both chemically and physically exceedingly impure. Several of the experimenter's patients par- took of the same water without any ill effect. He even claims that a gastric catarrh from which he was suffer- ing when the experiment was begun, improved during its course."^ The results of Emmerich's experiments, and of other well-known observations seem almost conclusive that the products of animal and vegetable decomposi- tion, taken into the body with the drinking water, can not be looked upon as certainly harmful. Should, however, water containing such impurities, or even water apparently pure, contain the germs of one of the specific diseases : cholera, typhoid fever, or perhaps yellow, malarial or scarlet fevers, or diphtheria, it is probable that such disease would be communicated to the consumer of the water. Many instances are on record where outbreaks of typhoid fever have been clearly attributable to pollu- tion of the drinking water by the germ of the disease from a previous case. One of the most remarkable of these outbreaks is that recorded by Dr. Thorne.f About the end of January, 1879, typhoid fever began suddenly in the adjoining towns of Caterham and Red Hill. Within six weeks three hundred and fifty-two cases occurred. * WoLFFHtTEGEL : WasserveTsorgung, in Pettenkofer u. Ziemssen's Handbuch der Hygiene. I. Abth., II. Hlfte., p. 97. t Report of the Medical OfiBcer to the Local Government Board for 1879. Quoted in Fodob: Hygienische Untersuchungen, etc., II, Abth. p. 261. 46 tp:xt-hook of irY(;iKNE. All other sources of the disease were excluded, except the drinking water, to pollution of which it was traced with almost absolute certainty. Caterham contained 558 houses and Red Hill 1700. Of the former, 419 and of the latter 924 draw their drinking water from a common supply, having its source in a well several hundred feet deep. The insane asylum with 2000 in- mates, and the military barracks in Caterham used water from a private well. There was no typhoid fever among the last two communities. During January one of the workmen engaged in some excavation near the public well was taken ill with diarrhoea and fever — probably tyx)hoid, but was still able to continue his work. His dejections were often voided where they were certain to become mingled with the water of the common sup- ply. This man's diarrhcea began on January 5th, and continued until the 20th of the month, during which time he remained at work. On the latter date, he was compelled to quit work and take to his bed. Exactly two weeks from the beginning of the man' s sickness, on January 19th, the first case of typhoid occurred in Ca- terham, and then rapidly increased. The first case occurred, therefore, just fourteen days — the incubative period of typhoid — after the presumed infection of the the drinking water by the dejections of the sick laborer, who had come from Croydon, where typhoid fever was at the time prevalent. Within two weeks from the appearance of the first case, the epidemic had reached its height, and then rapidly declined, disappearing almost entirely in a month after the outbreak. It was shown by Dr. Thorne that nearly all the houses in which the disease appeared were supplied with water from the source above mentioned, while other houses in the im- mediate vicinity of the infected ones remained free from the disease. WATER. 47 In 1874 there was an outbreak of tj'plioid fever in the town of Over Barwen, in which nearly 10 per cent, of the inhabitants were attacked. Here the source of the disease was also traced to an infected water supply. Dr. Buchanan has shown that an outbreak among the students of the University of Cambridge, was like- wise attributable to an infected water supply. In this country the reports of the Boards of Health of the various States teem with accounts of localized outbreaks of typhoid fever referred to infected or pol- luted drinking water. In most instances the evidence furnished by the observers is not conclusive. In many, however, especially of those found in the Massachusetts and Michigan reports the fact of the communication of the disease in this manner seems unquestionable. One of these is as follows : Out of forty families, all using water from a certain well, there occurred 23 cases of typhoid fever. Out of forty-seven families living in the same neighborhood, but using water from differ- ent sources, only two had typhoid fever.* Dr. C. F. Fol- som has published a very suggestive account of a house epidemic, t where nine cases in a single house, who all drank water from a well which was proven to be in- fected from a privy, were attacked by this disease. The numerous cases of typhoid fever, which have been attributed to the use of infected milk may be in- cluded in this category. It is probable that the milk became infected either through polluted water used for the purpose of cleansing the milk vessels, or in diluting the milk. Mr. Ernest Hart has recorded:}: fifty epidem- ics of typhoid fever, fifteen of scarlet fever, and seven of diphtheria, the cause of which he has attributed to infected milk. * Transactions Mich. Med. Society, 1883, p. 401. t Boston Med. and Surg. Journal, vol. CII., p. 227, 261. t Transactions Int. Med. Congress, 1881, vol. IV. p. 391, 48 'I KXT-1UK)K OF IIV(;iK.M-: It is not ])robal)le, however, that typJioid fever is always, or in the majority of cases spread through the medium of polluted drinking water, but in many of the instances on record, the relations between cause and and effect, — impure water and typhoid fever, have been so clearly made out as to no longer permit any doubt upon the question. As it is with typhoid fever, so also with cholera. In a later chapter the origin and propagation of ty- phoid fever and cholera will be discussed more fully. At the present time only the relations of the drinking water to the spread of these diseases can be consid- ered. In the instance to be presently noted, the con- nexion between the infected water on the one hand and the outbreak of cholera on the other is so clearly shown as to be almost equivalent to a mathematical demon- stration. The facts in the case, were brought to light after a patient inquiry by a commission whose report drawn up by Mr. John Marshall, has made the occur- rence classical. In 1854, the people of a well-to-do, and otherwise healthy district in the Eastern part of London suffered severely from cholera. Upon inquiry the fact was elicited that a child had died of cholera at No. 40 Broad street, and that its excreta had been emp- tied into a cess-pool situated only three feet from the well of a public pump in that street, from which most of the neighboring people took their drinking water. It was further discovered that the bricks of the cess-pool wall were loose and permitted its (contents to drain into the pump-well. (It should be noted that the commu- nication between the cess-pool and well was direct ; that there was immediate drainage, not percolation through the soil). In one day 140 to 150 people were attacked and it was found that nearly all the persons who had the malady during the first few days of the outbreak drank the water from the pump. When the pump WATER. 49 was closed to public use by the authorities, the epidemic subsided. The most singular case connected with this outbreak was the following: In West End, Hamp- stead, several miles away from Broad street, there oc- curred a fatal case of cholera, in a woman, 59 years old. This woman formerly lived in Broad street, but had not been there for many months. A cart, how- ever, went daily from Broad street to West End, carry- ing among other things, a large bottle of water from the pump referred to. The old lady preferred this water to all others, and secured a daily supply in the manner stated. A niece who was on a visit to the old lady drank of the same water. She returned to her home, in a high and healthy part of Islington, was likewise attacked by cholera and died. There were, at this time, no other cases of cholera at West End, or in the neighborhood of these last two persons attacked. Most of the English medical officers in India hold strongly to the view that cholera is spread by polluted drinking water, and the evidence in its favor is very strong. The evidence in favor of the influence of impure drinking water on the causation of other diseases than those mentioned is not sufficient to justify any conclu- sions at present. The source of a water-supply may be pure, and yet pollution may occur before the water is used by the persons to whom it is distributed. Supply pipes may become defective and the water become contaminated with sewage or other deleterious substances. It is a current belief that no impurity can gain access to hy- drant pipes between the reservoir, or source of supply, and the point of discharge of the water. Neverthe- less, such contamination may occur very readily. The author and his colleague. Dr. J. W. Chambers, of Bal- timore, proved this conclusively a few years ago, by 50 TEXT-BOOK OF HYGIENE. establishing an undoubted connexion between a house- epidemic of typhoid fever and a defect in the hydrant supplying the family with water.* The hydrant was one of the class known as Clark' s patent non-freezing hydrant. The mechanism of these hydrants is as fol- lows : At the lower end of the vertical discharge pipe is a glazed earthenware plunger, which works through a ring of rubber packing into a vacuum chamber. At the bottom of the vacuum chamber is a valve regula- ting the entrance of the water from the conducting pipe. When the water is shut off, this valve is kept closed by a spiral spring. When the crank of the hydrant is turned forward, that is, when the water is 'turned on,' the plunger is forced to the bottom of the vacuum chamber, presses on the spring, opens the valve and allows the water to discharge. When the crank is turned back, the plunger is raised, releases the spiral spring, which forces the valve into its bed, and shuts off the water. The partial vacuum produced by the raising of the plunger, draws the water which is in the ve??tical discharge pipe into the vacuum chamber, which is so far below the surface as to be unaffected by frost. In course of time, and with use. the rubber packing gets worn and permits gradual leakage into the vacuum chamber, of the dirty, stagnant water by which this part of the hydrant is always surrounded. Outbreaks of typhoid fever having a similar origin, in which the connexion between cause and effect was clearly shown have been reported by other physicians of the. same city, f Aside from the practical question of the causation of disease by polluted water, a more abstract and aes- thetic idea is involved in consciously taking any impu- * On Preventable Polluiion of Hydrant Water and its Relation to the Spread of Typhoid Fever. Maryland Med. Journal, Vol. VII., p. 271. + Local Causes of In.sanitation in Baltimore, By John Morris, M. D. . Report Md. State Board of Health, 1678. WATEK. 51 rity into the system. The instincts of man as well as of most animals revolt at it. These inborn instincts which constitute the sanitary conscience, as Soyka says, demand purity of food and water, as they insist on cleanliness of the body, of clothing, and of the dwelling. STORAGE AND PURIFICATIOJST OF W^ATER. Wherever a large supply of water is needed, un- less drawn direct from a well or spring, or pumped di- rectly from its source, arrangements for storage are necessary. Cisterns and large reservoirs are made use of for this purpose. River water, especially, requires a period of rest in a storage reservoir in order to allow deposition of the large amount of suspended matter in it. Prolonged storage also gives opportunity for the conversion of possibly deleterious organic compounds into simple, and perhaps harmless, compounds. Usual- ly in an elaborate system of water- works, a series of reservoirs is built in which the water is stored succes- sively, so that before its final distribution through the street mains, it has become quite clear and pure. Filtration on a large scale is also used in connexion with storage reservoirs, in order to secure greater puri- ty of the water. In the distribution of water, care should be taken that nothing deleterious is taken up by the water in its passage through the pipes. Lead poisoning is not infrequent from drinking water that has passed through a long reach of lead pipe, or which has been standing in a vessel lined with lead. Tanks and storage cisterns should therefore not be lined with lead, and the use of lead pipe in the supply-service should be avoided as much as possible. Fortunately most natural waters pos- sess a considerable proportion of carbonic acid, which forms with the lead an almost insoluble carbonate of 52 TEXT-BOOK OF HYGIENE. lead. This carbonate of lead is deposited on the in- side of the pipes, and protects both the pipes against erosive action from other constituents of the water, and also prevents the contamination of the water by the lead. An excess of carbonic acid in the water renders this deposit soluble, and may cause serious poisoning. Any water which is shown by analysis to contain over one-twentieth of a grain of lead per gallon is danger- ous and should be rejected. Owing to the possibility of defilement of the water from improper construction of hydrants, all out-door hydrants should be discouraged as much as possible, and should be replaced by a simple tap-cock indoors. The pipes should also be laid deep enough under-ground, or otherwise protected against freezing in winter. A number of methods, all more or less efficient, have been introduced to purify water, when it needs jiurilication before being lit for use. These methods either comprise liltration, or seek to purify the water without the aid of this process. One of the methods of purification without filtration, consists in exposing the water to the air in small streams. This was pro- l)Osed by Lind more than a century ago, and has since been frequently revived. The water is passed through a sieve, or a iDerf orated tin or wooden plate, so as to cause it to fall for a distance through the air in finely divided currents. By this process sulphuretted hydrogen, offen- sive organic vapors, and possibly dissolved organic matters are removed. This x>rocess has been used in Russia on a large scale. By boiling and agitation, carbonate of lime, sul- phuretted hydrogen and organic matter are removed, or rendered innocuous. Vegetable germs are usually destroyed, although Tyndall has shown that some bac- terial germs withstand a temperature higher than that of boiling water. WATER. 53 As has already been mentioned/'^' alum is one of the readiest and most elRcient means of removing suspen- ded matters from water. Permanganate of potassium is sometimes used to purify water containing considerable organic matter. The permanganate rapidly oxidises the organic mat- ter and is believed to render it harmless. There is no certainty, however, that the germs of specific diseases are destroyed by the action of this salt, in the propor- tion in which it could be used for the purposes of water XDurification. , A yellow tint is given to the water by the perman- ganate, which is due to finely divided peroxide of man- ganese. This does no harm, but is unpleasant.. Water, unfitted for use by organic matter, is some- times rendered usable by infusing certain vegetable astringents in it. Thus, it is said that the Chinese drink water only in the form of tea, in certain parts of China, where the water contains large quantities of organic matter. The tannin of the tea-leaves precipi- tates the suspended matters and renders the water fit for use. Mixing the water with red wine, which is as- tringent, has the same effect, f Filtration is an efficient means of removing sus- pended matters. Charcoal, sand, gravel and spongy iron are used as filtering material. The most economical filter is one made of fine, clean sand, above which lay- ers of gravel of a gradually increasing size are x)laced. The coarser particles of suspended matter are arrested before the sand, which removes most of the coloring and organic matters, is reached. TESTS FOE IMPURITIES m WATEE. Accurate and reliable quantitative analyses of water can only be made by chemists of experience. Every * See page 42. t Champouillon, quoted in Med. and Surg. Hist, of the War, pt. II., Med. Volume, p. 613. 54 TEXT-BOOK OF HYGIENE. intelligent person should however know how to deter- mine the presence or absence of suspected impurities. The following methods are simple and easily carried out : To determine the presence of chlorine, or chlorides, (often indicating sewage contamination), acidulate about half an ounce of the water to be tested with pure nitric acid, and add a few drops of a solution of nitrate of silver, (24 grains to one ounce of distilled water). A white precipitate, gradually changing to gray, is produced if chlorides are present. The degree of cloud- iness produced will indicate approximately, the amount of chlorides. 'One grain of chlorine per gallon gives a haze ; four grains per gallon give a marked turbidity ; ten grains, a considerable precipitate.'* If the chlo- rine is found by this test to exceed one grain per gal- lon, the source of the contamination should be searched for. If drainage from a cess-pool is suspected, a quan- tity of salt water may be thrown into it, and the water again tested after an interval of four hours to see whether the chlorine has increased. The presence of nitric acid, or nitrates, even in very minute quantities, is shown by the following test : A small quantity of the water is evaporated to dry- ness, and a few drops of a solution of carbolic acid in four parts of concentrated sulphuric acid and two j)arts of distilled water, added to the residue. If nitric acid is present, a brownish red color results, which turns green and then yellow upon the addition of ammonia. Nitrous acid or nitrites will give a reaction with iodide of potassium and starch. Twelve to twenty ounces of water in a flask are acidulated with a few drops of dilute sulphuric acid, and a little solution of iodide of potassium added. About half a dram of fresh- ly prepared starch is added and the mixture shaken. * Parkes, 1. c, p. 77. WATEE. 55 If nitrons acid is present, the iodide is decomposed setting free tlie iodine, which combines with the starch, causing a blue color. The test is a very delicate one. The following test will indicate the presence of am- monia. Make a solution of one part of bichloride of mercury in thirty x>arts of water, and another of one part of carbonate of potash in fifty parts of water. Five drops of each of these solutions are added to about 24 ounces of the water to be tested, in a tall glass. If ammonia is present, a white cloudiness will appear in the water. If, after an interval of several hours, no turbidity has developed, no ammonia is present. To determine the presence of ml'plniric acid., or sulphates, the water is acidulated with hydrochloric acid, and a solution of chloride of barium added, which gives a white precipitate of sulphate of barium if sulphuric acid is present. Organic matter is indicated by its reaction with chloride of gold, or potassium permanganate. A solu- tion of permanganate added to water contnining organic matter becomes almost instantly decolorized. The ad- dition of chloride of gold, and boiling the water pro- duces first a pink color, gradually changing through violet to black. The water should be first slightly acid- ulated. Neither of these tests for organic matter is abso- lutely reliable, as nitrous acid, sulphuretted hydrogen, and ferrous salts produce similar reactions. SIGNIFICATION or THE VARIOUS IMPURITIES INDICATED BY THE ABOVE TESTS. The following summary gives, in a brief compass, the inferences that may be drawn from the result of the above tests :* * Parkes' Hygiene, vol. I, p. 79, 66 TEXT-BOOK OF HYGIENP:. 'If chlorine be present in considerable quantity, it either conies from strata containing chloride of so- dium or calcium, from impregnation of sea-water, or from admixture of liquid excreta of men and animals. In the first case the water is often alkaline from sodium carbonate ; there is an absence, or nearly so, of oxidized organic matters, as indicated by nitric and nitrous acids and ammonia, and of organic matter; there is often much sulphuric acid. If it be from cal- cium chloride, there is a large precipita te with ammo- nium oxalate after boiling. If the chlorine be from impregnation with sea-water, it is often in very large quantity ; there is much magnesia, and little evidence of oxidized products from organic matters. If from sewage, the chlorine is marked, and there is coinci- dent evidence of nitric and nitrous acids and ammonia, and if the contamination be recent, of oxidisable or- ganic matters. 'Ammonia is almost always present in very small quantity, but if it be in large enough amount to be de- tected without distillation it is suspicious. If nitrates, etc., be also present, it is likely to be from animal sub- stances, excreta, etc. Mtrates and nitrites indicate previously existing organic matters, probably animal, but nitrates may also arise from vegetable matter, although this is probabh^ less usual. If nitrites largely exist, it is generally supposed that the contamination is recent ; the coincidence of easily oxidized organic- matters, of ammonia, and of chlorine in some quantity, would be in favor of an animal origin. If a water gives the test of nitric acid, but not of nitrous acid, and very little ammonia, either potassium, sodium or calcium nitrate is present, derived from soil impreg- nated with animal substances at some anterior date. If nitrites are present at hrst, and after a few days dis- appear, this arises from continued oxidation into ni- WATER. 57 trates ; if nitrates disappear, it seems probable this is caused by the action of bacteria, or other Ioav forms of life. Sometimes in such a case nitrites may be formed from the nitrates. Lime in large quantity indicates calcium carbonate if boiling removes the lime, sulphate or chloride or nitrate if boiling has little effect. Test- ing for (salcium carbonate is important in connexion with purification with alum.* Sulphuric acid in large quantity with little lime, indicate sulphate of sodium, and usually much chloride and carbonate of sodium are also present, and on evaporation the water is alkaline. Large evidence of nitric acid, with little evidence of organic matter, indicates old contamination; if the organic matter be large, and especially if there be nitrous acid as well as nitric present, the impregna- tion is recent.' [The following works are recommended to those desiring fuller information upon the subjects embraced in the foregoing chapter : Water Supply, by Wm. Ripley Nichols, N. Y., 1884. A Guide to the Microscopic Examinatinn of Drinking Water, by J. D. Macdonald, R. N. F. R. S. Some of the Organic Impurities found in Drinking Water, by C. W. Chamberlain, M. D., Rep't Ct. State Board of Health, 1880, p. 260. Mi- croscopical Examination of Potable Water, by W. J. Lewis, M. D., Ibid., p- 216.] * See page 42. CHAPTER III. FOOD. In order to preserve health and vigor, it is neces- sary for animal beings to consume at intervals a suffi- cient qiiantitj^ of substances known as foods. Alimen- tary substances, or foods, may therefore be briefly defined as materials, which, taken into the body and assimilated, sustain the processes of life, promote growth, or ]irevent destruction of the organized con- stituents of the body. QUALITY AND CIIAEACTER OF FOOD NECESSARY, It has long been known, as the result of the em- pirical observation of feeding large bodies of people, that the various proximate principles must be combined in certain definite proportions in the food in order to preserve the normal degree of health and vigor of the body. Within a comparatively recent period, physiol- ogists have made experiments upon animals and human beings, which have led to the same conclusions, and have enabled these i:)ro23ortions to be fixed with more or less exactness. Considering man as an omnivorous animal, it may be laid down as an invariable rule, that the following four alimentary principles are necessary to his exist- ence.* Neither of these principles can be dispensed with for a prolonged period without illness or death resulting. 1 . Water. — This must be supplied in sufficient quan- tity to permit the interchange of tissue to be carried on in the body. * Laxdois, Physiologie, ate Aufl. p. 448. FOOD. 59 2. Salts. — Inorganic compounds of various kinds are necessary to tlie preservation and proper construc- tion of the tissues. They are all found in sufficient quantities in the various alimentary substances con- sumed by man and the lower animals. A deficiency of inorganic constituents in the food is followed by dis- ease. 3. Proteids. — Organic nitrogenous material, either animal or vegetable, is a necessary constituent of the food of man. Continued existence is impossible with- out a sufficient supi^ly of nitrogenous substances. 4. Fats, or Carho-hydrates. — The organic non-nitro- genous, or carbonaceous principles of food are also nec- essary to the continuance of health. They are sup- plied either by fats, or by carbo-hydrates, (sugar, starch, etc. , ) which may be used as substitutes for each other. Voit has shown that seventeen parts by weight, of starch, is equivalent as carbonaceous or oxidisable food to ten parts of fat. According to Moleschott, the standard diet for a man of average height and weight, doing moderate work, should be as follows: Proteids, 130 grams (4.59 oz.); fats, 84 grams (2.96 oz.); carbo-hydrates, 404 grams (14. 26 oz.). The proportion of nitrogenous to non-nitrogenous food-stuffs would therefore be l:3f, or speaking roughly, 1:4. When very hard work is re- quired, as from a prize-fighter in training, the pro- teids are about doubled, the fats increased by about one-fourth, and the carbo-hydrates decreased by two- thirds. In addition to maintaining a proper proportion be- tween the various alimentary principles, it is necessary to vary the articles of food themselves, otherwise they are liable to prove nauseating. The necessity of variety in the food, in order to preserve the appetite, is famil- iar to everyone. 60 TEXT-BOOK OF HYGIENE. The table here given,* shows the relative propor- tions of nitrogenous to non-nitrogenous alimentary- principles in the various substances named : By keeping these proportions in view it will be seen at once that if a man wished to live on beef alone, he would have to eat four and a quarter pounds per day, in order to get a sufficient amount of non-nitrogenous food. Of potatoes, in order to get enough nitrogenous food he would have to eat daily eighteen pounds. No human stomach could prove equal to the task of digest- ing this excess of material. On the other hand, it is to be noted how perfect the combination of the various principles is in human milk. In cow's milk, which is nearest in composition to human milk, the non-nitro- genous principles are deficient. Hence, the important practical point that when ordering milk diet for a pa- tient a small portion of carbonaceous food, (bread) must be added, if the standard of health shall be reached, or maintained. Climate has probably very little influence upon the amount of food required by the individual. The actual quantity of food consumed varies little between various races, or in different parts of the earth. It is true, however, that a larger proportion of fat is re- quired in cold climates. That fatty articles of food NITROGENOUS. NON-NITROGENOUS. Veal, Beef, Lentils, Beans, Peas, Fat JIutton, Pork, Cow's Milk, Human Milk, Wheat Flour, Oat Meal, Potatoes, Rice, Buckwheat Flour, 10. 1. 10. 17. 10. 21. 10. 23. 10. 23. 10. 27. 10. 30. 10. 30. 10. 37. 10. 46. 10. 50. 10. 86. 10. 123. 10. 130. *Landois, op. cit., p. 449. FOOD. 61 readily undergo oxidation and furnish a large amount of animal heat is proven both by observation and ex- periment. The albuminoid proximate principles of the food, proteids, are represented by the nitrogenous constitu- ents of organic tissues. These are the vitellin and albumen of eggs, albumin, fibrin, globulin, myosin, syntonin and other nitrogenized principles of flesh and blood ; the casein of milk, the gluten, fibrin and legu- min of cereal and leguminous seeds and plants, gelatin and chondrin. Fat constitutes an integral component of animal tissue, and is found in abundance as a constituent of nerve tissue, marrow, and sub-cutaneous connective tissue. In food it is represented especially, in the fatty tissue of meat, the yelk of eggs, butter, etc. The carbo-hydrates are represented especially by various products of the vegetable world, as sugar, starch, dextrin, etc. Water and the various other inorganic proximate principles, chief among which are compounds of cal- cium, sodium and potassium, are usually found in sufficient proportion in the other alimentary sub- stances. The food should be taken in appropriate quantities and properly prepared, A larger quantity than neces- sary may overtax the digestive organs and thus yield less than the required amount of nutritive material to the body. Physical exertion increases the consumption of albuminoid and fatty principles. Hence, as in the cases of the athlete or prize-fighter in training, larger quantities of these principles are required to keep the nutrition of the body at the standard of health. Du- ring mental work, however, less nitrogenous material is consumed than during physical labor. 62 TEXT-BOOK OF HYGIENE. In youth the processes of combustion (])roduction of carbonic acid) go on with greater rapidity than after adult life is readied. For this reason young j^ersons rarely get fat, tlie fat-producing food being burnt up in the body by the greater metabolic activity of the young cell. Hence, fats and carbo-hydrates should form a larger relative proportion in the diet of the young, than in that of grown persons. Low external temperature causes a greater and more rapid consumption of fat than high external tem- perature. During febrile conditions, however, the de- struction of the stored-up fat in the body — the wasting away — is one of the most notable phenomena. Hence, the importance of supplying fat and fat-producing food in chronic febrile diseases. 'Der Mensch ist was er isst,' said Ludwig Feuer- bach.* The pungency of the epigram is somewhat lost in the translation, which is literally: 'Man is what he eats.' The intimate relations of mental, moral and physical conditions of health to the quality and quan- tity of food deserve the earnest attention of the edu- cated physician and sanitarian. FOODS. Foods or victuals are generally divided into foods proper, and so-called accessary aliment. The classi- fication is not exact however, as the latter, which are commonly regarded as articles of luxury, may under certain circumstances become necessities, and hence should not be considered as forming a separate class. Foods are either of animal or vegetable origin. Those derived from animal sources are milk, the flesh of animals, birds, reptiles and fish, and the eggs of the three last-named. * Gottheit, Freiheit und Unsterblichkeit von Standpunkt der Anthropologic, p. 5. FOOD. 63 The foods derived from the vegetable kingdom comprise the seeds of various plants (cereals, legumes) roots, herbs, ripe fruits, the fleshy envelopes of various seeds (which may properly be classed with the fruits), and various fungi. There are also in common use a number of bever- ages, e. water, alcoholic liquors, alkaloidal infu- sions (tea, coffee, cocoa), etc. In addition, a number of substances or compounds are in common use as condiments. Their function is either to lender victuals more palatable, or to promote digestion and assimilation. Vinegar, mustard, and common salt, are familiar examples. FOODS OF AKIMAL ORIGIlSr. Milk. — Human milk is, so far as known, the one perfect food for man found in nature. It contains, in proper proportion, representatives of all the different classes of proximate principles necessary to nutrition. One hundred parts contain about 3.5 parts of proteids (casein and albumin); 4 parts of fat (butter); and 5 parts of sugar. The reaction of human milk is slightly alkaline ; that of fresh cow' s milk is neutral. In human milk there are 12.21 parts of solid mat- ter to 87.79 of water, while in cow's milk the propor- tions are, solids 11, water 89 parts. Of the solids in milk, cow's milk contains more proteids, while human milk is richer in fats and sugar. Hence, in using cow' s milk as a substitute for human milk, the proteids are diluted by the addition of water, and the non-nitrogenous components increased by ad- ding sugar, and under some circumstances, fat (cream).' On standing, the fatty constituent of milk, the cream, separates, and on account of its less specific gravity, rises to the surface, where it forms a layer of varying thickness. 64 TEXT-BOOK OF HYGIENE. After standing a longer interval, the milk under- goes certain physical and chemical changes. Lactic acid is formed at the expense of part of the sugar of milk (a sort of fermentation taking place), and acting upon the casein, produces coagulation. This is the so- called 'bonny-clabber.' When the fermentation con- tinues, especially under a slightly elevated tempera- ture, the solid portion becomes condensed (curd), and a sweetish-acid, amber colored liquid, the whey, sepa- rates. The curd, after further fermentation, under appropriate treatment, becomes converted into cheese. Whey is sometimes used alone, or mixed with wine, as an article of diet for the sick. Butter is made from the cream by prolonged agita- tion in a churn. The fat-globules adhere to each other and form a soft, unctuous mass, of a yellowish color, solid at ordinary temperatures. After the butter is all removed in this way the balance of the cream remains in the churn as buttermilk. This is an article of con- siderable nutritive value, although its excess of acid renders it unsuitable as an article of diet in many cases. The specific gravity of fresh milk should not be below 1030. It should, however, be borne in mind that the richest milk is not always that which has the highest specific gravity. In fact, a sample of rich milk, containing a large proportion of cream, may show, when tested with the lactometer, a lower specific gravity than a specimen of much poorer milk. Hence, the lactometer, although a useful instrument in guard- ing against excessive dilution of the milk with water, is not a very reliable guide in determining the quality of the milk. Objections are often urged against the use of so- called 'skim-milk,' i. e., milk from which the cream has been removed. In some cities in this country, the FOOD. 65 police, or representatives of tlie sanitary anthorities, seize and confiscate all skim -milk found in possession of dealers. There appears to be no rational basis for the opinion held by many that skim-milk is not a proper and useful article of food. Before the lactic acid fer- mention has taken place, it differs from fresh milk merely in the fatty and other matters removed in the cream. It may be used as an article of food with great advantage and entire safety. In certain diseased states, it is of exceptional value, as an article of diet. The sole objection of any weight to skim-milk is that it may be at times sold fraudulently as fresh milk. This is, however, a question of little sanitary interest, but one principally of ethics. Milk is frequently adulterated by the addition of water, chalk and water, or other more deleterious sub- stances. An excess of water gives the milk a bluish tinge, and reduces its specific gravity. The addition of water may become especially dangerous by intro- ducing the virus of some of the acute infectious dis- eases. Thus, loca^lized epidemics of typhoid and scarlet fevers, have in a number of instances been traced to mixing the milk with water containing the poison of these diseases. It is a mooted question whether acute or chronic infectious diseases of the milk-giving animal may be communicated to persons using the milk of such ani- mals. Facts at present known seem to negative the proposition. At the same time it would seem to be prudent to avoid the use of milk 'from diseased ani- mals, if possible, or to destroy any organic virus the milk may contain by previously boiling the milk. After thorough boiling little fear need be entertained of com- municating either acute or chronic infectious diseases through this medium. 66 TEXT-BOOK OF HYGIENE. The milk of cows fed upon the refuse of breweries and distilleries, — 'swill milk,' is believed by many- physicians to be unwholesome. If so, it is probably only by reason of the unfavorable hygienic conditions under which the animals are kept. If the stables are clean, dry and well ventilated, and the animals re- ceive plenty of fresh air and exercise, swill-fed cows should produce as nutritious milk as when they are fed upon different food. Much of the present agitation against 'swill milk' is more prompted by political demagoguery than by scientific knowledge. In order to prevent the rapid fermentation of milk various methods of preservation have been adopted. The addition of alkalies, or antiseptics retards the lac- tic acid fermentation, while the abstraction of a por- tion of the water and addition of sugar (condensed milk) preserves it for an indefinite time. The mere ad- dition of water restores it to nearly its original condition. Butter. — Butter is of esi)ecial value as food on account of the large amount of easily digestible fat which it contains. It is almost always used as acces- sary to other articles of food, to render them more pal- atable. When pure and fresh, it is one of the most delicious of creature comforts. It soon undergoes the butyric acid fermentation, however, becoming ' ran- cid,' as it is termed, when it is unfit for food. The great demand for butter and its consequent high price, have led to its extensive sophistication. Butter is now very largely substituted by an artificial product termed ol^o-margarine or butterine. This ar- tificial butter is made from beef-suet by the following process : Fresh beef fat is melted at as low a tempera- ture as possible, never higher than 126°-128° F. All membrane and tissue are then removed, and the result- ing clear fat is put into presses, where the stearine is extracted. The liquid fat, free from tissue, and with FOOD. 67 nearly all its stearine removed, is known as 'oleo-mar- garine oil.' The next step in the process is 'churn- ing.' The oil is allowed to run into churns containing milk and a small quantity of coloring material (annatto), where, by means of rapidly revolving pad- dles, it is churned for about an hour. When this part of the process is complete, the substance is drawn off from the bottom of the churn, into cracked jce. When cool, it is taken from the ice, mixed with a proper quantity of salt, and is then worked like butter and put into firkins for the market. It is also moulded into attrac- tive prints, in imitation of dairy butter.* When the materials from which oleo-margarine is made are sweet and clean, and when the process of manufacture is prop- erly conducted, the resulting product is an entirely harmless article, and probably differs very little in nu- tritive value from butter itself. Clieese. — The value of cheese as a food depends upon the large amount of proteids and fat which it contains. The rich varieties of cheese, such as Fro- mage de Brie and Roquefort, contain on an average thirty per cent, of fat, and twenty-seven per cent, of proteid compounds. Parmesan contains only about eight per cent, of fat, and nearly thirty-three per cent, of proteids, while Edam and Chester cheese which may be considered as standing about midway between the above, contain twenty per cent, of fat, and nearly twenty-eight per cent, of proteids. From these fig- ures it appears that cheese is one of the most nutritious aliments obtainable, but it cannot be eaten in large quantities at a time, as it is exceedingly liable to cause disturbances of the digestive organs. The constipat- ing property of cheese is well-known to the i:)ublic. Cheese is not often adulterated. The only articles * Dk. W. K. Newton, Fifth Annual Keport of the State Board of Health of New Jersey, 1881, p. 107, 68 TEXT-BOOK OF IiyOIENE. used with success in its sophistication are lard and oleo-margarine, which are incorporated with the casein during the process of manufacture. It sometimes un- dergoes chemical changes which render it intensely poisonous when eaten. Meat. — The flesh of mammals, reptiles, birds, fish, and invertebrate animals is used as food by man. Falck*has classified the varieties of animals which fur- nish food to the inhabitants of Europe. There are forty- seven varieties of the mammalian class, one hundred and five of birds, seven of amphibia, one hundred and ten of fish, and fifty-eight of invertebrates. 