(M Presented Sy ^j\ %, DR. WILLIAM J. GIES,^' ^^ .^^iii Mil intljeCttpofl^fttifork College of ^fjpgiciang anb burgeons! Xibrarp ■Bulletin No. 21. 129 U. S. DEPARTMENT OF AGRICULTURE. OFFICE OF EXPERIMENT STATIONS. METHODS AND RESULTS INVESTIGATIONS ON THE CHEMISTRY AND ECONOMY OF FOOD. W. O. ATV7ATER, Ph. D., Professor of Chemistry in Wesleyan University, Director of the Storrs {Conn.) Agricultural Experiment Station, and Sjiecial Agent of the United States Department of Agriculture. PUBLISHED BT AUTHOEITY OF THE SKCllETART OF AGEICULTUEB. WASHINGTOI^: GOVEl^NMENT PRINTING OFFICE, X895, lA CONTENTS. Pago. CifAPTER I. Introduction 9 Public need of iuforraatiou about food ecouoniy 9 Purpose and plan of this bulletin 10 Collaborators 10 Chapter II. Food and its uses fob nutriment 11 Coruposition of food materials — Nutrients and their func- tions in nutrition 11 Classes of nutrients 11 Uses of food — Functions of nutrients 12 Buildino- and repair — Functions of protein compounds. 13 Fuel — Functions of fats and carbohydrates 13 The potential energy of food — Fuel value 14 Definition of food 16 Chapter III. Composition of food materiai^s 17 Historical development of food analysis 17 Analyses of American food products 19 Tables of composition of American food materials 21 Analyses of sides of beef and mutton 21 Composition of side of beef 23 Composition of side of mutton and side of lamb 24 Worli now needed in analysis of foods 38 Improvement of methods of analysis 38 Chapter IV. The digestibility op food 53 The quantities of digestible nutrients in food 54 Historical summary 56 Experimental methods 56 Method of quantitative test of proportions of nutrients digested from food by man 57 Results of experiments upon quantities of nutrients di- gested from different foods 60 Further considerations regarding digestibility 71 Eft'ects of preparation of food upon digestibility — Cool^ing. 73 Effects of food adjuncts on digestion — Flavoring materials. 76 Summary 78 Suggestions as to experimental work now needed 79 Chapter V. Preparation of food — Cooking 81 Preparation of food — Konig's summary of investigations.. 81 Effects of condiments upon digestion 81 Effects of cooking upon digestibility and nutritive value 83 Boiling, broiling, and roasting of meats and other ani- mal foods 83 Baking of bread 91 Effects of cooking as stated by Halliburton 91 Atkinson's definition of cooking 92 Investigations by Mrs. Richards and Mrs. Abel &2 Essentials for good cooking apparatus 93 Cookery of meat 94 Composition of beef juice, beef tea, etc 96 How long broth may be kept 96 Pea soup 97 Suggestions as to investigations needed 97 Effects of cooking on digestion 98 3 4 CHEMISTRY AND ECONOMY OF FOOD. Pago. Chapter VI. Uses of food in the body— Metabolism 99 Metabolism of matter and energy in tlie body 99 • Metabolism of material — Daily income and expenditure of thebody 101 The respiration apparatus 106 Chapter VII. Metabolism of enehgy— Income and outgo of body 113 Potential energy of food — Heats of combustion — Fuel values 115 Calorimeters and calorimetry — Historical development IIG Thompson's calorimeter — Investigations of Frankland. 116 Stohmann's calorimeter and investigations - 119 The bomb calorimeter of Berthelot 120 Modifications of the bomb calorimeter by Mahler, Hempel, and Atwater 123 Results of determinations of heats of combustion .: 126 Investigations of heats of combustion now needed 129 Isodynamic values of nutrients 130 Fuel values of protein, fats, and carbohydrates 133 Eespiration calorimeters 133 Rubner's experiments "with the respiration calorimeter .. . 134 Other respiration calorimeters 135 Chapter VIII. Pecuniary economy of food 136 Cheap V. dear food 137 Chapter IX. Food consumption 141 Studies of dietaries — Historical summary 141 Special investigation s of dietaries 143 Dietary studies in the United States 144 Investigation of dietaries in connection witii the Massa- chusetts Bureau of Statistics of Labor 144 The dietaries and tlie people nourished by them 145 Dietary of a boarding house in Connecticut 155 Dietaries of hand weavers in Zittau, Saxony 163 Dietaries of people of the poorer classes in Naples 173 Tabular statements of results of dietary studies 177 Comments upon dietaxies summarized in Table 37 184 Suggestions regarding studies of dietaries 198 Classes of people and localities for dietary studies 205 Chapter X. Standards for dietaries 206 Methods of estimating dietary standards 206 European and American dietaries and standards 207 Suggestions for dietary standards 212 Chapter XI. Errors in our food economy 214 Cheap V. dear food 215 Food of the poor 215 One-sidedness of our dietaries 216 Overeating — Injury to health 217 Waste of food in American households 219 LIST OF ILLUSTRATIONS. Page. Fig. 1. Diagram of cuts of beef 23 Fig. 2. Cells of a raw potato, with starch grains in uatural condition 88 Fig. 3. Cells of a potato boiled in water one-half hour 89 Fig. 4. Cells of a potato well steamed and mashed 89 Fig. 5. Pettenlcofer's respiration apparatus 106 Fig. 6. Pettenkofer's respiration apparatus. Pumping machinery 107 Fig. 7. Pettenkofer's respiration apparatus. Ex^ilanatory sketch 108 Fig. 8. Voit's respii'ation apparatus 108 Fig. 9. Thompson's calorimeter 116 Fig. 10. Stohmann's caloiimeter 119 Fig. 11. Ber fchelot's bomb calorimeter 121 Fig. 12. Mahler's bomb calorimeter as mounted for use 122 Fig. 13. Bomb calorimeter as modified by Hempol and Atwater 124 Fig. 14. Bomb calorimeter of fig. 13, as mounted and standing in water 125 Fig. 15. Top of bomb calorimeter of fig. 13 126 Chart 1. Composition of food materials 22 Chart 2. Pecuniary economy of food 138 Chart 3. Dietaries and dietary standards 208 5 LETTER OF TRANSMITTAL United States Department op AaRicuLTUEE, Office of Experiment Stations, Washington, B. C, October 20, 1894. Sir: I have the honor to trausmit herewith for publication Bulletin No. 21 of this Office, on "Methods and Kesults of Investigations on the Chemistry and Economy of Food," by W. O, Atwater, Ph. D. The circumstances Avhich have led to the publication of the present bl^lle- tin need, perhaps, some words of explanation. Investigations of the hygienic and pecuniary economy of food are of comparatively recent date. It is scarcely fifty years since the classical researches of Liebig began to pave the way for finding practically all we know to-day of the ingredients of our food materials, the ways in which they are used in the body, and the kinds and combinations which are best adapted to health and purse. ISTearly all of the best experimental inquiry in these lines has been carried on in Europe. There have, indeed, been iDioneers in the United States, but their work belongs mostly to the last two, and all of it to the last three, decades. The first analyses by modern methods of materials used for the food of man or domestic animals in this country were made in 1869 by the author of this bulletin, then a student in the Sheffield Scientific School of Yale University. With the rise of the experiment stations, inquiries into the composition of feeding stuff's and their appropriate use in the nutrition of domestic animals have been undertaken and during the past few years have been carried on quite actively. The first at all extensive series of investigations of materials used as the food of man undertaken in the United States were studies of the chemistry of fish, prosecuted under the auspices of the United States Fish Commission in the chemical laboratory of Wesleyan University by Professor Atwater in the years 1878-1881. In connection with this work, analyses of meats and other food materials were made under the auspices of the Smithsonian Insti- tution. The first accurate investigation of the chemical and economical sta- tistics of food consumption in the United States were undertaken in the year 1886 by Col. Carroll D. Wright, then chief of the Massachu- setts Bureau of Statistics of Labor and now United States Commis- sioner of Labor, in coox)eration witii Professor Atwater at Middletown, Conn. Thus far but extremely little has been done in the United States by way of exact experimental inquiry regarding the laws of human nutrition. But the growth of the j)i"eliminary forms of investi- gation points to a speedy development of research of a high character 7 8 CHEMISTET AND ECONOMY OF FOOD. in tills direction also. It is a very gratifying fact tliat already a consid- erable amount of investigation regarding the composition of our food materials and the economy of their use has accumulated, and, what is more to the point, earnest and capable investigators are addressing themselves to the still more extended and thorough study of the subject. A large part of the work thus far done in the United States has been at private expense. But, as often happens, the inquiries thus benevo- lently begun have proven so useful that public funds are becoming available for their prosecution. On the recommendation of the Secre- tary of Agriculture the sum of $10,000 was included in the appropria- tions for the Department of Agriculture for the present fiscal year, the purpose of which is to enable him to investigate and report upon the food economy of the people of the United States. The supervision of the investigations thus provided for has been assigned to the Office of Experiment Stations, and Professor Atwater has been appointed special agent in charge. The agricultural experiment stations established by authority of Congress are authorized to make inquiries in this same direction, and are called upon to report their results to the Secretary of Agriculture. In order to facilitate such investigations, not only by investigators in experiment stations, but by those associated with the colleges and other institutions for research and instruction, it has seemed desirable to i)repare a statement of the results of inquiries already reached, questions which now demand attention, and the best methods for their study. It was, however, found impracticable to make a complete pres- entation of the subject without greatly delaying the publication of such information as seemed almost essential to the further prosecution of researches in this line in this country. An effort has therefore been made to outline in a general way the field to be traversed, to show with detail sufficient for jiresent purposes what portions need first to be cultivated and to indicate how the work should be carried on. It is hoped that the remaining material may in due time be collated and published. Eespectfully, A. 0. True, Director. Hon. Ohas. W. Dabney, Jr., Acting Secretary of Agriculture, THE CHEMISTRY AND ECONOMY OF FOOD. CHAPTER I. INTRODUCTION. PUBLIC NEED OF INFORMATION ABOUT FOOD ECONOMY. Food constitutes the chief item of the living exiDenses of the people, of our agricnltnral production, and of our exports. Half the earnings of wage workers in this country and in Europe is spent for food. The health and strength of all are intimately dependent upon their diet. Yet most people understand very little about what their food contains, how it nourishes them, whether they are economical or wasteful in buy- ing and preparing it for use, and whether or not the food they eat is rightly fitted to the demands of their bodies. The result of this igno- rance is great waste in the purchase and use of food, loss of money, and injury to health. Underneath all this is still another evil. Our food products as a whole are not such as are best fitted for healthful and economic nutri- tion or for the most profitable export. Our agricultural i)roduction is out of balance. Here, again, the facts are not clearly understood, as they must be to make the needed reform possible. The reason for this ignorance is simple enough. Fifty years ago no man knew what our bodies and our foods were composed of; how the different nutritive ingredients of the food served their purj)oses in nutri- tion ; how much of each of the ingredients was needed to supply the demands of i^eople of different age, sex, and occupation; and how best to adjust the diet to the wants of the user. We do not to-day know as much about these things as we ought. For that matter, we never shall be able to lay down hard and fast rules to applj^ to all cases, because of the differences between individuals in respect to their demands for nutriment and the ways in which their bodies can make use of different kinds of foods. But the research of the past twenty-five years has brought a great deal of definite information. Nearly all of the exact inquiry in this direction has been done in Europe, and the greater part of it in Germany. We are beginning it in the United States. To remove this ignorance two things are needed. The first is a more definite knowledge of the actual facts. The second is that the infor- mation be brought to the people. The knowledge can be gained by research. To secure its diffusion the results of inquiry must be pub- lished in detail. They can then be popularized and made useful to the people at large. 9 10 CHEMISTRY AND ECONOMY OP FOOD. PURPOSE AND PLAN OP THIS BULLETIN. This bulletin has a twofold purpose : to summarize some of the results of late inquiry as to the physiological and pecuniary economy of food, and to indicate questions now demanding study aud desirable methods of investigation. Among the results of inquiry dwelt upon are the chemical comi)osi- tion of materials used for the food of man; the proportions of nutritive ingredients; their digestibility; their fuel values; the ratios between their values for nutriment and their cost; the kinds of food and ijro- portions of nutrients best adapted to the demands of people of different classes and occupations; the errors in our food economy; and the sociological and agiicultural bearings of the subject. Tlie questions proposed for study are sucb as the above-named topics suggest. They center around the general j^roblem of food economy. Some are abstrusely scientific and reach into the higher realms of chemistry and physiology, but these are as necessary for the practical inquiry as the foundation is for the house. All bear directly or indi- rectly upon health, home life, and household, agricultural, and national economy. The methods of inquiry recommended are mainly such as have been elaborated more or less completely by experience and described succinctly by specialists. Some, however, are new and still in the process of development. COLLABOKATORS. In the preparation of this bulletin the author has enjoyed the valu- able assistance of Messrs. C. D. Woods, H. B. Gibson, aud C. F. Lang- worthy. Mr. Woods has performed a large part of the labor of com- piling the analyses of foods, and the results of his experience in the study of methods and the actual work of analysis in the laboratory during the last fifteen years or more are embodied in the description of methods of analysis recommended. He has also assisted in the studies of dietaries and compilation of results. Dr. Gibson, who has likewise shared in the studies of foods and dietaries for several years, has done a large part of the work of compiling the results of such studies. Dr. Langworthy has shared in the collating of studies of dietaries and has been especially helpful in the collating of the results of investiga- tions of the digestibility of foods. CHAPTER 11. FOOD AND ITS USES FOR NUTRIMENT. A jiouiid of lean beef and a quart of whole milk contain about the same amounts of actually nutritive material. But the pound of beef costs more than the quart of milk, and its nutrients difter not only in number and kind, but are, for ordinary use, more valuable than those of the milk. This illustrates a fundamental fact in the economy of foods, namely, that the differences in the values of different foods depend upon both the kinds and the amounts of the nutritive materials which they contain. Add to this that it is essential for health that the food shall supply the nutrients in the kinds and the i)roportions required by the body, and that it is likewise important, from a pecuniary stand- point, that the materials be obtained at the minimum cost, and we have the fundamental principles of food economy. COMPOSITION OP POOD MATERIALS — NUTRIENTS AND THEIR FUNC- TIONS IN NUTRITION. Ordinary food materials — such as meat, fish, eggs, potatoes, wheat, etc. — may be regarded as consisting of refuse and edible portion. Refuse. — This includes the bones of meat and fish, shells of shellfish, skin of potatoes, bran of wheat, etc. Edible portion. — This includes the flesh of meat and fish, the white and yolk of eggs, wheat flour, etc. The edible portion consists of water and nutritive ingredients, or nutrients. Current usage recognizes the following as the principal kinds of nutri- ents: Protein, fats, carbohydrates, and mineral matters. The water, refuse, and salt of salted meat and fish are here desig- nated as '^ non-nutrients." The water is, of course, indispensable for nourishment, but is not a nutrient in the sense in which the word is here used. In comparing the values of different food materials for nourishment the refuse and water are left out of account. CLASSES OP NUTRIENTS. The following familiar examples of compounds commonly grouped with each of the four principal classes of nutrients will serve to define the terms as here used, and may j^erhaps help to avoid the confusion 11 12 CHEMISTRY AND ECONOMY OF FOOD. which unfortuuately results from the variations in usage by different writers ; 'Albuminoids: e. g., albumen of eggs; myosin, the basis of muscle (lean meat); the albuminoids Proteids ^ which make vip the gluten of wheat, etc. Gelatinoids: Constituents of connective tissue which yield gelatin and allied substances, e. g., collagen of tendon ; ossein of bone. "Nitrogenous extractives" of flesh, i. e., of meats and fish. Protein I These include kreatin and allied compounds, and are the chief ingredients of beef tea and most meat extracts. Amids: This term is frequently applied to the nitrogenous non-albuminoid compounds of vegetable foods and feeding stiift's, among which are amido acids, such, as aspartic acid and asparagin. Some of them are more or less allied in chemical constitution to the nitrogenous extractives of flesh. rFat of meat; fat of milk; oil of corn, wheat, etc. The ingre- I dieuts of the "ether extract" of animal and vegetable foods Fats «^^^ ^^""^^ ^^^ muscular Carbohydrates are transformed into fat ^ ^ ' and serve as fuel. ^ In being themselves burned to yield energy, the nutrients protect each other from being consumed. The protein and fats of body tissue are used like those of food. An important use of the carbohydrates and fats is to protect protein (muscle, etc.) from consumption. DEFINITION OF FOOD. In this view food may be defined as material which, when taken into the body, serves to either form tissue or yield energy, or both. This definition includes all the ordinary food materials, since they both build tissue and yield energy. It includes sugar and starch, because they yield energy and form fatty tissue. It includes alcohol, because the latter is burned to yield energy, though it does not build tissue. It excludes creatin, creatinin, and other so-called nitrogenous extractives of meat, and likewise thein or caffein of tea and coffee, because they neither build tissue nor yield energy, although they may, at times, be useful aids to nutrition. CHAPTER HI COMPOSITION OF FOOD MATERIALS. Nearly all of our definite knowledge of tlie cliemical composition of food materials and their nutritive values lias accumulated witliin com- paratively few years. Yet so active Las been tlie inquiry, especially in the last one or two decades, that the data are to-day quite extensive. HISTORICAL DEVELOrMENT OF FOOD ANALYSIS. The first effective impulse to the systematic investigation of the chem- istry of food was given by Liebig. It was be wlio distinguished clearly between the different constituents and indicated their several uses in nutrition. He attributed relatively more importance to the nitroge- nous ingredients than later research has justified. He taught that they are the chief sources of muscular force, a doctrine which few would accept to-day. But in the main his classification of the nutrients and tbeir functions has stood the severe test of forty years of experiment and criticism. In the hands of his followers the methods of analysis have been developed and more accurate distinctions have been made between different classes of ingredients. The individual compounds and the changes they undergo in the plant and in the animal have been studied and, with the rapid spread of research in organic, physiological, and agricultural chemistry, in physiology, and in bacteriology, new fields of inquiry have been opened up and research is being pushed forward with great activity. An adequate historical view of the subject would haixUy be in place here. The progress may be clearly seen by referring to the works on food and nutrition which have been the standards at various epochs, beginning with the early editions of Liebig's works on physiological and agricultural chemistry which appeared in 1842 and succeeding years, and including Dietrich and Konig's magnificent compilations of the results of investigations upon composition and digestibility of feed- ing stuff's for domestic animals^ and Konig's equally valuable comiDila- tiou regarding the foods and food adjuncts used by man.^ The comj)ilations just referred to illustrate most strikingly the accu- mulation of data in Europe during comparatively few years. The first edition of Dietrich and Konig's compilation of analyses of feeding stuffs •Dietrich and Kiinig. Znsammensetzuny und Verdaiiliclikeit der Fiittermittel. Zweite Auflage; Bde. I and II; Berlin, 1891. 2 J. Konig. Cheniie der raenscliliclien Naliruugs- uud Genussmittel. Dritte Autlage ; Pde. I and II; Berlin, 1889-1893. 8518— No. 21 2 17 18 CHEMISTRY AND ECONOMY OF FOOD. was publislietl in 1874. It is a thin volume of between 90 and 100 pages, consisting mostly of tabular statements of results of analyses with references to the original publications, and very brief comments. The second edition, seventeen years after, likewise in qnarto form, is in two volumes. These contain 1,433 pages, l^early the whole is devoted to statements, mostly in figures, of results of analyses and of experi- ments upon digestibility of feeding stuffs. Konig's compilation regarding the chemistry of materials used as the food of man has lately reached its third edition. The first volume contains 1,189 pages. Introductory statements fill 184;pages of this volume; the rest is devoted to tabular statements of results of analyses and brief comments. The second volume includes 1,401 pages, and is devoted mainly to detailed descriptions of the different kinds of food materials. While it is hardly possible to exaggerate the value of these monu- ments of German painstaking scholarship, they are very far from meet- ing the needs of English-speaking people, especially in the United States, not only because they are in the German language and written for German readers, but also because much that people in this country who are interested in such matters want to know is not contained in them. Our food materials, our habits of food consumption, and our food production all differ to a greater or less extent from those in Germany, and we need information fitted to our special circumstances. It would be hardly jn^oper to omit from even so brief an account of the development of food analysis as this a reference to what has been done since the introduction of the so-called Weende method, of which the late Professor Henneberg was the author. This dates practically from the year 1864, at which time a plan for methods for analysis of feeding stuffs was presented at tlie second Convention of German Agricultural Chemists.^ As long ago as 1830 Boussingault repoi ted analyses^ of a number of feeding stuffs, laying especial stress upon the quantities of nitrogen. In 1831 Boussingault and Le Bel reported analyses of milk.^ The methods, however, were quite imperfect. For a number of years the chief stress was laid upon the quantities of carbon and nitrogen. Even in the works of Payen, as late as 1865, the simpler methods which took into account little else than the water, nitrogen, and carbon were fol- lowed, although more or less effort was made to determine the quauti- iLandw. Vers. Stat., 6, 496. zReclierclies sur la Qiiantite d' Azote conteniie dans les Foiirrages, et sur leurs fiquivaleus; par M. Boussingault. Ann. Cliim. et Phys., yoI. 63, p. 225, 1836. Reclierclies sur la Quantite d' Azote contenno dans les Fourrages, ct sur leurs Equiva- lens; par M. Boussingault. Ann. Chim. et Pliys., vol. 67, p. 408, 1838. Ibid., 68, p. 408. sRecLerches sur I'lnfluence de la,- Nourriture des VacLes, sur la Quantite et la Constitution cliimique du Lait; par MM. Boussingault et Le Bel. Ann. Cliim. et Phys., vol, 71, p. 65, 1839. COMPOSITION OF FOOD MATERIALS. 19 ties of fats and to distinguish between tlie different nitrogenous compounds, as well as the carbohydrates.^ A distinct advance is found in some of the publications between 1840 and 18(54:, but it was not until the Weende method came into use and compilations of results of analyses made in accordance with it had become current that chemists generally adopted the forms which are now in general use. ANALYSES OF AMERICAN FOOD PRODUCTS. The lirst analyses made by these modern methods in the United States "were a series of analyses of Indian corn by the writer under the direction of Prof. S. W. Johnson in ISTew Haven in 18G9.^ With the exception of the excellent work by Professor Storer at the Bussey Institution, comparatively little was done in this direction until the establishment of the experiment statioiis. The station at Middle- town, Conn,, made a nnmber of analyses in the years 1877-1879. Others followed in rapid succession, though nearly all of the attention was given to feeding stuffs. The compilation of analyses of American feed- ing stuffs by Jenkins and Winton,^ w^hich "was designed to include all analyses published before September 1, 1890," and does include very- nearly all, contains results of examinations of 3,207 specimens. The condensed tabular compilation of these fills 138 pages. The compilation just referred to contains very few analyses of mate- rials used as the food of man, and it is not until within a short time past that much attention has been given to this particular branch of investigation. A large number of analyses, indeed, have been made of milk, butter, aiul cheese, but the purpose of these has been mainly agricultural. A considerable number of analyses of fruits and vege- tables have also been made by tlie Bussey Institution, the Division of Chemistry of the Ujiited States Department of Agriculture, and the Maine, Massachusetts, Connecticut, JS'ew York, Tennessee, California, and other experiment stations. The first at all extended series' of examinations of materials used as food from the standpoint of their nutritive valne for man in the United States was a study of American fishes and the invertebrates. This was undertaken at the instance and partly at the ex]3euse of the Smithsonian Institution and the United States Fish Commission through the infiuence of the late Prof S. F. Baird. The work was performed in the chemical laboratory of Wesleyan University under the dire(ition of the writer. In connection with this, at the instance of the United States ISTational Museum, a series of analyses of American meats was undertaken. These investigations were carried out during the years 1878-1891, and included analyses of 1 See, for instance, Substances Alimentaires. Payeu, 1865. 2 Am. Jour. Sci., vol. 48, 1869, p. 352. =5 A Compilation ol' Analyses of American Feeding Stuffs, by E. H. Jenkins, Ph, D., and E. L. Winton, Pb. B. U. S. Dept. Agr., Office of Experiment Stations; Bui. No, 11. Washington, 1892, 20 CHEMISTRY AND ECONOMY OF FOOD. the iiesli of some 200 specimens of sea aud fresh-water fishes, oysters, clams, etc., aud of nearly 100 specimens of meats. A few analyses of milk, butter, cheese, flour, bread, etc., were also included. The results of the analyses of fishes and the invertebrates have been published by the United States Commission of Fish aud Fisheries,^ those of meats and vegetable foods were published by the Storrs (Conn.) Experiment Station.^ The number of analyses of dairy products in the United States has grown to be very large — so large indeed that complete compilation would be extremely difficult and perhaps of doubtful value. A considerable number of specimens of materials used for the food of man, especially of canned vegetables, have been made in the Division of Chemistry of the Department of Agriculture under the direction of Prof. H. W. Wiley. ^ Quite a number of analyses have also been made in connection with the studies of adulteration of foods in the same laboratory. Some years previous a considerable number of analyses of specimens of American flour and the bread made from them were made in the same laboratory by Mr. Clifford Eichardson.* A series of analyses of milling products of wheat was made by Pro- fessor Kedzie in Michigan some years ago.^ In his report on cereals, which was published in the volume on agri- culture of the Keport of the United States Census for 1880, Prof. W. H. Brewer has given analyses of a number of cereal products. During the years 1890-1894, in connection with studies of dietaries by the Storrs (Conn.) Experiment Station, a number of analyses of food materials iave been made. These, however, have been published only in part. The collection of food materials at the World's Fair at Chicago, in 1893, offered an unusually favorable opportunity for obtaining speci- mens for chemical examination. ■ This fact was appreciated by the World's Columbian Commission, and Prof. H. W.Wiley, of the United States Department of Agriculture, was called upon by the Bureau of Awards of that Commission to execute analyses of a large number of specimens of grains and milling products from them. These investiga- tions are being continued in the chemical laboratory of that Depart- ment, and are not fully completed at the time of this writing. At the same time the writer was invited by the Bureau of Awards to make examinations of such other food materials as seemed advisable. The remarkably favorable occasion for securing specimens of meats and meat products as prepared at the great slaughtering establishments in Chicago was also ntilized. Some 500 such specimens of food materials iThe Chemical Composition and Nutritive Values of Food-Fishes and Aquatic Invertebrates, by W. 0. Atwater, Ph. D. Eeport U. S. Commissioner of Fish and Fisheries, 1888. Washington, 1891. 2 W. O. Atwater and C. D. Woods. Eeports Storrs (Conn.) Experiment Station, 1891, 1892, and 1893, passim. 3Bull. 13, Div. Chem., U. S. Dept. Agr., pp. 1015-1167. ^Bull. 4, Div. Chem., U. S. Dept. Agr. 'Kept. Mich. Bd. Agr., 1877, p. 350. COMPOSITION OF FOOD MATERIALS. 21 froiii the exhibits by the various nations at the fair in Chicago and from the sUiughtering- establishments in the city were collected and ana- lyzed. Part of the work was done in Chicago during the fair, and the rest was completed later in the chemical laboratory of Wesleyan Uni- versity, in connection Avith the work of the Storrs Station, which is con- ducted there. The results of these analyses still await publication. TABLES OF COMPOSITION OF AMERICAN FOOD MATERIALS. The compilation of the results of analyses of American food materials np to the present time is greatly to be desired. An effort in this direc- tion is already begun, but the results are not yet ready for publication. Tables 1 and 2, which follow, give a summary of the results thus far published. It is essentially the same as that published in the report of the Storrs (Conn.) Experiuient Station for 1891. ^ To the figures there given have been added the results of examinations of specimens of canned vegetables by Professor Wiley and his assistants which were previously mentioned. It will be observed that the table gives in the first column the num- ber of analyses of specimens of each kind of material. In a large nnm- ber of cases only a single analysis had been made at the time, or at any rate had been found by us at the time when the table was prepared. In other cases, several analyses are available. Where more than one analysis has been made, the maximum, minimum, and averages are given. It should be explained, however, that the figures for maximum and minimum indicate the largest or smallest jiercentage of each ingredient found in any case, so that the figures for maximum or minimum of a given material do not all refer to the same specimen. The figures for fuel value give the estimated calories in the protein, fats, and carbohydrates in 1 j)ound of the material. These figures are not the result of direct determinations, but are found by multi- plying the number of grams of j)rotein, fats, and carbohydrates by the factors 4.1, 9.3, and 4.1, respectively, and adding the products as explained above. (See p. 15.) Table 1 gives the composition of the food materials as they are ordinarily purchased in the markets, includ- ing both the refuse and the edible portion, while Table 2 gives the com- position of the edible portion after the removal of the refuse. In some animal foods, as milk, cheese, and oysters (shell contents^, and most of the vegetable foods (such as tiour and bread) there is no refuse, and con- sequently the analyses of such materials appear, for the most part, in Table 2 alone. The relative composition of a small number of common foods is graphically shown in Chart 1. ANALYSES OF SIDES OF BEEF AND MUTTON. People in general have very little idea how wide may be the differ- ences in composition of different specimens of meat of the same kind, as, for instance, beef from different animals and different cuts of beef 'Tlie Composition of Food Materials. JBy W. O. Atwater aud Clias. D. Woods. 22 CHEMISTRY AND ECONOMY OF FOOD. Chart 1.— COMPOSITION OF FOOD MATERIALS. Nutritive i7igredients, refuse, and fuel value. Nutrients. Non -nutrients. Protein. rieshforminj substances. Fats. Carbo- Mineral hydrates, matters. "Water. Kefuse. Fuel ingredients , Nutrients, etc., per ct. I Fuel value, calories 400 40 OO COMPOSITION OF FOOD MATEKIALS. 9 P. from tlie same animal. These difiereuces are illustrated in the analyses in Tables 1 and L* belo^y, and still more forcibly in Tables 3 to 10' and in fig. 1. . COMPOSITION OF SIDE OF BEEF. Tables 3 to G give results of analyses of a side of beef which was butchered in Chicago and sold in Middletowu, Conn. The side was called by the dealer in Middletowu an average one as regards weight and fatness, etc. Its total weight at the car in the station at Middle- town, where it was received, was 326 pounds, the fore quarter weight 176 pounds, and the hind quarter 150 pounds. It will be noticed in Table 6 that the sums of the weights of the individual cuts make the side weigh 317.6 pounds, and that the falling off in weight was almost wholly in the hind quarter, which weighed 150 pounds at the car and Fio. 1. — Diagram of cuts of beef. by individual cuts only 142 pounds. The side, "when received, was partly frozen, and the fore quarter was anal^^zed first. These two facts may account for the shrinkage in the weight of the hind quarter, which was kept for a longer time before the analyses were made. The cuts were made in accordance with the usage in New York markets, and are shown in the diagram herewith. The fore quarter was thus divided into 15 and the hind quarter into 9 cuts. Each cut was weighed and a portion taken for analysis. The edible portion (flesh) and the refuse (bone, gristle, etc.) were separated and each weighed b}^ itself. Table 3 shows the composition of the water-free substance of the edible portion; Table 4 the composition of the flesh (edible portion), and Table 5 the composition of the several cuts and of the whole side, including both refuse and edible portion. 'Taken from Report Storrs (Couu.) Experiment Stntiou above referred to, pp. 59-65. 24 CHEMISTRY AND ECONOMY OF FOOD. In Table 6 the results of tlie analyses of tlie wliole side and the several cuts, which in Table 5 are represented in percentages, are calculated into pounds, so as to give the actual weights of the several ingredients in the different cuts and in the whole. COMPOSITION OF SIDE OF MUTTON AND SIDE OF LAMB. The side of mutton was from a Connecticut-grown sheep, 2 years old, of about medium fatness. One whole side was taken for analysis, the different cuts being made in the usual manner as specified in the tables. The side of lamb was from a Gonnecticut-grown lamb 6 months old. The dressed weight was about 39 i^ouuds. It was above rather than below medium fatness. The plan of the tables is the same as those for the side of beef. Table 1. — Composition of food materials as found in the markets, including hothedihle portion and refuse. Num- Kefuse (bones, skin, shell, etc.). Edible portion. Nutrients. ber of analy- ses". Salt. Water. Fuel value of 1 pound. Food materials Total. Pro- tein. Pat. Car- bohy- drates. Min- eral mat- ters . JIEATS, ETC. Calo- Beef: P.ct. P.ct. P.ct. P.ct. P.ct. P.ct. P. ct. P.ct. ries. f Min .. 3 18.4 47 28. 9 14.9 11.8 0.8 800 Neck shead, entrails re- moved Eed bass, whole Kinglisli, wliole Weakflsh, whole ( Min . . Blackflsh, whole . . ^ Max. . Avg. Min Blackflsh, entrai removed Is (Mm.. --tAvg.. Hake, entrails removed Cusk, entrails removed... Haddock, entrails ) t,^"^ ' removed {Max. . Min Cod, whole . ( Mm . . < Max. ( Avg. f Min .. Cod, dressed < Max Uvg Tomcod, whole Pollock, dressed f Min Halibut, sections. . < Max (Avg Turbot, whole _ Min Flounder, whole . ( Mm .. >,l i l\Iin .. Salted cod < Max. . (Avg.. Smoked herring Smoked haddock ( Min .. Smoked halibut. . . < Max. . (Avg.. Num- ber of analy- ses'. Salt. P. et 1 7.1 2 17.2 2 17.3 2 17.2 ] 6.5 1 1.4 2 12 2 12.1 2 12.1 Kefuse (bones, skin, shell, etc.). P. ct. 48.0 42.8 53.6 5(i 54.8 02.7 oo. 1 57.2 63.2 48.6 57.1 54.9 51.2 01.8 63.2 62.5 56.. 1 55.8 55.9 55.9 40 45.3 52.5 48.9 57.3 65.1 60 66 56.5 63.5 56.6 51.9 56.2 64.1 60.1 53.6 57.8 55.7 52.5 40.3 48 52.9 51 48.5 56.5 52.1 25.5 33.7 29.9 59.9 28.5 11.2 23.1 17.7 47.7 56.2 57 56.6 57 45.8 51 33.3 24.3 25.5 24.9 44.4 32.2 5.9 8 6.9 Edible portion. Water r. ct. 40.3 40.1 34.6 34.7 34.6 30 50. 7 34.1 29.7 32.5 39.7 35.1 37.4 27.8 28.9 28.4 34.8 34.8 35.3 35 46.9 36.8 43.7 40. 3 27.8 31.1 29.9 26.9 31.3 29.8 34.4 38 29.2 33.7 31.5 33.5 36.4 35 39.5 49 38.5 42.9 40 35.1 42.3 38.7 .55.3 62.1 58.5 32.7 .54.3 60.9 62.6 61.9 37.3 35.8 37 36.4 35.8 38.5 40.2 28.1 40 40.5 40.3 19.2 49.2 44.9 47 46 Nutrients. Total. P.ct. 11.1 17.1 9.4 11.7 10.6 7.3 14.2 8.7 7.1 8.7 11.7 10 11.4 9 9.3 9.1 9.1 8.9 9.3 S.l 13.1 10.7 11 10.8 7.1 12 10.1 7.1 12.2 0.7 9 10. 1 6.7 10.1 8.4 8.7 10 9.3 8 10.7 8.6 9.6 9 8.4 9.2 8.8 11 12.4 11.6 7.4 17.2 16 26.5 20.4 15 6.8 7.2 7 7.2 15.7 8.8 31.5 17.2 18 17.6 29.9 17.2 33 37.1 35 Pro- tein. P. ct. 9.8 10.2 8.5 10 9.3 6.7 12.6 7.9 6.4 7.2 9.7 8.3 8.7 6.5 7.8 7.2 8.3 8.2 8.5 8.4 12 9.2 10 9.6 6.1 8.2 7.4 6.4 6.1 8.1 8.4 6.3 8.3 7.3 7.9 8.7 8.3 7.2 10.1 7.8 8.9 8.2 7.7 8.3 8 9.9 11.4 10.6 6.8 1.5.5 13.4 16.1 15.1 6.8 6.1 6.3 6.2 6.3 S.l 7.5 14.7 15.7 16.4 16 20.2 16.1 16.7 21.6 19.1 Fat. P.ct. .6 6.3 .4 1.1 .8 .2 .7 .2 .3 .7 1.6 1.1 2.2 1 2.1 1.5 .2 .2 .3 .2 .4 .3 .9 3.4 2.1 .2 2.9 .2 .4 1.1 .2 1.2 .7 .4 .3 .1 .1 .2 . 2 !i .3 .2 .2 .3 .2 .2 .6 1.7 9.4 4.4 7.5 _ 2 .3 .3 .3 7.2 .7 15.1 .3 .4 .4 8.8 .1 13.6 14.4 14 Car- bohy- drates. Min- eral mat- ters. .P. ct. .4 1.1 .7 1 .9 .7 1.7 1.2 1.2 1.2 .9 1 1.9 1.9 1.9 Fuel value ofl pound. COMPOSITION OF FOOD MATERIALS. Table 1. — Composition of food materials as found in the markets, etc. — Coiitiimocl. Kum- bci- of analy- ses. Salt. Refuse (bones, .skin, shell, etc.). Edible portion. Water. Nutrients, Fuel value of 1 pound. Pood materials. Total. Pro- toin. Fat. ,, Mm- "''**®^' ters. FISH, SHELLFISH, ETC.— cont'd. Slielltisb, etc. : (Min .. Oysters in shell . . . •? Max . . (Avg.. ( Mill .. Loug clams in shell < Max . . (Avg.. EouDfl clams in shell 34 84 34 4 4 4 1 1 4 4 4 1 1 1 P.ct. P.ct. 76.1 88.8 82. 4 42.1 40.1 43.6 68.3 49.3 47.5 09.4 62.1 55.8 79 76 P.ct. 9.2 22. 8 15.3 46.4 49.9 48.4 27.3 42.7 25.1 44.3 31.1 34.1 15.7 19.2 P.ct. 1 4.6 2.3 7.5 8.5 8 4.4 8 5.5 8.2 6.8 10.1 5.3 4.8 P.ct. .5 2.1 1.1 4.4 5.1 4.8 2.1 4.4 4.1 6.5 5.4 7.9 4.4 4.4 P. ct. .1 .4 .2 .5 .7 .G .1 .6 .5 .9 .7 .9 .7 .1 P.ct. 2 I'.Z .6 .9 1.4 1.1 1.3 2.1 P.ct. .1 '.i 1.2 1.6 1.5 .9 .n .0 .8 .7 1.3 .2 .3 Calo- ries. 40 120 145 135 65 145 ( Min .. Lobster iu shell. .. < ^fax.. (Avg.. 125 160 130 185 110 Green turtle in shell 85 Table 2. — Composition of food materials, edible portion. Food materials. Beef: Neck. Chuck rib.s Ribs. Brisket... Cross ribs • C Min . Shoulder < Max, (Avg. Shin Plate Navel _ Min Sirloin. f Min . < Max. (Avg. Socket f Mm.. Rump } Max . . ^Avg.. _Miu Round ( Min . \ Max. (Avg. Li^g To]) of sirloin Flank Fore quarter Hind quarter Side without kidney fat Liver Kidney Hearth Tongue Kidney fat Marrow (leg bone) Veal : ( Min . . Shoulder < Max.. (Avg.. Nnm- ber of analy- ses. Salt. ■Water. '. ct. 00.6 64.5 02 51.3 00.2 5S 40.2 49.9 48.1 47.4 43.9 56.2 09.2 63.9 73.8 44.4 47.6 58.9 61). 7 60 57.1 40.2 56.3 48.2 66 69.5 68.2 72.1 42.2 27.4 51.1 55.7 54.8 09.5 75.7 56.5 63.5 4.3 3.3 Co. 6 08.8 Nutrients. Total. P. ct. 35. 5 39.4 38 33. 8 48.7 42 50.1 53.8 51.9 52.6 .56.1 30.8 43.8 36.1 26.2 55.6 52.4 39.3 41.1 40 42.9 43.7 59.8 51.8 30.5 34 31.8 27.9 57.8 72.6 45.9 44.3 45.2 30.5 24.3 43.5 36.5 95.7 96.7 28 34.4 31.2 Pro- Fat. P. ct. P. ct. ' 18.3 14.5 20.2 20.1 19.5 17.5 16 14.7 20.4 32 17.6 23.5 14.6 32.9 16.1 37.1 15.4 35.6 14.6 37.2 13.7 41.6 17.1 10 21 2L6 19.5 15.6 22.7 2.3 15.4 39.4 15.1 36.5 16.9 10.1 22 22.9 18.5 20.5 16.7 25.2 14.7 26.8 16.1 44.3 15.4 35.6 19.5 8.3 21.5 13.4 20.5 10.1 21 5.7 13.8 43.7 12 59.9 17.3 27.7 17.1 26.3 17.2 27.1 20.1 5.4 17 4.8 16.3 26.2 17.4 18 .9 94.6 2.6 92.8 19.7 6.1 20.7 13.5 20.2 9.8 Carbo hy- drates. P. ct. 3.5 L3 Min- eral mat- ters. r. ct. 1 1.1 1 l!2 .U .y LI .9 .8 .8 .U -1.2 1 1.2 .j! .8 . 9 l!4 1 1 LI 1.3 1.2 1.2 .8 .7 .9 .9 .9 1.5 1.2 1 LI .2 L3 L2 1.2 L2 Fuel value of I pound. Calories 985 1, 190 1, TOO 960 1, 650 1, 320 1,690 1,860 1,790 1,840 2, 010 790 1, 300 1,020 S20 1, 950 L820 1,090 1, 290 1,210 1,375 1, 430 2,145 1, 790 745 93(1 805 630 2. 000 2, 7.')0 L49C 1, 430 1,465 665 545 L410 1,085 4, 010 3,965 640 935 790 28 CHEMISTRY AiSID ECONOMY OF FOOD. Table 2. — Composiiion of food materiaJs, edlMe portion — Continued. Pood materials. MEATS, ETC. — continued. Mutton : Shoulder Breast Back Ueck Leo Loin Flank Fore quarter Hind quarter Side witliout kidney fat. , Lamb: Shoulder Breast Neck Y"^ Loin Fore quarter Hind quarter Side without kidney fat. . Liver Heart I-iingi Pork: Num- ber of analy- ses. Shoulder roast. Poultry, etc. : 'Jhicken Chicken liver Chicken heart. .. Chicken gizzard. Turkey Turkey livor Turkey heart Turkey gizzard . ( Min .. } Max . . ( Avg . . f Min , < Max (Avg Hens' eggs in shell. <^ Max ■ vg. Preserved meats : Corned beeJ', rump f Min.. Corned beef, flank. < Max.. (Avg.. f Min .. Corned beef.canned < Max. . (Avg.. f Mill .. Dried beef < Max . . (Avg.. Tripe, soused Salt pork, fat Smoked ham _ Mill Pork sausage Bologna sausage. (Min .. :t. P.ct. P.ct. P. et. P.ct. 28. G 12.9 14.4 1.3 3d 12.9 .4 1.2 16.6 14.7 .7 1.3 15.8 13.9 .6 1.3 28.9 14.9 13.3 .7 17.8 35.3 1.4 1.1 81.9 74.6 1.9 5.4 23 21.2 .3 1.6 23.8 21.7 .4 1.6 23.4 21.4 .4 1.6 21.2 22.2 .3 1.7 47.2 22.1 22.6 2.5 25.4 23.7 .2 1.5 35.9 18.2 14.4 2 39.4 23 35.6 2.1 37.7 20.6 35.1 2 29.9 19.9 8.7 1.3 33.6 19.2 11. I 1.3 42 21.3 23.5 1.4 37.1 20.1 15.7 1.3 43.6 25.3 12.7 5.6 27.3 21.5 4.1 1.7 45.2 16.9 24.8 2.5 47.3 17.7 27.9 2.7 40. 3 17.3 26. 3 2.6 25.7 21.8 2.3 1.6 8.6 4.2 .6 1.8 1.2 18. 3 8.5 1.7 6.7 2.8 12.9 6.1 1.2 3.6 2 11.6 5.9 1.5 3.2 .8 14.8 6.6 1.8 5.6 1.1 12.8 6.3 3.6 4 .9 14 7 2 4.1 1.3 15.4 8 2.2 5.2 1.4 14.7 7.4 2.1 3.9 1.3 13.9 8.1 1 1.5 2.1 15 ^9 1.2 2.5 3 14.2 8.6 1 2 2.6 ]5. 5 9 1.3 2.9 2.3 33.8 6.5 .4 4.2 2.7 17 10.4 .8 3 2.8 17.2 14.4 1.1 1.3 22.2 15.1 .3 5.7 3.5 19.7 14.7 . 2 3.4 1.4 15.8 8.7 1.1 4.1 3.9 15.7 12.3 1.5 1.6 20.8 17.8 2.5 1.9 18.2 14.6 1.9 l."7 20.6 17.4 .5 2. 2 23.8 20 3.7 2.8 22.3 18.7 1.1 2.5 18.8 17 .5 1.3 •i2.9 17.8 2 3.1 19 16.5 .8 1.8 21 16.7 2.3 2.1 20 16.5 1.5 2 29.2 25.6 1 2.6 25.5 21 3.5 1 20.2 18.5 .5 1.2 13 3.6 t 4.7 .7 80.5 1 85 .5 3 63.2 26 30 .8 3.7 73 30.6 38.3 3.5 4.8 69.8 28.3 35.5 3.8 4.2 58.7 38.4 6.8 8.9 4.6 89 .6 85 .4 3 FISH, SHELLFISH, ETC. — Cont'd. Fresh fisb — Continued. Tnrbot C Min . Flounder < Max. ( Avg. Lamprey eel Skate . .' Preserved flsh: Desiccated cod f Min . Salt cod ^Max. (Avg. Boned cod Salt mackerel Smoked haddock. Smoked halibut . . Canned mackerel. Canned salmon . . . ( Min . . {Max.. (Avg.. Min . Max. Avs- Canned sardines ... Canned tunny Canned salt mack- erel. Canned smoked haddockT. Shelliish, etc. : f Min. Oysters in shell < Max. (Avg. ( Min . Oysters, " solids ".< Max . Uvg- . Min , Canned oysters C Mm .. . .9 .5 L2 .9 1.4 1.8 1.6 .2 .3 .2 .6 .4 .8 .C .6 .4 .2 1.1 .3 .3 1.5 .3 .5 .4 2.7 3.7 3.1 .9 4.1 L4 Fuel value of 1 pound. Calories 210 90 80 27.5 446 80.3 595 745 64.1 483 310 615 470 90 1-iO 110 S.'^O 75 D5 85 95 90 135 110 70 115 85 100 195 130 230 265 250 56 140 110 375 COMPOSITION OF FOOD MATERIALS. 33 Tai'.le 2. — Com2)osi1ion of food inaicriaJn, idihle portion — Continued. rood materials. VEGETABLE FOODS— continued. -Oatmeal Pearl barley . - Eye flour 1^ Min.. Max.. Avs:.. •Wheat tiour. i'SVm.. ^ilax.. ( .Mill.. ....{ :Max.. (Avg.. i :\rin.. , Graham flour < Max.. (Avs.. f .Min.. Entire Tvheat tlour n !Max.. (Avg.. i Min.. Cracked wheat < Max.. (Av-.. C lliu.. Buckwheat flour < ^lax. . I Avg.. Buckwheat farina Buckwheat eroats Wheat bread . Grabam bread Eye bread Boston crackers Soda crackers Pilot (bread) cracker^ Oyster crackers Oatmeal crackers Graham crackers Starch Sugar, granulated Molasses Olax. (Avo-. !N"uni- ^er of c.iit ai.aly- ^'^1^- ses. Water. Xutrients. P. et. e. 2 8.8 7.8 11.8 12. i 13.6 13.1 8.2 14.3 12.5 12.1 13.7 13.1 12.9 13.1 13' 9.8 11.1 10.4 12.8 17.6 14.6 11 2 10.6 31.2 33.5 32.3 34.2 30 8.3 8 7.9 3.9 4.9 5 2 2 24.6 Total. Pro- tein. Fat. Carbo- hy- drates. P.ct. P.ct. P.ct. P.ct. 91.2 12.9 6.1 67.3 93.8 16.3 8.8 70.1 92.2 14.7 7.1 68.4 88.2 8.4 .7 7S. 1 86.4 .6 .8 77.9 87.6 7.1 .9 70.5 86.9 6.7 .8 7.S.7 85.7 8.6 .6 71. 91.8 13.6 1.8 79.5 87.5 11 1.1 74.9 86.3 11.3 1.5 71.6 87.9 12.4 1.9 72 80.9 11.7 1.7 71.7 86.9 13.1 1.9 69. 5 87.1 14.1 2 70. 5 87 13.6 2 70 88.9 11.9 1.5 73. 9 90.2 12 1.8 75.2 89.6 11.9 1.7 74.6 82.4 4.2 .7 71.6 87.2 8.1 1.8 79.0 85.4 6.9 1.4 70.1 88.8 3.3 .3 84.8 89.4 4.8 .6 83. 4 66.5 8.6 .6 5.5.2 68.8 9.2 2.5 58.5 67.7 8.8 1.7 56.3 65.8 9.5 1.4 53.3 70 8.4 .0 59.7 91.7 10.7 9.9 68.7 92 10.3 9.4 70.5 92.1 12.4 4.4 74.2 96.1 11. 3. 4.8 77. 5 95.1 10.4 13.7 69.6 95 9.8 13.6 69.7 93 97.8 97.8 98 75.4 73.1 Min- eral mat- ters. Fuel value of 1 pound. P.ct. 1.8 1.7 2 1.8 1.4 1.4 1.4 1.4 1.4 1.4 .7 1.3 1 .4 .6 .6 1.2 .9 1.6 1.4 2.4 1.8 1.1 2.5 1.4 1.9 2.3 Calories 1, 820 1, 875 l,8-)5 1, 635 1, 615 1,625 1,625 1, 625 1, OSO 1,645 1,610 1,645 1,625 1,615 1,660 1,640 1,600 1,700 1, 6S0 1,560 1,640 1,605 1,650 1, 665 1,245 1, 300 1,280 1,225 1,285 1,895 1, 9lH) 1,795 1,855 2.065 2, l)5(^ 1,820 1,820 1, 360 Table 3. — Composition of water-free siihstauce of edible 2)orfion of side of heef of medium fatness. Portion taken for analysis. First cut neck Second cut neck Third cut neck Pirst cut chuck ribs. Second cut chuck rib Third cut chuck ribs First cut ribs Second cut ribs Third cut ribs Brisket Shoulder clod Cross ribs Shin Plate Navel Small end sirloin Hip sirloin Socket Kurap First cut round ...... Second cut round Leg Top of sirloin .'. , Flank... Kidney Jat Kitrouen I'er cent. 7.64 9.09 8.19 5.90 7.46 8.37 4.58 4.63 4.82 4.16 9.94 3.94 13. 99 4. 35 4.75 6.72 6.08 6.29 4.02 9.20 10.87 11.99 3.80 2.75 .17 Protein (N. X 0.25). Per cent. 47.75 56.83 51.19 37.44 46.63 52. 31 28.63 28.94 30. 13 26 62. 13 24.63 87.46 27.19 29.69 42 41.76 39.32 25. 13 57. 50 67.94 74.94 23. 75 17.19 l.CG Fat. Ash. Per cent. 51. JO 40. 8J 4.5. 49 01. 34 48. 48 45.90 69 69. 85 68. 80 70. 09 34. 55 74.13 8.78 70. 85 69.52 54. SO 55. 76 58.76 74.18 3'.V48 28/16 20.33 75. 57 82.55 98.88 Per cent. 2. 42 3.02 2.69 '.:. 09 2. 79 3. 02 1.64 1.67 1.70 1.54 3.56 1.36 4.76 1.44 1.58 2.22 2^29 2.37 1.31 3.17 4.36 4.31 1.31 .90 .20 Protein, Protein fat, by dif- and ash. ference. Per cent. 101.36 100. 65 99. 37 100. 87 97.90 101. 23 99. 27 100. 46 100. 69 98. 23 100. 24 100. 12 101 99. 48 100. 79 99. 02 99.81 100. 45 100. 62 10.). 15 100. 46 99. .io 100.63 100. 64 100. 14 • cent. 46.39 56.18 51.82 36. 57 48.73 51. i!8 29.36 28.48 29.44 27.77 61. 89 24.51 86.46 27.71 28. 90 42. 98 41.95 38.87 24.51 57. 35 67. 48 75.36 23.12 16.55 .92 8518— Ko, 21- 34 CHEMISTEY AND ECONOMY OF FOOD. Table 4. — Composition' of flbsh {edihle portion) of side of beef of medium fatness. Portion taken for analysis. First cut neck . . Second cut neck . Third cut neck. . Total nock First cut cliuck ribs. . . Second cut chuck ribs. Third cut chuck ribs. . Total chuck ribs First cut rihs . . Second cut ribs Thii'd cut ribs . - Total ribs . Brisket Shoulder clod Cross ribs Shin Plate Navel Total fore quarter. Water. Per cent. 60.64 C4.48 61 Small end sirloin Hip sirloin Small end and hip sirloin.. Socket Eump I First cut round Second cut round First cutand second cut round I Leg ; Top of sirloin Flank j 'Total hind quarter, ex- cept kidney fat Kidney fat Whole side Whole side, except kidney fat 61.99 53.11 58.21 63.67 58.06 46. 21 48.64 47.82 47.41 66.61 43. 95 73.80 44. 36 47.59 54.12 60.68 58.86 59.86 57.12 40.23 66.04 09.53 66.70 72. 15 42. 20 27. 45 4.30 52.43 54.77 Water- free sub- stance. Per cent. 39. 36 35. 52 39 .01 46.89 41.79 36.33 53.79 51.36 51.52 52.18 52. 59 33. 39 56. 05 26.20 55.64 52.41 45.88 39.32 41.14 40.14 42.88 59.77 33. 90 30.47 33.24 27.85 57.80 72. 55 95. 70 47.57 45.23 Protein b\ dif- ference. Percent. 18.20 19. 96 20.21 19.25 17. 15 20.38 18.57 15.82 14. 63 15. 10 15.22 14. 58 20.66 13.73 22. 66 15.41 15.14 17. 27 16.92 17.26 17.07 16.67 14.65 19.48 20.57 19.71 20.99 13. 36 12.01 16.44 17.20 Fat. Per cent. 20.15 14.49 17.74 17.74 28. 76 20. 25 16.67 Ash. Per cent. 0.95 1.07 1.05 1.02 .98 1.10 1.09 37.09 35. 87 35.48 30.08 37.20 11.54 41.56 2.30 39. 43 36.44 27.65 21. 53 22. 94 22.17 25.19 44.34 13.40 8»57 12.40 5.66 43. 68 59.89 .88 .81 1.19 .76 1.24 .80 .83 Protein (X. X 6.25). Per cent. 18.79 20.18 19.96 17. 56 19. 50 18. 95 15.38 14. K6 15. 52 13. 68 20. 74 13-80 22. 90 15.13 15. 56 Water, protein, fat, and ash. Percent. 100. 53 100. 22 99. 75 .90 .Si .94 .90 1.02 .78 1.08 1.33 1.13 1.20 .76 .65 94.62 30.20 27.07 .19 .93 .96 16.50 17.18 16.86 15.02 19.53 20.71 20.87 13.75 12.47 1.02 1(10.41 90. 12 100. 38 99.56 100. 23 ioo! 36 99. 10 100. 08 100.07 100.24 99. 72 100. 42 99. 58 99:92 100.19 100. 37 100. 05 100. 14 100. 39 100. 46 COMPOSITION OF FOOD MATERIALS. 35 Table 5. — Composition of side of beef of inedinm fatness as received, including hoth edible portion and refuse. Portion taken for analysis. First cut neck .. Second cut neck. Tliird cut neck. . Total neck . Krst cut cliuck ribs . . - Second cut cliuck ribs Third cut chuck ribs . . Total chuck libs First cut ribs . . Second cut ribs Third cut ribs... Total ribs. Brisket Sbouliler clod Cross ribs Shin Plate Navel Total fore quarter Small end sirloin Hip sirloin Small end and hip sirloin . Socket Eump First cut round Second cut round First cut and second cut round Leg Top of sirloin Flank Refuse. Per cent. 18. m IS. 74 li2. 86 19.54 19.45 19. 59 lU. 31 Edible portion. Per cent. 81.03 81.26 77.14 80.46 80.55 80.41 83. 09 Edible portion. Water. Per cent. 49. 50 52. 40 47.06 49.88 42.78 40. 81 53. 29 21.36 22. 70 20.35 21,34 14.33 15.62 12.17 40.16 I 17.90 11.41 78.64 77.30 79.05 86. 34 37.60 38.61 78.66 18.45 Total hind quarter, ex- cept kidney fat , Kidney fat "Whole side "Wholeside, exceptkidneyfat. 24. 46 27.32 25.79 35.79 10.18 7.74 32. 12 14.13 62. 22 3. 23 11.47 18.48 19.21 85.07 84.38 87. 83 59.84 82.10 88.59 37.62 Water- i'ree sub- stance. Per cent. 32. 13 28.86 30.08 30. 58 Nutrients. Protein by dif- ference. Per cent. 14.90 16, 22 15.59 15.49 37.77 33. 01) 30.40 34.06 42.30 39. 70 41.04 41.04 40.62 56.21 38. 60 44.16 36.42 42.10 45.05 28.17 49.23 15.68 45.68 46.43 81.55 75.54 72.08 74.21 64.21 83. 82 92.20 67.88 85.87 37.78 96.77 I 88.53 100 81.52 80.79 44.13 45. 84 42.78 44.42 36.68 33. 72 60.93 47.20 57. 33 27.26 40. 84 24. 30 37.42 4.39 42.74 44.25 29. 70 29.90 29.79 27. 53 50.10 31. 33 20.68 28.54 10.52 55. 93 64. 23 35.37 13.. 82 10.39 15.54 15.48 Fat. er cent. 10. 45 11.77 13. 68 14.27 23.16 16.28 13.95 17.69 Ash. Per cent. 0.78 .87 .81 12.44 11.31 12.07 11.97 20.17 27. 73 28.26 28.38 12.49 17.43 12. 06 13. 56 12.05 13. 41 31.87 9.74 36.50 1.38 32. 13 32.28 14.09 22.55 12. 78 12.54 12.67 10. 70 12. 28 17. 97 13.96 16.92 7.93 12. 9.i 10.63 16.26 16.68 16.45 10.17 37.17 12. 36 5.82 10.65 2.14 42.27 .53. 02 95.70 38.78 36.54 13.40 13.90 94.02 24.62 21.87 .82 .79 .93 .91 .69 .00 .71 36 CHEMISTEY AND ECONOMY OF FOOD, Table 6. — Composition of side of beef of medium fatness {weights of ingredients in meat as received). In whole specimen, as taken for analysis. Portion talven for analysis. Total weight of cut. Refuse. Edible portion. Edible portion. Water. Protein by dif- ference. Fat. Ash. Founds. 8.09 6.05 4.33 Pomuls. 1.48 1.13 .99 Pounds. 6.61 4.92 3.34 Pounds. 4.01 3.18 2.04 Poinds. 1.21 .98 .67 Pounds. 1.33 .71 .59 Pounds. 0.06 .05 .04 18.47 3.60 14.87 9.23 2.86 2.03 .15 11.75 20.60 9.44 2.28 4.04 1.54 9.47 16.50 7.90 5.03 9.64 5.03 1.63 3.38 1.47 2.72 3.35 1.32 .09 .19 .08 Second cut chuck ribs Total chuck ribs ■ 41.79 7.86 33. 93 19.70 6.48 7.39 .86 7.23 6.82 9.41 1.54 1.55 1.91 5. G9 5.27 7.50 2.63 2.56 3.63 .90 .77 1.14 2.11 1.89 2.66 .05 .05 .07 Third cut ribs Total ribs 23.46 5 18.46 8.82 2.81 6.66 .17 13. 64 17. 1.'5 14. 70 11.11 15.37 19.51 1.90 2.68 1.80 4.46 2.75 2.23 11.68 14.47 12.96 6.65 12. 62 17.28 5.54 9.64 5.69 4.91 5.60 8.22 1.70 2.99 1.78 1.51 1.94 2.62 4. 35 1.67 5.39 .15 4.98 6.30 .09 .17 .10 .08 .10 .14 Shin Plate Total fore quarter 175. 26 32.34 142. 92 77.35 24.69 39.52 1.36 13.44 11.74 25. 18 9.66 12.61 37.52 13. 33 50.85 8.58 10.24 13.18 3.29 3.21 6.50 3.46 2.04 2.90 4.28 7.18 . 5. 34 .33 1.51 10.15 8.53 18.08 6.20 10.57 34.62 9.05 43. 67 3.24 9.91 11.67 6.16 5.02 11.18 3.55 4. 25 22.87 6.29 29.16 2.34 4.18 3.21 1.72 1.47 3.19 1.03 1.55 6.74 1.86 8.00 .68 1.33 1.40 2.18 1.96 4.14 1..56 4.69 4.64 .78 5.42 .18 4.33 6.99 .09 .08 .17 .06 .08 .37 .12 .49 04 Small end and hip sirloin First cut and second cut round Leg Top of sirloin Flank .07 Total hind quarter, ex- cept kidney fat 130. 30 20.36 103. 94 57.87 17.78 27.31 .98 Kidney fat 12 317.56 305. 56 12 258. 86 246. 86 .52 135. 74 135. 22 .11 42.58 42.47 11.35 78.18 66.83 02 58.70 58.70 2 36 Whole side, except kidney fat. 2.34 Table 7. — Com;position of ivater-free suhstance of edible i)ortion of side of mutton and side of loQnb. Portion taken for analysis. Nitrogen. Protein (N. X 6.25). Fat. Ash. Protein, fat, and ash. Protein by dif- ference. Side of mutton : Shoulder Breast Neck Eack Leg Loin Flank Kidney and kiduey fat Side of lamb : Shoulder Breast Neck Leg Loin Per cent. 6.97 3.51 5.75 6.47 7.59 4.69 4.07 1.21 6 6.96 6.53 8.95 6.89 Per cent. 43.56 21.94 35.94 40.44 47.43 29.31 25. 44 7.56 37.50 43.50 40.81 55.94 43.06 Per cent. 54.09 75. 00 61.76 57.50 49.69 69.01 73.48 94.20 61.54 53.91 57.28 43.38 55.60 Per cent. 2.28 L62 1.79 1.72 2.36 1.43 .75 .50 2.12 2.31 2.27 3.04 2.34 Per cent. 99.93 99. 16 99.49 99.66 99.48 99.75 99.67 102. 26 . 101.16 99. 72 100.36 102. 36 101 Per cent. 43. 63 22.78 36.45 40.78 47.95 29.56 25.77 5.30 36.84 43.78 40.45 53.58 42.06 COMPOSITION OP FOOD MATERIALS. 37 Table 8. — Composition of fesh {edible portion) of side of mutton and of side of Inmh. Portion taken for analy.sis. Water. Water free sub- stance. Protein by dif- ference. Fat. Ash. Protein (N. X 6.25). Water, ])rotein, fat, and ash. Side of mutton : Shoulder Per cent. 58. 56 37.60 55.69 54. 94 52.22 61.80 49.27 38.73 54.67 18.81 51.83 56. 24 56. 69 55. 06 64.72 51. 82 60.88 57.94 Per cent. 41.44 62.40 44.31 45.06 47.78 38.20 50. 73 61.27 45. 33 81.19 48.17 43.76 43. 31 44.94 35.28 45.18 39.12 42.06 Per cent. 18.08 14. 22 16. 16 18.38 16.96 18.32 14.99 15.78 16.92 4.30 17.51 19.16 17.54 18.12 18.91 19 18.96 18.53 Per cent. 22.41 47.17 27. 36 25.91 29. 88 18.98 35. 01 45.03 27. 53 76.48 29.64 23.59 24.81 25. 82 1.5. .30 25.12 19.09 22.50 Per cent. 0.95 1.01 .79 .77 .94 .90 .73 .46 .88 .41 1.02 1.01 .96 1 1.07 1.06 1.07 1.03 Per cent. 18.05 13.69 15.93 18.22 Per cent. 99.97 99.47 99. 77 Eack 99.84 X,e<'' 18.12 14.87 15.59 99.80 99.88 Flank 99.81 E-idney and kidney fat. .. Side of laiiib : 6.14 18. 06 19.04 17.67 101. 84 100. 55 99.88 100. 13 Leo- 19.74 19.45 100. 83 100. 45 Hind quarter "Whole ."^ide, except kid- ney and kidney fat Table 9. — Composition of side of mutton and side of lami as received, including l}ofh edible portion and refuse. Portion taken for analysis. EefVise. Edib'e portion. Edible portion. Water. Water- free sub- stance. Nutrients. Protein by dif- ference. Eat. Ash. Side of mutton : Slioulder Breast Jfeck Hack Fore quarter Leg Loin Elank Hind quarter Kidney and kidney fat. . Whole side, except kid- ney fat , Side of lamb : Shoulder Breast Neck Fore quarter Leg Loin Hind quarter Whole side, except kid- ney fa"* Percent. 16.29 14.95 27.58 19.28 18.97 18.12 15.75 2.15 15.65 17.30 20.33 19.09 17.67 18.84 17.70 12.18 15. C5 17.30 Per cent. 83.71 85. 05 72.42 80.72 81.03 81.88 84.25 97.85 84.35 100 82.70 79.67 80.91 82.33 81.16 82. 30 87.82 84.35 82.70 Per cent. 49.02 31.98 40.33 44.35 42.31 50.60 41.51 37.90 46.11 18.81 44.23 4L29 45.50 46.67 44.69 53.26 48.14 51.35 47.92 Percent. 34.69 53.07 32.09 36.37 38.72 31.28 42.74 59. 95 38.24 81.19 38.47 38.38 35. 41 35.66 36.47 29.04 39. 68 33 34.78 Per cent. 15.14 12. 09 11.70 14.84 13.74 15 12.63 15.44 14.27 4.30 14.01 13.96 15.50 14.44 14.71 15.56 16.69 15.99 15.32 Per cent. 18.76 40.12 19. 82 20.91 24.22 15.54 29.50 44.06 23.23 76.48 23.71 23.61 19.09 20. 43 20.95 12. 60 22. 06 16.11 18.61 Per cent. 0.79 .86 .57 .62 .76 .74 .61 .45 .74 .41 .75 .79 .81 .88 .93 .90 .85 38 CHEMISTEY AND ECONOMY OF FOOD. Table 10. — Composition of side of mnHon a7}d side of lamb {iveiglits of ingredients in materials as received). Portion taten for analysis. Total weight of cut. Refuse. Edible portion. Edible portion- Water. Nutrients. Protein by dif- ference. Eat. Ash. Side of mutton : Shoulder Breast Neck Eack Eore quarter I-eg Loin Plank. ...1 Hind quarter Kidney and kidney fat. . Whole side Whole side, except kid- ney fat Side of lamb: Shoulder Breast Neck Eore quarter Leg Loin Hind quarter Whole side, except kid- ney fat Pounds. 3.17 1.98 1.73 2.29 9.17 5.20 3.26 .93 -9.39 .39 18.95 18.56 2 85 3.57 3.03 9.45 5. .50 3.32 8.82 18.27 Founds. 0.52 .29 .48 .45 L74 .94 .51 .02 1.47 3.21 3.21 .57 .68 .53 L78 .97 .41 1.38 3.16 Pounds. 2. G.-) 1.69 1.25 1.84 7.43 4.26 2.75 .91 7.92 .39 15.74 15.35 Pounds. 1. .55 .63 .69 1.01 3.88 2.62 1.36 .35 4.33 .07 8.28 8.21 1.18 1.63 1.42 4.23 2.93 1.60 4.53 8.76 Pounds. 0.48 .24 .20 .34 1.26 .79 .41 .14 1.34 .02 2.62 2.60 .40 .55 .44 1.39 .86 .55 1.41 2.80 Pounds. 0.59 2.22 .81 .96 .41 2.18 .30 4.70 4.40 .68 .62 .73 1.42 Pounds. .03 .02 .01 .01 .07 .01 .02 .01 .07 .14 .14 .02 .03 .02 .07 .05 .03 .08 .15 WOKK NOW NEEDED IN ANALYSIS OF FOODS. In the present condition of our knowledge of the composition of materials used for the food of man and with the results which have accumulated up to the x)resent, investigation is especially needed in two directions: (1) The study of the methods of analysis with a view to their improvement, and (2) analyses of a sufficient number of speci- mens to give a clear idea of the range in composition and the average proportions of ingredients in the materials in common use in the United States. The study of methods is one of the pressing necessities of physiological chemistry at the present time. So many analyses of food materials have been made by the current methods that it is hardly desirable to devote a very large amount of labor to further analyses except for specific purposes, such as the study of dietaries, i. e., the actual food consumption of people in different places and under differ- ent conditions of life, and the study of the food supply of particular places and of the composition of certain classes of food materials of which but few analyses have thus far been made. If the studies of dietaries shoukl be carried out in different parts of the country in the manner and to the extent which now seem to be desirable the analyses involved will bring the larger part of the information that is most needed regarding the composition of our ordinary food materials. IMPROVEMENT OF METHODS OF ANALYSIS. , Among the things of fundamental importance for furthering the knowledge of the vahie and proper uses of foods is the improvement of methods of analysis. This necessity will be clearer if we consider COMPOSITION OF FOOD MATEiaALS. 39 what are tlie things we have to analyze and exactly why we analyze them. We have to distinguish here between the materials whicli are used as the food of man and those which are fed to domestic animals. The former may be conveniently designated as food materials or foods and the latter as fodder materials or feeding stuffs. The methods of analysis used for foods are similar to those for feed- ing stuffs, and the two classes of materials need to be studied together. Classification of ingredients. — We make analyses of foods and feeding stuffs to learn their value for nutriment and the proper ways to use them. In doing so we classify the ingredients in different groups, as stated on pages 11 and 12, and assign to each group a specific nutritive value. Present usage makes the groups practically the same for all vegetable substances, thus ignoring the wide differences of kindred compounds in different plants and parts of plants. We even go so far as to make nearly the same grouping for animal as for vegetable compounds. Not only do we thus place compounds of widely different chemical and phys- iological characters in the same group, but we frequently jDut into a group compounds which do not belong there at all. In our analyses we attempt to separate the ingredients and determine their respective amounts. We base our methods of analysis mainly upon two classes of properties, the elementary composition of the com- pounds, and their solubilities; and yet our knowledge of these proper- ties is imperfect at best, and in some cases scarcely suffices for more than to assure us of the incorrectness of our methods of estimation. In many instances, esxjecially with vegetable materials, the solubility of the compounds in laboratory reagents, their digestibility in laboratory tests by the so-called method of artificial digestion, their actual diges- tibility in the body of the animal, and their nutritive effect are depend- ent upon the ways in which they are held in the vegetable tissues, e. g., the nature of the cell walls or incrusting substances. Of these things ordinary chemical analysis tells little or nothing, and we must look to the vegetable histologist for information about them. Meanwhile, in ignorance of them we commit more or less serious error. In vegetable materials by our present method we determine, or assume that we determine, one group, which we call i)rotein, by multiplying the total nitrogen by G.2o. In many cases we know this factor is wrong, in many others we have no proof at all that it is right. We assume to determine a second group, which we call fats or crude fats, by extract- ing with ether. We know that, especially in vegetable feeding stuff's, the ether extracts a good deal of material which can not be properly classed with the fats and that it may leave more or less of the true fats unextracted. We estimate what we call fiber or crude fiber by extracting with dilute acid and alkali, and do not know the constitution of the residue, although we are certain that it varies with the conditions of extraction, and that it may contain more or less of other materials than cellulose and lignin. We determine what we call ash bv inciner- 40 CHEMISTRY AND ECONOMY OF FOOD. ation, and take the residue as representing the mineral matters, altliougii the method does not tell us their forms of combiuation and the result does not even represent their exact amount. Even the cur- rent methods of determining water are extremely faulty.' We keei) the substance for a certain time at a temperature near that of boiling water, either in air or in a current of hydrogen, and reckon the loss of weight as water. We do not know how much water remains in what we call the water-free residue, but it is certain that in many cases more or less of the organic matter is volatilized and sometimes the quantity which thus escapes is very considerable. And when we have made these rough estimates of water', protein, fat, crude fiber, and asli, we add them together, subtract their sum from the whole weight, and call the difference " non-nitrogeuous extract" or "carbohydrates." When this is done we make more or less rough estimates of the digesti- bility of the several classes of nutrients by use of digestion coefficients of doubtful accuracy. And finally, having thus estimated the total and digestible nutrients, we apply certain figures for estimated heats of combustion of protein, fats, and carbohydrates, and thus calculate the fuel values of our foods and feeding stuff's. JSTotwithstanding all these difficulties and sources of error it is probable tha^t the results for animal foods are not very far from the truth. With many vegetable foods the case is no worse. Perhaps it is safe to say that the present methods of analyses of animal and vegetable foods are accurate enough to give tolerably fair estimates of their nutritive values, but they are very far from what they should be. The demand for investigation which shall lead to imi^rovement is immediate and pressing. With vegetable feeding stulfs the case is much worse, so bad indeed that some of the leading experimenters in the United States are inclined to make but little use of chemical analyses in feeding experiments. In my judgment this is going too far, decidedly so. But nevertheless the fact obtains that in estimates of the nutritive values of feeding stulfs, the results of our feeding trials and the teachings of experience are often at variance, and it is not easy to see why. We shall not make them harmonize until we learn how to make our analyses more correct. If the need of improvement of the methods of analysis of food is great the need of improving the methods for feeding stuffs is still greater. At the same time there is much to encourage us. If we are still using the so-called " Weende methods" of thirty years ago with com- paratively little modification we have found out how to get results that are pretty nearly uniform. To this latter consummation the work of such organizations as the Association of Official Agricultural Chemists in the United States and the Association of ExjDeriment Stations in Germany have materially contributed; and it is no disparagement of the great value of that work to say that it is not of exactly the kind that is needed to bring the best results. The general plan of the cooperative experiments made by these associa- tions is that of testing certain prescribed methods of analysis. The COMPOSITION OF FOOD MATERIALS. 41 method of analysis to be followed may be either one in common use or a new one which is to be tested. The details of the operation are minutely described and the substance or substances in which the deter- minations are to be made are definitely agreed upon. A single sample of a substance of a given class is selected by one analyst and dis- tributed to the others, or each analyst selects the substance for himself. The analyses are made, reported, and compared. Generally little or no effort is made to determine the actual constituents of the compounds that are being dealt with or the conditions of combination and sei)ara. tion which so materially affect the accuracy of the analysis. The work is aj)t to be mainly a comparison of methods of manipulation in the hands of different men. This is valuable, indeed indispensable, but it does not go to the root of the matter. It is empirical and not truly scientific. It does not reveal the real sources of error and the ways of avoiding them. It is working sj'.stematically but not ijhilosophically. It is an attempt to find a path by groping in the dark, where light is needed to show the obstacles, the pitfalls, and the safest and nearest route. /Sources of error and the investigations needed to develop correct meth- ods. — The time has come when systematic effort ought to be made to inii)rove our current methods of analysis. To decide what are the first steps we shall do well to consider the especial difficulties. To do this satisfactorily would require a treatise of considerable length. The present pur^jose will be served by very brief recapitulation of some of the main points. Water. — It is becoming evident to experienced analysts that the accu- rate determination of water is one of the most difficult in this branch of analysis. Just what are the sources of error we do not fully know. We are not certain, for instance with respect to any ordinary material, just how long heating, either at a temperature of 95°, which is common iu an ordinary drying oven, or at the exact temperature of b'>ibi>g water which we sometimes attempt to maintain, or at the higher tem- perature of 105° or 110° which is occasionally recommended, is neces- sary for complete expulsion of the water. But we do know that at either of these temperatures there is more or less danger of volatiliza- tion of organic substances. Pure filter paper is gradually decomposed and finally charred at temperatures much below 100°. The volatile fatty matters may escape at even lower temperatures. Nitrogenous compounds are likewise driven off" under the same circumstances. Some fatty matters absorb oxygen and increase in weight when dried in air; hence the necessity of drying in hydrogen. Not knowing what better to do, we have recourse to the entirely empirical method of dry- ing a given weight of a given substance for a given time at a given temperature, and assuming that if the water is not entirely expelled enough organic matter will be driven off" to compensate for the error. But it is clear that in so doing we are not getting accurate results. 42 CHEMISTRY AND ECONOMY OF FOOD. Nitrogenous svhstances. — The method of multiplying the totnl nitro gen by 6.25 and taking the product as a measure of the nitrogenous substances is a most unsatisfactory makeshift. It does not tell the total quantity of nitrogenous substances, still less does it tell the amount in any given form of combination. Conventionally we call the product protein. We assume it to include in animal foods: (1) The albuminoids; namely, native albumins, derived albumins, including casein, globulins, coagulated proteids, albumoses, and pejj- tones. (2) The so-called '^ gelatinoids," namely, those which make the basis of connective tissue, and derivatives from them. The most important of these are the ones which yield gelatin and chondrin, though the substances which yield elastin and mucin are generally classed with them. (3) Cleavage products of albuminoids and gelatinoids other than proteoses and peptones. The most important of these for our present purpose are the so-called non -nitrogenous extractives, the group to which kreatin and kreatinin belong. In the flesh of vertebrates, at least of those most commonly used for food, the total nitrogen multiplied by 6.25 is found to very nearly equal the total nitrogenous substances; in other words, the nitrogen factor 6.25 is a fairly accurate one. But the albuminoids, gelatinoids, and extractives have different functions in nutrition. It is especially important to devise means for accurately separating the extractives. Considerable work on the methods of analysis of muscular tissue has been performed in the writer's laboratory, the larger part by Dr. H. B. Gibson. We have thus far found no easy and accurate way for sej)a- rating the nitrogenous extractives, nor have we been able to make an at all satisfactory separation of the albuminoids and gelatinoids by the use of either hot water or dilute (one-flfth per cent) hydrochloric acid. The method which is commonly recommended for separating the gelatin by boiling water proves to be unreliable. In the muscular tissue of beef, from which the fat had been removed as completely as was con- venient, and in the flesh of codfish nitrogenous material was dissolved as long as the treatment with hot water was continued, and it was evi- dent that under the treatment some kind of decomposition was con- stantly going on. This was not surjmsing in view oi^ the decomposi- tions which take place in the treating of pure albuminous matter, sucli as blood fibrin, by very dilute acids or alkalis with heat. It accoitls with the observations that various albuminoids maybe changed to sub- stances allied to if not identical with peptones by such treatment. The exxoerience with the dilute hydrochloric acid, which is supposed to dis- solve the albuminoids and. leave the gelatin-like compounds undis- solved, was equally unsatisfactory. A further result of the investigation just referred to, which still awaits publication, is worth noting here. Muscular tissue of beef and COMPOSITION OF FOOD MATERIALS. 43 of codfish was partially dried by lieat in air in tlie way commonly fol- lowed in preparini;' substances for fnrther analysis. This heating' in air was continued until the substance was dry and liard enough to be pulveri/ed. The total quantity of nitrogen in the fresh substance and that in the same substance after drying were determined by the Kjel- dahl method. It was found that from 1 to 3 per cent of the nitrogen was lost in the process of partial drying. The operation was repeated in a current of hydrogen, Avhich, after passing over the substance, was conducted througli hot' sulphuric acid. In this way the nitrogen of the volatilized material was approximately determined. In some of the cases with meat it reached 2 per cent, and in some white fleshed fish 2^ per cent of the total nitrogen in the substance. The nitrogen thus volatilized, added to the quantity in partially dried material from which it had escaped, was found in some cases to be almost exactly equal to that in the original substance. Whether the volatilized nitrogenous compounds were nitrogenous extractives or otlier and more volatile cleavage products was not determined. We suspect that they might have belonged to the latter class, one reason being that the fish was hardly as fresh as the meat and that the flesh of fish is known to yield volatile amins as decomposition products. This experience has an important bearing upon the determination of nitrogen in animal substances. It is evident that if we partially dry the substance before making the determination of nitrogen we run the risk of loss of nitrogenous material^ and yet this is exactly what is done in the ordinary method of analysis. It also has an important bearing upon the determination of water. Ordinarily we estimate the loss of water in the partial drying and then take a smaller portion of the partially dry substance, heat it further until it ceases to lose weight, and call the total loss water. If the water is all expelled and as much volatile organic matter escapes witli it, as the observation just men- tioned would imply, the water determinations must be wrong. The studies just referred to imply that there may be a loss of nitro- gen in the complete drying which follows the partial drying in the ordinary routine of analysis of animal tissues. This Avould aft'ect the final result in the same ways as the loss in partial drying. The nitrogenous substances in vegetable foods include: (1) Albu- minoids of various kinds; (2) so called aniids, i. e., synthesis and cleavage products of various kinds. The vegetable albuminoids appear to be more variable in composition than the animal albuminoids, and the nitrogen factor for them needs to be fitted to the compounds as they actually occiir in different classes of food materials. Such investigations as those of Osborne and Chit- tenden^ upon this subject are valuable; indeed inquiry of this kind is of fundamental importance. ^Conuecticiit State Experitneut Stixtioii Reports, passim; Am. Chem. Jour., vols. 13, 14, 15, passim; Jour. Am. Chem. Soc, XVI, 703. 44 CHEMISTRY AND ECONOMY OP FOOD. So-called ^^amids" occur to only a small extent in most of our vege- table foods. In potatoes, however, the quantity is very large and their further study is more to be desired. In feeding stuffs, especially the grasses and forage plants, Avhich are ordinarily harvested during the period of growth and marked cellular activity, the proportions are often large. The method of Stutzer for the separating of so-called '^ albuminoids" and '^non-albuminoids" of vegetable substances is frequently used and is regarded by some as measurably satisfactory. In the writer's lab- oratory the experience has not been as favorable as is to be desired, and there is little risk in saying that further investigation of the subject is much needed. The practice of determining nitrogenous substances by multiplying the total nitrogen by 6.25 is at best a temporary makeshift. In meats, fish, milk, and the cereal grains it is x>robably not far out of the way, but in all of these, and especially in the meats and fish, it is of the greatest importance to distinguish between the albuminoid nitrogen and that which exists in other forms. The same is true to equal if not greater degree in potatoes and other roots, in ordinary vegetables, and in many feeding stuffs. Terminology. — One ma.tter that demands attention is the terminology of the nitrogenous substances. This is in almost hopeless confusion. American, English, French, German, and other chemists disagree widely and most curiously in their usage. By a large number the term albuminoid is used in the sense in which it is used here. But it is employed by others not only for other allied compounds, but even for such substances as hsemoglobin. The word "proteids" also meets pro- miscuous handling by different authorities. Some make it synonymous with albuminoids; with others it includes what are here called "albu- minoids" and "gelatinoids;" by others it is applied to a different and greater variety of nitrogenous materials. And while the term is applied by most physiological chemists, so far as I know, to sijecific compounds, it is occasionally used by writers on the subject for the total nitrogenous substances in food materials without regard to their composition. It is, of course, desirable that a nomenclature for the nitrogenous compounds be agreed upon. Provisionally it seems to the writer wise to conform to what is coming to be a very common usage with respect to one term, "j)rotein;" namely, to apply this to the total nitrogenous substance (exclusive of nitrogenous fats) whether obtained by multi- plying the nitrogen by 6.25, which is now commonly accepted as the measure of the nitrogenous substance, or by difference as is done with the animal tissues which contain very little carbohydrates. Fats — Ether extract. — The case with the so-called "crude fat" is no better than with the nitrogenous comi^ounds. In such animal sub- stances as muscular or connective tissue, and milk and its products, COMPOSITION OF FOOD MATERIALS. 45 when they are fresli, i. e., when the cleavage of proteicLs which comes with exposure and the action of bacteria has not i)roceeded too far, the ether extract, if obtained by proper manipulation, contains probably all the so-called "neutral" fats or "triglycerids" (i. e., the normal pro- penyl compounds with the fatty and oleic acids), and little else. The amounts of lecithins in these tissues are very small and very probably their extraction by ether may be complete enough for practi- cal purposes. In eggs the extraction of lecithin with ether alone is hardly feasible by the ordinary method, indeed, the experience in the writer's laboratory has shown it to be extremely slow and difficult with ether or alcohol, or even with a mixture of ether and alcohol, although I do not feel competent to say that it can not be done easily and quickly by proper manipula- tion. This is one of the minor details of method that need further investigation. The comi)ounds commonly extracted from vegetable products and denominated "crude fat," "ether extract," or simply "fats," are very diverse; nor are we at all sure what proportion of them we extract by our ordinary methods. We have to deal not only with the true fats, i. e., glycerids of the fatty acids and the fatty acids themselves, which may be properly classed with the fats in estimating nutritive values, but also with a great variety of other compounds of widely differing constitution, and of whose functions and value in nutrition but little is known. Among them are substituted glycerids, including lecithins, waxes, alkaloids, cholesterin, hydrocarbons, and chlorophylls. Of these, the lecithins appear to have a special value in nutrition, while some of the alkaloids are poisons. An especial and serious difficulty is found with the fats which become insoluble in ether when heated in air. These seem to be abundant in some seeds and grasses. We assume that they are of the nature of the drying oils, like linolein, and take up oxygen on exi^osure to air. We therefore dry the substance in a current of hydro- gen before extracting with ether. This is very essential. Tlie writer has found the quantity of material dissolved by ether from seeds, e. g., of maize, to be reduced three-fourths by drying in air. We have not found this difficulty to occur in animal tissues, and probably the general experience is to the same effect. Unfortunately there is still much doubt as to just what are the bodies which become insoluble in ether by drying in air or the list of materials in which they occur. It is doubtless wise to use hydrogen, especially in the analyses of vegetable materials and to make sure that the hydrogen is free from oxygen. The use of illuminating gas instead of hydrogen for this purpose, which has been found satisfactory in some laboratories,^ is worthy of more con- sideration. 1 See Foerster, Landw, Vers. Stat., 37, 1890, 57 aucl Experiment Station Record, 5, p. 383; and Marcker, Bieler and Scliueidewiud, Pie agrikultur-cliemisclie Yersnclia' Btation Halle a/S,, p, 11, 46 CHEMISTRY AND ECONOMY OF FOOD. If the substance to be analyzed is finely ground, free from water, and in otherwise normal condition, and the cell structure allows easy extraction we may in general expect that ether, applied in accordance with the official method, which is commonly followed by our stations, will take out the Avliole of the true fats and fatty acids, and more or less of the lecithins, wax, chlorophyll, cholesterin, alkaloids, and hydrocarbons, and that more or less. of the compounds other than true fats and fatty acids will remain undissolved. If the ether contains alcohol the extract may be expected to contain more of the other com- pounds. If water is i^resent the extract nuiy be larger, as has actually been found to be the case in numerous observations. In other words, the extract, as obtained by the ordinary method, contains either part or all of the fats and fatty acids, as the case may be, and with them more or less of other substances. With animal foods, except eggs and such materials as the edible j)ortion of oysters in which different organs are included, it is doubt- less safe to say that the ordinary method of ether extraction is reason- ably satisfactory. With vegetable foods the case is complicated by the presence of other compounds than the true fats (normal propeuyl conii)ounds) and by the fats that become insoluble in drying. But with the cereal j)ro- ducts and potatoes, which make ux^ the bulk of our vegetable foods, the ordinary method appears to do very well. The worst difficulty is with feeding stuffs. In these we have a great variety of other substances than the true fats, and considerable amounts of the fat which oxidize in air, and furthermore we have to do with the in crusting substances which materially hinder extraction. The ether extract is apt to be mixed with materials that do not belong with the fats and to contain only part of the true fat. There is only one way to remedy this difficulty. It is to find what the substances are which vary so greatly in solubility, in what mate- rials, and under what conditions they occur, and how to classify, sep- arate, and determine them. The nutritive values of the materials whicli are more properly grouped as fats, i. e., the glycerids of the fatty acids, and the fatty acids them- selves, are pretty well understood, though further investigation of the molecular constitution of some, and of the fuel value of all, is needed. According to the i^resent outlook it seems probable that, although the waxes and x)erhaps the lecithins may be classed with the fats in estimations of the nutritive values, a separate classification of some or all of the others will be necessary ; and it is clear that a more definite knowledge of the chemical constitution of all the materials, other than the neutral fats and fatty acids, is indispensable to any cor- rect estimate of their values for nutriment. Crude fiber — Cellulose. — The term "crude fiber," like protein, is prac- tically a conventional expression for bridging over the present igno- COMPOSITION OF FOOD MATEEIALS. 47 ranee of the actual substances to wliich it applies, and the conventional method for its determination is another of the provisional makeshifts of the analytical laboratory. In the analysis of food this is of minor conseqnence; the vegetable foods have but little cellulose and less of the incrusting substances which are associated with it, while animal foods have none. In many feeding- stuffs the cellulose and ligneous substances which we lump together as crude fiber are a disturbing factor, and a very serious one, in the analysis and in the determination of the digestibility and the nutritive value. Cellulose is a comparatively well-defined chemical compound, or to speak more accurately, the celluloses found in different plants consist of more or less clearly defined chemical compounds. The celluloses are more or less digestible even by man; they can be converted into sugar, and though their oxidation in the body in such way as to make their ])otential energy largely available has been called in question, later experimental inquiry ascribes to them, in so far as they are digested, practically the same nutritive value as other carbohydrates. Intimately associated with cellulose are the ligneous substances. These are as yet but little understood. Such terms as "lignin," "zylo- gen," "cuticle," and "woody fiber" have been applied to them and to the hardened cell walls or other parts of plant tissue in which they occur. They abound in the more or less completely matured stems of the grasses and cereals and in the outer coatings of seeds. Hence we meet them in hay, straw, cornstalks, bran, and oil cake. They seem to be especially characteristic of what are called coarse fodders. It is these substances, indeed, with others more or less closely allied, which make such fodders indigestible and "coarse."^ There is extremely lit- tle of them in flour and meal of cereal grains, in the seeds of the legu- mes, tubers, roots, or ordinary fruits. Hence they are not responsible for any large part of the difficulty in the analysis of food materials, but do make a great deal of the trouble we have with feeding stuffs, both in their analysis and in the estimates of feeding value. Practically what we do in the so-called determination of crude fiber is to treat vegetable substances in an entirely empirical way with dilute acid and alkali, assuming that these remove the nitrogenous substances, and call the undissolved residue crude fiber. How much of cellulose or ligneous compounds may be dissolved we do not know, but we do know very well that more or less nitrogenous and other compounds are often left in the residue thus crudely separated and crudely designated. 1 See articles on tliis general snbjectl)yDr. J. B. Lindsey, entitled "The Composition of Wood," in Agricultural Science, ] 893, Nos. 1-4. These include accounts of inves- tigations by the author and a summary of the late researches upon the celliiloses, lignin, and the carbohydrates, and other references to the literature of the subject. 48 CHEMISTRY AND ECONOMY OF FOOD. These incriisting substances affect the whole work of analysis of vegetable foods and feeding stuffs. As regards the bodies which we are wont to classify as " amids," "ether extract/' "nitrogen-free extract," and "crude liber/' and which we attempt to estimate by treatment with water, ether, dilute acid and alkali, or other solvents, we are coming to appreciate that their solu- bility is influenced not only by the fineness of grinding of the sami:>le, the time and temperature of the extraction, the quantity of the water, the purity of the ether, the strength of the acid or alkali, the time and temperature of extraction, and, by chemical changes induced in the compounds by fermentation, or by long standing, or by drying in the air, but also by the ways in which they are held within the cells or occur as constituents of the plants. The observations of the greater digestibility of cellulose in young than in older plants and in plants grown on rich as compared with those grown on poor soil, illustrate this point. We are beginning to realize that the permeability of the cell walls and other mechanical conditions affect the ease or difficulty of extrac- tion 5 that the histological structure of the plant is a most important factor; in other words, that here is one of the places where the chemist must have the help of the vegetable physiologist if he will learn to do his work as it ought to be done. Nonnitrogenous extractives — Garhohydrates. — The use of the term "non- nitrogenous extractives" is another makeshift for covering our igno- rance of the compounds we are dealing with and the imperfections of our methods of analysis. The carbohydrates as chemical compounds are coming to be well understood, thanks to the labors of such inves- tigators as Fischer and Kiliani, which are revealing their molecular con- stitution, and of Tollens and F. Scliulze and their associates, who are finding what they are and where they occur. These remarks apply not only to the amyloses, glucoses, and sucroses, but also to the pentoses and the gummy substances from which they are derived, although the nature of the latter is only beginning to be understood. The late prog- ress of research in this direction is most gratifying, not only in the results achieved and promised, but also in the examples it gives of the usefulness of such abstract inquiry. It is a matter of especial congratu- lation that a number of gentlemen connected with colleges and experi- ment stations and other institutions in the United States, including Messrs. Allen, De Chabnot, Flint, Liudsey, Stone, and Wheeler, have been engaged in this field of inquiry, and it is much to be hoped that their work may be continued. The current practice of lumping the known and unknown materials together indiscriminately and simply estimating their total amount, as is done with the nonnitrogenous extractives, is most unsatisfactory. It leaves us in the dark as to the character and nutritive values of the compoundSj and is only a rough approximation to their quantity. COMPOSITION OF FOOD MATERIALS. 49 Witb the cereal grains and the flour and meals prepared from them, and with the leguminous seeds commonly used for food, the present state of affairs is not very serious. Tlie error in water determinatiou in drying- in hydrogen is probably quite small; the nitrogenous com- pounds are mostly albuminoids with a nitrogen factor ]iot very far from 6.25, though this factor evidently needs to be fitted to each kind of seed in both the cereals and the legumes; the ether extract may be expected to contain all the true fats, the fatty acids, the bulk of the lecithin, and very little else; the quantity of crude fiber is very small and consists mostly of cellulose; the content of mineral matters is so slight that the error in their determination may be disregarded ; the estimate of carbohydrates by difference is thus not very far out of the way; and finally the carboliydrates themselves are reasonably well understood and their heats of combustion are readily determined. In potatoes the nonnitrogenous extractives consist chiefly of starch, and their estimation by difterence may not be very far from correct, provided a way is found for correct determination of the nitrogenous compounds. Eoots, as beets and turnips, and fruits contain large pro^jortions of the bodies to which such names as pectose and pectin are given. Very little is known of the constitution of these compounds. Very likely they may approach the carbohydrates in nutritive value. It is in the feeding stuffs that the nonnitrogenous extractives are most puzzling. Indeed in the coarse fodders we know extremely lit- tle of their nature, and the errors in determining the other ingredients make the estimating of their amounts by ditterence little better than guesswork. We have been accustomed to think of the carbohydrates as offering no difficulty in the analyses of animal foods, and are only lately coming to see our mistake. In muscular tissue, e. g., meats and the flesh of fish, they have been entirely ignored; but the late w^ork of Kulz, Pfliiger, and others shows that the glycogen content of these substances is much too large to be ignored in accurate investigations of either their composition or their uses in nutrition. The only carbohydrate supposed to occur to any extent in milk is lactose. Considering that the accurate determination of the water in milk is by no means one of the easy op.erations of the laboratory, and that any error in this, unless compensated by the slight but very prob- able errors in determination of protein and fats, will aflect the estimate of sugar by difterence, it must be allowed that even here the present method is not perfect. Mineral matters. — That the residue left on incineration and commonly called ash does not exactly represent the ndneral matters in the sub- stance analyzed goes without saying. But so long as we are not con- cerned with the functions of the mineral matters this slight analytical error need not be taken into account. 8518— No. 21 4 50 CHEMISTRY AND ECONOMY OF FOOD. Summary. — When we summarize the sources of error in our present methods of analysis it is clear that the worst difficulties are those with the feeding stuffs. IsTevertheiess there is serious need of reform in the methods for analysis of foods. With animal foods the subjects of which investigation is most press- in gly needed include — (1) Determination of water. (2) Separation of nitrogenous extractives from proteids of muscular tissue and determination of both. (3) Study of the constitution of the proteids of animal tissues. (4) Separation and determination of glycogen in muscular tissue. In vegetable foods it is especially desirable to investigate — (1) The albuminoids. (2) The nonalbuminoid nitrogenous compounds, especially in tubers (potatoes). (3) The lecithins and other compounds containing nitrogen and X)hos- phorus. With respect to all these substances the heats of combustion consti- tute a most important branch of the needed inquiry. The need of an understanding of the molecular constitution of com- pounds in order to devise correct methods for learning their digestibil- ity and nutritive values is illustrated by the albuminoids. What is the residue left undissolved by pepsin and trypsin to which the term "nuclein" has been applied? Is there reason for a separate classifica- tion of nucleo-albumens? Is there in these or other albuminoids a molecular group containing phosphorus which resists the digestive fer- ments and is the basis of the undigested ]3ortion of the compounds in which it occurs? If so, what is its relation to the nucleus or the nucle- olus of the cell? Shall we not have to look to a union of organic chem- istry and vegetable physiology for the facts we must have in order to devise plans for correct analyses and determinations of digestibility, potential energy, and nutritive value of the compounds? The results of future research will doubtless lead not only to changes in the general groupings and methods of analysis, but also to special groupings and methods of analysis for different classes of vegetable and animal foods and feeding stuifs. It is hardly to be expected, for instance, that we shall always hold to the same grouping of compounds for grasses, cereal grains, leguminous plants and their seeds, root crops, milk, and meats. It is more iDrobable that groupings for differ- ent classes of materials which shall correspond with methods of analy- sis and of estimating the nutritive values will prove both necessary and feasible. It is safe to say that all of the work which has been done in the past and is being done to-day in the analysis of feeding stuffs and the feed- ing trials based upon them will have to be revised and much of it dis- carded. A large amount of experimental inquiry is being done which COMPOSITION OF FOOD MATERIALS. 51 is not bringing tlie needed results and can not in the nature of tbe case be of the highest and most enduring value, and much of it may liave to be done over again when correct methods shall have been devised. The first step toward reform must be research in analytical, organic, physical, and physiological chemistry. The needed improvement of our methods will evidently come only as fast as does the chemical and physiological knowledge which must serve as a basis for changes. This means that the most abstract and profound study is necessary. For- tunately such study is more and more engaging the attention of chem- ists and vegetable physiologists. From the chemical standpoint we need: First, such studies as will bring definite knowledge of the kinds and amounts of proximate com- pounds contained in each substance to be analyzed — that is to say, (1) in different species of plants, as grasses, grains, cereals, legumes, tubers, roots, etc. 5 (2) in plants of the same species grown under different conditions; (3) in different parts of the same plant, as the stalk and seed of nmize and wheat, and the different parts of the wheat grain; (4) in the same plant at different periods of growth ; (5) in animal tissues and fluids. For some of the information needed the aid of the histo- logist must be sought. Second, studies of each compound regarding its behavior with reagents — 1. e., solubility, etc.; its elementary compo- sition; its cleavage products; its molecular constitution; the changes it undergoes by the action of ferments; its digestibility, and its poten- tial energy. Third, classifications of the compounds based upon the properties named. Fourth, improved methods for separation and esti- mation based upon the same properties. Fifth, as the outcome of all this, more correct methods of estimating the nutritive values. Investigations in these lines have already been undertaken by the Division of Chemistry of the United States Department of Agriculture, by several of the experiment stations, and by other institutions of research. The work of the Association of Official Agricultural Chem- ists in developing and improving the methods of analysis has been of decided value. It has, however, confined its attention too closely to empirical com^^arisons of methods of maniimlation. For the collating of the results of previous inquiries, and for the pros- ecution of the necessary investigations, cooperation of a large number of specialists will, of (iourse, be requisite. We may confidently expect that experiment stations will be able to dev^ote more and more labor to these higher inquiries. The increased resources of our agricultural colleges will enable them to encourage such researches. The scientific value of this work is such that chemists in other colleges and univer- sities ought to be led to join in it. And is it too much to suggest that international cooperation might be secured? The expense of this research may be best met by the wise expenditure of relatively small sums of money judiciously expended, so as to stimulate investigations and bring them to completion. In what the Smithsonian Institution 52 CHEMISTRY AND ECONOMY OF FOOD. has done in times past in promoting research by small amounts of money we have an illustration of what might be accomplished here. The result would be useful in several ways. It would encourage research, develop talentj and improve the intellectual tone of the institutions where such work was being doiie. Its influence upon the development of science in this country would be excellent and the practical value of the out- come would manv times exceed the cost. CHAPTER IV. THE DIGESTIBILITY OF FOOD. The value of food for uutrimeiit depends not only upon Low much of nutrients it contains, but also upon llo^y much of these the body cau digest and use for its support. The question of tlie digestibility of foods is very complex, and it is noticeable that the men wlio know most about the subject are generally tlie least ready to make definite and sweeping statements concerning it. One of the most celebrated physiologists of the time, an investi- gator in whose laboratory this particular subject has been studied more than in almost any other, says in his lectures that, aside from the chemistry of the process, and the quantities of nutrients that may be digested from different foods, he is unable to affirm much about it. The contrast between this and the positiveness with which many per- sons discourse about the digestibility of tliis or that kind of food, is marked, and has its moral. One source of confusion is the fact that, what people commonly call the digestibility of food includes several very different things; some of which, as the ease with which a given food material is digested, the time required for the process, the influence of different substances and conditions upon digestion, and the effects upon comfort and health, are so dependent upon individual peculiarities of different persons, and so difficult of measurement, as to make the laying down of hard and fast rules impossible. Why it is, for instance, that some persons are made seriously ill by so wholesome a material as milk, and others find that certain kinds of meat, of vegetables, or of sweetmeats, "do not agree with them," neither chemists nor physiologists can exactly tell. Late investigations, lu»wever, suggest the possibility that the ferments in thedigestive canal may, with some people, cause particularcompoundsto be changed into injurious and even poisonous forms, so that it may some- times be literally true that "one man's meat is another man's poison."' But digestion proper, by which we understand the changes which the food undergoes in the digestive canal in order to fit the digestible portion to be taken into the blood and lymph and do its work as nutriment, is essentially a chemical process. About this a.great deal has been learned within a comparatively few years, so that here again we have many important facts that have not yet got into current literature.^ ^See interesting statements upon tliis subject in Dr. Burdon-Saudersou's "Dis- orders of Digestion." See also article on " Digestibility of Food " in Century Maga- zine, September, 1887. 2 An excellent treatment of the general subject of the chemistry of digestion may be found in Gamgee's Physiological Chemistry, Vol. II. 53 54 CHEMISTRY AND ECONOMY OF FOOD, Professor Maly very aptly compares food to ore, and the nutriment digested from it to the metal extracted from ore. In the chemical lab- oratory a metal is sometimes separated from the earthy matters with which it is mingled by pulverizing the ore, j)iitting it in a flask, pour- ing acids upon it, and stirring the whole together. The acids dissolve the metal, leaving a residue of earthy matters undissolved. To sepa- rate the dissolved materials from the residue, the whole is put upon a filter, through which the solution runs, leaving the undissolved residue in the filter. Something analogous to this takes place in the digestion of food. Instead of the metal and earthy matters of the ore, we have the digestible and the undigestible constituents of meat, or bread, or other material. The grinding is done, not by pestle and mortar, but by the teeth; the digestive juices are the solvents; instead of the flask the dis- solving is done in the stomach and intestine. Finally, the digested material has to pass, not through a filter, but through the x)orous walls of these last organs. The changes which the digestive juices cause are manifold, and not yet fully understood. But the main fact for consid- eration here is tliat the undigested residue gives a more or less accurate measuring of the digestibility of the food. To judge accurately of the nutritive value of food, then, we must know how much of each nutrient will be digested. This is a matter that can be determined more or less accurately by experiment; but a great deal of labor is needed to make the experiments accurate. The line of research is new, the methods are not yet perfectly matured, and the results thus far obtained, though interesting and valuable when taken together, are still very far from complete. The side ques- tions, such as differences in the digestive apparatus of different per- sons, the effects of exercise and rest, or the mode of preparation of the food, and of the flavoring materials and beverages taken with it, tend to complicate the problem and make satisfactory results still harder to obtain. Yet even here experimental research has brought some definite information. THE QUANTITIES OF DIGESTIBLE NUTRIENTS IN FOOD. The question here is. What proportion of each of the nutrients in different food materials is actually digestible ? In a piece of meat, for instance, what percentages of the total protein a^nd fats will be digested by a healthy person, and what proportion of each will escape digestion? The proportions of food constituents digested by domestic animals has been a matter of active investigation in the European agricultural experiment stations during the past thirty years. During the past fifteen years not a little has been done in some stations in the United States. Briefly expressed, the method consists in weighing and analyz- ing both the food consumed and the intestinal excretion. Since the latter represents nearly the amount of food undigested, if we subtract it from the whole amount taken into the body the difference will be nearly the amount digested. THE DIGESTIBILITY OF FOOD. 55 Sucli esperimeuts upon Imman subjects, however, are rendered mucli more difficult by the fact that iu order that the digestibility of each par- ticular food material may be determined with certainty, it must not be mixed with other materials. Hence the diet during- the experiments must be so plain and simple as to make it extremely unpalatable. An ox will live contentedly on a diet of hay for an indeiinite time, but for an ordinary man to subsist a week on meat or potatoes or eggs is a very different matter. iS"o matter how palatable such a simple food may be, at first, to a man used to the ordinary diet of a well-to-do community, it will almost certainly become repugnant to him in a few days. In consequence, the digestive functions are disturbed, and the accuracy of the trial is impaired, a fact, by the way, which strikingly illustrates the importance of varied diet in civilized life. For instance, in one of a series of experiments conducted in the physiological laboratory at Munich by Dr. Eubner, the subject, a strong, healthy Bavarian laborer, lived for three days upon bread and water, a diet the monotony of which was much more endurable than one of meat or fish, or almost any other single-food material would have been. He was able to eat 1,185 grams of bread per day. This contained 670 grams of carbohydrates, mainly starch, of which only about 5 grams, or a little less than 1 per cent, escaped digestion. In this case, therefore, about 99 per cent of the carbohydrates of the bread was digested. The bread contained 81 grams of protein, of which 13 i)er cent was undi- gested and 87 per cent digested. The quantity of fatty matters in the bread was too small to permit an accurate test of their digestibility. In another series, conducted by the writer in the same laboratory, the digestibility of meat in the form of beefsteak, and of fish (haddock), was tested. The subject, a medical student, consumed less than 2 Ijounds of meat per day, and though it was cooked with butter, pepper, salt, and onions, so as to make it to his taste, " extraordinarily well flavored," it was very difficult for him to swallow it the second day, and required still greater effort the third. The digestion, however, seemed to be normal, and all but about 1 per cent of the protein was digested. Other trials with meat have brought similar results, and it is reason- ably safe to say that when a healthy person, with sound digestive organs, eats ordinary meat or fish in proper quantity, all or nearly all of the protein is digested. Some of the fats of meat, however, seem to fail of digestion. The number of actual exi)erimeuts of this kind is very small . linearly all have been j)ublished within the past fifteen years. The majority have been made in the physiological laboratory of the University of Munich, of which Yoit is the director. Most of the subjects have been men with healthy digestive organs, two or three laboratory servants, a soldier, several medical students, and a few others. Several have been made, however, with children of a few families. All but a very small number have been conducted in Germany. 56 CHEMISTRY AND ECONOMY OF FOOD. HISTORICAL SUMMARY. Observations upon the quantities of uutiieuts digested from a mixed diet were made by Beiieke in 1854; the earliest publication of the results that has come to our notice appeared iu 1878.^ Raulie,^ in 1862, pub- lished accounts of quantitative tests of the digestibility of meat, but the duration of his experiments was iu each case only one day, and the methods of separating the undigested residue from that of the food taken before and after the experiment had not been well elaborated at that time. In 1870 Weiske^ published a careful study of the digesti- bility of crude fiber by a man with a diet consisting of cabbage, tuberous-rooted celery and carrots. Very little has since been done uiDon the digestibility of crude fiber by man. A large amount of valuable work upon the digestibility of different food materials by men was carried out by Eubner* in the Munich physiological laboratory and published between 1879 and 1882. The subjects were a laboratory servant, who was a strong, hearty, rather stolid man of the laboring class, a soldier, and several students and assistants in the laboratory. All, or nearly all, Avere Bavarians. Bread, meat, milk, eggs, and numerous other articles of food were studied and full details were i^ublished. During the past ten years inquiry iu this direction has been somewhat active. Such staples as bread, meat, and milk have naturally received a large share of atten- tion from many investigators. Besides Eubner, who has worked with all three, Prausuitz and Meyer have done much with bread ; Ranke, Atwater, and Malfatti have reported results with meat ; Atwater with fish; Camerer and Uftlemann with milk; and A. Mayer with butter and oleomargarine. Brief results of some Japanese work have been pub- lished but with no details as to method. Among the latest and best investigations in this line are those by Prausuitz in Yoit's laboratory, in Munich. We have found accounts of some 150 digestion experiments which seem accurate enough to be used for statistical inferences. They have been collated in tabular form and from them the selections in Table 11 have been made. Of the total number, 114 have been made with men, 5 with women, and 13 with children from 6 weeks to 14 years of age. Fourteen of the tests were made in Italy, 12 in Holland, and 3 in Japan ; the rest were made in Germany. A number were made in connec- tion with studies of dietaries ; such were those iu Table 11, numbered 39, 40, 41 and 42. EXPERIMENTAL METHODS. The real question to be considered in such a study is. What pro- portions of the several classes of nutrients are actually digested from 1 Ziir Ernabrungslelire des gesnuden Menscheu, 1878, 299. * Konig, Chein, d. meusch. Nalir. uud Genuss., I, 1889, 37. 3 Ztschr. Biol., 1870, 456. 4 Ibid., 1879, 115; 1880,119. THE DIGESTIBILITY OF FOOD. 57 ditferent food materials by persons under normal conditions as to food consumed, luibits, and liealtli ! Two methods are commonly used for the study of this question, those of artificial digestion and of actual digestion experiments. The experiments on artificial digestion are made by treating the materials with solutions containing digestive fer- ments, as pepsin and trypsin. The most valuable work in this line has been done by Stutzer^ and others. The experiments on actual diges- tion- are made by letting the subject, man or animal, consume a certain amount of food of known composition and couiparing the quantities of water-free substance, protein, "ether extract," ash, etc., of the food and of the undigested residue, the difference being taken as the measure of the amount of the several ingredients digested. The exx^eriments witli artificial digestion are at best only a inore or less close imitation of a natural process. The value of this kind of inquiry is beyond question, but much further elaboration of details of reagents and manipulation is needed to make the method satisfactory for accurate measurement of the actual digestibility of food materials by either men or domestic animals. The only reliable method now available for determimng the digesti- bility of food by man is direct experiment with x^ersons under different and well-defined conditions. Even by the use of this method we are not sure of absolutely accurate results. The chief difficulties are three, (1) theiuaccuracy of the present methods of analysis of food and excreta; (2) the difficulty of distinguishing between the metabolic products and the residues of undigested food in the feces, and (3) in case of mixed diet, the impossibility of distinguishing between the undigested residues from the different materials and the effect of one food material upon the digestion of another. The digestion of different food materials in a mixed diet has received some considerable attention recently from Prausnitz.^ As he points out, there are three possibilities: either (1) each food digests as if it were used alone, or oue is (2) hindered or (3) helped in digestion by the presence of the others. The question is a very important oue. Another question, and one which demands more attention than it has received, is the effect of the methods of cooking upon the digestibility of food.* Very little accurate experimenting has been done in this especial field. METHOD OF QUANTITATIVE TEST OF PROPORTIONS OF NUTRIENTS DIGESTED FROM FOOD BY MAN. The method ordinarily used for testing the quantities of nutrients actually digested is, in substance, the following: The subject and the diet having been determined upon, samiDles of the food actually eaten iLandw. Vers. Stat., 1889, 331; Z^stclu•. pLysiol. Clieni., IX, 211; XI, 207, 529. ^Ztschr. Bio]., 1879, 115, etc. 3 Arch. Hyg., 1893, 626. ^Ki3uig, Cliem. d. meusch. Nahr. nud Gennt■ Ol CO 00 '6 ■* eq cocj CJ CO co co HO ; 1 a •sojtj.ip.OioqjTJO f^ : ; I !«> *^ ^ C-l CO IM CO . ■ .-l" t~ r-i lO rH in CO 00 tH in t^ CO I 'l~ a •■;oc.i)xo.i.n[43; o CO oi in ^ 1 ? •g in 00 -i) OK! c-1 03 in ^ M CO t- CO t- Til c^ o- X COCl bX) ■nogo.ijiti ic^oj. • IM !M r-t ;i;Al • ■* lO (M ^ r)l -* in t- 1- OS XCO Xin -310 Mt- c-os goo ■M CS ■Hot- t- Cl i m m CI x^ ••qsy g C-i .-O iH (N <3 -Til r-l O) 00 t- • Cl in t- CO o 05 •S3Ji;.ipA'll0q.Tl!3 8 o <3 »OTd OJ (N T^t- in c- X ■CO ■!;01!.I!JX9 .19ll^a: co in -d> iHin CO • in o S ;5 g !•! rH ^ S c: CO CO i-H a CO CO OS [~ '3 ■uo.oOJtin lu^ox |rHrH iH i-H •CQ Cl d Cl CO tJO Cb M « ?] r^ -# 00 cocn -* 03 • in Cl in COX •8onc}s g C-; c-; vn CO O — -* in rH in • CO 3 ■qtiS9ci.u-ja;i!j\i^ X-. CJ Cl ^ TtHOS O o; CO!M CO • OC • CO CO d iH •ooni;}S s; ifi --\ :3 oi • t- .CO => . in ^ g := lo (M CO CO CO 5 t>; -i) ?-i CO CO ■M -# 00 't in Oi ^ CO t~ •iiey S X uri r4 CO 00 o t- -r^ ^ e,Hr-l ^ <-^ O i-H Cl rH CO 5 « • . T*^ CO 00 Cl ^ ^ •eo;«.Tp.Ciioqjvo s 8 • • CI rt C3 • • C ~. -1 • ■ .-H CO CO a a X d 03 osca 05 in -!)( r- CO .- C~ 33 CO X •■|0i;jjx3 Jaq;a c ?i ca Tti o S = S S ;^ S o O ^ T-H " rH « o'^ oc 00 CO in ■ CO t- -f CO CO ,H CO ■ in I CO OS in •naSoi:nn ib:>ox g Co' C: r-l go' ; lo = in o CO ■^ Cl r-iiH rH s t- . o ^ s:=i !5 : M =0 00 -:*< I> CQ ' CO ^ t- 00 -* t fH • CO r~t t- •o.xre^s g •-£) CO CO rA • CO L- in -f o OJ yA -qiiKOO.ij-.i.):iUA\. ^ CO CO rH (M ' 3 o s 5 s ■3 o o J^ - • o o ."a o s a "■ = /4 " t a: c5 Ti kjr ^ -^ r- ' » a> <^ .- = ^ » ■ u c; cs i: 5 3 C3 o O « .sqpq ilfsH 3 ^ p ?: "^ coco -*CO i CO •:>n9 llTJ9ttX9 JO aC^Bd 00 OO OOCO - 00 t^ C~ X 00 . X X a. X . X 00 i X I OS cs X •'^m (lurjodxa jo -o^ IH M CO tH lO cc t- X =-. =J ,H Cl r-l T* in CO S 00 OS § 62 CHEMISTRY AND ECONOMY OF FOOD. •qsy lo in id 05 CO lO O "^ 00 o »o OS •S9:;i3jp.f[[oq.i'BQ . cc irj iri ITS CO ^ •ijoBJ'jxe aaq^a; ■to Tt< rH »0 CO OS in . CO :d CO t-^ CO CO ->J< C- CO (M rt CO* CO c-i CO CO iHooco in C-i (XP 05 t^ ■rjt in iH •ngSoaijta its'^oj, CO CO in CO O OCJ tH l--^ -qii8 99 Jj-jott; A\ (X|i CO O 00 -TjH •t[SY 00 5D t> CO oi o t-^ i> •89[;i3jpjfqoq.i'B3 •q.ot'J':^x9 a;ot[;a[ •aegoj^in p'jox «in -* S . . ■> (MC^ -* CO t-r-l lO n' S^' 1-J -qns 99.IJ-J9 j-ii M SS OD C- .-I 6 r-l!N in -*coo-i ■qne ijsgj^g; •qsy 05 "^ CO 00 t-^ 00 r-J t^^ •sg^uap.CqoqauQ •:}0BJ!fX9 J9q'ja[ =0 OS ^ in •ngSoj^iu Tis^jox e r-l o m CO ^ t^^CO 00 ^ •90UT!'JS -qns 99JJ.-J0'.]'B^ 55 r-H 05 INOSC- -d^ o ci ■■* O: -i< ^ o ^ in i> i> ;9on'c^s ■que qs9J^ CO CO O C5 r-i -^ CD C^J f- C<] in CO 00 03 « S : g cSCl C .CQ s^-^ .^£ ' fc/J © I £ OJ rt CD. m iC ^^-^ fH O 00 05 O ^H CCI CO (M(MffQ <^1 (N(N IM iM ITQCOCOCIJ CO THE DIGESTIBILITY OF iOOD. 63 r-i a IS 0> in • 1 . CO CO CO ■ bJD = m o 3 6 "c3 a o o o g 3 00 s« o i 1 1 CO 00 CO rH 00 o» TO CO o •* .0^2; 1-H "—DC CM 2 ^ CI CO »^ ^ C5 IT 00 35" . ( I;- ^ cog; o' 'Oi ^ - ^T.^ ~ CO - s r^ i-H ,* Qo :i ' _; .-^^-SS. CS ^ : O v'J- .. ^ S^ 00 .• o roo"^S -'JO is . t;3 "■" tt:Q o . S5 CJ-S — '-' 0,5 -• ?='^a-3 5-52^ r^ £s^^ c c^: .— I-^1-lr^c<^l^^^^^c^^c^o:>cQcO'Ti^■^T3« 64 CHEMISTRY AND ECONOMY OF FOOD, Table 12. — Crude fiber {cellulose) di[/estedin experiincnfs with men. 1886 1886 1869 1869 1886 1892 1892 1892 1892 1892 1892 1892 1892 1892 1892 1892 Food used, (quantitica per daj' in grnms). Potatoes, 1,700 grams ; fat, 100 grams ; beer, 500 cubic cen- timeters ; gluten, 200 grams Potatoes, 1,700 grams ; fat, 100 grams ; Ijeer, 500 cubic cen- timeters Celery, cabbage, carrots, total 1,050 grams Celery, cabbage, carrots, total 8S:i.3 grams Bread, fruit, dry fruil, oil, total 1,802 grams Bread, fruit, dry fri^t, oil, total 1,764.8 grams Kico and barley, .salted radish, vegetables, total 2,150 grams llice, salted radish, vegetables, etc., flsh, total 1,800 grams. 1-iice, salted radish, A-egetables, etc., meat, total 1, 500 grams Wheat and rye bread (with yeast) 1,000 grams Wheat an I rye bread (with yeast), 900 grains Wheat and rye bread (leavened), 1,000 grams Wheat and rye bread (leavened), 900 grams Decorticated' (entire) rye bread (with yeast), 1,01)0 grams . Decorticated (entire) rye bread (witii yeast), 900 gr.ims. Decorticated (entire) wheat bread (with yeast), 1,000 grams Rye bread (with yeast), 1,000 grams Rvebread (with yeast), 900 grams Wheat bread (with yeast), 1,000 grams Wheat bread (with' yeast) 900 grams 139 117.8 719 092. 5 523. 8 615.7 580.1 010. 3 554.6 019.1 557.2 617. 3 582.6 6-10.8 023 570 010.2 570. 1 Cruking the connective tissue of some of the tougher meats is disintegrated. The collagen which serves as the bind- ing material is changed to more or less soluble gelatin, the meat is made tender and can be chewed more finely, the further disintegration in the alimentary canal is facilitated, and the proteids and fats are more per- fectly exposed to the solvent action of the digestive juices. The following remarks of Professor Chittenden bear directly upon this subject:^ More important from a dietetic standpoint is tlie efi'ect of cooliing or preparation of proteid foods on their digestibility, and in this connection it mnst he remembered that digestion in the broad sense of tlie word is a complex process, dependent npon tlie harmonions woi-lving of several closely allied processes. By way of illustration it may be mentioned that a given food stnff may owe its lack of digestibility either to an inherent resistance to the solvent action of the digestive juices or more directly to the fact that its ingestion fails to cause the requisite flow of the necessary digest- ive secretion. Now, one of the effects of cooking is to improve, or rather develop, an agreeable flavor in the food, thus increasing its palatability and causing a pleasurable stimulation of the sense of taste. This at the same Time leads to a greater outpouring of the needed digestive juices, thus furnishing the means for more rapid and complete digestion. Farther, the very increase in palatability incidental to proper and intelligent cooking leads to a more thorough mastication of the proteid food, while at the same time the cooking tends to facilitate its separation and mechanical subdivision. This latter, as already stated, greatly aids the digest- ive process by enabling the different digestive secretions to come into more intimate contact with the individual particles. This tendency toward disintegration and general softening incidental to cooking is due mainly to the complete or partial hydration of the connective tissue fl^bers by which the muscle tissue is held together into gelatin, which is far more readily digestible and assimilable than the collagen itself. In all methods of cooking meats, as indeed all forms of proteid food, whether by boiling, roasting, or broiling, the proteid or albuminous matter undergoes more or less complete coagulation. This, howcA^er, is essential in any process of cooking by which a rich and appetizing flavor is to be developed, and if not accomplished at too high a temperature offers no obstacle to easy digestibility ; indeed, it has already been stated, owing to the conversion of the collagen of the surrounding connective tissue, digest- ibility maybe even increased. At the same time, it is well to remember that raw beef, for example, if very finely divided by chopping, is somewhat more easily dis- solved by the gastric juice than when coagulated by cooking. All things considered, however, proper cooking unquestionably tends to increase the general digestibility of i)roteid foods. At the same time it alters the consistency and constitution of the food stuff, joining to it an odor and taste which would otherwise be wholly lacking, and, no less important, causes the destruction of disease germs or other related organ- isms possibly present. The many methods of preparing proteid foods for consumption need hardly be con- sidered here; they have little bearing on the direct digestibility of the various food stuffs, except so far as they modify the degree of coagulation of the proteid matter, the mechanical subdivision of the tissue, and the removal or addition of admixed fat. More important, however, is the indirect effect on digestibilty incidental to the degree of palatability produced, with the corresponding degree of stimulation of the secre- tory processes by which digestibility is so greatly augmented. ' Loo. cit. THE DIGESTIBILITY OF FOOD. 75 Palatability and digestibility go hand in liaud, and the intelligent preparation of a so-called cheap or tough piece of meat, for example i may result in as digestible and nutritive a product as the more careless preparation of a piece of tenderloin. Some iuteiestiiig experiineuts upou the rapidity of digestion of meats, cooked aud uncooked, and of milk in various forms, liave been con- ducted by Jessen at Tiibingen.^ They were made by the methods of artificial and natural digestion, those of the latter kind being per- formed with a dog and with a man. To test the effect of cooking lean beef, portions were finely chopped and the tendons and other connective tissue were separated as com- pletely as practicable, Tlie material thus prepared was divided into several parts. One part was left raw, others were boiled, and still others were roasted. Of the boiled and roasted portions some were rare, or, as Jessen calls them, "half done," and others well done. The raw, lialf-done, and well-done portions were tested by artificial diges- tion with pepsin, by experiments in the stomacli of a dog, and by experiments in the stomach of a healthy man. In the experiments by artificial digestion the meat was placed in glass tubes, an acid solution of pepsin was put upon it and the tut)es with their contents were kept at about the temperature of the body for 24 hours, with occasional stirring. With the dog a fistule was used consisting of the usual metal tubes, permanently inserted through the skin into the stomach, aud opened or closed with a stopper at will. The meat was inclosed in a cloth, inserted through the tube, and removed after the desired time. In the experiments with the man, a laboratory .servant, the food was taken into the stomach when the latter was empty, and after diges- tion for the desired time, withdrawn by a stomach pump. The results of the experiments of the three kinds were essentially concordant. The raw meat was digested more readily than the cooked. In the trial by artificial digestion the residues unaltered by the pepsin were small- est with the raw meat and largest with that which had been most thoroughly cooked by boiling or roasting. In those with the man the digestion was completed in different lengths of time as set forth in the figures of Table 15, herewith. Similar trials were made with other kinds of meat and with milk. The results of the experiments with the man are summarized in Table 15. Table 15. — Eelative time recpiired for digestion of coolced and uncool-ed foods in a man's stomach. MEATS. Beef: Fours. Eaw 2 Boiled, half don e 2i Boiled, Avell done 3 Roasted, half done 3 Eoasted, well done 4 Mutton, raw 2 Veal, raw 2^ Pork, raw 3 iZtschr. Biol., 1893, p. 128. 76 CHEMISTRY AND ECONOMY OF FOOD. MILK. Cows' milk, 602 cubic ceutimcters : Hours. Uncooked 3^ Boiled 4 Sour 3 Cows' milk, 675 cubic centimeters, skimmed 3|- Goats' milk, 656 cubic centimeters, uncooked 3^ It will be seen that the raw veal required somewhat longer time for digestion than the mutton, and that the pork, which doubtless con- tained a larger percentage of fat, was still slower in digestion. The boiled milk was digested somewhat more slowly and the sour milk a little more quickly than the uncooked milk.^ It should be insisted that the experiments of this kind, of which the number on record is small, do not suffice for satisfactory generaliza- tions. They can not be taken as exact .measures of the degrees of digestibility of the different materials. It should be born in mind, fur- thermore, that they apply only to what takes place in the stomach; while the normal process of digestion goes on in the intestines after the food has left the stomach. At the same time, these results are the more worthy of confidence because they accord with the chemistry and his- tology of the subject. It is a familiar fact that tough meats are made tender by long heat- ing at a comparatively low temperature. The best explanation of this is, perhaps, to be found in the disintegration of the connective tissue with the formation of gelatin. Unquestionably the principle is an important one in its practical applications. Vegetable foods often require cooking to fit them for use. This is especially true of starchy foods, .such as wheat, corn, beans, peas, and potatoes. The starch is contained in cells, the \s^alls of which are acted upon comparatively slowly by the digestive juices. By cooking the cells are disrupted and the starch itself undergoes more or less of a chemical change, so that it is more easily and completely acted upon by the digestive ferments. • EFFECTS OF FOOD ADJUNCTS ON DIG-ESTION — FLAVORINa MATERIALS. A great deal has been said, much has been written, and a small amount of accurate experimenting has been done upon the effects exerted upon the digestion of food by food adjuncts, sucb as spice, mustard, and other flavoring materials; beef tea and meat extract; tea, coffee, choco- late, and similar beverages, and alcoholic drinks. Professor Forster, in speaking of what the Germans call " Genussmittel" — appetizers is perhaps the nearest corresponding word in English — the materials which are taken with food either for their own agreeable flavor or to 'See summary of later experiments on the digestibility of milk in Experiment Station Record, 5, pp. 959, 960. THE DIGESTIBILITY OF FOOD. 77 improve the flavor of the food aud which are often supposed to help digestion, says in substance, as follows : ^ There is uo doubt that the human digestive apparatus can be excited to activity in varioxis ways with Gcnnssmittel, inchiding such as are used by man in a refined civilization, at the beginning and end of his meals, e. g., meat broth, salt and salt condiments like caviar, cheese, etc. * * * We know that when brought iuto coutact with the mucus membraue of the stomach and intestines of a living animal, they cause the filling of the blood vessels and secretion of the digestive juices. Sugar and salt are hardlj^ brought iuto the mouth before tliey excite abnndaut eff'usion of saliva. Indeed, the same effect is produced even by the sight or smell of savory foods, aud some of the well-tasting substances may act upon the digestive apparatus aud its glands hj simply being taken into the blood circulation. Thus, I have observed experimentally a rich secretion of gall after an injection of a solution of sugar into a vein (vena mesenterica). * * * It is very natural to infer from this that the work of digestion will go on better with the aid of such condiments than without them, in two ways : Either moi'e nutriment might be digested from the same food, or, if there were no increase in the amount digested, it might be digested more quickly Avith their help, which would likeAvise be a gain. * ^ * But, important as this may seem to physiologists, it is of minor conseqnence with healthy persons. Thus, in experiments made with a man nnder my direction, when meat had been treated with water [to remove the ''extractives" which give meat its flavor and which are the chief constituents of beef tea and meat extract] and was so tasteless as to be eaten in any considerable quantity with difficulty, the quantity digested and observed to pass into the circulation was as large as with the same weight of meat roasted in the ordinary way; and both Bischoff and Hofmanu have found that meat extract taken with bread or with a mixed diet did not materially affect the digestion. And in experiments by Fliigge with a mixed diet so tasteless as to make it, when continued some time, extremely repugnant, so that great effort was required to eat it, the digestion seemed to be iinaff'ected thereby. For the sick and convalescent, on the other hand, the effect of these appetizers upon the digestion is of great importance, especially where the digestive apparatus has been for a time more or less inactive aud requires stimulating. Thus the observations of Kemmerich show the usefulness of bouillon and meat extract in case of enfeebled digestion. In the case of the ore, there must be plenty of acid or it can not dis- solve. If the supply of digestive juices is iusufncient the food can not digest. The chief use of these food adjuncts would seem to be to stim- ulate the production of digestive juices. The results of later experi- mental inquiry and tb e teaching of the most reputable physiologists seem to be in line with the experiments here quoted. It would thus appear that while the materials which we call appetizers may often be very helpful where digestion is enfeebled, they are, for healthy people, unnecessary and without very great effect upon the utilization of food in the body. This subject, however, is one upon which we should speak with tlie greatest caution. In the present state of experimental knowledge categorical assertions are hardly justifiable. It is easy to cite statistics upon the quantities of nutrients digestible from different food materials, but all discussion of the effects of condiments, stimu- 'In the volume ou Eruiihrung uud Nahrungsmittel, of Pettenkofer and Ziemssen's Handbuch der Hygiene. 78 , CHEMISTRY AND ECONOMY OF FOOD. lants, and cooking upon ease or time of digestion — and these are the most essential tilings from the hygienic standpoint — must be of that general and indefinite character which is most unsatisfactory to the careful student and investigator. As to the effect of the quantity of food upon the proportions digested, tlie experiments at hand seem to point to the interesting conclusion that when a moderate amount is taken it is digested more completely than a very large, or, at times, even a very small quantity; so likewise a moderate amount of water taken with the food seems favorable, while too much has been found to interfere with digestion. As to the effect of moderate exercise just after eating, observations differ, some experiments indicating that muscular labor retards digestion, others that it does not. During sleep digestion has been found to be dimin- ished. But the conditions upon which a proper answer to such ques- tions depends are so complex and the definite knowledge is so limited that their discussion is neither easy nor agreeable. SUMMARY. In considering the digestibility of food we have to take into account (1) the quantity digested, and (2) the ease and time of digestion. As regards the quantities digested from reasonable amounts of ordinary food materials by healthy i^eople, the besfc experimental evidence indi- cates that: (1) The protein of our ordinary meats, fish, and milk is very readily and completely digested. The protein of vegetable foods is much less completely digested than that of animal foods. Of that of potatoes and beans, for instance, a third or more may escape digestion, and thus be useless for nourishment. (2) Much of the fats of animal food may at times fail of digestion. This is presumably true of vegetable fats, but the quantities are in gen- eral so small that the determinations of the proportions digested are not very accurate. (3) The carbohj^drates, which make up a large part of vegetable food, are in general very digestible The crude fiber or cellulose is an excep- tion, but the quantities of this in the materials used for the food of man are too small to be of importance. Sugar is believed to be completely digested. This is assumed to be the case with the sugar of milk. The other carbohydrates of animal foods are very small in amount. (4) The animal foods have in general the advantage of the vegetable foods in digestibility, that they contain more protein and that their pro- tein is more digestible. (5) The quantity digested appears to be less affected by flavor, flavor- ing materials, and food adjuncts, and to differ less with different persons, than is commonly supj)osed. Concerning the relative ease and time of digestion of different foods, and consequent comfort and health, the lack of accurate experimental THE DIGESTIBILITY OF FOOD. 79 data renders it more dililcult to uiake concise statements. Coolsing and other conditions are very important. Very much depends upon the individual peculiarities of different ])eople. SUGGESTIONS AS TO EXPERIMENTAL WORK NOW NEEDED. To promote a better understanding of the digestibility of different kinds of food by different individuals several Hues of inquiry need to be prosecuted. They have to do with: (1) Artificial digestion. {a) Improvement of methods. (h) Actual tests of digestibility of different materials. (2) Actual digestion. (a) Investigation of metabolic products, their occurrence, nature, and amount. (&) Improvement of methods. (c) Systematic series of experiments on digestion. Artificial digestion. — Concerning the experiments upon artificial digestion, it will suffice to say that what is now most pressingly needed is (1) a compilation of the results of inquiry already obtained, and (2) the elaboration of the methods of inquiry. These methods have, indeed, been worked out with no small degree of success, and it is now possible to make artificial tests of digestibility of various kinds of food materials the results of which agree tolerably well with the results of digestion tests by healthy men. But the conditions which affect diges- tion by the two methods are uot yet well enough understood and the results by the artificial method as carried out to-day do not bring entirely accurate indications of the actual digestibility in the human organism. Of course similar remarks may be made regarding the artificial diges- tion of feeding stuffs and their natural digestion by domestic animals. The whole subject demands careful inquiry and promises most valuable results. Actual digestion. — In experiments upon natural digestion by man, aside from the intrinsic difficulty of working with individual food mate- rials, which become speedily distasteliil and can not be endured by the average man for a very great length of time without danger of inter- ruption of the normal digestive functions, the chief obstacle to the getting of accurate results is found in the metabolic products. It is greatly to be desired that investigations be made to learn more defi- uitely what these materials are and in what quantities they are secreted under different conditions as to the characteristics of the individual and the kinds and amounts of food eaten. Eeference was made above to exxDeriments in which this subject has been studied. More inquiry is greatly needed. The investigations might be carried on some such j)lan as the following : Suppose the question be, How much metabolic nitrogen will be excreted by a person of a given class, e. g., a healthy man, with a given 80 CHEMISTRY AND ECONOMY OF FOOD. amount of food'? A ration may be planned wliicli shall consist mostly of fats and carboliydrates and shall contain only enough nitrogenous material to make it i^alatable. The nitrogenous material may consist of a material, like lean beef, which has been found to be almost, if not quite, completely digestible. The quantity of undigested nitrogen in such a ration will be extremely small and its amount can be estimated approximately from the experimental inquiry already made, and still more accurately if further investigations of the digestibility of meats accumulate. From the whole nitrogen excreted by the intestines that of the undigested residue can be subtracted and the remainder taken as the measure of the metabolic nitrogen. Of course it is desirable that the nitrogenous compounds in the excreta be separated and studied as far as practicable. In like manner the quantities of fat, or, more properly speaking, ether extract, in the metabolic x)roducts may be approximately deter- mined. For this purpose it is desirable to devise a ration consisting mainly of protein and carbohydrates with a minimum of fats and other materials which would be extracted by ether. The nature as well as the amount of these compounds in the food can be studied. Pains can be taken to be sure that they are in as digestible form as possible. The quantity of ether extract in the undigested residue will thus be reduced to a minimum, and some information as to its nature will be had in advance. The ether extract in the excreta can then be determined quantitatively and qualitatively. Comparison of the extracts in the food and excreta will throw light upon the nature and amounts of ether extract in the metabolic products. Of course other reagents than ether might be used for the extractions. " Ether extract " is here referred to because ether is the substance most commonly used in our present method of analysis. The above suggestions indicate in a general way the manner in which the metabolic products can be studied. Of course the individual investigator will decide upon the details. It is, however, to be hoped that some cooperation between investigators in this line may be brought about. Meanwhile it is possible to make tolerably accurate determination of coefficients of digestibility by tlie methods now in vogue. The quanti- ties of metabolic products can be roughly estimated and allowance made for them in the summing up of the results. The time is ripe for a systematic series of experiments on the digestion of our ordinary food materials — meats, fish, eggs, milk, butter, cheese, bread, crackers, and other substances made from cereals, and potatoes and other vegetable products. It would not be difficult to plan such a series of experiments and to carry them out successfully, especially if the cooperation of a number of investigators could be secured. CHAPTER V. PREPARATION OP FOOD— COOKING. What lias just been said regardiug the effects of cooking upon diges- tibility covers only a small part of the ground which needs to be trav- ersed. Among the specific questions which neect investigation are the temperature best adapted to the cooking of different materials in dif- ferent ways — as roasting, frying, boiling, steaming, and stewing; the chemical changes involved in the process; the loss of nutritive mate- rial in ijreparing it for use; the effects upon flavor, palatability, and increase or decrease of digestibility. This represents a wide and useful field of inquiry, which is almost unexplored. How little is definitely known of this subject is illustrated by the fact that in the work of Konig on the Chemistry of Foods and Food Adjuncts, which is by far the most complete treatise upon this subject available, and which con- sists of two volumes, of nearly 2,600 royal octavo pages, only nine pages are given to the cooking of food. This chapter is, however, so inter- esting that the substance of it is given below. PREPARATION OP FOOD — KONIG'S SUMMARY OF INVESTIGATIONS.^ Uncivilized man takes his nourishment like animals — as it is offered by nature. Civilized man prepares his food before eating, and in ways which are, in general, the more perfect the higher his culture. Tbe art of cooking, when not allied with a degenerate taste or with gluttony, is one of the criteria of a people's civilization. The chief advantage of the preparation of food for eating is to facili- tate digestion. This is accompanied by (1) adding condiments and giving it an agreeable appearance, so as to make it more appetizing, and thus increase the secretion of the digestive juices; (2) by loosening its texture and exposing it more fully to the solvent action which is the essential part of digestion. EFFECTS OF CONDIMENTS UPON DIGESTION. Flavoring materials and an agreeable appearance do not increase digestion directly, but act rather upon the nervous system, which, in turn, transmits the stininlus to the digestive organs and incites them to greater activity. While this may be helpful, it does not necessarily increase the amount actually digested from tbe food. Meat that has 'Chemie der menschliclien N;ilirungs-und Genussmittel. Von Dr. KGnig. Dritte Anflaaie; II, Band, pp. 138-139, 605-611, 1244-1252. 81 8518—^0. 21 6 82 CHEMI8TRY AND ECONOMY OF FOOD. been extracted by water and made entirely tasteless lias, according to Foster and E-ynders, been found in actual experiments to be as quickly and completely digested as an equal weight of meat roasted in the ordinary way; and the same is stated by Fliigge to have been the case with a mixed diet so tasteless as to be repulsive. The principal condiments that influence digestive secretions are salt, sugar, alcohol, and spices. Salt increases the flow of saliva and of gastric juice, hence one value of its use at meals in side dishes like caviar, olives, and pickles. The salting of food is so indispensable that salt is in some regions consid- ered a necessity, and the lack of it has been a cause of war. Sugar is very agreeable to the palate, and the niei-e thought of it often makes the mouth water; in other words it causes the secretion of saliva. Doubtless the flavor is the chief cause of the great demand for sugar, for although it is a valuable aliment, it hardly surpasses starch, dex- trin, and other carbohydrates in nutritive value. Alcohol. — Taken in moderate quantities in such forms as cognac, brandy, wine, beer, and other beverages, alcohol is likewise an impor- tant stimulant to digestion. Brandy, whisky, sherry, and the like are therefore favorite remedies in disturbances of the bowels and stomach, and this helps to explain why the poorer classes, who often live upon a wretched diet of the less digestible foods, such as coarse bread and potatoes, have a craving for strong and stimulating alcoholic drinks. It is the improper and excessive use of alcoholic beverages which makes them a scourge to man by weakening his digestive apparatus and undermining his general health. At the same time it should be said that sugar and alcohol, until they are absorbed by the system, hinder, temporarily, the actual process of digestion, at least in the stomach. After their disappearance from there the digestion goes on more vigorously than if they had not been taken. The influence of carbonated waters and salts is often very beneficial. Spices, — Some of these act directly upon the glands which secrete the digestive juices, as is the case with pepper, wliich contains piperin, and with mustard, which contains an oil that increases the flow of bile. Others first delight the sense of smell, which then stimulates the flow of saliva. Such are vanilla, cinnamon, and cloves. A similar influence is exerted by onions, parsley, and the like, which contain aromatic substances. Fruits, likewise, contain, besides aromatic oils, more or less malic acid, which directly aids digestion. Meat extract, tea, coffee. — These are stimulants, and, like wine and beer, excite more particularly the nervous system, and in so doing they are at times very useful. The stimulating agents in tea and coflee are alkaloids and essential oils; those in beer and wine are alcohol and fragrant ethers. Tea and coflee, taken in moderation, have no disturb- ing efl'ect upon digestion. PREPARATION OF FOOD. 83 EFFECTS OF COOKING UPON DIGESTIBILITY AND NUTRITIVE VALUE. Cookiug changes the texture of food, makiug it in some cases more and in others less digestible. In general, the digestibility of vegetable materials, as flour and potatoes, is increased, and that of animal foods, as meat, is diminished by cookiug, though there are exceptions. Cook- iug can not add to the amount of nutritive material in food, except in so far as it may increase the proportion which is actually digested; but it may, and often does, remove considerable quantities, as in the boiling of meats. We may consider the effects of cookiug under different categories, as the boiling, broiling, and roasting of meats, the boiling and baking of vegetables, and the baking of bread. BOILING, BROILING, AND KOASTING OF MEATS AND O'lHER ANIMAL FOODS. Boiling, as commonly understood, is heating in water. This is done generally with the water at or near the boiling point. But much cook- ing in water is done at a lower temperature, because the water is not always heated to the boiling point, and, more especially, because when meats and other materials are immersed in boiling water, as is usual in cookiug, the heat does not penetrate so as to bring the temperature of the interior up to that of the water. On the other hand, there are cases where, as in the preparation of gelatin, the water and the meat or bone or other material are heated much above the temperature of boil- ing water. Steaming is similar to boiling, the difference being that the material is surrounded by steam rather than water. Boiling and steaming effect four kinds of change in the food. (1) It is made more soft and tender. In meats the connective tissue is softened, weakened, and, to a greater or less extent, gelatinized and dis- solved, and thus the fibers of the meat are loosened. (2) Some material is made soluble. This is the case with the gelatinoid substance of meat as just stated, and especially with that of bone. By long boiling the albuminoid materials of meat are dissolved to slight extent. On the other hand, more or less of the albuminoids of meat, as the albumin and myosin, are coagulated and hardened by boiling. (3) Flavors are developed which make the materials, especially meats and fish, more agreeable to the taste, and hence tend to promote the secretion of digestive juices and thus aid digestion. (4) More or less material is dissolved out of the food by the water. When used for sou^) the dis- solved materials are well utilized, otherwise they are lost. Yaiious experiments' have proved that boiled, roasted, or smoked meat, for examj)le, is not as quickly and completely digested as raw meat. Our x>reference, then, for meat so prex)ared only shows how 'Chittenden and Cummins, Am. Cliem. Jour., 6, 318; M. Popoff, Ztschr. pliysiol. Cliem., 1890, 14, 524; A. Stutzer, Centbl. allgcm. Gesuudlieitspflege, 1892, 59; Jtisseii, see above, p. 75. 84 CHEMISTEY AND ECONOMY OF FOOD. much value we attach to the pleasing- tastes, odor, and physical con- dition of our food. The cooking of meats and fish in ''dry heat," by roasting, broiling, or frying, likewise effects several kinds of change. (1) The albuminoids are coagulated. The result of this generally, though not always, is to harden the fiber more or less and thus make the flesh less easily and comi:)letely digestible, especially on the outside. (2) Flavors are devel- oped which make the flesh much more i)alatable and tend to favor secretion of the digestive juices. Thus, while tlie heating tends to make the material less digestible, the eiiect maj^ perhaps be counter- acted in part by the x)roviding of more of the ferments which digest the food. (3) More or less of the juices of the meat are driven out by the heating. These commonly are saved in roasting-, but lost to a greater or less extent in boiling. When meats and fish are heated, whether in roasting, broiling, frying, or even boiling, much water is driven off. Boiling of meat. — Meat contains from 5 to 8 per cent of substances soluble in water, namely, all>nmen, meat bases (creatin, creatinin, sar- kin, etc.), organic acids, glycogen, inosit, and salts. When meat is boiled with water albumen is rendered insoluble and remains in the meat tissue, or j)roduces the scum floating upon the broth. Some con- nective tissue is transformed into gelatin and is dissolved j apart of the melted fat passes into the broth. In boiling meat two methods are employed; either (1) the meat is X3laced in cold water, which is then heated more or less slowly to boil- ing and kept boiling for some time, or (2) the meat is put into water already boiling. The results differ. In the first case the cold water penetrates the piece of meat and extracts more or less of the juices and soluble constituents ; upon boiling the albumen partly collects upon the surface of the liquid as scum. In the second case only a little of the soluble material is extracted. The albuminoids at the surface of the meat coagulate and form an impenetrable layer. This cooking i^re- vents the extraction of the soluble materials, and the inner parts are left more or less juicy. Consequently, to obtain a strong, nutritious broth, consomme, or soup, we use the first method, warming the water slowly, but if the boiled meat is to remain juicy and is to be eaten as meat, the second method is followed. This view is confirmed by experi- ments of A. Vogel,^ who found that meat cooked by gradual warming with cold water lost much nitrogen and gave a richly nitrogenous broth, while meat placed directly in boiling water retaiued its nitrogen and juice but yielded a poor broth. As a general thing, however, meat is not completely extracted even in making soup, and bones are often boiled with it to secure a strong broth. Von Wolff luigel and Hiippe^ have observed the temperature iu the > Chem. Centbl., 1884, 639. 2 Mittlieilungen des kaiserlichen Gesundlieitsamts, I, and Abst. iu Jahresber. Tiei. Chem., II, 1881, 441. PREPARATfON OF FOOD. 85 interior of cooking meat and found it always considerably lower than tlie outer temperature. In a piece of meat weighing 4.5 kilograms the interior temperature after four hours' boiliug was only 88° 0. The inner temperature of meat which was being roasted varied from 70 to 95° C, according to the size of the piece. When canned meat in large and even in small cans was kept in a salt-water bath at 102 to 109 ^O., the interior temperature of the meat rose oiil^^ to 72 to 98° 0., according to the size of the cans. This explains why large cans of meat always have more bad spots than smaller ones. The heat is not sufficient in the large cans to destroy the bacteria or other organisms that cause the meat to decompose. It may be ttiat the formation of an insoluble layer of albumen prevents the penetration of both the boiling water and the heat. Meat broth. — The quantities of ingredients in meat broth are illus- trated by an experiment. We boiled 500 grams of beef and 189 grams of veal bones in the ordinary (German) household way, and obtained a little more than half a liter (513 cubic centimeters) of strong broth or soup. This contained by weight: Per cent. Water ....1. 95.18 Total dry substance 4. 82 Nitrogen 19 Protein (N. X 6.25) 1. 19 Fat - 1.48 Extractives (carboliydrates, etc. ) 1. 83 Ash :.. .32 Potash 15 Phosphoric acid 09 Good broths may also be made from less meat and more water, by adding savory herbs to improve the flavors. A. Payen^ gives the fol- lowing figures for the materials used in making broths and the compo- sition of the broths as actually prepared from them: A. — Materials used for malcing meat hrotlis. • Meat. Bones. Salt. Ve.eeta- ble.s and spices. Water. Xo. 1 Gratns. 500 1, 433. 5 500 Grams. Grams. Grams. Grams. 1,500 Ko. 2 430 40.5 8 5,000 2,000 No. 3 32.2 B. — Percentage composition of meat iroths prepared from above. Water. Total dry residue. Organic substance. Salt. No. 1 Per cent. 9S.41 97.21 97.95 Per cent. 1.59 2.79 2.05 Per cent. 1.27 1.68 1.25 Per cent. 0.32 No. 2 1.11 No. 3 .80 SuLstauces Alimeutaires, 1865, 94-105. 86 CHEMISTRY AND E(5'0N0MY OF FOOD. It appears from these anal3^ses that the amount of solids in ment broths is generally small. Oonseciuently their strong taste and stimu- lating effect upon the nervous system nuist be ascribed to the meat bases, creatin, carniu, etc., and potassium salts. A bowl of nourisbing soup or bouillon made in the ordinary way — from 3 to 4 grams of meat extract with the addition of spices, egg, salt, etc. — contains only 4 grams of solids. Of these, 3.4 grams is organic matter, 0.34 gram nitrogen, and 0.8 gram is salts having about 0.3 gram of potash. Besides meat bases, sou]3S contain also more or less gelatin, varying directly with the quantity of bones used in the making. From the composition of bones such as occur in ordinary meat it may be esti- mated tliat 100 grams would yield by ordinary kitchen boiling: G-raris. Total dry substance 2.0 to 7.5 Nitrogenous matter 0.2 to 2.8 Fat 0.6 to 5.5 Other organic matter 0.1 to 0.5 Salts 0.1 to 0.2 After the meat has been boiled to make bictli it still contains meat fiber, part of the albumen, connective tissue, and fat, and if not com- pletely extracted, small residue of meat bases also. Boiling disinte- grates the fibers. This is the reason why boiled meat can be more easily chewed and is preferred to raw meat. Boiled meat. — -Of course boiled meat has not the same nutritive value as fresh raw meat. Aside from the fact that meat may be rendered less digestible by boiling, it also loses nutritive material. Dogs have died when fed upon meat which has been extracted by boiling. As it is chiefly the withdrawal of salt which makes the extracted meat an incomplete food, the restoring of the salts will increase its nutritive value and lessen its injurious effects. Meat which has been long boiled should not be used as exclusive diet without at least the soup which it has served to make. It should be remembered, however, that when the meat is put into boiling water at the outset, especially if it is in large pieces, it loses comparatively little nutritive material. Boasting, frying or broiling is a decidedly more rational way of cook- ing meat, since the juices are mostly, if not entirely, saved and the tissue and fiber are at the same time loosened by the heat, or by the steam and the fat vapors which the heat generates. In roasting and frying meat a crust is formed on the outside by the coagulating and hardening of the albuminoids. It is supposed that at the same time trifling quantities of carbon and nitrogen are driven off and a small amount of acetic acid is produced which dissolves some of the ingredi- ents of the meat. The fat undergoes apartial decomposition into fatty acids and glycerin, and a little of it is volatilized. The following analyses, made in Konig's laboratory, show the com- parative composition of specimens of fresh meats, boiled and roasted. PREPARATION OF FOOD. 87 Compavatlve composition of incatu hcfurc cdkI after coohimj. Beef: Before cooliing (raw) Same after bofliug Same after broiliijg (as beefsteak) Veal cutlets : Before roasting (raw) Same after roasting Water. Kitroge nous matter. Tar vent, 70.88 56.82 55.39 71.55 57.59 Per cent. 22. 51 a4. Vi 34.23 20.24 29 rat. Per cent. 4.52 7.50 8.21 6.38 11.95 K.xtractiv matter. Salts. Per cent. 0.8G .40 .68 .03 Per cent. 1.23 1.15 1.45 1.15 1.43 The water decreased by roastiiig aud boiling from about 71 to 57 iDer cent. But such analy-ses as these permit of iio accurate conclusions as to the other changes and losses by roasting. One trouble with them is the difficulty in obtaining perfectly homogenous pieces of meat with the same jDroportions of fat for the comparative tests. Furthermore, raw prepared meat dishes can not be compared exactly in composition with the same meats after they have been roasted or boiled or fried, because the fat added in the ordinary cooking of beefsteali, cutlets, or roasts alters the comx)osition of the cooked product. On the other band, cooking without fat Avould be abnormal, since precisely this addition of fat hinders the decomposing and volatilizing of other constituents of tbe meat. These considerations should be taken into account in com- paring the figures of the table herewith in which the figures of the pre- ceding table are recalculated to the basis of dry matter; that is to say, the water is taken out and the composition of the water-free substance is shown in each case. Comparative composition of ivatcr-free suhsfance of meats hefore and after coolcing. Nitrogen. Beef: Per cent. Before cooking 12. 37 After boiling.': 12. Go After roasting 12.27 Veal cutlets: Before cooking 11.39 After roastiuo- 10. 93 ibfitrogc- nous matter. Per cent. 77.31 79.06 76.73 71.17 68.36 Fat. Per cent. 15.47 17.38 18.41 22.45 28.18 Extractive miitter. Per cent. 2.98 .90 1.59 2.32 .09 Salts. Per cent. 4.24 2.60 3.27 4.06 3.37 These figures show, notwithstanding the objections just mentioned, that in roasting, as in boiling, some extractive matter and some salts are removed from the meat. The reason is that in the roasting, as everyone knows, a small part of the juice oozes out. To take the lat- ter as gravy with the roast is, therefore, entirely rational. Boiling of hones. — When bones are boiled more or less of their nitrog- enous cartilage (ossein) is converted into soluble gelatin. If the boiling is done under high pressure nearly all cartilage is removed from the bones, and after certain manipulations comes into commerce in thin, brittle, colorless tablets. This pure gelatin is used for making jellies, puddings, etc. Glue is impure gelatin. Soft and spongy bones yield most gelatin. Large, hollow ones are lii'oken into small i)ieces before extraction. 88 CHEMISTRY AND ECONOMY OF FOOD. Boiling of mill: — The object of tliis is to kill tlie bacteria in the milk aud thus for a time x)revent its souring. In the boiling a film forms on its surface, which consists of casein, and the peculiar odor given off is due to sulphureted hydrogen.^ Apparently no other important changes in composition take place; but E. Jessen^ finds,nevertheless, that boiled milk is less rapidly digested than raw milk. Boiling and baking of vegetables. — Vegetable foods are more difficult to digest than animal foods. Their preparation is therefore more com- plicated aud thorough. The nutritive substances are in- closed in cells, often with thick walls, and are not readily acted upon by the digestive iiuids. But when vegetables are boiled the cell contents expand and burst through the walls. The fra- grant and savory substances are set free with the other materials which have been inclosed in the cells, and their astringency and bitterness are tempered. Some of the constituents are dissolved by the water or suffer other change. Starch, an impor- tant ingredient of many vegetable foods, such as potatoes, wheat, rice, and oat meal, takes up water and assumes the soft, pasty condition which is necessary for its transformation into soluble dextrin and sugar. The boiling of foods, especially vegetables, may therefore be called a preparatory digestive process. The accompanying diagrams-' (figs. 2, 3, and 4) illustrate the differ- ences in the structure of the starch grains of the potato. jSTo. 1 shows the cell in the raw state. In No. 2 the potato had been boiled a half hour. The starch granules are swollen, but not enough to entirely fill the cells. In ISTo, 3 the potato had been well steamed and then mashed ; the cells are filled to distention and a number have burst open so that the starch, now an entirely amorphous mass, is considerably scattered. Cells from other plants behave like those of the starch-bearing tubers of the potato. The seeds of legumes, such as beans, peas, and 1 Schreiner, Aiutl. Bericlit. d. 50. Versammluug dentsclier Naturforscher und Aerzte, Miinchen, 1877, 218. Abst., Jahresber. agr. Chem., 20, 1877, 422-423. 2S.ee above, p. 75. ''Marcker, Studien iu der Spiritusfabricatiou. Fig. 2. — Cells of a raw potato, \rith starch grains in natiiral condition. PREPAEATION OF FOOD. 89 EltJ. 3. — Cells of a potato boiled in water one-half hour. lentils, .are, in tbeir natural state, difficult to digest, because tlieir starch granules lie closely packed within the indigestible cell walls. On boiling the starch swells, the cells burst open, their contents are changed into a pulpy mass which, when strained through a line sieve, makes a very nutritious and di- gestible dish. The pre- dominant constituent of the nitrogenous matter " legumin " is dissolved and made more digestible by the phosphate present ; but it forms an insolu- ble compound with, lime; hence these vegetables can not be boiled advan- tageously with hard water. Flour and starch iu their ordinary dry state are hardly fit for food for man. Cooking with milk or water softens and gelatinizes them sufficiently for making puddings, cakes, omelets, pies, macaroni, etc., but for cakes or bread a porous light dough is obtained by particular treatment with yeast or baking powder, as will be explained beyond. By the baking and roasting of starchy foods some starch is also con- verted into more assimila- ble dextrin, as in the hard, brown crust of bread, the surface of toasted bread, baked potatoes, and macaroni. Souj)s a ml so up m aling. — The following tables illus- trate the composition and nutritive values of some home-made soups. The data are from experiments in Konig's laboratory. The soups were made in accordance with the methods practiced in ordinarj^ (German) households, to wit: Pea soup, by boiling peas with smoked sausage and Fig. 4.— Cells of a imtalo \-,( 11 steauu'd and inaslad. 90 CHEMISTRY AND ECONOMY OF FOOD. straining off the pulp; potato soup, by boiling potatoes witli waste pork; bread soup, from pieces of bread, sugar, and water; farina soup, from barley farina and milk. Composition of soups {as made in German liowseholds). Pea soup . . . Potato soup Bread soup. Fariua soup Specific gravity. 1. 0540 1.0385 1. 0455 1.0415 Water. Per cent. 88.26 90.96 88.81 87.66 Nitrog- enous matter. Per cent. 3.38 1.37 1.25 2.44 Fat. Per cent. 0.93 1.55 0.16 1.48 Extractive matter (carbo- hydrates, ' etc). Per cent. 5.60 4.87 Cellu- lose. Per cent. 0.70 .26 .38 .09 Ash. Per cent. 1.13 Evidently these figures can have no general value, as the composi- tion of soups must vary with the materials used and the methods of preparation, neither of which are ever uniform. Loss of nutritive substance in the boiling of vegetables. — This is illus- trated by some observations by P. Wagner and K. Schaefer.^ The following are their figures : Loss of mineral matters in the hoiling of potatoes ivith and witliout shins. The boiling water poured off from 1 kilogram of potatoes contained — Total min- eral mat- ter. Potash. Phosphoric acid. Lost from original amount in the potatoes. Total min- eral mat- ter. Potash. Pliosphoric acid. TJnpeeled potatoes : Boiled steamed Peeled potatoes : Boiled Steamed Grams. 0.28 .09 2.15 .55 Grams. 0.10 .03 1.25 .26 Grams. 0.02 .005 .35 .07 Percent. 3.64 1.17 28.86 7.28 Per cent. 3.32 .69 38.33 6.93 Per cent. 1.12 .03 22.87 4.57 After the boiling of other vegetables as well as potatoes the excess of water is commonly thrown away. That this may involve consider- able waste is shown by the following experimental results: Ingredients in waste ivater from 1 hilogram of green vegetables. Total solids. Nitroge- nous matters. Nitrogen-free extractives (carbohy- drates, etc.). Total inor- ganic matter. Potash. Phosphoric acid. Grams. 8.578 15. 252 Grams. 1.684 3.312 Grams. 3.519 5.609 Grams. 3.375 6.331 Grams. 2.326 4.196 Grams. 0.322 Carrot tops (chopped) .348 The loss varied from 9 to 18 per cent of the total amount of soluble matter in the unboiled vegetable foods. 'Sachs, landw. Ztg., 1885, 33, p. 369. Abst., Jahresber. agr. Cliem., 28, 1885, 443. PREPARATION OF FOOD. 91 BAKING OF BREAD. In the inakiug of flonr from cereal grains tlie less digestible outer coating is removed by tlie process of milling, and the more easily and completely digestible material is left in tlie flour or meal. The starch grains of the product thus prepared are inclosed in cells, the walls of which, as explained above, make it difficult for the digest- ive juices in the alimentary canal of man to get at tliem and prepare them for absorption. We accordingly mix the material with water or milk and heat it. The starch swells, the cells burst open, and a paste or dough is formed, and thus the material is partly prepared for digestion. But in the baking of bread still further steps are taken which result in loosening the mass or making it "light," to use a common phrase, while at the same time the taste is greatly imjDroved. Flour simply mixed with water and baked is neither as palatable nor as digestible as is to be desired. It is difficult to chew, and the small, impenetrable pieces when swallowed resist the action of the digestive fluids. Hence, in the making of the dough some substance or sub- stances are added to make it " rise" — that is, to generate in it a multi- tude of small bubbles of gas. Such materials are leaven, yeast, and baking powders. The two former convert some starch of the flour by fermentation into alcohol and carbonic acid; the latter, which usually contain mixtures of suitable chemicals, generate carbonic acid upon contact with the moisture of the dough. In making so-called " aerated bread" carbonic acid ready made is worked into the dough by machin- ery in closed vessels. When dough thus prepared is put into the hot oven the bubbles of gas which permeate it are expanded and thus make larger cavities. At the same time the minute, hard granules of starch, hitherto unchanged, are by the moist heat softened and gelatin- ized. The ferments of yeast and leaven are killed by the heat and thus their further action upon the bread is prevented. The outer sur- face of the bread is more heated than the interior and much of the starch is changed to dextrin, which is more soluble and believed to be more digestible. Hence the crust is often recommended for persons with enfeebled digestion. The same change occurs in the outer, browned surface of pieces of bread when toasted. EFFECTS OF COOKIX& AS STATED BY HALLIBTTRTON. To the statements of Professor Konig, above cited, the following summary of the eftects of the cooking of food, by Professor Hallibur- ton, of King's College, London, may be added : ^ The cooking of foods is a de\-elopment of civilization, aud mucli relating to this subject is a matter of education aud taste rather than of physiological necessity. Cooking, however, serves many useful ends : (1) It destroys all parasites and danger of infection. This relates not only to bacterial growths, but also to larger parasites, such as tapeworms and trichiua. (2) In the case of vegetable foods it breaks up the starch grains, bursting the cellulose and allowing the digestive juices to come into contact with the granulosa. ^Tbe Essentials of Chemical Physiology, p. 34. 92 CHEMISTRY AND ECONOMY OF FOOD. (3) In the case of animal foods it converts the insohible collagen of the uni- versally distributed counective tissues into the soluble gelatin. By thus loosening the binding material, the more important elements of the food, such as muscular fibers, are rendered accessible to the gastric and other juices. Meat before it is cooked is generally kept a certain length of time to allow rigor mortis to pass off. Of the two chief methods of cooking, roasting and boiling, the former is the more economical, as by its means the meat is first surrounded with a cofvt of coagulated proteid on its exterior, which keeps in the juices to a great extent, letting little else escape but the dripping (fat) ; whereas in boiling, unless both bouillon and bouilli are used, there is considerable waste. Cooking, especially boiling, renders the proteids more insoluble than they are in the raw state ; but this is counterbalanced by the other advantages that cooking possesses. ATKINSON'S DEFINITION OF COOKING, The subject is viewed from a somewhat different standpoint in the concise definition by Dr. Edward Atkinson: ^ We may define the art of cooking as consisting in applying heat to each of these subjects in such a way as (1) to render it digestible, so that its nutrient properties may be assimilated in true proportion in the human system; (2) to render it appe- tizing by the development of its own specific flavor ; (3) to combine diiierent kinds of food material in such a way that each will render the other palatable; (4) to remove certain portions which may not be palatable or digestible after the first application of heat, either as waste, like bone, as excess, like much of the fat that may be used for other purposes, or as woody fiber in many vegetables ; (5) to add to the essential elements salt in its due proportion in almost every process, and sugar in some com- binations, and other condiments, spices, or flavorings in such a way as to develop rather than to disguise the true flavor of the princiiDal food material entering into each dish. INVESTIGATIONS BY MRS. RICHARDS AND MRS. ABEL. In 1889 and 1890 a grant was made by the trustees of the Elizabeth Thompson fund for experiments upon cooking. This was supple- mented by private gifts for the same purpose. The experiments were carried out by Mrs. Ellen H. Eichards and Mrs. Mary H. Abel. They included some trials with the Aladdin oven, the invention of Dr. Edward Atkinson, through whose instrumentality the investigations were under- taken. The following statements are from the reports of Mrs. Eichards and of Mrs. Abel to the trustees of the Elizabeth Thompson fund. They are taken from a paper by Dr. Atkinson on " The right application of heat to the conversion of food material," read at the meeting of the American Association for the Advancement of Science, in Indianapolis in August, 1890 : The investigation of certain scientific princij)les of hygienic and economic cook- ery, in aid of which a grant of $800 was made from the Elizabeth Thompson fund, was to cover four points : (1) The determination of the time and temperature required for the best results in flavor and digestibility of the several classes of food materials, i. e., meat, vege- tables, etc. 1 Suggestions Regarding the Cooking of Food, published by the U. S. Department of Agriculture, 1894. PREPARATION OF FOOD. 93 (2) To ascertain the difference, if any existed, in the chemical character of bread quickly baked and that baked for a long time. (3) To endeavor to secure a simple and effective measure of oven heats. (4) To modify the ovens in common use in order to obtain more digestible food and to secure more economical use of food materials. The study of these jioints was made by Mrs. Mary Hinman Abel in connection ■with the work of the New England Kitchen, thus securing more than mere labora- tory results. The analyses were made in the laboratory of sanitary chemistry of the Massachusetts Institute of Technology by Messrs. G. L. Heath, F. S. Hollis, W. R. Whitnoj^, and Misses Bragg, Day, Sherman, and White. The apparatus is being used constantly in further experiments. The accompanying report gives in detail the results of the six months' work. It may be briefly summarized as follows : (1) Two standard dishes haA^e been perfected which have stood the test of six months' daily sale with constantly increasing popularity. The time and temperature necessary for these dishes are known, as well as the exact proportions of the neces- sary ingredients. Meat and vegetables are represented. The two dishes are beef broth for invalids, and j)ea soup. From the beef broth other soups are made. (2) The change in the composition of bread when baked a long time at a moderate temperature has been demonstrated. (3) The question of an oven thermometer has not been satisfactorily settled. (4) In regard to the American cook stove we have come to the conclusion that no general improvement' in the character of prepared food can be expected with so crude and unreliable a means. As wo have demonstrated that for most substances along time and a moderate heat is required for the best results, we must find an apparatus to secure this. Nothing which we have seen or heard of quite meets the ideal requirement. In our practical experiments we have confined ourselves to the effect of a moderate degree of heat, continued for a considerable time. We have not considered to any extent the methods of broiling or so-called roasting, becaiise it is well known that only tender, high-j)riced cuts of meat can be thus made fit for the table. ESSENTIALS rOR GOOD COOKING APPARATUS. For ordinary cooking apparatus the following are essential points: (1) The degree of heat should be under perfect control, increased, diminished, or withdrawn at will, and without loss of time. This can only be perfectly attained with liquid or gaseous fuel. Solid fuel demands constant and equable running, and gives best results in large masses. The small fire box of a cook stove, and the urging of the fire for a short time three times a day are fatal objections to the use of anthracite. (2) A tightly closed vessel heated by steam, or hot water, or hot air, offers many advantages over the top of a red-hot stove or the inside of a nearly red-hot cast-iron oven for cooking, except for the broiling and the roasting of meat and for some other methods of cookery which require the quick apj)lication of heat. (8) For all purposes of slow cooking the oven should have a non-conducting cover- ing which retains the heat where it is wanted, and also allows of tight closing and of security from the constant watching required by the fitful heat of a stove. This use of a close oven with a non-evaporative atmosphere, seems to be the secret of the retention of the delicate and volatile flavors which usually flavor the house and street, and not the food as it is brought to the table. Three kinds of apparatus are now in the market which meet more or less of these requirements, and all may be used with a kerosene lamp. The Arnold steam cooker uses steam generated in a sort of flat boiler. For some purposes, such as the cook- ing of cereals, as mush, and also for the prepartion of a fe^v quarts of soup, and for the slow cooking of meat in its own juices, we find this cooker very effective. The liability to leakage and the difficulty of mending are drawbacks, and there is no non-conducting covering. 94 CHEMISTKY AND ECONOMY OF FOOD. The Wanzer cooker we have not been able to purchase, as it is held by an English patent. It has a special lamp of bome merit and it has good i)oiuts_. as the demon- stration which the patentees gave us showed. The loss of heat is, however, very large and the lamp will run only four hours. The Aladdin oven or covered stove. This is a square or oblong box of sheet iron of any desired size, with a non-conducting covering of magnesian cement or wood pulp, and is heated with a kerosene lamp or gas burner. The size in use for these experiments is 18 by 12 by 14 inches, and gives a cooking space at least equal to that of a No. 8 Crawford cook stove, and when empty can be heated to about 300° F. in an hour, and maintain that temperature for 8 hours by a single kerosene lamp of the Kochester-burner type, Avith the consumption of 1 quart of kerosene. When well filled with food materials in small portions the heat is sufficient to heat them in about twice the time allowed by an ordinary cook stove. When the space is . completely filled with a vessel containing, for instance, 40 pounds of meat and bone and 15 quarts of water, the whole is raised from a temperature of 70 to 180° F. in 7 hours, and to 212° in 12 hours. If the lamp is then taken away or allowed to go out the temperature does not fall below 190° for 4 hours. For this 12 hours, IJ- quarts of kerosene are needed, or a gas burner can be used. For simplicity, eflective use of heat, economy of fuel, and development of flavor in the food cooked, combined with increase of its digestibility, the Aladdin oven is an apparatus far exceeding in merit any other now in market. It will not meet all the demands that the modern cook now makes of the kitchen stove, and it may be in several respects improved, but in the aijplication of well-known and long-tried scientific principles to the cookei-y of food, it is a distinct advance and a most valuable invention. * * * COOKERY OF MEAT. The ideal pre^iaration of a food for human use requires that the nutriment it con- tains should be utilized to the fullest extent, and this implies not only that it shall be in such a state that the digestive juices can best act on it, but that these digestive juices shall be proj)erly stimulated to do their work by the taste or flavor of the food. Therefore in the cooking of meat we undertook to answer this question: What method can be employed that will yield the most in nutrition and flavor? It was determined to experiment first with beef of the cheapest cuts, as the neck and shin, these cuts although tough being among the richest in nutriment as showai by analysis, and to utilize this nutriment in tlie form of broth or as a basis for soups. In examining a shin of beef we find it to consist, as f;ir as our uses are concerned, of, first, nmscular fiber ; second, connective tissue; third, bone. We have here three distinct food materials, which if treated separately would require quite different processes. (1) Muscle fiber. To prepare this for the digestive juices requires only that slight application of heat that develops the flavor which is most agreeable to the civilized palate, and so increases the nutritive value of cooked muscle fiber over raw, at least for the civilized stomach. A familiar example of the most pei-fect method of cook- ing the muscle fiber alone is broiling. (2) The connective tissue and tendons. We find these intimately connected with the muscle fiber, and their food material is finallji^ obtained mostly in the form of gelatin. To render these substances available for food they must be first hydrated, and then to a greater or less extent dissolved. The length and difliculty of tliis process differs with the age of the animal, its food, and also on the length of time the meat has been kept after killing, all of which aftects the toughness of the envel- oping membrane. The connective tissue in a sirloin steak is so tender that the heat necessary to cook the muscle fiber, as in broiling, is sufiicient also to hydrate the connective tissue by merely heating the water contained in the steak; that of the tougher cuts, like that of the shin, need a much longer application of heat. (3) The bones also contain a substance which yields gelatin, and to extract it PREPARATION OF FOOD. 95 requires a loug applicatiou of heat. It became evident at this step in the investij^a- tion that eiuce muscle fiber, conuective tissue, aud bone must be cooked by the same process, aud that this process must be a long cue iu order to affect the necessary changes iu the conuective tissue aud the bono, some means must be devised to prevent the overcooking of the muscle fiber from dissipating its flavor. This settled the first requirement of the cooking vessel to be used, namely, that it must be tightly closed. On this account the ordinary iron pot was rejected, but the long famous Papin soup digester with its tiglitly screwed toj) was given a good trial on the kitchen range. But other requirements were to be met. Tlie perfect hydration of the gelatin yielding connective tissue of meat and the jiroper cooking of the albumen would require that the temperature be perfectly under control. It was found to be impossible to regulate the temperature inside the digester; for, added to the ordinary difficulty found in using the variable kitchen range, Avas the fact that the tightly closed digester gave no sign of the rising temxicrature till the mis- chief was done. Placed over the more easily regulated flame of gas or kerosene so large a vessel showed great unevenness in the temperature iu the top and bottom, aud both of these methods were expensive as to fuel. We uext tried cooking the meat in earthen jars placed in the Aladdin oven to which the heat of a kerosene lamp was api)lied, and the results obtained were so good that it became evident that we were on the right track. The meat nnd bone placed in a jar and covered with cold water rose slowly aud steadily, without any attention on the part of the cook, to a required temperature and could be held there for any length of time by simply lowering the flame of the lamp. The non-conduct- ing shell of the oven assured nearly the same heat to the bottom, top, and sides of the cooking vessel, and did the work Avitli a minimum amount of fuel. We had aimed to produce a food that should hold nitrogen comijounds in solution with all the flavor available. This would require that the extraction of the food material from the meat should be effected as nearly as possible before that tempera- ture was reached at which the flavor once developed would be dissipated by the escaping steam. It was found by later experiment that the agreeable flavors i>ecu- liar to boiling soup were not brought out till the boiling point was uearly reached. This by our present metliod is 12 hours after the beginning of the cooking, and near the end of the process, so that the least possible quantitj' of these flavoring substances is lost by further cooking. We, therefore, had a tin-lined copper vessel holding 30 quarts made to fit the oven, thus utilizing the entire inside space. Three of them have been in constant use in tlie kitchen since our early experiments demonstrated their value. By this method only have we been able to meet our requirements for the proper cooking of meat of the tougher cuts, and at the same time extract from bone and tendon a due amount of gelatin. We consider it quite probable that a steam apparatus might be devised that would do the work on exactly the same iiriuciple by surrounding the cooker with a heated medium easily regulated and using low pressure; the steam jacket of the restaurant does not answer the requirements, but to have something of this kind constructed did not come within our means. Whether the Aladdin oven is the ultimate best form of a cooker we do not attempt to say, but it certainly deserves a high place because constructed on the principle of holding the heat to its work by a non-conducting covering, and for using an easily regulated fuel. Other contrivances examined by us, however convenient and ingen- ious, are on the old lines and show no distinct advance toward an application of scientific priuciiiles to cooking methods. The method employed in the Aladdin oven is the same whether the meat and bone are cooked with a small quantity of water aud used in the form of a stew, or with a larger quantity of water, the meat at the end of the process being pressed dry of its juices. This latter method is the one most employed at the kitchen because of our large consumption of this broth, merely salted as beef broth for invalids, and as a basis for our various soups. 96 CHEMISTRY AND ECONOMY OF FOOD. COMPOSITION OF BEEF JUICE, BEEF TEA, ETC. In view of the unexpected demand for the broth for the sick room we were obliged to study the composition of the various preparations in use and the possibilities of the yield of meat under various kinds of treatment. Beef juice obtained from the best steak which has been merely warmed through over the coals and then entirely deprived of soluble substance by a screw press, is undoubtedly the most concentrated of the liquid foods. If prepared with the most scrupulous care, from the best material, and used at once, it j)robably leaves nothing to be desired. But in unskilled hands the risks are considerable in using this raw and most easily putrescible material. It is also a slow, laborious, and expensive operation. Beef tea, as ordinarily made, is of uncertain composition; it may be only the juice of the meat set free by the coagulation and shrinking of the fiber on heating. Such is the beef extract made by heating chopped steak in a bottle. It maybe an aqueous infusion of very variable strength, containing chiefly phosphates, kreatin, and cer- tain extractive matters, agreeable to the palate, but of little nutritive value. It occurred to us to prepare on a large scale a broth of constant composition from both meat and bone, in such a manner as to secure a nuti'itive value at least equal to that of milk (without its fat), and without sacrificing the ajipetizing flavor. The bone gives a proportion of gelatin which, when flavored with the meat extract, is believed to be of high nutritive value. The following table gives a comparison of these different preparations: Meat. Total solids. Solids, juice fil- tered be- fore coag- ulation. Solid.s, juice fil- tered af- ter coag- ulation. Coagula- ble albu- men. Extract of meat. Salts or ash. Beef juice from meat slightly- broiled and pressed (round) Beef juice from meat sliglitly broiled and pressed (neck) Beef tea, chopjied beef heated in Per cent. 26.8 21.9 26.4 11.9 9.9 7.91 3.-23 10.8 9.4 4.93 4.72 5.72 2.55 6.97 5.18 2.19 .68 Per cent. 3.90 3.56 2.09 1.36 Beef tea, New England Hospital, Beef tea, with equal weight of water 2 hours at 75° U., then 2.15 2.62 4.40 Beef tea with twice its weight of water 2 hours at 70° C, then Beef broth, Isew England kltch- 3.53 It will be seen that the yield of lean beef to water is only about 2 per cent, that is to say, from 3 pounds of juicy steak only about 1 ounce of solid matter is obtained. The broth of the kitchen adds to this 2 per cent from the meat, 2 per cent of gela- tin from the bones. HOW LONG BKOTH MAY BE KEPT. We have taken some pains to determine how long this broth will keep under dif- ferent conditions, an investigation in the field of househoukl bacteriology. We have settled for our own practice the great importance of: (1) Sterilizing with boiling Avater every utensil used in the process. (2) Rapid cooling of the broth as soon as made, to below the temperature most favorable to the growth of bacteria. (3) Keep- ing the broth at as low temperature as possible. . _ As a. result of several experiments during the hot days of July, it was found that broth which spoiled in 12 hours in a cellar where the thermometer stood at 70"^ F. kept sweet for 7 days if placed while still hot in small jars in an ice chest at 32° F., the cake of fat on the top remaining undisturbed. PREPAKATION OF FOOD. 97 PEA SOUP. Of our many exjierimeuts in the cooking of cereals and vegetables we consider only one complete and satisfactory enough to report upon. The principles here demon- strated can, however, be applied to many different dishes. On account of the high food value of the legumes and the general impression that as ordinarily prepared tliej^ are indigestible we determined to make careful experi- ments on methods of cooking them. First, we undertook to make what would be a standard soup out of dried split pea. We found that in this case also the principle of long, slow cooking was the secret of success. * * * It was found that not until the split pea was. cooked 4 or 5 hours, was the result that thick puree of rich and mellow flavor that has been so popular in the Xew England kitchen. SUGGESTIONS AS TO INVESTIGATIONS NEEDED. A comraou remark made by tliose who have studied tlie conditions of living- of people of moderate incomes and the poor in the diiferent parts of onr country is that one of the things most needed for the improve- ment of the home life of people of these classes is an improvement in their cooking. To replace dear food badly cooked by economical food well cooked is important for purse and health. To make the table more attractive will be an ef&eient means for making home life more enjoyable and keeping the fatlier and sons from the saloon. Those who have had experience in cooking schools have come to realize the need of better understanding of the i)rinciples which under- lie the right preparation of food. The ordinary kitchen stove and the receipt book do not meet the demand, and nothing short of accurate research can meet it. "The coming fad is domestic science." Indeed that fad is not coming but is already here. The danger is that it may go as a fad and leave no permanently useful imiDression. But it may be made, instead of a fad, a most salutary educational movement. There is good ground to hope that it will prove so, but only on one condition, namely, that it be based upon thorough scientific knowledge. Such knowledge must be based upon research, just as accurate and just as thorough as that which is given to the study of the other profound problems of chemfs- try, j)hysics, and hygiene in their application to daily life. The time is ripe for this inquiry. The leaders in physical, hygienic, and economic science have learned that such subjects are worthy of their attention. The higher institutions of education and research are finding that such inquiry and the teachings that go with them are a part of their truest function. Among the men and women connected with the cooking schools, the experiment stations, the agricultural and mechanical colleges, and other institutions for technical training, tlie medical schools, and the chemical, physical, and biological laboratories of the universities, there are not a few who are capable of carrying on such inquiries, and with most excellent results. The general character of the investigations now needed is illustrated by what was said above regarding the digestibility of food and the effects of cooking. More specific suggestions will be best made when the work is ready to be done. 8518— K"o. 21 7 98 CHEMISTRY AND ECONOMY OF FOOD. EFFECTS OF COOKING ON DIGESTION. One of the most important practical topics now demanding investi- gation is the effect of cooking upon the digestibility and nutritive value of food materials. The general lines of inquiry needed were referred to in connection with the description of experiments above. Some such plans for details as the following are at least worthy of consider- ation : Suppose the question to be the effect of the frying of meat upon its digestibility, aud that the investigator has at his disposal a subject, a healthy man for instance, who has been trained for the investigation and who is able to attend to some of the mechanical and less agreeable details. A piece of lean beefsteak of proper size could be divided in six parts of like weight and composition and set aside in a refrigerator. Portions representing the whole could be analyzed. The six portions could be eaten, each with given amounts of starch and other carbohy- drate materials, and with butter and other substances which would furnish the fats. A ration could be provided which would be fit for sustenance and at the same time would not contain any considerable quantity of material which would interfere with the determination of the actual digestibility of the meat, especially its protein. Three of the por- tions could be used, during a period of 3 days, nearly raw. The experi- ment of this period would thus show the digestibility of the meat under the most favorable circumstances ; in other words, what might be called its intrinsic digestibility by the subject with whom the experiment was made. The remaining three portions could be fried until well done or overdone, and eaten during a second period of 3 days in the same man- ner as before. The experiment in this period would show the digestibility of the meat when thus fried. Comparison of the results obtained in the two periods would show the effect of the frying upon the quantity of the meat digested. It must be borne in mind, however, that one series of two comparative experiments would not suffice, but that the investigation should be repeated with the same person and also with different per- sons. When the experimenter has the method for this kind of work well in hand, it is not extremely laborious, and if conducted for a consider- able time will bring results of decided x)ractical value. This, of course, is only a suggestion for an experiment for testing the eifect of one kind of cooking upon one kind of food, but it serves to illustrate how such inquiry may be carried on. Such inquiries are greatly needed, the time is ripe for them, and there are i:»ersons who are competent to conduct them. Experience will lead to improvements in methods and indicate the questions which are most desirable for study, and the results will find immediate aud widespread application. Here, again, systematic, cooperative work will bring the best results with the least expenditure of time, energy, and money. CHAPTER VL USES OF FOOD IN THE BODY— METABOLISM.' TLe body of the auimal and tlie food which nourishes it are composed of the same elements. The compounds in the body are more or less similar to those in the food. The processes by which the elements are transformed into the compounds in the plant which serve the animal for food are essentially synthetic. Those by which the compounds of the food are transformed into the compounds of the body are partly synthetic and partly analytic. Those by which the compounds of the food and of the body are utilized in the performance of the bodily functions and are finally excreted are mainly analytic. The generali- zation of Liebig, that the chemical changes in the plant are synthetic and those in the animal analytic is, in the main, true, but there are important exceptions both in the animal and in the plant. The later development of science has given us clearer ideas not only of the chemical but also of the physical changes that take place in the living organism. The physical processes in the plant are mainly those of the transfor- mation of kinetic into potential energy; those in the animal are mainly transformations of potential into kinetic energy. The latent energy of the food is changed to heat and muscular power as the food is used in nutrition. METABOLISM OF MATTER AND ENERGY IN THE BODY. To these kinds of change the term metabolism is frequently and appro- priately applied. The processes of metabolism in the body are of two definite but closely allied kinds — the metabolism of matter and the metabolism of energy. It is commouly assumed that these two pro- cesses conform, the one to the law of the conservation of matter and the other to that of the conservation of energy. Exactly this form of statement is not usual. Indeed, I do not recall having met it in x>rint ■The experimental inquiry upon metabolism lias been very active during the last few years, and a reasonably full treatment of the subject within the time allowed for the present bulletin is impracticable. It has seemed best, therefore, to present the following brief statements herewith and leave the more detailed treatment fox a subsequent publication. 100 CHEMISTRY AND ECONOMY OF FOOD. at all, but the principles thus enunciated have been more or less defi- nitely assumed by writers and experimenters during the last 20 years or more. In the following pages the attempt will be made to dis- tinguish between the chemical and physical changes involved in bodily metabolism, and to explain briefly some of the ways by which the changes are measured, and the use that is made of these measurements in the discovery of the ways in which food performs its functions in nutrition. The bringing of these complex processes into line with the two funda- mental laws of the conservation of matter and the conservation of energy helps greatly toward simplifying the whole subject, clearing up details that have been obscure and placing the doctrine of nutrition upon a rational and simple basis. In the light of these laws many of the results of experimenting are more easily interpreted, imperfections in plan and errors in execution of past experimenting are brought out, and the ways in which the unsolved i)roblems before us may best be studied are laid open. Experimenter, teacher, and student are alike helped by this same coordination of principles. At the same time the theory of nutrition thus becomes plainer to the practical man. He can understand it more easily if it is put in terms of "flesh formers" and "fuel values "than if he must consider protein, fats, and carbohydrates in the ways which have become so generally current. Food has two chief functions — to build tissue and to serve as fuel. In the building of tissue we have to do with the metabolism of matter. In serving as fuel, to yield heat and muscular power, we have to do with the metabolism of energy. The protein compounds are the tissue formers. The fats and the carbohydrates are the chief fuel ingredi- ents; but protein compounds also serve as fuel. In this service as fuel the nutrients replace each other in proportion to their potential energy. The economy of food in nutrition requires sufficient protein for the for- mation of tissue and sufficient energy for supplying heat and strength. The fat of the body is its reserve store of fuel. The fuel value of the fats is more than twice as great, weight for weight, as that of the pro- tein or carbohydrates. Fat is body fuel in its most concentrated form. Therein lies the economy of nature in the storage of fat in the body. The fat of the food is stored as fat in the body. The protein and carbohydrates of the food are transformed into body fat. The fuel value of the food thus becomes a measure of its caijacity for fat formation. Of course the whole doctrine of nutrition is not as simple a matter as these statements would imply, but they do represent its fundamental principles. In the meWibolism of matter and energy we have the foundation of the theory of nutrition, the starting point of experimental inquiry, and the means of simplifying the theories which we have to teach. USES OF FOOD IN THE BODY. 101 METIEOLISM OF MATERIAL — DAILY INCOME AND EXPENDITURE OF THE BODY. To measure tlie quantities of material metabolized it is necessary to take into account the total income and outgo of matter. The income of matter consists of food, drink, and oxygen of inhaled air. Part of this material is transformed into blood, muscle, fat, bone, and other tissues. The rest, together with the materials worn out with use, undergo various chemical transformations and are finally given off from the body in the form of gases through the lungs and skin, of liquids and solids excreted by the kidneys and skin, and undigested residue of food and metabolic jiroducts excreted by the intestines. The substances excreted in these ways constitute the outgo of material. In accurate experiments upon the income and outgo these materials are measured by their chemical elements. It is assumed that all of the gain or loss of nitrogen represents the food and body protein. It is customary to take the quantity of nitrogen multiplied by the factor 6.25 as the measure of this protein. It is also assumed that all of the nitrogen of the income is that of the i^rotein of the food; that all of the nitrogen of the outgo is contained in the nitrogen excreted by the kidneys and intestines. The difference between the nitrogen taken in and that excreted is the measure of the gain or loss of body nitrogen. If there be less nitrogen excreted than was contained in the food, this nitrogen has been stored in the body. Assuming that all has been stored as protein, we have simply to multiply the quantity by the factor 6.25 and we have the quantity of protein stored in the body. In like manner, if there be loss of nitrogen, this quantity multiplied by the same factor gives the loss of protein from the body during the same experi- ment. The protein contains besides nitrogen certain quantities of carbon, oxygen, and hydrogen. The assumed average comj)osition of protein will give the quantities of these elements stored in the body as protein or lost in that form. The nitrogen of income and outgo is thus used as the measure of the gain or loss of body protein and also of the gain or loss of carbon, oxygen, and hydrogen in that body protein. For determining the gain or loss of protein, we next consider the gain or loss of fat. This is comparatively simple, if we assume that there is no gain or loss of carbohydrates. In this case we have need only to use the figures for gain or loss of carbon. Part of the carbon goes with the nitrogen of the protein. If, after this has been calcu- lated out, there remains a loss of carbon, the inference is that the body has lost fat, and as the compOvSition of the fat in the body is practically constant, it is very easy to calculate from the loss of carbon the quan- tity of fat which the body has lost. In like manner, if the income of carbon is more than the outgo the inference is that carbon has been stored as fat and the quantity of fat thus stored is easily calculated. 102 CHEMISTRY AND ECONOMY OP FOOD. In what was jns^ said it was assumed that the quantity of carbohy- drates in the body remains constant. To determine whether this is actually so or not, the exact gain or loss of hydrogen and oxygen, as well as of carbon, should be known. Unfortunately experimental inquiry has not yet attained to the degree of perfection which makes it possi- ble to determine the hydrogen and oxygen with the desired accuracy. The determinations of income and outgo of nitrogen are made very easily, since practically all of the nitrogen involved, with the excep- tion of the extremely small amount excreted by the lungs and skin, is given off by the kidneys and intestines and can be determined with great accuracy. The quantity excreted by the intestines is a nearly accurate measure of the quantity digested, the only disturbing factor here being found in the metabolic products. The quantity excreted by the kidneys gives an approximately accurate measure of the total quantity metabolized. The determination of gain or loss of protein is, therefore, a comparatively simple matter, and experiments in which these determinations are made are very common. The larger part of the carbon of the outgo is excreted in the respira- tory products. To determine its amount it becomes necessary to meas- ure and analyze the respiratory products. This is accomplished by means of the respiration apparatus. Various forms of respiration apparatus have been devised. The most successful is that of Petten- kofer, which has been somewhat modified by Voit. With this, carbon of inhaled and exhaled air can be determined with quite satisfactory accuracy. The determinations of hydrogen have been less successful. The materials determined have been carbon dioxid and water. In late experiments atMockern and Gottingen with domestic animals the hydro- carbons have also been determined. The tabular statement herewith will serve to indicate succinctly the ways in which the chemical and physical changes take place in the body, in so far as they are now understood, and to compare them with the changes that take place in the calorimetric apparatus which is used for the experimental study of the subject. It should be borne in mind, however, that portions of the food are being constantly stored in the body and becoming parts of its tissues and organs, while pre- viously stored material is at the same time being consumed. The materials stored and consumed may, like those of the food, be grouped as protein, fats, carbohydrates, and mineral matters. USES OF FOOD IN THE BODY. 103 Transformation of material and energy in calorimeter and in animal hody. A.— METABOLISM OF MATTER. Comijouiids in food. Chemical products into which the compounds are transformed hy — Direct oxidation in calorimeter. Cleavage and ultimate oxidation in body. Fats, carbohy- drates, alco- hol, organic acids, etc. Proteids, am- ides, eto. Call toCOj HalltoHjO forms CO2 and H2O CalltoCOj HaU toH^jO Sail to [Hj] SO4-... Pall to [H3]P04.... N becomes free N? forms compounds as above. C appears as CO2 "l Ofrespi- H appears as H2O }■ ratory appears as CO2 and II2O J products. Creatin and allied com- pounds. • As above . C appears as CO2 .... ^ Of respiratory H. appears as HjO ) products. S appears as SO4' ......"I Excreted by P appears as PO4 > kidneys IT appears as urea, etc. J and skin. enters into compounds as above. Not metabolized, (f) EXCEPTIONS. 1. In respiratory products: Minute quantities of C and H, and perhaps N, P, or S, are given off in hydrocarbons and other volatile com- pounds. 2. In the excretion of kidneys (and skin) : Considerable amounts of C, H, O, N, S, and P appear in urea, uric acid, crea- tinin, alcohol, etc. 3. In the excretion of the intestine (which includes con- siderable amounts of undigested or partly digested residues of the food, and with them more or less of metabolic products, mainly from the digestive juices) C, H, 0, N, S, and P appear as: a, TJnde- composed proteids, fats, carbohydrates, etc. b, Cleavage products, e. g., salts of organic acids, tau- rin, skatol, COo, CH4, H, andNJ. iJn combination with bases, metallic or organic. B.— METABOLISM OF ENERGY. The potential energy of the compounds of the food is transformed by — Direct oxidation in calorimeter — Cleavage and ultimate oxidation in body — Completely into heat. 'Mostly into — 1. Heat 2. Muscular power . . . . 3. Intellectual and nervous energy . ( ? ) But part remains untransformed in the partially oxidized or unoxidized compounds given off from : 1. The lungs and skin in respiration, viz (very minute quantities of): Hydrocarbons and other volatile compounds. 2. The kidneys (and to very slight extent from the skin), viz: Urea, uric acid, creatinin, or other compounds. 3. The intestine, viz: Undigested residues, and cleavage products of food, and metabolic prod- ucts, from digestive juices, etc. In ordinary experimenting the metabolism of mineral matters is not taken especially into consideration, as the quantities of mineral matter and energy metabolized are extremely small. The total quantity of carbohydrates in the body tissnes is also small, and is, like that of the mineral matters, assumed to be very nearly constant. Hence the metabolism of the carbohydrates belonging to the body is ignored in ordinary experiments upon the income and outgo 104 CHEMISTRY AND ECONOMY OF FOOD. of the body. For accurate results, liowever, it is essential to determine whether the body loses or gains carbohydrates. The i)rotein and fats of the body are constantly increasing or decreas- ing; in other words, the metabolism of body protein and body fat has to be accurately measured and taken into the account in the balancing of the incoming and outgoing of material. The total transforjnation of energy in the body includes that of body material as well as that of food. It is assumed that the potential energy of body protein and body fat is the same as that of protein and fat of the food. No way has yet been devised for measuring the exact quantities of body protein and body fat metabolized in a given time. What experiments on income and outgo of material do show is the total gain or loss of mate- rial in the body. That is to say, if the body during an experiment of 24 houis contains a gram more of fat than at the beginning, the infer- ence is that whatever may have been the quantity of body fat metab- olized the quantity of fat stored was equal to this and one gram more. If, on the other hand, the body has lost fat, this loss measures tlie excess of metabolized fat over that of fat stored from the food, but in neither case do we know the amount of body fat metabolized. What we do learn is the amount of this difference. The determination of the income and outgo of protein may be illus- trated by an actual experiment.^ The question was this: From a given quantity of the protein of muscular tissue how much will be digested by a healthy man, and will the quantity digested suffice to maintain the supply of protein in his body*? In other words, will the man gain or lose protein, or will he simx)ly hold his own on this dief? The subject was a medical student. For protein he ate, in the case here cited, very lean beefsteak. This contained, along with protein, a very small quantity of fat in the form of minute particles which could not be removed with shears and forceps. The diet consisted of the beefsteak cooked with butter, seasoned with pepper, salt, and Wor- cestershire sauce, and taken with water, beer, and wine. The experi- ment lasted 3 days. The total quantity of nitrogen of the food was somewhat over 39 grams, of which 38.5 grams were digested, while the rest was excreted in the undigested residue with a small amount of metabolic nitrogen which is not taken into account here. Thirty-seven and two-tenths grams were excreted daily by the kidneys. Assuming that the digested nitrogen of the food represents the income of protein, the gross income of nitrogen, then, is represented by the digested nitro- gen of the food, the gross outgo of digested nitrogen by that excreted through the kidneys. Each of these quantities of nitrogen corresponds to a definite quantity of protein which we assume to be equivalent to 6| times the weight of the nitrogen. It is commonly assumed that for every gram of protein there will be about 4^ grams of muscle, tendon, iW. O. Atwater. Ueber die Verdauliclikeit des Fischfleisolies. Ztsolir. Biol., 1888, p. 16. USES OF FOOD IN THE BODY. 105 etc., in tlie meat, aud that there will be the same ratio between the weight of muscular tissue consumed in the body and the protein, the nitrogen of which is excreted by the kidneys. That is to say, for every gram of digested nitrogen of the income and outgo there will be Q^ grams of protein and (6^x4 J) about 27 grams of muscle, exclusive of lat. The gain, then, may be put thus. On a diet of 2 pounds and 10 ounces of lean meat and an ounce of butter per day, was the store of protein in this man's body increased or decreased? In other words, so far as muscular tissue is concerned, did he gain or lose or hold his own"? Here are the figures : Income and outgo of digested nitrogen in experiment ivith a man on diet of lean meat. Grams. Total nitrogen (per day) 38. 5 Nitrogen, kidneys (per day) 37. 2 Balance stored in tlie body (per day) 1.3 That is to say, this young, vigorous man, a student, at his ordinary occupations, studjdng in his room, listening to lectures at the university, working several hours each day in the laboratory, walking a little for exercise, and living on a diet of protein with a very little fat, gained nitrogen at the rate of 1.3 grams per day. These 1.3 grams of nitrogen represented about 8.2 grams of protein or 35 grams (IJ ounces) of muscle gained per day during the three days of the experiment. In other words, so far as the lean flesh in his body was concerned he just a little more than held his own. The difference, that is to say, the gain or loss of fat or of portein, is determined by comparison of income and outgo of material, and thus gives the resultant metabolism of body material. This resultant meta- bolism of body material expressed in the form of gain or loss of protein or fat must be used in measuring the metabolism of energy. As the factors for this measurement, we may have the total potential energy of the food, the energy of material gained by the body or lost from it, and the energy given off from the body in the form of heat radiated or external mechanical work performed. The income of energy will include the potentialenergyof the food, and the outgo of energy that of the heat radi- ated and exterior mechanical work done. If there is a gain by the body in the form of protein or fat ; that is to say, if it stores from the food more protein or fat than it consumes of its own substance, the outgo of energy will be diminished by the potential energy of the protein or fat thus stored. If, on the other hand, the body loses protein or fat; that is to say, if it consumes more of its own material than it stores from the food, the potential energy of the material thus lost will go to increase the energy of the outgo. It is clear, therefore, that if w^e are to study the energy of income and outgo accurately, we must not only determine the energy of the food and that of the heat radiated and exterior 106 CHEMISTRY AND ECONOMY OF FOOD. meclianical work done, but also the energy of the body material gained or lost. The amount of material gained or lost is determined by compari- son of the income and outgo of nitrogen, carbon, and other elements. THE RESPIRATION APPARATUS. The experiment above described sufficed to show the nitrogen and protein balance. It showed that the diet of meat and butter with protein and fat sufficed not only to keep up the store of protein in the body for the three days, but also to slightly increase it; but the experiment does not show whether these nutrients supply the body with heat and mus- cular energy, or whether some of the fat of the body was consumed to make up for the deficiency in the diet. Fig. 5.— Pettenkofer's respiration apparatui The only way to answer this question is to measure the income of other elements and especially of carbon. For this purpose the respira- tion apparatus is used. To attempt a description of all of the forms of respiration apparatus which have come into use during the past 40 years and the results of the experiments made with them would ftir exceed the limits of the present article. The most interesting form and the one which has thus far been most useful is that of Pettenkofer. The following description of this apparatus and of some of the experiments performed with it though originally intended for a more popular exposition, will perhaps suffice for the present purpose:^ 'The description and illustrations are taken from an article by the writer in the Century Magazine for June and July, 1887. USES OF FOOD IN THE BODY. 107 The respiration apparatus is a device for measuring the respiratory products. Many forms have been devised, from one in which the products of rcsx)iration of a piece of muscle taken from an animal just killed can ha measured, the lespiratory process being maintained by artificial circulation of blood through the muscle, to one in which an ox may be kept for days or weeks, and the composition of the iuhaled and exhaled air likewise determined. A very interesting form is that used by the French experimenters, Regnault and Reiset a number of years ago. This was a small chamber of glass, inside of which the animal was placed, some rather complicated appliances being used to continually renew the supply of oxygen and remove the carbonic acid and other products of respiration. But from insufficient ventilation and other minor difficulties this form of apparatus has not quite sufficed for satisfactory experiments, esj)ecially with the larger animals and with man. Fig. 6. — Pettenkofer's respiration apparatus. Pumping machinery. By far the \uost satisfactory apparatus is that invented by Professor Pettenkofer, of Munich. This is one of the most interesting devices of modern experimental science. The first one was built through the munificence of the King of Bavaria. The peculiar features of this apparatus are that the subject of experiment, be it a dog, an ox, or a man, is in a comfortable, well ventilated room, and that the air, which passes through it in a continuous current, is measured and is analyzed both before it goes in and after it comes out. We can thus tell just what the animal has added to it — in other words, what material has been given oft' as gas or vapor from the body. The arrangements do not provide for estimating all the respiratory products ■with absolute exactness, but they suffice for reasonably accurate result«. The form, used for experiments with man consists of a chamber — a "salon," it is called ; as a matter of fact it is an iron box — through which a current of air is drawn by a large pump, the latter being worked by an engine. The salon of the large apparatus at Munich is made of plates of iron, similar to boiler iron, aud is in the form of a cube about eight feet each way. It has glass 108 CHEMISTRY AND ECONOMY OF FOOD. windows, and a door large enougli.to admit a man. The large eugraviug (fig. 5, p. 106) sliows the apparatus as it is now arranged. On the left is the chamber in which the man under experiment stays; near are a table holding apparatus for analyzing the air before and after it jiasses through the chamber, and a large meter for measniing the quantity of air which passes through. In an adjoiniug room is the machinery by which the ciirrent of air is pumped through the apparatus. The smaller sketch Fig, 7. — Pettenkofer's respiration apparatus. Explanatory sketch. explains the working in more detail. The air enters the chamber at its left side and passes out on the right through the large pipe P P into the large meter M, in which it is measiired. A small tube t t takes from the pipe P P a portion of the air, which has been passed through the chamber and contains the products of respiration, into two small meters m in, where it is measured, and through the apparatus on the the table T, where it is analyzed. A similar small tubh t' t' brings air for analysis Fig. 8. — Toit's respiration apparatus. from the outside of the apparatus, taking it from the left of the chamber where it enters the latter and carrying it into two other small meters (not shown in this sketch), where it is measured, and through apparatus, also not shown here, by which it is analyzed. In the engraving (p. 106) the four small meters and apparatus for analyzing the air are shown on the table between the chamber and the large meter. Comparisons of the quantity and comj)osition of the air which has passed through USES OF FOOD IN THE BODY. 109 the cliamber witli tlio outside air show what the iiiau has imparted to the air in hreatliiug, and thus tell the amounts of the products of respiration. The food and drink and the solid and liquid products of its consumption in the hody ai-c at the same time measured, weighed, and analyzed, and thus all of the items of Income and outgo of the body are determined. Figure 9' represents a smaller form of respiration apparatus deviseil by Voit. It is identical in principle with the larger apparatus. It is intended for experiments with dogs, geese, and other small animals. Its object is to provide for analysis of the air before and after it has been breathed by the animal, and thus show what products of respiration the animal has imparted to it. The box in which the animal is kept is made of glass. Through this box a constant current of air is drawn and measured by the large meter on the table. A small portion of this, howsA-er, is drawn through two of the small meters by which it is measured, and through appa- ratus on the table by which it is analyzed. Air taken from outside the box is at the same time drawn through the other two small meters and apparatus on the table, and thus measured and analyzed in like manner. The first man to enter the respiration ai:)paratus for experiments upon himself, I believe, was Professor Ranke, of Munich, who has described his experiences in his book on The Nutrition of Man (Die Ernahrung des Menschen), as well as in special memoirr-. He tells us that in trials in which he took no food the fasting was some- what disagreeable, but far loss painful than many would think. " I found myself at the end of the iirst 24 hours entirely well ; at the end of the second 24 hours with- out food or drink, during which sleep had been disturbed, the head was somewhat heavy and there was an oppressiveness in the stomach and considerable Aveakness; but the sensation of hunger, ^ * ^ which was strongest about 30 hours after the last food was taken, * * * tlid not ap]5ear any more." In the greater number of Professor Ranke's. experiments he took a reasonable amount of food. The diet was simple, and consisted of such materials as lean meat, bread, white of egg, starch, sugar, butter, etc., and was found to serve the purpose very well. After some exjierieuce a ration was arranged which corresponded very well in composition with that used by ordinary working people, and was at the same time not at all unacceptable. When a number of experiments with Professor Ranke had been completed, several series were made Avith other persons. One of these latter series I will briefly describe. The subject was a strong, healthy mechanic, a watchmaker, 28 years old, and weighing about 156 pounds. Three experiments were made, each occupying 24 hours. In the first, the man took nothing but a little meat extract, salt, and water, and did no work. In the second, he had a liberal allowance of palatable food, but still remained at rest. In the third, he had the same diet as in the second, but worked hard at turning a lathe for 9 hours, so that he Avas thoroughly tired at night. Dur- ing the daytime of the first two experiments, I should say, he read, cleaned a watch, and otherwise occupied himself to AA'hile away the time, making, howcA-er, A-ery little muscular effort. The three experiments, then, show the effects of fasting and rest, food and rest, and food and muscular exercise upon the income and outgo of this man's body. "NYe will note only A^ery briefly some of the details of the experiments, the full accounts of which fill many pages. The diet of the first experiment consisted of: Meat extract, 12.5 grams (a little less than one-half ounce) ; salt, 15.1 grams (a little oA-er one-half ounce) ; water, 1027.2 grams (about a quart). The day's ration of the second trial included a third of a pound of lean meat, a pound of bread, a little over a pint of milk, and about a quart of beer, and other materials as follows : 1 Century Magazine, XXIV, 1887, p. 402. 110 CHEMISTKY AND ECONOMY OF FOOD. Day's food in second experiment. Grams. Meat, lean beef 140 Egg albumen (white of egg) 42 Bread 450 Milk 500 Beer 1,025 Lard 70 Butter . Starcli . Sugar . 30 70 17 Salt 4 Water 286 The diet of the third experiment was essentially the same as that of the second, except that the man drank a little more water. The income included, besides the food and drink, the oxygen consumed from the inhaled air. The estimated quantities were: Oxygen used in 24 hours. Grams, First experiment, fasting and at rest 779 Second experiment, liberal ration and at rest 709 Third experiment, liberal ration and at work 1, 006 The final balance sheets of the experiments, which show the details of income and outgo in terms of the chemical elements, carbon, nitrogen, etc., are too extensive to be reported here. That for each experiment would nearly fill one of these pages, but as some readers may be curious to see what they are, I give the principal data in abbreviated form : Daily income and exjpenditure of chemical elements. Carbon. Hydro- gen. Nitrogen. Oxygen, Experiment with no food (except meat extract) and no work : Income Outgo Grams. 2.4 209.5 Grams. 115.1 221.6 Grams. 1.2 12.5 Gram,s. 1698. 4 2301.4 Loss. 106.5 11.3 603 Experiment with liberal ration of meat, milk, bread, etc., and no work: Income Outgo R15. 5 275.7 270.9 248.2 19.5 19.5 2712. 9 2630. 2 Gain. 22.7 0.0 82.7 Experiment with liberal ration, as in preceding experiment, and hard work : Income Outgo 309.2 336.3 297.7 304.9 19.5 19.5 3232. 5 3246. 5 Loss. 27.1 7.2 0.0 But we wish to know what quantities of flesh and fat the man gained or lost under these different conditions of food and fasting, labor and rest. The figures just cited are for the chemical elements of which the protein and fats are composed. Knowing the proportions of the elements in each compound, it is easy, from the figures for the elements, to estimate the quantities of the compounds. Omitting details of the calculations the results are given in the balance sheet of compounds herewith. Regarding the carbohydrates, however, I should explain that since the body has extremely little of its own, and those of the food are consumed, they are left out of account in the experiment without food, and the amounts received and .consumed in tlie experiments with food are taken as balancing one another. USES OF FOOD IN THE BODY. Ill Income and expenditure of chemical compounds hy tody of man. Fasting (no work). Liberal ration (no work). Liberal ration (hard work). Pro- tein. Fats. Carbo- hy- drates. t^ei^: ^-ts. Carbo- hy. drates. Pro- tein. Fats. Carbo- hy- drates. Grams. 7 78 Grams. 216 Grams. None. None. Grams. Grams, 122 117 122 52 Grams. 332 332 Grams. 122 122 Grams. 117 173 Grams. 352 352 Gain +, or loss — —71 —216 None. +65 -56 The proteiu gained or lost was mainly from the muscles and similar tissues, or what we may call flesh as distingtiished from fat. Taking the figures for protein and lats gained and lost as shown in the last line of the balance sheet of income and expenditure of compounds, changing grams to ounces, and assuming that with each ounce of protein would be water, etc., enough to make the equivalent of 4^ ounces of lean flesh, i. e., muscle, tendon, etc., we have this final result of the trials; the quantities, as before, are those gained or lost in one day : Ouicoine of the experiments as regards increase or decrease of lean flesh and fat within the l)ody. Lean flesh (muscle, etc.). Fats. Ounces. 11 None. None. Ounces. 73 'i 2 Tliat is to say, fasting, and without muscular labor, the man lived upon the tissues of his bodj^ and consumed daily a trifle less than three- quaiters of a pound of mus- cle, and with this nearly half a pound of the fat previously stored in his body. With plenty of food, and still resting, he neither gained nor lost lean flesh, but gained 2| ounces of fat in a day. And when he set himself to hard muscular work, with the same amount of food, he likewise held his own so far as lean flesh was con- cerned, but lost 2 ounces of fat. The body used for its support protein and fats, in each case, and carbohydrates when it had them. When the nutrients were not sup- plied in food, it consumed a little jirotein and a good deal more fat from its own store. With a ration which sufficed to exactly maintain its protein without gain or loss, the body gained fat when it had only a little more than its own muscular work to perform (that included in breathing, keeping the blood in circulation, etc.), and lost fat again when this work was increased by manual labor. If wehadonly theseexperimentsto judge from, we might infer that muscular energy comes from consumption of fat, and that the special work of the proteiu of the food is to repair the wastes and make up for the wear and tear of the protein of the body; and this would be true as far as it goes. But, of course, many other experiments and of many different kinds are needed to settle these questions. The majority of the most useful ones, thus far, liave been made with other animals than man. In studying the laws of animal nutrition the most convenient organism, for many purposes, is that of the dog. The dog thrives upon both animal and vegetable foods, utilizes large quantities of food to advantage or endures long fasting with patience, and makes ready responses by changes of .bodily condition to changes in the food. In reading the accounts of the famous feeding trials conducted by Bischoff and Voit, one is surprised to see what control they obtained of the organisms of the dogs experimented with. By altering the kinds and quantities of food constitu- ents, Voit was able eitlier to reduce both the flesh (protein) and the fat of the 112 CHEMISTRY AND ECONOMY OF FOOD. animal's body or to increase both flesh and fat, or to reduce the one or to increase the other. Indeed, the manipulations effected in this way seemed almost equivalent to getting into the tissues aud directly removing or adding flesh or fat at will. The principles thus learned from experin-ents with the dog and other animals apply in the main, though not in all the details, to the nutrition of man. The effect of one-sided diet is very well illustrated in some experiments by Pro- fessor Eanke. They were made in the respiration apparatus at Munich, and belonged to the series of which I have already spoken. After he had studied the changes that went on in his body when fasting, he proposed to himself these questions: What will be the effect of a diet of protein with very little fat and no carbohy- drates on the one hand, and of a diet of fats and carboliydrates without protein on the other? In other words, how will the composition of the body be affected by food rich in protein and containing little else, and how will the store of fat aud protein be altered by leaving the protein out of the food and living on the other nutrients ? For the diet of protein, he took lean meat, with butter and a little salt, essentially the same diet as was used by the student in the experiment described above. He had found himself able to eat 2,000 grams of the lean meat in the course of the day, but in this experiment, which lasted 24 hours, he ate only 1,833 grams (about 4 pounds) of meat and with it 70 grams of fat, 30 grams of salt, and 3,371 grams (nearly 3 quarts) of water. Without going into the details, suffice it to say, that, according to Professor Ranke's calculations, his body lost 15.1 grams of fat aud at the same time gained 113 grams of protein during the day of the experiment. In the other experiment, which likewise continued for 24 hours, the food consisted of 150 grams of fat, 300 grams of starch, and 100 grams of sugar, an even less appetizing mixture perhaps than the lean meat and butter for an exclusive diet, but yet one which, if put together with proper culinary skill, makes a cake that can be swallowed. This time he lost 51 grams of protein and gained 91.5 grams of fat. The results of these two experiments may be recapitulated thus: On the diet con- sisting chiefly of protein (lean meat, etc.) the body gained protein (muscle, etc.) and lost fat. On the diet consisting chiefly of fats and carbohydrates (starch and sugar) the body lost protein and gained fat. This is just what we might expect. But it is interesting to have the facts and figures to show exactly what did take place, and other exj)eriments make it safe to say that if either the quantities of food or the condition of Professor Ranke's body had been different, the results would have been different also. Thus in the first experiment if he had eaten less meat he would have stored less protein ; indeed, with a small enotigh ration he would have lost both protein and fat, and it seems probable that if he had not been a rather fat person he would not have lost fat so readily on the protein diet. Experiments confirm and to some extent explain the fact so well attested by gen- eral experience, that a mixed diet is best for ordinary people in health. Profeaeor Eanke found that when he did no muscular labor, his body neither gained nor lost; that, in other words, he just about "held his own" with food, containing per day: Protein, 100 grams (3.5 ounces); fats, 100 grams; carbohydrates, 240 grams (8.5 ounces). CHAPTER VII METABOLISM OF ENERGY— INCOME AND OUTGO OP BODY. lu considering the metabolism of energy we liave to deal with the principles of thermochemistry as applied to animal and vegetable organisms. For the present purpose we may confine our attention to the changes which go on in the animal body. The principles to be applied may be expressed in various ways. They are enunciated by Eerthelot in the following terms :^ I. Frinciple of molecular [atomic] worlc. — "The quantity of heat evolved is the measure of the sum of the chemical and physical work accomplished in any reaction." II. Principle of conservation of energy. — "When a system of bodies — simple or compound — starting from a given condition undergoes either IDliysical or chemical changes, which bring it into a new condition with- out producing any mechanical effect on external bodies, the amount of heat evolved or absorbed, as the total result of these changes, depends solely on the initial and final states of the system, and is the same, whatever may be the nature or order of the intermediate states." III. Principle of maximum worlc. — " In any chemical reaction between a system of bodies not acted on by external forces the tendency is toward that condition and those iDroducts which will result in the greatest evolution of heat." It is with the second and third of these principles, and especially the second, that we have to do. In discussing this subject Professor Cooke says : We readily accept BertLielot's secoud fundamental principle of thermo-chemistry when enunciated as above, because it so obviously falls under the general law of conservation of energy; but it is obvious that this principle could not have been, assumed prior to its experimental verification any more than could the principle of the conservation of mass prior to the experiments of Lavoisier, and as Lavoisier worked out this last great principle with the balance, so Berthelot and Thompson have demonstrated with the calorimeter the corresi^onding fundamental principle of tliermo- chemistry, which must be regarded as a generalization from the results of their work. Moreover, although in cases of simple direct combination the principle under discussion is almost self-evident and has been long admitted, yet before the investigations of Eerthelot and Thompson no chemist conceived of its application in the very complex and indirect reactions by which the greater part of the thermo- chemical data have been obtained. In like manner it may be said that the application of the second and third of these principles, and especially the second, in the living organ- ism has long been believed, but has lacked the absolute demonstra- tion. During the past ten years, however, an approach to such demon- ^Essai de m^canique chimique. Tome I, Introduction, pp. xxviii, xxix. See also ,T. P. Cooke in Amer. Jour, of Sci., bd. ser., XIX, pp. 261-267; and Pattison-Muir, Thermal Chemistry, pp. 297 and 245, note, 8518— No, 21 8 m 114 CHEMISTRY AND ECONOMY OF FOOD. stratioii has been made by several experimenters, notably by Eubiier in experiments with dogs, and although these have not the completeness necessary to place the principle beyond all peradventure, and especially to show the details of its application, they suffice to confirm the belief in the general application of the principle. The experimental study of this question is carried on in two lines. Potential energy — Heats of comMistion determined hy the homh calorim- eter. — The first of these kinds of inquiry has to do with the determin- ing of the potential energy of the materials concerned in the metabolic processes. These materials are (1) the nutrients, i. e., protein, fats, car- bohydrates, etc., of the food; (2) the substances, mainly protein and fats, which are either stored in the body or taken from the store con- tained in the body and consumed; and (3) the excreted compounds which are not completely oxidized and which in consequence still con- tain potential energy; these are chiefly the urea and other organic com- pounds excreted by the kidneys and the uudigested residue of the food. The heats of combustions of the compounds, as determined by oxidation in the bomb calorimeter, are taken as the measure of their fuel value. Income and outgo of energy in the body — Respiration calorimeter. — The second branch of the inquiry concerns itself with the balance of energy in the body. It involves the determination of the total income and outgo expressed in terms of both matter and energy. The income and outgo of matter are determined by the aid of a respiration appa- ratus, which shows the quantities of chemical elements and compounds taken in and given off by the body, and inferentially the quantities of material which are either stored in the body during the experiment or consumed from its previous store. The income of energy is repre- sented by the potential energy of the materials which constitute the income of matter. Their potential energy is learned from the heats of combustion developed when they are burned with oxygen in the calor- imeter. The outgo of energy is made up essentially of three factors. One is the potential energy of the excreta, which is determined by burning with oxygen in the calorimeter; another and the principal one i^ the heat radiated from the body. To measure this, diflerent appli- ances have been used. The most successful results thus far published have been obtained by Eubner with a respiration apparatus which has special arrangements for determining the quantity of heat radiated from the body. Perhaps the most convenient designation for such forms of apparatus Is that here used — respiration calorimeter. The third factor is the mechanical work done by the body, i. e., that which manifests itself as external work, and not including the internal work such as is involved in respiration and the circulation of the blood. The heat equivalent of this external mechanical work, added to the heat radiated from the body and the heat of combustion of the excreta, would make up the total outgo of energy, ISo successful attempt to measnre all these factors in the same experiment has yet been published. Jn the study of the nutrition of man in relation to his health and METABOLISM OF ENERGY. 115 useful work the sources, miture, aiul econoiny of intellectual energy constitute a most important factor, but one upon ^vllich cbeniical pLysi- ology lias as yet thrown very little li,iiht. POTENTIAL ENERGY OF FOOD — HEATS OF COMBUSTION — FUEL VALUES. The food performs essentially two fuuctions in the body — the building aud rei)air of tissue and the yieldiug of energy. In being consumed the nutrients yield energy in the form of either heat or muscular power. Part of this potential energy becomes kinetic in the cleavage of com- plex compounds to simpler ones; part is liberated in the processes of oxidation. ISTeither the chemical nor tlie physical changes which take place are now fully understood. Of this nuich, however, we are certain : The processes are complex, and although the ultimate chemical products may be the same as those of direct oxidation, the processes by which they are formed in the body are much more complex than those which take place when they are burned either in the furnace or the calorimeter. But it is believed that, in accordance with the principle of the conser- vation of energy, the quantity of potential energy which is transformed into kinetic energy will be the same in the one case as in the other, provided the final products are the same. Furthermore, in accordance with the principle of maximum Avork the tendency is toward those changes which result in the greatest evolution of heat or other form ot kinetic energy. We may therefore take the heats of combustion of the nutrients of the food as equivalent to their potential energy; we may also take this potential energy as the measure of their fuel values, i.e., their value for the j)roduction of heat and muscular work when they are consumed in the body. The same principle applies to the materials, mainly protein aud fats, which the body takes from the food and makes a x>art of its tissue before they are consumed. It applies also to the incompletely oxidized excretory products like urea and to the undigested residue of the food which is excreted by the intestine, in so far as their potential energy is concerned. That is to say, if we subtract the poten- tial energy of these products from that of the total material from which they are formed the diJference will be the amount of energy Avhich has been liberated in their consumption in the body. If, however, a portion of the food has been stored as part of the tissue of the body, the poten- tial energy of the compounds thus stored must also be subtracted from that of the total food in order to learn the quantity of energy actually liberated. Speaking in general terms, then, the quantity of heat which is set free when, a given food material is burned with oxygen in the calorimeter may be taken as the measure of the fuel value of that food material. Such is the theory. It needs further experiment for complete demon- stration, but the balance of probability is now very strongly in its favor, and groAviug more and more so as accurate research accumulates. It becomes very important, therefore, to determine accurately the heats of combustion of the ingredients of food and their iiietabolic products. 116 CHEMISTRY AND ECONOMY OF FOOD. CALORIMETERS AND GALORIMETRY — HISTORICAL DEVELOPMENT. The history of caloriinetry as applied to determining the heats of combustion of organic substances is too comprehensive a subject for treatment here, but a brief review of the part of it which bears most directly upon the fuel values of the compounds concerned in metab- olism will not be out of place. THOMPSON'S CALORIMETER— INVESTIGATIONS OF FRANKLAND. In determining the heats of combus- tion of such compounds two distinct forms of apparatus have been employed. In both the substance is burned with oxygen and the heat is measured by the rise of temperature of a certain weight of water to which the heat is communicated. The older one is that of Lewis ThomiDSon.' This was used for determining the heats of combus- tion of organic compounds as early as 1866.2 The apparatus consisted event- ually of a stout copper cylinder closed at the bottom and standing upright inside a so-called '' diving bell," also of copper. The cylinder and diving bell were immersed in a suitable vessel containing 2 liters of water. In per- forming the exj)eriment a given weight, about 2 grams, of the substance, whose thermal value Avas to be determined, was intimately mixed with 19.5 grams of potassium chlorate, to which about 2.5 grams of manganese dioxid had i been added. This mixture was placed in the cylinder; a small piece of cotton, previously steeped in a solution of potassium chlorate and dried, was in- serted as a fuse. The temperature of the water was then carefully ascer- by a delicate thermometer, and, after the end of the cotton had been ignited, the tube, with its contents, was placed in the riG. 9. — Thompson's calorimeter. tained thread 1 Described briefly by Frankland, Proc. Roy. Inst, of Great Britain, June 8, 1866., and Phil. Mag. [4], 32, 182. 2Loc. cit. See also resume of subject by Stobmaun, Jour, prak, Chem. (N. F., id), 1879, 145, METABOLISM OF ENERGY. 117 bottom of tlie copper diving bell and lowered to the bottom of the water. When the mixture burned the gaseous products of combustion issued from numerous small openings at the bottom of the bell and rose to the surface of the water — a height of about 10 inches. At tlie end of the def- lagration the water was admitted to the diving bell and replaced the remainder of the gaseous products, which were allowed to escape through a small tube. The water was well mixed by moving the bell up and down rei^eatedly, and its temperature was again carefully observed. The rise in temperature of the water, compared with its specific heat, gave the quantity of heat liberated in the combustion. Corrections were applied for (1) the heat absorbed by the apparatus, and (2) the heat evolved by the decomposition of the chlorate of potassium, the former being added to and the latter subtracted from the heat given off in the combustion, as measured by the rise in the temperature of the water. Both corrections were determined experimentally once for all, and the values thus obtained were applied in each determination of the heats of combustion of the substance studied. A series of determi- nations were made by Frankland, who states the results as follows. The heat units are small calories: Actual energy developed by 1 gram of each substatice when hitrnt in oxygen. [Heat tinits.] Name of substance (dried at 100° C). Exiicriiiient. First. Second. Tliird. Fourth. Mean. Beef muscle purified by repeated washing with 5,174 5,009 9,069 P, 330 2,045 2,121 5,002 4,987 5,195 5,088 5 103 4,998 Beef fat 9,069 5,437 2,585 2,302 5.383 2 615 TJrea 2,207 2,197 2 206 The special purpose of these investigations was to get information regarding the quantity of energy which could be developed in the body from the consumption of protein. With reference to this question, Frankland makes the following statements and calculations : It is evident that the above determination of the actual energy developed by the combustion of muscle in oxygen represents more than the amount of actual energy produced by its oxidation within the body, because when muscle burns in oxygen its carbon is converted into carbonic auhydrid, and its hydrogen into water, the nitro- gen being to a great extent evolved in the elementary state; whereas when muscle is most completely consumed in the body the products are carbonic anhydrid, water, and urea; the whole of the nitrogen passes out of the body as urea, a sub- stance which still retains a considerable amount of potential energy. Dry muscle and pure albumin yield, under these circumstances, almost exactly one-third of their weight of urea; and this fact, together with the above determination of the actual energy developed in the combustion of urea, enables us to deduce with certainty the amount of actual energy developed by muscla and albumin, respectively, when consumed in the human body. It is as follows: 118 CHEMISTRY AND ECONOMY OF FOOD. Actual energy developed hij 1 gram of each snhaiancc when consumed in the iody. Name of substances (dried at 100° C). Heat iiiiits (mean). Beef muscle purified by etlier. Purified albumin 4,36S 4,263 Arguing that the source of auirnal heat and of inuscuhir power is to be found in the transformation of the iDotential energy of tbe food into kinetic energy, and that "from this point of view it is interesting to examine the various articles of food in common use, as to their capa- bilities for the production of muscular power," Professor Frank land " made careful estimates of the calorific value of different materials used as food with the same apparatus and in the same manner as described above." The results are summarized in the following table: Results of experiments with food dried at 100° C. [Heat units.] Name of food. Cheshire clieese , Potatoes Apiiles Mackerel Oatmeal (not dried) Lean beef White of egg Carrots Pea meal (not dried) Flour (not dried) Arrowroot (not drieil) Butter Ham. boiled and lean Lean veal Hard-boiled egg - Yolk of egg. . .". Isinglass Cabbage Whiting Ground rice (not dried) Cod -liver oil Cocoa nibs (not dried) Residue of milk Bread crumb Bread crust (not dried) Lump sugar (not dried) Commercial grape sugar (not dried) Kesidue from bottled'ale Residue from bottled stout Experiment. First. Second. 6,149 3,502 6, 134 4, 018 5,260 4,940 3,759 4,006 3,931 3, 9;;2 7, 291 4,498 4, 595 0,187 Third. 3. 8r.7 5,410 4, 927 4, 520 3,744 4, 320 3,824 9,080 6, 937 5,320 3.984 4,488 3, 294 3,277 3,744 6,455 From the data thus obtained Frankland estimates the quantities of energy actually developed by these materials when oxidized in the body, making allowance for the nitrogenous material which is not completely oxidized. He adds that "it must be borne in mind that it is only on condition of the food being digested and passed into the blood that the results given in these tables are realized, and that the force values experimentally obtained for the different values in these tables, must, therefore, be understood as the maxima assignable to the substances to which they belong." The tables in which the compila- tions are given are somewhat detailed and need not be repeated here. METABOLISM OF ENERGY. iiy STOHMAXN'S CALORIMETICR AXD IXVKSTIGATIONS. After tlic x>i^blk'ation of Fraiikland's investigations in 186G, no fnrtlier investigations of importance in tliis direction were announced or undertaken until 1S77, wlien Stohniann began work in Leipsic. His results were first published in 1870. His method was the same in prin- ciple as that followed by Frankland. Stohmann, however, gave much attention to the sources of error, and devised a form of calorimeter with which the attempt was made to avoid them. The figures of Fraukland above cited show wide discrepancies iu the dnjdicate determinations of the heats of combustion of the same material. iStohmann's first effort was to trace these dis- crepancies to their source. Tlie principal causes of error were found in the oxidation of the cop- per of which the cylinder was made and the irregularity of a secondary thermal process inci- dent to the combustion, namely, the solution of the potassium chlorid formed by the decom- position of the chlorate. The former error was obviated by substituting platinum for cop- per in the combustion cylinder and the latter was controlled by the direct determination of the potassium chlorid in solution at the end of the combustion. Stohmann used at first an appa- ratus which was obtained iu Lon- don and was essentially the same asthatof Tliouipson which Frauk- land had employed. He soon modified it, however, by making the combustion cylinder of plati- num instead of copper, as just stated, and by substituting a vessel of brass in the place of one of glass for holding the water. ' In the elaboration of the method and finding the sources of error and means of avoiding them. Stohmann, with his two assistants. Dr. Spindler and Dr. von Eech- euberg, made " at least a thousand combustions." In the apparatus thus described a layer of nonconducting material (wool) was put around the outside of the brass cyl- inder which contained the water; no other means was used to prevent the radiation Fig. 10. — Stohmarin's calorimeter. ' A description of this apparatus with diagram is given by Stohmann iu .Jour, prak. Chem., 127 (X. F. 19), 1879, p. 115. 120 CHEMISTRY AND ECONOMY OF FOOD. of heat from the water in the cylinder outward, or the passage of heat from without into the water. Later, Stohmaun provided a series of three concentric cop- per cylinders. The sjiace in the interior of the inner cj'linder which was not occu- pied by the apparatus was filled with air; the space hetween this cjdinder and the second was also filled with air ; that hetween the second and the outer one was filled with water. The outer cylinder Avas wrapped in felt. There were thus 2 layers of air, 1 of water, and 1 of felt hetween the calorimetric ai>paratus jiroper and the external air. Mechanical devices were provided for stirring water in the calorimeter so as to secure uniform distribution through it of the heat from the combustion. The temperature of the water was measured by a thermometer with divisions such as to permit reading to one-thousandth of a degree with the aid of a magnifying glass.' The apparatus thus perfected was used for ten years or more by Stohmaun and his pupils, Von Rechenberg and Danilewski in Leipsic, by Rubner in Munich, and by Gibson in the writer's laboratory. THE BOMB CALORIMETER OF BERTHELOT. In the combustions by the Thompson- Stohmann method just described the oxygen is obtained from potassium chlorate. Considerable time is required for the determination, but the chief difficulty with this method is that the combustion is not always complete. Berthelot has devised an apparatus and, with the assistance of Vieille and others, has developed a method for the use of oxygen under high pressure. The apparatus consists essentially of a steel bomb lined with platinum, within which the substance is burned. The bomb is immersed in water contained in a metal cylinder; this calorimeter cylinder is placed witli its contents inside of concentric cylinders containing air and water. Tie heat developed is measured by the rise in temperature of the water, due allowance being made for the heat absorbed by the metal of the appa- ratus and for that introduced in igniting the substance by an electric current and developed by the oxidation of an iron wire through which the current is passed, and in the formation of a small amount of nitric acid. The reactions are simple, the oxidation of the compounds in completing the determination requires a comparatively short time, and the results are very satisfactory. The only drawback is the great cost of the apparatus which is due to the large amount of platinum employed in its construction.^ The bomb calorimeter was first used by Berthelot in measuring the heats of com- bustion of gases by detonation. The gas to be burned was mixed with the exact amount of oxygen required, or a slight excess at ordinary atmospheric pressure within 1 Seedescription by Stohmann with diagram; Landw. Jahrb., 13, 1884, 513. It is also pictured in the Century Magazine, July, 1887. . 2For descriptions see Berthelot. Ann. Chim. et Phys. (5), 23, 160; Berthelot and Vieille, Ibid. (6), 6, .546; Berthelot, Trait6 pratique de calorimetrie chimique, Paris, 1893, p. 128, and, for an especially clear account of the apparatus and method, Stoh- mann, .Jour. prak. Chem., 147 CN. F. 39), 1889, 503. An engraving of the bomb with a brief description may be found in Ztschr. analyt. Chem., 1893, 77. The apparatus employed by Stohmann was obtained from Golaz in Paris, who made it in accord- ance with Berthelot's directions. It cost, with accessories, including compression pump, etc., not far from $1,200. METABOLISM OF ENERGY. 121 the bomb and ignited by the passage of an electric spark. Gases -wore easily bnrncd in this way, but the combustion of solids was ini2:)racticable. Attcmi^ts were made to remedy the difficulty with solids by intimately mixiug them with potassium chlorate and good results were obtained as in the Thompson-Stohmann method. Berthelot and Vieille ' found later, - however, that when oxygen Avas introduced under a pressure of from 7 to 25 atmospheres, the combustion was complete with all organic substances even when no potassium chlorate was added. Tlie bomb originally employed by Berthelot was in the shape of a cylinder, with hemispherical ends and divided in two parts, one of which screwed into the other. It was made of steel with the interior lined Avith gold by electroplating. Fig. 11. — Berthelot's bomb calorimeter. The later and i>ermanent form of Berthelot's bomb is cylindrical with a rounded bottom and flat cover. It is made of steel Avith a heaA^y lining of platinum. The size nia«y A'ary. In the one made by Golaz for Stohmann the diameter is appi-oximately 10 centimeters and the height to-the upper surface of the coA^er about 13 centimeters; lAnn. Chim. et Phys. (6), 6, 546. Hn 1885. The jirinciple was discovered and investigated by Frankland in 1864 and 1868. See investigations by him "On the combustion of iron in comin-essed oxygen." Jour. Chem. Soc, II, 1864 ; 52. "On the combustion of gases under press- ure. Brit. Assoc. Eep. XXXVIII, 1868 ( Sect. ) ; .37. " On the combustion of liydrogen and carbonic oxid in oxygen under great pressure." Proc. Eoy. Soc, XVI, 1868; 419. 122 CHEMISTRY AND ECONOMY OF FOOD. the walls are somewhat over ;i ceutimeter in thickness. It contains 2,717 grams of steel and 1,233.3 grams of platinum. The internal capacity is about 300 cubic centi- meters and it holds, under a pressure of 24 atmosY)heres, 7 liters, or, in round num- bers, 10 grams, of oxygen. The cover fits into the top of the cylinder after the manner of a stopper. It is pressed in and held very tightly by an oiiter cap or collar which screws on to the outside of the cylinder at the top. The fittings have to be made with the greatest care in order to prevent the escajie of gas. The material to be burned is shaped into a small cake by means of a powerful j)ress and is held in a platinum capsule. This capsule is sustained by a platinum wire which is fastened to the under side of the cover. Another platinum wire passes through the cover, from which it is insulated by gutta percha, or other appropriate material. These two wires are so arranged that they are easily con - nected by a piece of fine iron wire hanging over the substance to be burned in the platinum capsule. An electric current passed through the platinum wire heats the iron wire to a temperature where it burns in the oxygen and, melting, falls upon the substance so as to ignite it. An arrangement at the top of the cover provides for admitting the oxygen. The oxygen is introduced either with the aid of a compression pump, or, more conveniently, from iron or steel cylinders, in which it is held under sufiticient pressure. Both Berthelot and Stohmann use such cylinders without the aid of a pump. Experience has shown that it is desirable to have fully three times as much oxygen present as is theoretically necessary for the combustion. The quantity of water in which the bomb is immersed is generally about 2 liters. It is contained in a calorimeter cylinder of brass or other metal. A stirrer, not easily described without a diagram, plays between the bomb and the cylinder in such Avay as readily to mix the water and insure uniform tempei'ature after the combustion. The outer cylinders which are employed by Berthelot and Stohmann to protect the apparatus from gain or loss by heat outside, as above described, are made of coj^per. It is found that 2 concentric cylinders so arranged as to hold a layer of water between tbem, the inner being large enough to leave a considerable air space around the calori- meter cylinder, suffice for accurate work. In Stohmann's laboratory the arrange- ments to insure accuracy are quite elaborate. The work is done in a basement room surrounded by very thick walls of stone. Special dcTices are employed to keep the temperature of the room exactly constant. The stirrer is moved by a small motor, which is so regulated as to make the movement the same for all determinations. Berthelot uses a motor for the stirring, but conducts the combus- tions in the laboratory rooms where other work is done and without special arrangements to insure uniform temperature. The Berthelot bomb calorimeter serves its purpose admirablj^. It is comparatively simple, easily handled, and does not get out of order when jiroperly cared for. Practically all kinds of ordinary organic compounds are completely oxidized when the proper excess of oxygen is used at an initial pressure of 25 atmospheres. With an accurate thermometer the rise in temperature of the water is measured with great accuracy. The corrections, of Avhich the chief is the thermal water equivalent of Fig. 12 Mahler's bomb calorimeter as monnted for iise. METABOLISM OF ENERGY. 123 tlie apparatus, are not particularly cliffifult to deteriuiue. The skill and care re([nire(l in the uianipulation are not beyond any thoroughly expert operator, and the results are very satisfactory indeed, as may he seen hy comparing those obtained by Berthe- lot and Stohraann in determining the heats of combustion of the same material in their respective laboratories. The only drawback to the Berthelot bomb is the expense, as said above. This is due mainly to the amount of platinum used for the lining. The steel of which the bomb is made is especially exposed to corrosion. Berthelot protects the outside of the bomb by plating with nickel, which serves the purpose very well, as water and air are practically the only corrosive agents to which it is exposed. But with the interior the case is very different. The oxygen at high jiressure is very active in itself. The carbon, sulphur, and phosphorus of the substances l)urned arc completely oxidized, and carbonic, sulphuric, and ]ihosphoric acids are formed. Indeed, Berthelot has shown that the apparatus may be used for detennining carbon, sulphur, and phosphorus in these forms. More or less of the free nitro- gen which is mingled with the oxygen used in the combustion is oxidized and forms nitric acid. It is necessary that the inner surface be covered Avith some sub- stance which will resist these acids as well as the oxygen. Such materials are easily found, hut the practical difficulty has been to find an inexpensiA^e lining Avhich will insure permanent i^rotectiou to the steel. In Berthelot's first bomb, electro- plating with platinum was tried, but the platinum soon began to scale off. After a few combustions gold was substituted for platinum and with better success, but it has not been used with oxygen under pressure, MODIFICATIONS OF THE BOMB CALORIMETER BY MAHLER, HEMPEL, AXD ATWATER. Various modificatious of Berthelot's apparatus have beeu devised esi)ecially to obviate the difficulty of exi)feusive liuing. Mahler uses a bomb (tig-. 12) of forged steel with enamel lining.' The cylinder is somewhat narrowed at the top and the cover is screwed directly upon it, the junction being made tight by a washer of lead. The enamel is easily put on or replaced, and it is stated that a single coat- ing has been used for 300 combustions without injury. 1 have under- stood, however, that the enamel is apt to scale off in constant use. The form described by Mahler has an internal capacity of 600 cubic centi- meters or nearly double that of Berthelot's bomb, as above described. Hempel uses, for determinations of heats of combustion of coal, a sim- ple bomb of steel without lining. This suffices for technical purposes, but is not recommended by him for scientific use.^ In accordance with suggestions by the author. Professor Hempel has most courteously had a bomb made by the mechanician who makes the bombs of his devising, and lined by Heraeus, of Hanau, with a thin sheet of platinum. The principle is the same as in Berthelot's form; but, whereas Berthelot's cover fits into the cylinder in the manner of a stopper, the cover in this rests directly upon the upper edge of the cylinder, a projection of the latter fitting iiito a groove in the former. iCompt. rend., 113, 774, and 862, and Gdnie Civil, 1891,20, No. 12, 198. See also Ztschr. analyt. Chem., 189.^, 79, and Berthelot, Calorimetrie Chimique, 13.S. -Hempel, Gasanalytische Methoden. 1890, 355. See also English translation; Methods of Gas Analysis, published by McMillan, New York. 124 CHEMISTEY AND ECONOMY OF FOOD. A wavSher of lead is set in the groove of tlie cover and makes perfect closure feasible. The form of the apparatus is essentially the same as that shown in fig. 13. The quantity of platinum required is small, and the cost of the whole apparatus, including vise grip and lever for screwing the outer cover, a cylinder with compressed oxygen, fittings, manometer, and screw press for making hard pellets of the substance to be burned, was less than $220. It has served a most excellent purpose in our laboratory. Mr. 0. D. Woods, who has done considerable work with it, has obtained results agreeing very closely with those of Berthelot and Stohmann. For measuring the temperature of the water, we use a thermometer made by Fuess aud calibrated by the Physikalisch-tech- uische Eeichsanstalt in Berlin. It is gradu- ated to hundredths of a degree, and the divisions are of such length as to permit easy estimation to thousandths by the aid of a magnifying glass. We are persuaded that in this way measurement of the temperature of water to thousandths of a degree can be made with as close an approach to accuracy as the weighings to the tenth of a milligram with an ordinary laboratory balance. In place of copper for the cylinders out- side the calorimeter cylinder, we have used vesselsof ''indurated fiber," which is a good nonconductor of heat. They have proved very satisfactory. The bomb just described has not been found in every way satisfactory. It has, furthermore, seemed desirable to attempt to find a cheaper lining than platinum. Eiforts are being made by the writer and his associate, Mr. Woods, to devise some needed improvements, find a less expensive lining than platinum, and develop an effect- ive apparatus which may be made in this country at a cost that will bring it within the reach of ordinary laboratories. The results of these attempts are very encouraging, but are not yet ready for publication. Figure 13, herewith, will help to explain the apparatus in the form in which we are using it. A represents the cylinder, C the screw cap, and B the cover of the bomb, which is placed upon the top of the cylinder and held down by the screw cap. A and C are made of gun steel. In a bomb lately made by the Pratt & Whitney Company, of Hartford, Conn., the steel is the same as is used for the Hotchkiss guns which are being manufactured by them. The metal has an unusually high tenacity and seems especially well fitted for the purpose. The cover (B) is provided with a neck into which fits a cylindrical screw (E), holding another screw (F). On the side of the neck is an aperture (G) between the lower end of D and the shoulder. In Fig. Vi. — Bumb calorimeter as modified by Hempel and Atwater. METABOLISM OF ENERGY. 125 VW/X-AVk'// '//,A///,/ t FlO- 14.— Boml} calorimeter of fig- 13, as mounted and standing in -svater, 126 CHEMISTRY AND ECONOMY OF FOOD. Fig. 15.— Top of bomb calorimeter of flg. 13. D is fi washer of lead on Avhicla the lower edge of E fits. By opening or closing the screw F the narrow passage from G is opened or closed. The opeuiug is used for admitting oxygen at a high pressure through a narrow passage to charge the bomb. In B is an aperture through which passes a jilatinnm wire (H), which is separated from the metal of the cover by insulating material. Hard vulcanized rubber serves A'ery well for this purpose. Fastened to the lower side of the cover is another plati- num rod (I), between which and H an electrical connection is made by a very line iron wire. A screw ring holds the small platinum capsule, in Avhich the substance to be burned is placed. At K K are ball bearings of hard steel to avoid friction in screwing the cap down. Fig. 14 shows the bomb as mounted and standing in the water, which is contained in the calorimeter cylinder. The large cylinders (N and O) are made of indurated fiber and covered with plates of vulcanized rubber. A stirrer (L) serves for equalizing the tempera- ture of the different portions of water after the combustion is comx^leted. The situatiou of the thermometer (P) is likewise shown. Wires (H' I') serve for bringing the electrical current to the platinum wires in the bomb. RESULTS OF DETERMINATIONS OF HEATS OP COMBUSTION. The iiiv^estigatioiis by Franklaiid in 186G, above cited, like a great deal of the best pioneer work, were of the highest value for their pur- pose, bnt liave not the accuracy which the later refinements of method have made possible. Determinations of the heats of combustions of a large number of substances by the Thompson-Stohmann method were made by Stohmann and his pupils. Von Eecheuberg aud'B. Danilewski, between 1877 and 1885. Those of a smaller number were made by Eubner in 1885, and by Gibson in 1800, before the method of Berthelot became well known. The greater convenience, rapidity, and accuracy obtainable by use of compressed oxygen with the apparatus of Ber- thelot, the first description of which was published in 1885, led Stoh- mann, in 1887, to adopt this method. Since that time he has, with Langbein, not only reviewed his previous results, but added a large number of new ones by this method. The following table summarizes the results obtained by use of the Thompson-Stohmann and Berthelot methods in determining the heats of combustion of the organic substances which occur in animals and plants, and are of special interest in physiological chemistry. They included all the determinations of this class which we have found up to July, 1894: 1 Since the above was written an extremely valuable article upon the subject by Professor Stohmann has appeared. See Experiment Station Record, vol. 6, and Ztschr. Biol., 31, 364. METABOLISM OF ENERGY. Heats of comhiistion of organic suhstanccs. 127 Berthelot method. Thompson-Stolimann melliod. Berthelot and asso- ciates. Stolimann and Laug- Lein. Stolimann and asso- ciates.' B. Danil- ewski.* Rubner.-' Gibson.* ALBUiMINOIDS, ETC. 6 5, 990. 3 6,141 6 5,961.3 6 5,941.6 65,917.8 6 5,907.8 6 5, 885. 1 6 5,867 6 5,849.6 6 5,840.9 6 5,832.3 6,231 1 55,910 6 5,626.4 5,950 5,717 5,786 8, 112. 4 6 5,793.1 6 5,745.1 « 5, 735. 2 6 5,720.5 6 5,672 6 5, 662. 6 6 5,640.9 6 5,637.1 6 5, 553 6 5. 510. 2 6 5, 479 6 5,355.1 6 5,298.8 5,573 6 5, 780. 6 6 5,687.4 6 5,728.4 5,579 Muscle, extractives and fat re- 5,778 5,598 5, 324 * 5,656 Do 6 5,529.1 5,511 5,709 "^ool 5 5,564.2 5,362 5,069 5,493 4,909 6 5,240.1 ■'5,342.4 5 5,410.4 5 5,095.7 64,655 6 4,140.8 65,330.6 65,039.9 6 4,979.6 64, 650. 3 Chitin 5, 637 2,465 3,053 AM IDS, ETC. 5^2,530.1 83,133.6 8 4,370.7 8 6,536.5 62,541.9 63,129.1 6 4,355.5 6 6,525.1 6 4,505.9 6 5,668.2 6 2,899 2,537 2,523 8 5,659.3 82,911.1 85,915.9 8 3,396.8 5, 642 6 3, 514 6 3,714.1 6 4,275.4 6 2,749.9 6 3,891.7 65,231.4 119,476.9 11 9, 485. 7 119,493.6 3,428 » (3, 206) 10 2, 754 2,021 FATS. 1. Animal: 9,380 9,357 9,406 9,410 9,330 9,345 9,324 9,398 9,192 12 9, 686 9,423 9,515 9 427 9,530 Fat of clog 1 Fat of duck Butter fat "9,215.8 9 185 Sperm oil 10, 001 1 Jour, pralv. Cliem., 139 (iST. F., 31), 273. These results were published in detail in Landw. Jahrb., XIII (1884), 413 ; later the figures were slightly changed as a result of the determination of the experi- mental corrections of the method and appear (corrected) as cited above (Jour. prak. Chem.). 2 Centbl. med. Wiss., 1881, Nos. 26 and 27. Ref. Jahresb. Tliier-Chem., 11 (ISSl), 7. 3Ztsclir.Biol.,21 (1885), 250. * Report of Storrs (Conn.) Experiment Station, 1890, 182. 6 Ann. Chim. et Phys. (6), 22, 25. 6 Jour. prak. Chem., 152 (N. F., 44), 1891, 336. ' Ann. Chim. et Phys. (6), 20, 13. 8 Ibid. (6), 22,1. 8 Extract of meat. i»Compt.rend., 110, 1267. I'Jour. prak. Chem., 150 (N.F., 42), 1890,361. 12 Kind of fat not specilied. 128 CHEMISTRY AND ECONOMY OF FOOD. Heats of combustion of organic substances — Continued. Berthelot metliod. Tbompson-Stolimann method. Berthelot and asso- ciates. Stohmann and Lang- bein. Stohmann and asso- ciates.! B. Danil- ewsld.2 Eubner.3 Gibson.* FATS— continued . 2. Vegetable: 9, 328 9,471 9,442 9, 489 9,619 CO, 130 I 9, 407 3.695 9 471 Do Do \ CARBOHYDRATES, ETC. 1. Pentcses: 5 3, 714 5 3, 739. 9 63,722 6 3,746 6 4, 340. 9 64,379.3 6 3, 909. 2 6.3,714.5 63,721.5 63,742.6 63,755 3 2. Hexoses : 3,659 3,692 '3,702 3,754 3. Heptoses : 8 3, 732. 8 9 3,961.7 4. Disaccharids : Cane sugar 63,955.2 63,951.5 6 3, 736. 8 6 3, 949. 3 3, 860 3,877 3,003 4, COl 3,921 93,777.1 .::::::: :::::::: 3,710 63,721.8 63,947 6 3, 550. 3 64,020.8 63,400.2 6 3,913.7 4, 190. G 6 4.185.4 6 4,182.5 64,112.3 64,133.5 5. Trisaccbarid.s : 64,020 ■6. Polysaccliai'ids : i»4,200 9 4, 228 9 4,180.4 9 4,187.1 11 7, 068 4,146 4, 123 Stareli 4,164 4,070 ALCOHOLS. 124.112.4 63,997.8 6 3,679.6 4,317 3, 908 94,001.2 6 3,676.8 11 3, 490. 4 1 3.959 ACILS. 139,352.9 9,226 9,420 Oleic 139,494.0 " 1, 998. 2 "^S, 006.2 1, 900 3.019 1,745 2, 397 Citric 112,477.9 1 Jour. prak. Cfiem., 139 (N. F.,31), 273. These results were published in detail in Landw. Jahrb.' XIII (1884), 413 ; later the figures were slijihtly changed as a result of the determination of the experi" mental corrections of the method and appear (corrected) as cited above (Jour, prali. Chem.). 2 Coutbl. nied. Wiss., 1881, JSTos. 26 and 27. Ref. Jahrebb. Thier-Chem., 11 (1881), 7. 3 Ztschr. Biol., 21 (1885), 250. ^Report of Storrs (Conn.) Experiment Station, 1890, 182. 6 Ann. Chim. et Phys. (6), 21 , 409. 6 Jour. prak. Cheni.', 153 (N. F., 45), 305, and private communication from Professor Stohmann. 'Ann. Chim. et Phvs. (6), 13, 304. sCompt. rend., 114, 921. 9Ann. Chim. et Phys. (6), 10, 455. i"Ibid. (6),6,546. iiJbid. (6),27, 310. 12 Jour. prak. Chem. 150 (N. F., 42), 1890, 361. "Ztschr. phvsikal. Chem., 10, ',892, 410. I* Ann. Chim. et Phys. (6), 23, 179. Note. — The most of Berthelot's work is also referred to by Stohmann under references ^-i^. Under reference 16 will be found a table summarizing all of Stohmann's work with the bomb and some of the results obtained by Berthelot and his associates. METAIJOLISM OF ENERGY. 129 INVESTIGATIONS OF HEATS OF COMBUSTION NOW NEEDED. This field of inquiry is new and offers most excellent o[)portunity for useful work. The directions in which inquiry are now most needed are practically two — the study of compounds of interest in physiological chemistry and the study of the foods and feeding- stuffs in which those compounds occur. In addition to the materials which are used in the nutrition of animals and plants the excretory products, which contaiu undigested residues and cleavage products from them, also demand investigation. Heats of combustion of organic compotinds. — The determination of heats of combustion of compounds of interest in physiological chemistry is desirable for two purposes, (1) for obtaining better knowledge of their chemical constitution, and (2) for securing the much-needed informa- tion as to their physiological uses, and especially their fuel values. The indications which the heats of combustion give regarding the molecular constitution is of the greatest importance in the present condition of chemical science; and, aside from the purely theoretical interest of the inquiry there are various practical applications of value to the chemist; as, for instance, in distinguishing between isomeric compounds. The imxDortance of the measurements of fuel value of the compounds has already been indicated and hardly needs to be insisted upon fur- ther in this place. The compounds which most demand study are of the kinds already studied and reported upon in the statements above. It is safe to say that all of the organic constituents of animal and vegetable tissues and their cleavage products, especially such as are formed by metabolism and living organisms, demand extended study; and it is of course desir- able tliat the determinations of the heats of combustion should accom- pany and be supplementary to the investigation of their general characters, chemical and physical. In many laboratories these com- pounds are being isolated and studied. It is extremely desirable that the heats of combustion be determined at the same time. What we need to do is to secure the materials in as large variety and of as great purity as possible and burn them in the calorimeter with due precaution, and record the results. If a number of investigators will undertake a research of this kind, the needed information will gradually accumulate. Heats of comhustion of foods and feed ing sturff's, etc. — But the materials in which the compounds occur likewise demand calorimetric investiga- tion. We may take, for instance, a food material, as wheat flour, study its composition, isolate its several constituents, and determine the potential energy of each, but at the same time It is desirable to burn the flour and observe whether its energy, as thus directly determined, corresponds with the energy as learned from the combustion of the sev- eral constituents. Investigations of this kind bring out discrepancies 8518— No. 21 9 130 CHEMISTRY AND ECONOMY OF FOOD. between the results obtained, by coiubiistiou of the material as a whole and by separating the several ingredients and determining their heats of combustion and thus estimating the heat of combustion of the whole material. It is only by careful comparative studies of this kind that we shall learn the reasons for the discrepancies, the sources of error, and means for avoiding them, and the correct methods for determining the fuel values of food materials. Although the work thus far done gives most cheering prospects of ultimate success, the results are not yet rii^e for publication. ISODYNAMIC VALUES OF NUTRIENTS. It has been assumed that the heats of combustion of the several ingredients of food represent the potential energy which is transformed into kinetic energy when the food is used in nutrition. This priucix)le may be expressed otherwise in saying that in their services as fuel to yield heat and mechanical (muscular) power their values will be directly proportional to the amounts of potential energy they contain. If this be true, we should expect that they would replace one another in pro- portion to their several heats of combustion. Late experiments, notably those of Eubner, imjDly that this is actually the case. A proper discus- sion of this subject will require the consideration of a large amount of detail. Eeserving that for another occasion, I quote here a short pop- ular description of experiments by Eubner which were made some ten years ago.^ Within a short time past, feeding trials with animals in the respiration apparatus have shown the proportions in which the several classes of nutritive ingredients of food do one another's work in serving as fuel in the body, and more extended experi- ments, with improved forms of the calorimeter, have given A^ery accurate measure- ments of the amounts of potential energy in the same materials. The respiration experiments have been made with dogs, in the Physiological Institute in Munich, by Dr. Rubner, who has also made an extended series with the calorimeter. The largest number of the experiments with food materials in the calorimeter, however, have been conducted by Professor Stohmann, of the University of Leipsic, and his assistants. The results of experiments with the respiration apparatus and with the calorimeter agree with most remarkable closeness. In supplying the body with fuel, the protein, fats, and carbohydrates replaced each other in almost exact pro- portion to their heats of combustion. That the living body should thus be proved to use its food with such perfect chemical economy is certainly interestiug and important. It is one more fact to add to the long lists that are bringing the functions of life more and more within the domain of ordinary physical and chemical law. Isodjjnamic values for 100 parts of fat. Nutritive substances, water free. As deter- mined by direct experi- meirta with animals. As deter- mined by calo- rimeter. Myosin Lean meat starch Cane sugar Grape sugar ' Century Magazine, July, 1887 225 243 232 234 256 213 235 229 235 255 METABOLISM OF ENERGY. 131 The quautii/ies of tlie several substances, loan meat, myosin (the chief protein com- pound of lean meat), starch, etc., are those which were found to yield, the same amounts of heat when burned in tlie calorimeter, or to render the s.ame service as fuel when consumed in the body of the animal, as 100 grams of fat. This explanation of the meaning of the expression "isodyuamic values for 100 parts of fat" needs a little qualification to make it perfectly correct, but it is as accurate as I can well make it without going into a discussion too abstruse for the pages of a magazine, and it is really accurate enough for our purpose. The figures mean, then, that the dogs in the respiration apparatus obtained, on the average, as much heat to keep their bodies warm and energy for the work their muscles had to do, from 243 grams of lean meat) i. e., meat enough to furnish 243 grams of nutritive material after the water had been driven out), as they obtained from 100 grams of fat, while 235 grams of the lean meat, burned to equivalent products in the calorimeter, wooild yield the same amount of heat as the 100 grams of fat. Considering the great difficulties in experimenting with live animals, these two isodynamic values, 243 by the respira- tion apparatus and 235 by the calorimeter, agree very closely indeed. But with starch, the results by the two methods, 232 and 229, are still closer, while with ordi- nary table sugar and grape sugar they are as good as identical. Taking our ordinary food materials as they come, and leaving out slight differences, due to the differences in digestibility, etc., Dr. Rubner has made the following general estimate of the amounts of energy in 1 gram of each of the three principal classes of nutrients: Potential enercnj in nutrients of food. Foot-tons. In one gram of protein 4. 1 6. 3 In one gram of fats 9. 3 14.2 In one gram of carbohydrates 4. 1 6. 3 These figures mean that when a gram (one-twentieth of an ounce) of fat, be it the fat of the food or body fat, is consumed in the body, it will, if its potential energy be all transformed into heat, yield enough to warm a kilogram of water 9.3 degrees of the centigrade theremometer, or, if it be transformed into mechanical energy such as the steam engine or the muscles use to do their work, it will furnish as much as would raise 1 ton 14.2 feet or 14.2 tons 1 foot. A gram of protein or carbohydrates would yield a little less than half as much energy as a gram of fat. In other words, when we compare the nutrients in respect to their fuel values, their capacities for yielding heat and mechanical power, an ounce of protein of lean meat or albumen of egg is just about equivalent to an ounce of sugar or starch; and a little over 2 ounces of either would be required to equal an ounce of the fat of meat or butter or body fat. The potential energy in the ounce of protein or carbohydrates would, if transformed into heat, suffice to raise the temperature of 113 pounds of water 1° F., while an ounce of fat, if completely burned in the body or in the calorimeter, would yield as much heac as would warm over twice that weight of water 1 degree. One principle which they bring into clear relief is the remarkable economy with which the animal organism uses its material when the supply is limited, and the pos- itive wastefulness it practices when the food supply exceeds the demand.. The dogs had very little room to move about inside the ajiparatu.s, and of course made very little muscular exertion. Hence they needed but little protein to make up for the wear of muscle; and, practically, the main demand of their bodies was for fuel to yield heat to warm their bodies and strength for the very little work their muscles had to do. When they fasted they consumed tlie fat and protein from the store in their bodies. How rigidly economical they were in this draft upon their previously accumulated capital was shown in the way that the consumption of fuel was affected by the temperature of the room. The interior temperature of the body romained very nearly the same, at "blood heat," all the while, as indeed it must, or 132 CHEMISTRY AND ECONOMY OF FOOD. the dogs would have died. In cold days more heat was radiated from the hody than in warm, more was needed to supply its place, and more material was consumed. When the room was warmer the body burned less fuel; and the quantities con- sumed marked the changes of temperature with a delicacy almost comparable with that of the thermometer. When the dogs had just food enough to supply their needs they used it with sim- ilar economy. In other words, when the income was equal to the-necessary expend- iture it was used as sparingly, as the sums taken from the capital had been. When the food supply was made larger, part of the extra material was stored in the body as fat and j)rotein, but at the same time the daily consumption increased. That is to say, when their income was more liberal they laid part of it by, but at the same time allowed their current expenses to increase. It has been found by numerous experiments that when the nutrients are fed in large excess the body may continue for a time to store away part of the extra material, but after it has accumulated a certain amount it refuses to take on more, and the daily consumption equals the supply even when this involves great waste. With the large income the body con- tinues for a time to add to its capital, but finally it comes to spend as much as it gets, and in so doing practically throws away what it can not profitably use. Dr. Rubner's dogs showed in still another way their economy of fuel when the supply was limited, and wastefulness when they had more than they needed. The same animal that adjusted its consumption of fuel so accurately to the temperature of the air as long as the amount did not exceed its need, used it with no apparent regard to the temperature, whether warm or cold, as soon as the supply of food exceeded the necessary demand. Physiologists have observed that the consumption of fuel in the body sometimes varies with the temperature and sometimes does not, and have been at a loss to explain the apparent discrepancies in their experimental results. These experiments help toward an explanation. But the interesting point is, not simply ihat the facts are learned, but that they are learned by studying the subject from the standjioint of the potential energy of the food. Previously the accounts have, so to speak, been drawn up in terms of protein, carbohydrates, and fats, and the balances have been difficult to calculate and still more difficult to explain. But in the experiments of which I have just been speaking, all the figures were reduced to terms of potential energy of the food and body substance consumed or stored. The results were calcu- lated in calories, and the balancing of the accounts was thus made simple and the explanation plain. Of course, I do not mean to say that Ave have thus suddenly come upon a complete explanation of the whole subject. This is simply an improvement of methods based on clearer understanding of principles and leading to clearer and more accurate results. It is, in short, the old story of clearing uj) an old mystery by use of a new and rational idea. As such, as well as for stronger reasons, it is of interest. It is so easy to magnify the importance of any new discovery, and so hard to avoid going too far in drawing inferences from it, that I am inclined to put in another word of caution here. For instance, from the experiments above described one would infer that the food ingredients yield strength for muscular labor in exact proportion to their heats of combustion. But the dogs in the respiration apparatus performed no muscular work except that inside their bodies for respiration, keej)ing the blood in circulation, etc., and though we naturally assume that if they had used their muscles for exterior work, such as running or working a treadmill, the muscular energy yielded by the food would have been likewise equal to its potential energy, and though the other known facts make this assumption entirely probable, the experiments do not absolutely prove it. The production of muscular strength is a problem which is still but partly solved. Still I think it is reasonably safe to say that, in general, the foods that have the most potential energy are the ones that yield, not only the most heat to keep the body warm, but also the most strength for muscular work. METABOLI^iM OF ENERGY. 133 FUEL YALUES OF PKOTEEN'. FATS. A>'D CAEBOHTDEATES. The isodynamic values of the nutrients as computed by Enbner are for protein and carbohydrates each 4.1, and for fats 9.3 ^ams. It is hardly supertluons to repeat tha? these values are tentative, and that tliey can not apply with exactness to the nutrients of all food materials. They represent the results of the small number of experiments thus far made. Xearly all of these have been made with dogs, and the num- ber of kinds of food material has been limited mainly to meats, a small number of kinds of fat, and to snch carbohydrates as starch and sugar. In the estimates for protein, allowance is made for the nitrogenous mate- rial, chiefly urea, which does not undergo complete combustion in the body. The figures are based partly upon direct experiments and partly upon a priori estimates. Doubtless a more critical study of the subject will call for more or less revision of these figures for the fats that have been experimented with, and there is no question that different figures will have to be assigned to the nutrients of the same class from different foods and feeding stuffs. The correct estimates must be found by the same kinds of experimenting as are needed to confirm the theory that the law of conservation of energy actually applies in the living organ- ism. These experiments will, of course, be calorimetric. They wiU be made in part by determinations of heats of combustion with the bomb calorimeter or other appropriate api^aratus, but the chief dependence must be put upon experiments by which accurate determinations are made of the total income and outgo of the animal body as expressed in terms of both matter and energy. The respiration calorimeter is such an apparatus. EESPFBATION CALOEDEETEES. During the past twelve years a number of efforts have been made to devise an apparatus by which accurate determination could be made of not only the chemical elements and compounds, but also the energy received and given off from the body. The most successful forms of which accounts have been published at all in detail are those of Eubner and Eosenthal. Each of these is essentially a small respiration ai^pa- ratus, with a device for measuring the heat radiated from the body. In the apiiaratus of Eubner^ the respiration chamber consists essen- tially of a metal box with double walls. In the interior are arrange- ments for keeping an animal for a considerable length of time, as in an ordinary respiration apparatus. Provision is made for conducting a current of air through this chamber and for measuring its amount and determining its composition. The apparatus of EosenthaP is similar in principle to that of Eubner. The respiration chamber is double walled and the quantity of beat radiated from the animal is estimated by the expansion of the air ' Calorimetrisclie Methodik, Marburg. Elwert, 1891. - Calorimetrisclie Untersucliaugen, Arch. Anat. Physiol., Physiol. Abth., 1894, 223-282. 134 CHEMISTRY AND ECONOMY OF FOOD. inclosed between the two walls. That is to say, in Eubner's aj)X)aratus the air, instead of being kept at a constant volume, is allowed to expand or contract, and the quantity of heat which passes through it is esti- mated from the increase of volume at constant pressure, while in the apparatus of Rosenthal the estimate is made by the variation of pres- sure at a constant volume. An especially noteworthy feature of the apparatus of Rosenthal is a device by which a definite volume of air is kept continually passing through the chamber. On emerging it passes through absorbents by which the respiratory products are removed, a fresh supply of oxygen being added at the same time, so as to maintain a constant volume. The space between the two walls of the box is filled with air, which is tightly confined so that none can escape. A manome- ter serves for determining the pressure, which is increased as the tem- perature rises and decreased as the temperature falls. The larger the amount of heat radiated from the body of the animal the higher will be the temperature, other conditions remaining the same, at which this confined i)ortion of air is maintained, and hence the greater will be the pressure as registered by the manometer. Professor Rosenthal has been at no little pains to explain both the theory and the practice of this method of measuring the radiation of heat. A number of experi- ments have been made, but they are mostly of a character either special or preliminary, and in those thus far published no complete measure- ment of the income and outgo of material energy has been given. Rub- ner's arrangements for measuring and analyzing the air passing through the chamber are the same as those in the small respiration apparatus which was described above as devised by Yoit on the princii)le of the apparatus of Pettenkofer. For full details of Eubner's apparatus as well as of Rosenthal's the original descriptions may be consulted. eubner's experiments with the respiration calorimeter. Rubner has lately published^ the results of a very interesting series of experiments with dogs, in which the metabolism of material has been measured in terms of nitrogen and carbon, and that of energy in terms of the heat of combustion of the food and the heat radiated from the body. The animals were entirely at rest, and there was, there- fore, no external work. Under these circumstances it was assumed that all of the energy given oif from the body would be in the form of radi- ated heat. The number of these experiments has been rather small. The published account does not contain the full details. The results are in part estimated rather than directly determined, but, as given, they confirm both the correctness of the figures for isodynamic values of nutrients, which Rubner had previously annexed, and the application of the law of the conservation of energy in the organisms of the animals. The whole results may be summarized in the statement of »De Quelle der tMerisclien Wiirme, Ztsclir. Biol., 30, 1893, 73. METABOLISM OF ENERGY. 135 Eiibner to the effect that, considering tlie aniuical as a calorimeter, the heats of combustion of the nutrients are found to be the same as when determined by direct combustion with oxygen in tiieThompson-Stohman, or bomb calorimeter. OTHER RESPIRATION CALORIMETERS. Professor Voifc, of Munich, has devised a form of calorimeter for experiments with a man or other animal, but has, so far as I am aware, published no description, and the information which I have gained from brief personal inspection is hardly ade- quate or appropriate for publication. Professor Chanveau, of Paris, has devised an ajjparatus which may be used for experiments with horses or oxen. It was in process of construction in the winter of 1892-93, but I have seen no detailed accounts of experiments made with it and can only refer to it in this very general way. A small respiration calorimeter, on a plan based upon a principle very similar to that employed by Rosenthal and Eubner, has been lately described by Messrs. Hal- dane. White, and Washbourn.i Reference has also been made in print to an appa- ratus for similar purpose by Professor Burdbn-Sanderson,^ of Oxford; but 1 am not aware that any accounts of actual experiments with complete determinations of income and outgo of matter and energy by either of the instruments just named have been published. An apparatus for similar purpose is now in process of development in the chemi- cal laboratory of Wesleyan University. It is of a size appropriate to exj)eriments with a man. iJour. of Physiol., 16, 1894, 123. 2 Phil. Mag. [5], 29, 306. CHAPTER VIII. PECUNIARY ECONOMY OF POOD. The cost of food is tlie principal item of the living expenses of the majority of people — of all, indeed, but the especially well-to-do in Connecticut and the other Eastern States.^ In the report of the Bureau of Statistics of Labor of Massachusetts for 1884 are summarized the results of investigations into the cost of living of people with different incomes in Massachusetts, in Great Britain, and in Germany. Divid- ing expenses into those for food, clothing, rent, fuel, and sundries, the percentage of the whole income expended for food averages as follows: Percentaf/e of family income expended for suisistenee. Annual income. Expended for food. GERMANY. Sf225 to $300 450 to (500 750 to 1, 100 500 ?i50 to 400 450 to 600 600 to 750 750 to 1, 200 Above 1, 200 Per cent. 62 55 In easy circum 50 GREAT BRITAIN. 51 MASSACHUSETTS. 64 Do.. 63 Do 60 Do 56 Do 51 The large majority of families in tliis country are said to have not over $500 a year to live upon. More than half of this goes, and must go, for food. The cost of preparing food for the table, rent, clothing, and all other expenses must be provided from the remainder. These statements apply less accurately to farmers than to the inhab- itants of the larger towns, but, although the farmer produces much of his food, yet taking everything into account the expense for nutriment is large even for him. Late statistics published by the United States Department of Labor imply a smaller relative cost of food in the Southern and Western States, where food materials are cheaper, than in the Eastern States. In some cases the expense falls below 50 per cent of the total earnings of wage workers. Although the cost of food makes so large a part of the whole cost of living, and although the health and strength of all are so intimately connected with and dependent upon their diet, yet even the most intelli- gent people know less of the actual uses and values of their food for ful- filMng its purposes than of almost any other of the necessities of life. 1 In portions of the West and South, where food is less expensive, its cost is some- what less in comparisoa with other living expenses. 136 PECUNIARY ECONOMY OF FOOD. 137 CHEAP V. DEAR FOOD. The cheapest food is that which supplies the most nutriment for the least money. The most economical food is that which is the cheapest and at the same time best adapted to the wants of the user. The maxim that " the best is the cheapest," does not apply to food. The best food, in the sense of that which is the finest in appearance and flavor, and which is sold at the highest price, is not generally the cheapest, nor is it always the most healthful or economical. Of the dift'erent food materials which the market affords, and which are palatable, nutritious, and otherwise tit for nourishment, what ones are iieculiarly the most economical ? There are various ways of com- paring food materials with respect to the relative cheapness or dear- ness of their nutritive ingredients. One, and x^erhaps the best, consists in comx)aring the nutrients obtained for a given sum in different mate- rials. Table 1 6, which follows, gives estimates of amounts of nutrients that could be purchased for 25 cents at the rates named. The calcula- tions are based upon the analyses in Table 1 and upon the retail prices current in Connecticut. The figures of the table tell their story so plainly that they need very little comment. A quarter of a dollar invested in the sirloin of beef at 22 cents per iiound pays for ly pounds of the meat with three- eighths of a pound of actually nutritive material. This would contain one- sixth of a pound of protein and one-fifth of a pound of fat, and sup- ply 1,120 calories of energy. The same amount of money paid for oysters at the rate of 50 cents per quart brings 2 ounces of actual nutrients, an ounce of protein, and 230 calories of energy. But in buying wheat flour at $7 a barrel the 25 cents pays for 6^ pounds of nutrients with eight-tenths of a pound of protein and 11,755 calories of energy. The price of food is not regulated solely by its value for nutriment. Its agreeableuess to the palate or to the buyer's fancy makes a large factor of the current demand and market price. There is no more nutriment in an ounce of protein or fat of the tenderloin of beef than in that of the round or shoulder. The protein of animal foods does, however, have an advantage over that of vegetable foods. Animal foods, such as meats, fish, milk, and the like, gratify the palate in ways which most vegetable foods do not, and, what is perhaps of still greater weight in regulating the actual usage of communities by whose demand tlie prices are regulated, they satisfy a real need by supplying protein and fats, which vegetable foods lack. People who can aflbrd it, the world over, will have animal foods and will comi)ete with one another in the j)rices they give for them. In general, the animal foods are more easily and completely digested than vegetable. There is doubtless good ground for paying somewhat more for the same quantity of nutritive material in the animal food. For persons in good health the foods in which the nutrients are most ex- pensive are like costly articles of adornment. People who can well nftbrd. them may be justified in buying them, but they are not economical. 138 CHEMISTRY AND ECONOMY OF FOOD. Chart 2.— PECUNIARY ECONOMY OF FOOD, Amounts of actually nutritive ingredients obtained in different food materials for 25 cents. [Amounts of nutrients in pounds. Fuel value in calories.] Protein. Fats. Carbohydrates. Fuel value. "Weights of nutrients and calories of energy in 25 cents' worth 'Voit. tAtwater. PECUNIARY ECONOMY OF FOOD. 139 Table 16. — Amounis of nutrients famished for 25 cents in food nuilerials at prices in Eastern States, Food materials as purchased. MEATS, ETC. Beef, neok | Chuck ribs \ Ribs ^ Shoulder j Sirloin \ Rump Round : First cut. Bluefish, dres.sed . . . Striped bass, whole Haddock, dressed . . Cod, dressed Halibut, steaks. Salt cod Salt mackerel Canned salmon Oysters: 50 cents per quart. 35 cents per quart. Lobsters : Whole Canned Second cut \ Flank, corned j Corned and canned \ Liver Mutton: Shoulder \ Leg j Loin 5 Pork, rib roast < Smoked ham, whole <. Salt fat pork \ Pork, sausage < Poultry, etc., chicken \ Turkey i Fish, ahad, whole \ Mackerel, whole < S Prices per pound. EGGS AND DAIRY PRODUCTS. Eggs: 35 cents per dozen 25 cents per dozen 15 cents per dozen Cents. 8 6 16 12 22 18 14 10 22 18 38 15 IS ]5 10 8 15 10 18 14 20 15 25 20 25 20 12 10 10 12 15 12 15 12 22 16 2:j 18 :5 10 18 15 10 15 10 18 12 8 5 10 8 6 20 16 8 5 16 12 20 25 cents will pay for — Total food ma- terials. 18.2 11 Pounds. 3.13 4.17 1.56 2.08 1.14 1.39 1.79 2.50 1.14 1.30 1.39 1.67 1.39 1.G7 2.50 3.13 1.67 2.50 1.39 1.79 3.13 1.25 1.67 1.00 1.25 1 1.25 2.08 2.50 1,56 2.08 1.67 2.C8 1.67 2.08 ].14 1.56 1.09 1.39 1.67 2.50 1.39 1.67 2.50 1.67 2.50 1.39 2.08 3.13 5 2.50 3.13 4.17 1.25 1.56 3.13 5 1.56 2.08 1.25 1 1.43 2.08 2.50 1.25 1 1.37 2.27 Nutrients. Total. Pound."). 0.95 1.27 .56 . 75 .47 .57 .57 .79 .37 .45 .63 .76 .44 .52 .52 .65 .74 1.11 .66 .85 .96 .44 .58 .31 .39 .43 ..53 .88 L06 .81 1.08 1.46 1.83 .98 1.22 .20 .27 .25 .31 .25 .37 .22 .25 .37 .19 .28 .14 .21 .28 .45 .29 ..36 .48 .26 .32 .55 .83 .49 .66 .46 .13 .18 .14 .17 .28 Protein. Founds. 0.49 .65 .23 .31 .14 .17 .30 .43 .17 .21 .19 .23 .25 .30 .35 .44 .21 .31 .37 .48 .63 .19 .25 .15 .19 .13 .16 .28 .34 .23 .31 .02 .02 .23 .29 .17 .24 .18 . 22 '.]5 .23 .14 .17 .25 .16 .25 .12 .17 .26 .41 .27 .33 .44 .19 .24 .50 .80 .23 .31 .25 .06 .11 .14 .23 Fats. .12 .17 .28 Poimds. 0.44 .58 .31 .42 .32 .39 .25 .34 .19 .23 .43 .52 .17 .21 .35 .18 .49 .73 .24 .31 .17 .24 .31 .16 .20 .29 .37 .58 .70 .54 .72 1.38 1.72 Carbo- hydrates. Pounds. Calories of poten- tial energy. .04 .05 Calories. 2,765 3.655 1,735 2, 350 1,610 1,960 1,615 2,235 1,120 1,360 2,170 2,620 140 CHEMISTRY AND ECONOMY OF FOOD. Table 16. — Amounts of nutrients fiirnislted for 25 cents in food materials at prices in Eastern States — Continued. Food materials as purcliascd. MISCELLAXEOUS. Milk: 8 cents per quart , 6 cents per quart , 4 cents per quart Butter C lieese, wliole milli Potatoes : $1 per busliel 80 cents per bushel 50 cents per bushel Sweet potatoes j Beets < Turnips -^ < Sugar i Dried beans < Maize, corn meal < Oatmeal •; Wheatflour i Wheat bread < Crackers, Boston < Prices per pound. Vents. 4 3 2 35 30 25 ]8 15 12 1.67 1.33 .83 5 3 2 1 2 1 5 G 5 4 3 1 5 4 3.5 3 7 25 cents will pay for — Total food ma- terials. Pounds. 6.25 8.33 12.50 .71 .83 1 1.39 1.67 2.08 15 19 30 5 8.33 12.50 25 12.50 25 5 4.17 5 6.25 7.14 8.33 3.57 5 2.08 3.13 Nutrients. Total. Pounds. .81 1.08 1.63 .64 .74 .90 .96 1.17 1.45 2.69 3.41 5.38 1.27 2.11 1.23 2.45 .93 1.86 4.90 3.64 4. 37 5.46 7.08 21.25 4.62 5.47 6.25 7.29 2.42 3. 38 1 91 2.87 Protein. Pounds. .23 .30 .45 .01 .01 .01 .40 .47 .59 .27 . .34 .54 .07 .10 .16 .32 .11 .22 .90 1.15 1.44 .77 2. 30 .76 .69 .79 .92 .31 .44 .22 .33 Fats. Pounds. .25 .33 .50 .60 .71 .85 .49 .59 .72 .01 .02 .02 .02 .03 .01 .02 .02 .04 Carbo- hydrates. Pounds. .29 .39 .59 .01 .02 .03 .04 2.28 2.09 4.56 1.14 1.89 .94 1.87 .72 1.44 4.89 2.47 2.96 3.70 5.88 17.65 3.41 4.68 5.35 6.24 2.01 2.82 1.43 2.15 Calories of poten- tial energy. Calories. 2.020 2 4 2 3 3. 2, 675 045 550 015 625 850 420 210 785 090 570 335 830 090 180 630 260 095 760 065 110 720 160 275 285 755 695 570 445 955 920 CHAPTP]R IX. FOOD CONSUMPTION. A most important branch of tlie subject here considered is the actual food consumption of people of different countries and classes. STUDIES OF DIETARIES — HISTORICAL SUMMARY. A large number of observations have been made in Europe to learn the amounts of food and of actual nutrients consumed by people of different classes and occupations and under different circumstances. Within a very few years past like studies of dietaries have been undertaken in the United States and in Japan. The method of making such observations consists in finding the amounts of food materials of different kinds consumed by one or more persons during a certain number of days and calculating the quantities of nutrients in each material from its amount and composition. During some time past I have, with the aid of Drs. H. B. Gibson and 0. F. Langworthy, endeavored to collate the results of the studies made in this direction up to the present time. We have found records of the examination of 491 separate dietaries, exclusive of army rations. The earliest were made in 1851 in England by Beneke, a German physician, afterwards professor in the University of Marburg. The majority have been made during the past 15, and by far the larger number of the most reliable ones during the past 10, years. The people whose dietaries have been studied have been of various classes, ages, and occupations. A few were in professional life and were decid- edly well to do. The most were wage workers. Some of these were very poor, but the larger number were in reasonably comfortable circum- stances as compared with the majority of people of like occupation in the countries where they lived. Some of the studies were made with the greatest care and thorough- ness, the food was accurately weighed and analyzed, and strict account was kept of the number, sex, and occupation of the persons who were nourished by it. In a few instances pains were taken to determine the proportions actually digested. But in a majority of the dietaries reported upon the amounts and composition of the food instead of being determined exactly by weighings and analyses were more or less roughly estimated, so that the results lack scientific accuracy. From the 491 dietaries we have selected 338 as accurate enough to warrant their use in drawing inferences. The number of persons whose food consumption was observed in each dietary of this selected list 141 142 CHEMISTRY AND ECONOMY OF FOOD. varied from a single iudividual to several liiiudred, and the time of observation in each case from 1 to 30 or more days. In addition to these the studies of some 41 Japanese and other Asiatic dietaries have been lately reported by Mori, Taniguti, and Eijkman, but we have not access to the details, a circumstance which is the more to be regretted because of the high value of the work. In the selected list of 338 (columns A and B of table herewith) are included 101 studies of dietaries in the United States and Canada, of which 38 were in New England, 25 in Philadelphia, and 26 in Chicago. This list of 338 we have divided in two classes. The first including all the studies that seem to us reasonably accurate and complete; the sec- ond including those which are less accurate but sufficiently so to allow their results to be included in the general averages. The classification of all these dietaries by countries and by completeness of detail is sum- marized in the following tabular statement: Nuniber of dietaries collated, classified ly countries and iy completeness of detail. [A. Eoasonablj' accuratfj ani complete. B. Less accurate, but included iu avera.c;es. C. Not included in averag(^s.] A B C A+B A+B +c Europe : 7 49 6 1 2 7 50 6 1 1 2 7 1 58 5 15 7 1 2 13 29 55 40 16 40 05 6 15 2 13 4 21 2 13 25 U 40 13 10 3 15 10 29 62 43 3 30 31 50 54 97 3 35 '"lO 15 5 1 151 3 2 15 186 3 2 15 12 30 ^^'^v 5 ^pai 1 90 133 144 223 i 13 367 Asia: 7 7 1 8 1 5 1 14 Total A sia 9 5 8 14 22 13 13 13 TJuited States : 19 5 25 20 ...... 19 18 25 26 19 13 19 25 26 13 75 1 88 101 338 89 13 88 1 102 112 226 153 1 491 1 1 Java Village, World's Fair, Ghicago. FOOD CONSUMPTION. 143 All of these studies iu the United States were observed duriug the past 8 years. Those in Philadelphia and Chicago were observed by Miss Amelia B. Shapleigii in the use of the Button Fellowship of the College Settlements Association, 1892-93. The rest were studied by the writer and his associates at Wesleyan University, in cooperation with the Massachusetts Bureau of Labor and the United States Depart- ment of Labor, and as part of the work of the Storrs (Conn.) Experiment Station. Of the European dietaries in the list only 7 are from England; these were estimated by Playfair some 30 years ago. Only 1 comes from France. Fifteen are from Sweden and Denmark and 29 from Eussia. From Germany there are 151, of which the earliest were by Liebig and the larger number are by Voit and his followers. From Italy are 15, including 8 by Manfred! and 6 by Albertoni and Mori, which are among the latest and most thoroughly studied of all. From Japan are 13, all of which have been made lately by Germans connected with the Uni- versity of Tokyo and by Japauese working with them. One was the dietary of Javanese in the Java Yillage at the World's Fair. This was studied in connection with the examinations of foods at the fair, under the direction of the writer, which were referred to iu the statements regarding analyses of foods above.^ The data thus collected are far from sufficient for satisfactory con- clusions. Indeed, perhaps the most important lesson they teach is the need of more such studies. Their general character may be inferred from the selections iu Table 37. The only European country from which the studies are numerous and accurate enough to be taken as in any way representative of the national food consunqDtion is Germany, although those from Denmark, Eussia, and Italy are most interesting and instructive. The American data are confined to Massachusetts, Connecticut, Philadelphia, Chicago, and a few places in Canada. The right of those from the Eastern States to be taken as representative is confirmed, in a general way, by the figures for food consumption in the family budgets published by the Massachusetts bureau and the United States Department of Labor, especially iu late reports of the latter on the cost of production. SPECIAL INVESTIGATIONS OF DIETARIES. It will be to the purpose here to cite some of the special studies of dietaries that have been made up to the present time as illustrative of the character of the work done, the methods followed, and the excel- lencies which may be imitated and the defects which should be abolished in future inquiry in this most important direction. To this end I select : (1) Several studies of dietaries in the United States, including some ' Pao-e 20. 144 CHEMISTRY AND ECONOMY OF FOOD. of tlie earliest and tlie latest. The former are the least accurate: the latter are more thorough, though they are very far from being all that could be desired. (2) A series made in Germany, which show how great care may be used in such inquiry aud at the same time serve to illustrate the possi- bility of further improvement of method. (3) A series of studies lately made in Italy, in which a decided advance in method is made in certain directions. These illustrations will be followed by a resume of the work in this direction up to the present time. DIETAKY STUDIES IN THE UNITED STATES. In connection with the Massachusetts Bureau of Statistics of Labor, a series of studies of dietaries of factory operatives, mechanics, and other people with moderate incomes, in private families and boarding houses, were made by the writer in 1886. At the same time, and later, several dietaries of students and laborers and one of a well-to-do private family in Middletown, were examined. These were the first at all extended inquiries in this direction with which I am familiar in the United States. Although the work thus done represented only the beginning of an investigation of an important subject, the result seemed to warrant, or at least to suggest, generalizations of no little interest, and at the same time served to indicate directions in which further inquiry is needed. The following account of the Massachusetts and Canadian studies is taken from a report by myself and Mr. C. D. Woods in the report of the Storrs (Conn.) Experiment Station for 1891. INVESTIGATION OF DIETARIES IN CONNECTION WITH THE MASSACHU- SETTS BUREAU OF STATISTICS OF LABOR. In order to obtain some definite information in regard to the ways of living and especially the food of factory operatives, mechanics, and other working people of native and foreign birth in Massachusetts, the statistics of the amounts and costs of food consumed, and age, sex, and occupation of the consumers, were collected by the bureau under the direction of its chief, Hon. Carroll D. Wright, in several manufac- turing cities in the State; and as many of the people, whose conditions of life and labor were thus studied, were French Canadians, who come in large numbers to Massachusetts, as to other States bordering upon Canada, and form a not unimportant factor of the population, an agent of the bureau visited Canada and collated similar statistics regarding the people in the places from which they come. The data thus collated were placed in my hands, and with the assistance of Mr. E. W. Eock- wood, then assistant in the chemical laboratory of Wesleyan University, the quantities of nutritive ingredients were estimated, the results of analyses of food materials to those of the dietaries being used as the basis of the calculations. FOOD ' CONSUMPTION. 145 THE DIETAKIES AND THE PEOPLE NOURISHED BY THEM. From a larger number collated by the bureau, 30, which were regarded as representative, were selected for chemical examinations and the makiug up of average results. The 30 dietaries summarized in the tables of recapitulations are divided in three series, as follows: Classification. Series A Series B, Series 0, luci^savjiuociio. Massachusetts. I Canada. Data given in tables of recapitulation Data not given, but results included in averages in tat)les of recapitulation •5 12 10 7 I 13 'Series A included 3 French Canadian dietaries which are averaged -with those of series B, mating 10 of the latter, all told, in the averages of series B, and only 7 in the averages for series A in the tables of recapitulations, bej-ond. A. 2IisceUaneous, Massachusetts. — These include 10 dietaries of fam- ilies and boarding houses. The families are nearly all laboring people, while the boarders in the boarding houses are mostly operatives in mills and factories, though some are clerks, dressmakers, etc. A few are French Canadians, The 5 dietaries of this series, of which the data are given iu the tables just referred to, include 3 of boarding houses and L' of families in Lowell, Lynn, East Cambridge, and Boston. Two more of boarding houses, 1 iu Lowell and 1 in Lawrence, are included only in the averages, for this series, in the tables. The results for 3 dietaries of French Cana- dian families in Xorth Cambridge, of this series, are included in the averages for series B in the tables of recapitulations. The persons are factory and mill operatives, mechanics, etc., with a few clerks and dressmakers. B. French Canadians^ Massachusetts. — These include 7 dietaries of families and boarding houses, allot French Canadians. The 5 dietaries of this series Avhich are used in the tables include those of 3 families and 2 boarding houses in Holyoke, Lawrence, and Lowell. Of those included only in the averages, 2 were of families in Worcester, of this series, and 3 of families in East Cambridge, of series A. With the exception of women, children, and others engaged in household duties, or in no actual labor, the peoj)le are mostly mill and factory operatives; a few are brickmakers. C. French Canadians, Canada. — These include dietaries of 13 families and boarding houses in Montreal, Quebec, and other places in Canada. The people are represented as all belonging to the laboring classes. The 5 dietaries of this series which are used in the tables include 1 of a boarding house and 4 of families in Quebec, St. John, Sherbrooke, Eichmond, and Riviere du Loup. The averages include, with these, 8 others of families and boarding houses. Data. — In the descriptions given in the report of the kinds of data 8518— :N'o. 21 10 146 CHEMISTRY AND ECONOMY OF FOOD. employed and the ways in wliich tbey were attained, they were classi- fied as follows : Class A. Those contained in statistics as collected by the agents of the bureau. They have to do with: I. Statistics of food materials, including: a, kind; h, quantity; c, costs. II. Statistics of consumption of food .materials, including: a, number; h, sex; c, age; d, occupation of persons nourished, and e, time. Class B. Data obtained from other sources and used in the computa- tions. They have to do with: I. Chemical composition of the food materials. Proportions of nutri- ents (nutritive ingredients) in each. These figures were em]3loyed in computing the quantities of actual nutrients in the dietaries. II. The proportions of nutrients required by persons differing in age, sex, etc. These proportions were used in estimating the numbers of men at moderate work who would be equivalent in demand for food to the men, women, and children nourished by the food for each diet- ary, the object being to place all the dietaries on a uniform basis for comparison. In collecting the statistics of Class A, the agents of the bureau vis- ited the houses where the people lived, and the cotton mills, shoe fac- tories, glass factories, machine shops, blacksmith shops, brickyards, and other establishments where they worked, examined the bills of dealers for food furnished, the family and boarding house accounts, and by these and other appropriate means secured as accurate figures as practicable. The chief source of error is undoubtedly to be found in the fact that the statistics give the amount of food purchased, not that actually eaten. How much was thrown away as refuse or otherwise wasted can not be ascertained. Of the data of Class B, those regarding the composition of the food materials used were estimates rather than the record of actual analysis of the materials which would be required for entire accuracy. For the estimates the results of analyses made in this laboratory, and included with those reported in the chapter on '^Composition of food materials," were employed. The other American analyses then available, mostly of dairy and cereal products, were also used. For the few materials of which no American analyses had been made, recourse was had to European figures. The data and methods used in estimating the com- position of the food materials are given in detail in the report. The following quotations will give an idea of what they were. The tables referred to are too extensive to be inserted here. The analyses of beef were those described in the chapter on "Composition of food materials" above, as made for the United States l^ational Museum. The method of estimating the coraposition of beef was as follows: A large amount, the larger part, we are informed, of the beef consumed iu many of our Eastern cities is so called "Chicago" or "Western" beef, which is slaughtered FOOD CONSUMPTION. 147 in Cliioago or elsewliere and brought East. From a car load of Chicago heef a side was selected by au experienced dealer as of average qiiality, especial pains being taken to secure one of average fatness. This side of beef was divided into 25 jiieces, or "cuts," in the manner common in New York markets, and portions of each piece, sufficient to represent the whole, were analyzed, the j)ropurtions of refuse (bone, gristle, etc.), water, and nutrients being determined. A diagram represcDting these divisions of the beef was placed in the hands of the collectors of the dietaries hero examined, who, so far as practicable, indicated in their statements the parts of the animal from which the beef of the several dieta- ries was taken. The manner of cutting up the beef differs in dili'erent places, but not sufficiently to very materially affect the estimates. A more serious matter is the variation of different specimens of beef, and it is, of course, a question how close the side selected for analysis, as above stated, comes to representing the average of the kinds in the dietaries. We are informed that in all the Massachusetts cities, where the dietaries were collected, nearly all the beef used is so-called Chicago beef, and it is probable that the analyses fairly indicate the quality of the beef sold. As the best way for utilizing these data, an assistant has gone over the dietaries, noted the cuts of beef where stated, and ascribed to each the percentages of nutri- ents fouud in the analyses of corresponding cuts. The results are shown in the fol- lowing table. Where the original includes two or more cuts in one entry, the average is taken. The several computations for roast beef are averaged together. The same is done for beef stew, beefsteak, etc., and some of these latter averages are incorporated in the table beyond, giving the percentages of nutrients in food materials assumed in analyses of dietaries. The figures used in calculating the amounts of nutrients in the dietaries are gen- erally given in the table showing the percentages of nutrients in food materials assumed in analyses of dietaries. In some sj)ecial cases, however, they are not given in this table, but are stated with explanations in the explanatory notes appended to the details of the dietaries in which they are used. To insure perfect accuracy it would, of course, be necessary to analyze the mate- rials actually used in each case. It is probable that while divergences, in some cases very wide, might occur, the figures for the composition of each dietary, as a whole, would be substantially accurate. The item about which there seems to be the most question is the quantity of fat in the meats, especially the beef. The analyses here used accord very closely with European figures for very fat beef.' Numerous observations, however, which can not be detailed here, but which seem to be but little short of decisive, imply that the beef commonly used on the Continent of Europe is, on the average, less fat than the average beef in our markets. It is certain that much of that commonly used in our Eastern cities is very much fatter than that here analyzed and taken as the basis of these computations. Attention has been called elsewhere to the fact that the figures for weights of food materials in the dietaries represent the quantities purchased and do not indicate how much was eaten. The rejection of a considerable part of the fat of meats by many persons is one of the most common of dietary facts, at least in the Northern and Eastern States. Some of the fat of beef is left with the butcher, much goes to the soap malcer, and much more into the garbage. But a surprisingly large part of the fat of our beef is so dittiised through the lean, much of it in invisible particles that when we have cut out the larger pieces of fat from our roast beef or our steak and left them on our plates, we, nevertheless, eat the bulk of the actual fat of the meat with the lean and the small jiortions of visible fat which adhere to it. Especial stress is laid on this point, because the dietaries hero studied indicate a remarkably large consumption of fat in this country. The possible bearing of this fact upon our national dietetics may be extremely important. ' See analyses quoted by Konig, Nahrungsmittel, Bd. I. 148 CHEMISTRY AND ECONOMY OF FOOD. lu the statistics of some of the Massachiisetts dietaries, and most of those collected in Canada, the quantities of certain food materials, especially vegetables, were not stated, and had to be estimated from the costs. The uncertainty as to the accuracy of the total estimates was thus increased, though, as was believed, not enough to seriously affect the value of the results for the purpose for which they were intended, namely, an exhibit of the general character of the food con- sumption and a means toward learning how such an inquiry may be best conducted. The method for estimating the number of men, at moderate work, who would be equivalent in demands for nutriment to the persons par- taking of the food of each dietary, is thus explained in the report: Since the people uoarislied by tlie dietaries liere examined dififer in age, sex, and occupation, and hence differ likewise in their demands for nutriment, and since a chief object of the examination is to compare the dietaries with one another in respect to the quantities of actual nutrients supplied, it is clear that to attain our object we need some standard for estimating the relative demands of people of differ- ent classes. If, for instance, we could take a particular class, as laboring men at moderate work, and find to how many average men of this class the people nourished by e^ch dietary would be equivalent in their demands for nutrients, we should simply have to divide the total quantity of nutrients supplied per day by this equivalent number of men to get the quantities per man per day. The results thus obtained for the several dietaries would, when compared with each other and with accepted standards, give us what we seek. We are of the opinion that the experimental data on record in Euroj)ean work, if rightly collated and worked up, would give a basis for at least an approximate estimate of the comparative requirements of the several classes of persons into which those nourished by the food of these dietaries woxild most properly be divided. Indeed, the current standards for daily dietaries will help in arriving at such a basis. Thus, the standards of Voit and the Munich school of physiologists call for proportions of nutrients, with estimated potential energy, as follows: Persons. Children to 1 J years old Children, 6 to 15 years old Woman at ordinary work Laboring man at moderate work Protein. Grams. 28 75 92 118 Fats. Gravis. 37 43 44 56 Carbo- hydrates. Grams. 75 325 400 500 Potential energy. Calories. 767 2,041 2,420 3,055 We may take the relative quantities of potential energy as the basis of our calcu- lations. The figures are in about the following relative proportions. We interpo- late an assumed value for children from 6 to 2 years of age. Estimated relative qiianUlies of potential energy in nutrients reqtiired hy persons of differ- ent classes. Laboring man at moderate work 10 Woman at ordinary work 8 Child, 15 to 6 years old 7 Child, 6 to 2 years old 5 Child, under 2 years old - - 2^ The application of these figures is simple. The food of dietary A, 1, for instance, suffices for 77 persons (factory operatives), 66 males aud 11 females. The figures FOOD CONSUMPTION. 149 allot to 1 working woman 0.8 as raucli nutritive material as to 1 laboring man at moderate work. This would make tbe 11 women equivalent to (8.8) 9 men, whicli added to 66 would make the whole 77 persons equal to 75 men. The 77 persons dur- ing 30 days, the tiuie covered by the dietary, would be equal in requirements to 1 man for 2,250 days. The estimates in the dietaries hereinafter presented are made in this way. Tlie details of one of the dietaries are quoted to show the nature of the statistics collated by the bureau, and the way in which the quanti- ties of nutrients were estimated. For statements of the ways in which the quantities were estimated from the costs in the cases in which they were not given, and for other details, the reader is referred to the origi- nal report, where the details of each of the 30 dietaries are given in full. Table 17. — Dietary. Series A, No. 1. [DesoipMoM.— Boarding-liouse in Lowell, Mass., of 77 persons, 66 males and 11 females. Boarders, mill operatives. Time, I month. Estimated as equivalent in demands for nutrients to 75 laboring men at moderate work for 30 days, or 1 man for 2,250 days.] FOOD MATEKIALS AND NUTRIENTS. Food materials. Nutrients. Kinds. Prices per pound. Quanti- ties. Costs. Protein. Fats. Carbo- hydrates. Beef: Roast Cents. 10 14 7 10 5 6 10 11 10 8 7 12 3 4i Founds. 400 272 350 62 167 20 150 160 70 260 168 50 40 50 $40. 00 38.08 24.50 6.20 8.35 1.20 15.00 17.60 7.00 20.80 11.76 6.00 1.20 2.25 Pounds. 60.4 39.4 40.3 9.2 23.4 4.2 17.1 23.4 2 Pounds. 79.9 42.4 99.8 9.5 52.3 .2 54.3 54.9 53.6 257.4 . 2 2'l 1.6 .2 Pounds. steak Corned Tongue stew Tripe Pork, I'oast Ham Salt pork Lard Haddock 13.9 7.6 4 8 Halibut Mackerel Salt fish (cod) Total meats, fish, etc 2,219 199. 94 252.9 708.4 Milk 2 11 22 audio 14 3,024 63.5 291 107 60.48 6.98 54.54 14.82 102.8 17.2 2.9 12.4 111.9 22.5 254.6 10.9 145.2 1.5 1.5 .6 Butter Eggs Total dairy jiroducts and eggs. . 3, 485. 5 136. 82 135. 3 399.9 148.8 Flour 3 74 4* 3 8 4 1 14 5.9 5.6 5.6 If 124 10 9 5 1,568 600 99 124 25 25 2,520 250 26 90 120 120 300 24 15 12 48 47.04 45.00 4.50 3.74 2.00 1.00 25.20 3.75 50 50 1.00 1.00 5.00 3.00 1.50 1.08 2.40 174 17.2 1, 182. 3 580 2 Sugar Molasses 70 3 28.8 1.9 3.8 47.9 1.3 0.3 1.6 1.1 1.6 .9 .6 .3 2.6 .1 1.8 5.0 .3 66.6 19.9 16.8 463.7 13.3 9 Onions Beets .1 . 2 '.i 9 6.1 Turnips Tomatoes Apples 3'^ 7 .1 15.1 9 5 Currants Corn starch Crackers 5.1 4.8 34 Total vegetable food 5,966 5, 704. 5 148.21 336. 76 269. 2 388.2 32.6 1, 108. 3 2, 537. 9 Total animal food 11,070.5 484. 97 657.4 1, 140. 9 9 636 7 150 CHEMISTRY AND ECONOMY OP POOD. Table 17. — Dietary. Series A. No. 1 — Continued, rOOD MATERIALS AND NtJTIlIENTS-Oontinued. Food materials. Nutrients. Kinds. Prices per pound. Quanti- ties. Costs. Protein. Fats. Carbo- liydrates. Cents. Pounds. .09 1.55 $0.09 .06 Pounds. .11 .06 Pounds. .31 .18 Pounds. Dairy products and eggs, pej- man .07 '2.54 2.65 .15 .07 .17 .12 .49 .01 .07 1.13 5.19 .22 .29 .50 1.20 Results. — The three tables which follow recapitulate the details of fifteen of the dietaries. Tables 18 and 19 recapitulate the statistics of the dietaries, as explained by their titles. Table 20 summarizes in shorter form the principal results set forth Id the two preceding. FOOD CONSUMPTION. 151 y rH l>(M C5 TO -* -Hin 00 C^l TO I TO : rH rt rHC^lS - •Ajv^s p JO jgqmnj^ ^ •'ri ^ ^ *ij nwwa^w 0000 • 1(5 (N tX (M t~ 1 in 1! t~-*t^00OS -* rH r-'lOOSt; -* •pooj ib;ox ^ (M (NC^(N Tt 1^ v-H7^ISTOTO TO •pooj eiq^^oHoA " 1; " 1 • TO 10 10 10 TO c- 000000303 TO TO TO 00 m C 00 o -d •Ii5*ox a- -— rii i-H rH n iHIM rH rHr- i' O 1 a 3 II 1 II •sSSa pUB S^Otl ■ t- TO lOiniM !£ coTO^in-H in| N coos^if CO ft -po.ifl A'aiBQ[ ^p* 1 1 1! ■o;9 ^05 OS O-J u t-(M^-*ooiH| -* coinosir in cS ^H r- (N 1 r- a 'nsg 'S'^BSK s 1 1 II . • ift OS M t^ C-IrJOSOSOS in r-i -(ji c £: lOTO rH inc U* 1 in CT iM CO ir a> a m •po oj eiq'B^gSeA ^ OS TO ^_ TO ^ K^ OJ (N CO in' Tt CI- cot-;s?aTH ^ to ooo^c (NCTCOTiitdi 03 rH MNiNC^ aJ o g • 00 T)l (M t- t- 1^ m 00 tx o- r-H in 03 CO CO ir 1^ S?^ inTO CM TO t> in -^ t- in in t^ TO ir OS P=H r^ ■l'«+0X fO *-^- (N'i-HC^O- c ■ rH rH rH C\ rH rH r- ' O =2 II •eSga in — 1 OS -T o- rH TO OS r- <= a tx in in OC in in 03:^1 TO OJ (M 00 TOCO U- l> •^ hx in •^ '3 a 5 puT! spn -poid ^.llBQ ^^ cc OS rH 00 TO oc TO in (M in oc TO in CO CO i- (M ■049 ^TO OS t~ OS cr X ■^ OS OS CT a CO COTO rH ir m 'qeg 'e;T59K ^^ = 'r- "r-;.- "rH t>3 c c OS OS OS .-^c •eaxBtng^ •»- '" ft 03 in in oc^o OJ l: CO (M "=, '°, •eoxBj^ 3 " rA^iU-, g c ^ •; ft p ft c c5 '^ c3 ^ V 'c > 1 -^ pis ft be _0 5 a 1 F- 1 r 1-1 p t- — - ft-;3 ft £ c8 S — ■ ^r-l'3 " " a ' *Eh 4J a a ^ SoSli ^ ^ ^ ; : ■ to o ft t/j a to H 1: ■< ;/} P c g s CO "^ c 1 CO r— ) 1 . c 'f !5 c R a. S -1 .2 S §1 S << C M a "o w I ^ .•'0 0" c CO p c a. ■s s s s - c fa 0, ^ 2 1^ P D M c be s a 0^ ci^ c W i^^ fat- - (- tl 1= c.-o a^s • r- jj .,-. J 2 1 UyAhAtA £ a 3 a rt £ ci Si^PnCCC ' :: (L w ;£ c« cS c« C r-il-(MOS TO-^rHinO oc « TO ^TO •jSjbjojij JO" OJ^ pUB 89tI9S " rH r^ "^ ^ •sSSa puB tH O! C^ fcj (C ^4 § rt C35 (N CO OIM Tf r^ in 00 05 IM L- OS O CO "1* in in in CO •tJI 1 i r» CO (M lO O lf5 g rH Oq rH(N C4 oc CO CD 00 CO C . o 00 03 o coc; ■nf!K 1-1 !N r-l ca CO I—" ft ft ^ ^ OS =c lO -( r-{ a Ci! t^ 03 CM in CM »n rH CD -^3 h 3 ■so:H3jp.fi[oqjBQ q ^- ^ rt M rt '-' ^ <1 !^ o rH ,-i rtrt w '■• r^^^r^ " f*. rs ft ^ o> C5 .-■ O) r^ in 05 O CM t> CM ^1 o Ph O EH •s;i3j ,0 CM lO CO ^ lO ^= ■ • • • T* CM in Tf in CO rH CM C^l CO CM CM 00 00 ^ in 1-1 -* CO CD 00 CO CO OS T)l 1 <1 W •ni9;oi •pooj 9iqnp§9A ^C) r-i i-H rH rH r-t Hd ■ ■ ■ tH 1-1 O iH iH CM 1 X IN incD rHCO ffQ Oi 00 r-i 3 ft 00 o =2 •mox ^r-lrHrHrHCq Hd • • ■ O O rH rH r- o wJ !25 -I- PM •sg99 pnu m CM Til CON OC -i W rHIM cq -Ti CM c O O O O C B '3 spnpoad i^ireo; Hd • • • a; t^ rH 03 i-H l> ^O-Orl- Hd ■ • • OC "Til in 05 -^ OC l> ■o:j9 'qsy; 's^B9J^ " O O rH iH t- 03 « 3 m o 00 s =1- "S CO c < .B. >.B. > ., < •Hf-.c ^ 11"=;^" g ll^^'i K "Z ^''lit u "r S cS C cs t S do ni o cS O c t^ h pHMfnP^f' pqfH : ; CD Tj< rHinC 00 CM CO tX CO •£xv loip JO -0^ pUT3 S9U9g "" < <: < < < p: p: p: PC p: C C c oc FOOD CONSUMPTION. 163 Tarle 19. — Persons staled to he nourished bij food of dietaries, and estimated numhers of laboring men at moderate work who tvould require the same quantities of nutrients. Persons reported. MISCELLANEOUS, MASSACHUSETTS. A 11 Patlier, mother, 1 other adult female, anil 'i cliildren of 5, 11, and 12 years. Boarding house: A 1 6(3 males and 11 females A 7 20 males and 16 females A 2 10 males and 60 females A 9 Husband and wife FKENCH CANADIAN, MASSACHUSETTS. B Father, mother, 2 adult children,' and 2 children of 9 and ]2i years B 4 Boarding house, 8 men, 7 women, and 3 children B 1 Pather, mother, and 4 adult children, 1 female B 5 Boarding house, 6 males and 4 females, I ages 16 to 40 years B 10 Two brothers^ and a sister, adults FRENCH CANADIAN, CANADA. C 18 Boarding house, 15 adults C 12 Father, mother, and 8 children, 2 to 13 I years old C 26 Fatlier, mother, and 3 children of 9, 12, and 14 years C 24 Father, mother, and 2 children, 6 months and 5 j^ears old C 6 Father, mother, and 6 children, 1 to 12 I years old Classification. Adults. Males. 66 11 20 16 10 CO 1 1 Fe- males. Children. 15 to 6 years. 0to2 years. Under 2 years. 77 75 36 33 70 58 2 n v.Bi ^ 5 15i 5i 9i 3 13A 6| 4 2i ' One male and one female. ''The men, blacksmiths, were at rather severe work, hence the 2 with 1 woman are estimated as equivalent to 3 men at moderate manual labor. Table 20. — Summary of statistics of dietaries. QUANTITIES OF FOOD MATERIALS. Food materials. Series A, miscellane- ous, Massachusetts. Series B, French Ca- nadian, Massacliu- setts. Series B, French Ca- nadian, Canada. Maxi- mum. Mini- mum. Aver- age. Maxi- mum. Mini- mum. Aver- age. Maxi- mum. Mini- mum. Aver- age. Meats, fish, etc Lbs. 1.36 1.70 Lbs. 0.63 .82 Lbs. 0.88 1.29 Lbs. 1.28 1.51 Lbs. 0.46 .21 Lbs. 0.81 .70 Lbs. 1.13 .98 Lbs. 0.35 .14 Lbs. 0.52 Milk, butter, cheese, and eggs .45 Total animal food 3.00 4.17 1.48 2.38 2.17 3.02 2 79 fi7 1.51 3.44 1.68 3.65 ..54 1.65 97 Vegetable food 5 65 1 ^ '« 2 49 Total food 7.17 4.12 5.19 7.26 3.02 4.95 4.89 2.20 3 46 1 The figures for maximum and minimum indicate the largest and smallest quantiiies in any single dietary, and those for average, the averages of all the dietaries of each series. Thus, the' largest quantities of meat, etc., per man per day'in any of the dietaries of Series A was 1.36 pounds, the smallest 0.63 pounds, and the average of the 7 dietaries of this series examined was 0.88 pound. The largest amount of total iood in any single dietary of this series was 7.17 pounds, the smallest 4.12 pounds, and the average 5,19 pounds. That the figures for total do not always equal the correspond- ing sum (for instance, the total animal food, maximum. Series A, is less than tire sum of the flsures for meats, tish, etc., and for milk, butter, cheese, and eggs) is due to the fact that the factors which would make up the sum are from diflcrent dietaries, while the figures for total are the masimuui, minimum, etc., for individual dietaries. 154 CHEMISTRY AND ECONOMY OP FOOD. Tablk 20. — Suminary of statistics of dietaries^ — Coutinued. COSTri OF FOOD MA.TERIALS. Food materials. Series A, miscellane- ous, Massachusetts. Series B, French Ca- nadian, Massachu- setts. Series B, French Ca- nadian, Canada. Maxi- mum . Mini- mum. Aver- age. Maxi- mum. Mini- mum- Aver- age. Maxi- mum. Mini- mum. Aver- age. Cts. 24 12 Cts. 6 4 Ots. 11 6 CIS. 18 11 Cts. 6 3 Ots. 11 5 Cts. 9 7 Cts. 3 1 Cts. 5 Milk, l>uiter, cheese, and eggs 3 36 1 10 11 G 17 j 20 8 13 10 6 16 8 13 8 5 5 8 6 47 16 25 i 39 17 24 19 11 14 NUTRIENTS IN FOOD MATERIALS. Protein Fats Carbohydrates Total nutrients - - Percentages of animal protein in total protein food Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. Lbs. 0.40 0.21 0.28 0.44 0.18 0.26 0.33 0.16 .50 .29 .41 .67 .28 .45 .39 .16 1.36 1.05 1.17 1.75 .72 1.21 1.50 .85 2.32 1.50 1.86 2.86 1.52 1.92 2.29 1.20 64 47 57 62 33 46 48 29 Lbs. 0.24 .24 1.16 1.64 37 1 The figures for maximum and minimum indicate the largest and smjlllest quantit-'es in any single dietary, and those for average, the averages of all tlie dietaries of each series. Tlius, the largest quantities of meats, etc., per man per day in any of the dietaries of Series A "S^'as 1.36 pounds, the smallest 0.63 pound, and the average of tlie 7 dietaries of this series examined -was 0.88 pound. The largest amount of total food in any single dietary of this series was 7.17 pounds, the smallest 4.12 pounds, and the average 5.19 pounds. That the figures for total do not always equal tlie correspond- ing sum (for instance, the total animal food, maxim um. Series A, is less than the sum of the figures for me:its, fish, etc., and for milk, butter, cheese, an.^ 2 9° a 00 'd j: » M ° rt 3 s a " g Ci 09 <-> r~ M ^ (M OS ^ tn 1 •naSoj^tn s iH ■-1 IM 00 CS 00 rH pa^aaoxa lu^ox e 03 wH ^ TO O rt inrH ^ 2 -J JS IM o to •majOcij e rr n Tii ^ irs iti as' C3 -!j( to c- irs 2 _, OD r O (M •noSomvj S r-^ O yi r-i 00 r^os ..s Cb '"' '"' •i!':(rA'i;a§ ogioadg g (M to -o n o O '^ ^ r/1 o rs ft to •jI^j'^UBn^ ^ o> 3S t a "^ •iie« S 1 ■O TO to 00 --I 8 d od i!q qj-L'O C! iH rH rH 1— ■'^'■m.i'i B n iri m' '^ica rlJ th' -X9 J9q^a 6 IM r* ^ OS OTO OC 00 IT •atajojj TO d ^ h c» to r-\ •u9Soj:jt^ g TO ° 00 ri Nr- 00 r^ 5i! i in rH •9.oni}:(sqn8 iri TO 99.IJ-J9:(15^ 5 CM ca IM IM TO cr rH s 00 to <> OS 00 •ptiil)t'j « W ITJ "-1 IM (M iH 1 TON 1 !i 1- «Mi in m 00 ::j a tH " 1 "^ § "^ t_ torn o- I-H OS OS o 1 ^OS TO • 00 t- •oonvjsqiis cr -* 00 |^- cc- r- IOCS in 00 OS 9» •pml)ti OS oo oc (M t- to incM -KIN CO TO IM TOlft OO r-l 00 (M OD CS • roto CO r- ^ 1 — rH in rH g<^^ : k ', '. ■3 6 I t4-l ,a • ffl in o • ^ a -ii ,= cS 1 -a to °''^TO c3 S^ ■°2 ; 00^3 • 'p. a I 3 :ri ci'a S a PI o o o ^ ^ 5 ra ,3 . ^-=in 3 S a a c . Sii'S' \ : 3 • a b -> •z) ps§ : r* ) ci ffl > Ph .. •• c o ..,_,- .. S S -ii O to 01 • sl o si SB i 11 a p.^ a = a? -1 p t- p. ffl f^ ase->?i lip R CO 00 a o d " "S-^ a* O o 1-1 ts- ^ Fm M o m ^ FM o m Gins. Gins. Gms. Gms. Gms. Gms. Gms. Gm,s. Gms. Gms. 278 33.1 1.71 10. 71 4.8 18.6 9.45 59.06 141.6 33. 1 2.19 13.68 7.1 12.3 i.3 10.56 66 9.6 116 21.6 1.32 8.28 1.5 11.7 1.5 7.09 48.08 4.6 245.9 45.7 3.06 19.09 5.7 20.8 1.1 11. 62 72.62 9 171.7 39.4 3.14 19. 62 3.8 ;6 .4 6.84 42.75 9.9 177.4 38.6 2.97 18.56 2.7 18.4 8.04 50.25 113 22 1.405 8.78 2.1 11.3 .6 9.245 57.78 10.8 153 24.8 1.57 9.81 3.8 11.1 8.05 50.31 278 45.7 3.14 19.62 7.1 20.8 i.5 11.62 72. 62 10.8 113 21.6 1.32 8.28 1.5 11.1 .4 6.84 42.75 4.6 178.3 32 2.17 13.50 3.9 15 1 8.937 55. 85 8.8 Gms. 11.16 12. 75 9.01 14.68 9.98 11.01 10.65 9.62 14.68 9.01 9.15 TABULAll STATEMENTS OF RESULTS OF DIETARY STUDIES. In Table 37, which follows, the final results of the 138 selected studies of dietaries, mentioned on page 144 above, are recapitulated. It was thought desirable to classify these dietaries by countries rather than by classes of people and occupation. 8518— No. 21 12 178 CHEMISTRY AND ECONOMY OF FOOD. Table 37. — Fove'uin and American dietaries. [Quantities per man per day.]* Dietaries. Nutrients. Foreign. (European, Japanese, and Javanese.) Well- fed tailors (prisoners) Hard-worked weavers (prisoners) Eoyal engineers, at active work. .. Physician, 37 yeai-s old, Copenhagen Principal of school, 35 years old, wife of No. 4. Medical students, 22 to 27 years of age, Stock- holm Mechanics, etc., at moderate work, southern Sweden, average of 6 individual dietaries . . . Mechanics, etc., at severe work, southern Sweden, average of 5 individual dietaries . - . 2 2 495 12 U 15 16 Factory operatives, near Moscow, average of 9 families Factory operatives, near Moscow, average of 50 boarding clubs composed of men Factory operatives, near Moscow, aver.Tgcof 10 boarding clubs composed o' women and boys. Peasants near Moscow, average of men's diet- aries Peasants near Moscow, average of women's dietaries (*) 3 2,670 *3 234 1. Scantily nourished. Laborer's family, father, mother, and child 6 years old - 20 22 23 WORKING PEOPLE IN LEIPSIC, SAXONY. Girl in factory, wages $1.20 (5 marks) per week, pale and sickly, food mostly bread and pota- toes, half a pound of meat per week, cost of food 8.2 cents per day Girl in printing office, wages $1.20 per week, food similar to preceding, cost 10.3 cents per day "Widow, straw plaiter, with 5 children, food mostly bread and potatoes, occasionally meat, cost of food 9.6 cents per day Two girls, one 24 years old, in paper factory, wages $2.16 (9 marks), the other 21 ye.irs, seamstress, wages$1.92 (8 marks), cost of food 8.6 cents per day Girl, 18 ypars old. inbook-hindery, wages $2.16 per week, cost of food 8.6 cents per day Painter, wages $4.32 per week, unmarried, cost of fond 11.5 cents per day Cabinetmaker, with wife and 6 children, wases $i .92 per week, cost of food 11 cents per day. Drugaist's clerk, with wife and 2 children, annual income $283 (1,180 marks), very litt'e physical exercise.cost of food 11.3 cents per day Farm JaborernearLeipsic, with wife and 4 chil- dren, food mainly vegetable, cost of food 7.2 cents per day (*) Grams. ' 131 151 144 135 95 127 134 189 Grams. Grams. 106 132 129 102 140 107 114 79 110 525 622 631 250 220 300 '523 Calories 3,055 3,570 3,950 2,8 2,285 3,035 3,435 = 714 4,725 584 487 589 471 287 63 301 39 303 56 440 51 229 41 347 64 366 57 466 69 351 37 504 * Quantities per person per day. 1 Including 22 grams alcohol. 1 gram alcohol = 1.71 grams carbohydrates. "^ Including 24.2 grams alcohol. ^ -Aji approximate estimate. 2, J 3, f 2,875 3,250 2,610 1,690 1,940 1,870 2,620 1,645 2,055 2,450 2,760 2,370 2,740 FOOD CONSUMPTION. Table 37. — Foreign and American dietaries — Continued. 179 Dietaries. WORKING PEOPLE IN LEIPSIC, SAXONY— COlltM. rarm laborer, Prussin, very poor, diet mostly vegetable Laboring woman of poorer class, Munich, vig- orous, but at rather liard work, food hardly adequate. Hand wenvers, Zittau, Saxony, average of adults in 28 families Average, Nos. 14 to 26 2. Prisoners. Inmates of Badstrasse prison in Munich, doing no work Inmates of prison in Brandenburg, without work Inmates of house of correction in Munich, at work 1 Inmates of house of correction in Brandenburg, at work 3. People not having active exercise. Inmates of house for old women in Munich ( Pfriindneranstalt) Inmates of house for old men and women in Munich (Pfiiindneranstalt) Man at rest, average of 3 tests in respiration apparatus Physician, 31 years old (Professor Beneke), Old- enburg, diet not quite sufficient to maintain bodily condition *1 1*56 *96 Same, diet estimated sufficient for normal main- tenance Professor Ranke, Mnnich, in respiration appa- ratus Same, food sliglitly diflerent from No. 36 Lawyer, Munich Young physician, Munich Young physician, Munich Average of Nos. 35 to 40, 6 dietaries of well-to-do professional men, food largely animal Official in civil service, a vegetarian. 4. People with more or less active muscvlar work. Mechanic in comfortable circumstances at light work, 60 years old, Munich Shoemaker, liostook Upholsterer, a strict vegetarian, 28 years old, Munich Well-paid mechanics, Munich Carpenters, coopers, locksmiths, Bavaria, average of 11 dietaries Porter, Munich, 36 years old, unmarried Cabinetmaker, 40 years old, Munich Bavarian mechanics, etc., at moderate work, average of N os. 45 to 48 ^477 1 Nutrients. Grains. 83 Orams. 17 87 109 104 127 80 92 137 Farm laborers, Bavaria, average of 5 dietaries. . Miners at severe work, Prussia Brewery laborers, Bavaria, average of 5 diet- aries Brickmakers (contract laborers from Italy) near Munich; diet, maize meal and cheese. . Machinists, etc., Krupp gun works, Essen * Quantities per person per day. 'This average is reduced to terms corresponding to a person weighing 57 kilos (125 pounds), the aver- age weight of all the men and women of the families. 300 800 100 126 80 127 134 117 108 54 151 122 133 131 Grams. 573 334 485 384 Calories 2,845 1,895 2,705 2,275 100 85 125 89 102 102 137 133 149 150 139 55 118 61 94 113 305 574 521 639 206 332 352 240 213 222 362 292 345 378 573 479 570 422 494 542 634 683 677 1,810 3,115 2,915 3,410 1,875 2,155 2,675 2,270 2,565 2.325 2,180 2, 400 2,835 2,695 2,505 2,850 2,525 2,710 2,775 3,085 3,150 3,160 3,195 3,150 3,295 4,195 4,275 4,290 4,395 l! 7.4 5.1 9.2 4.1 6 5.8 5.5 4.7 4.7 3.8 5.6 4.7 3.2 6.3 4.4 3.9 4.5 4.3 5.1 11.5 4 5.3 4.8 5 4.7 4.9 6.7 6.7 180 CHEMISTRY AND ECONOMY OF FOOD. Table 37. — Foreign and American dietaries — Continued. Dietai'ies. Nvitrients. WORKING PEOPLE IN LEIPSIC, SAXONY— cont'd. 4. People with more or less active muscular work — Continued. Farm Inborers, Bavarian highlands, large, niu.scular men at severe "work, average of 3 dietaries ^ Lumbermen, Bavarian highlands, large, mus- cular, vigorous, doing heavy worli in rig- orous climate, average of 3 dietaries German army ration, iieace footing , German array ordinary ration, war footing German army extraordinary ration, in war German army extraordinary ration, Franco- German war Farm laborers, Transyh'ania, at harvesting diet, maize meal and beans ITALY. Poor peo%ile in Naples, loiver class. Mechanics, etc., average of 5 dietaries Servants, etc. (women), average of 5 dietaries.. Peasant, fiirm laborer, near Ferrara, average of winter and summer dietaries Wife of No. 63, average of winter and sum- mer diet aries Son of !Nos. 63 and 64, 14 years old, average of winter and summer dietaries Italian army ration, peace footing FRANCE. Physician, 48 years old CHILDREN (GERMANY, RUSSIA, AND SWITZER- LAND). Under 2 years old, average of 3 individual diet- aries From 2 to 6 years old, average of 14 individual dietaries From 6 to 10 years old, average of 8 individual dietaries From 10 to 14 years old, average of 13 individual dietaries t Children, 6 to 15 years old, in orphan asylum, Munich Boys, 8 to 15 years old, in children's home at Gehlsdorf, near Eostock Girls, 14 to 19 years old, Krupp industrial school, Essen Prisoners without work, Tokyo Prisoners at work, Tolcyo, average of 2 dietaries. Employees in retail store, Tokyo Y. Mori, assistant in University of Tokyo; dietary of self (ordinary diet with meat).' Students, Kioto, average of 2 individual diet- aries Cadet school at Tokyo Government school, Tokyo ; pupils, 17 to 25 years old Private school in Tokyo; pupils, 11 to 21 years old (*) (*) n *72-85 1 2 (n *130 *21 JAVA. Java village, "World's Fair, Chicago Grams. 137 130 114 134 192 157 118 95 67 114 92 27 53 65 72 79 87 101 115 79 Grams. 202 292 39 45 285 62 Gram,s. 540 724 480 489 678 66 19 331 977 325 628 499 332 592 Calories 4,680 6,215 2,800 3,095 3, 985 4,650 5,235 2,290 1,795 3,665 2,940 2,000 3,025 115 155 217 249 247 508 415 372 544 394 438 631 254 770 1,245 1,575 1,780 1,680 2,905 2,815 1,785 2,585 1.895 2, 345 3,060 3,355 2,370 1,490 Quantities per person per day. FOOD CONSUMPTION. 181 Table SI.^Fovc'kju and American dietaries — Contiuued. Dietaries. American (Unitep States and Canada).' series a.— miscellaneous, factory oplcita- tives, mechanics, etc., massachusiitl s. Boarders, operatives in cotton mills : Boardinji house, Lowell Board ill j;; bouse, Lowell Boar bridge, fathers, brickmakers, at severe ) work Average SERIES B.— FUENCH CANADIANS, FACTORY OPERA- TIVES, MECHANICS, ETC., MASSACHUSETIS. Family, Lawrence, mill operatives Boarding house, Holyoke, operatives in paper mills Boarding house, Holyoke, factory operatives.. Family, Hidyoke, mill operatives Family, "Worcester, mill operatives Family, Worcester, father, printer Family, Lowell, blacksmiths at hard work Average Average SERIES C. — FRENCH CANADIAN'S, CANADA, ALL LABORING PEOPLE. Boarding house, Montreal- r Family, ~:Miinl real Family, (Quebec Familv, Queltec Family, St. John Family, St. John Boarding house, vSorel Boarding house, Sorel Boarding house, Kiviere du Loup. Family, St. Hyacinth 1 Family, Slierbrooke Family, Richmond Family, Eichmond 70 150 36 80 6 2 Nutrients. Grams. 1:B 132 105 114 127 95 182 12 237 251 180 Grams. •Ill 2U0 136 150 195 132 254 Grams. 545 594 477 522 523 481 017 363 365 132 100 95 95 141 82 114 118 200 Average - CONNECTICUT.^ Family of chemist Family of college professor : Food purchased Food eaten 3,205 4,145 4,080 1 Collated by Massachu.setts Labor Bureau. *"Witli the exception of Nos. 118 and 119 all Connecticut dietaries are in MiddletowOi 123 119 100 141 132 136 123 82 91 86 73 105 150 86 104 102 108 129 12S 236 173 145 186 268 268 132 127 177 304 77 177 100 127 114 91 73 86 86 86 168 91 100 826 1,150 632 750 545 514 Calories 4,890 4, 6C0 3, 650 4,000 4,480 3. 5'.)U \ 5,640 4,415 7,805 8, 850 327 554 495 504 509 705 573 723 513 641 582 431 514 473 386 468 536 477 522 5,285 5,810 4, 250 3,845 4,635 4, 340 4, 220 5,340 3,595 3,715 4,215 6,905 4,620 4,625 7.6 7.5 7.5 7.6 8.2 7.6 7.5 6.5 11 7.8 9.7 9.4 8 9 8.3 8.2 9.7 6.9 7.7 7.4 3,475 5,190 3, 575 4,365 3,950 2,950 3,160 3, 090 2,680 3,1.50 4, 375 3, 155 3,495 5.6 6.8 7.5 7.8 8 6.4 6.1 7.9 7.2 526 . 3,585 183 177 467 466 6.8 6.8 182 CHEMISTRY AND ECONOMY OF FOOD. Table 37. — Foreign and American dietaries — Continued. Dietaries. u « Nutrients. 1^ CONNECTICUT— continued. Pamily of college professor, Storrs : Winter dietary, January and February — Food purcliased , Food eaten Summer dietary, July — • Food purchased Food eaten Family of a retired merchant, son chemist: Food purchased Food eaten Averages of Nos. 116 to 120; families of well-to-do professional men — Food purchased Waste Food eaten M. club, college students; 3 dietaries of same club : First dietary — Food purchased Food eaten Second dietary — Food purcliased Food eaten Third dietary — Food purcliased Food eaten N. club, college students : Food purchased Food eaten Students' club, divinity school: Food purchased Food eaten Average of Nos. 121 to 1'25; boarding clabs of college and professional students — Food purchased Waste Food eaten Average of Nos. 116 to 126, professional men and students — Food purchased Waste Food eaten College football team : Food purchased Food eaten Boarding house, well-paid machinists, etc.: Food purchased Food eaten I'amily of a machinist: Food purchased Food eaten Family of a blacksmith : Food purchased Food eaten Family of a stone mason : Winter dietary, December — Food purchased Food eaten Spring dietary, April — Food purchased Food eaten Family of a carpenter : Food purchased Food eaten Family of a carpenter: Winter dietary, December — Food pure hased Food eaten Grams. 106 133 129 Orams. 145 139 130 145 126 117 Grans. 405 398 475 472 483 478 Calories 3,450 3,335 3,885 3,800 3,530 3,390 115 4 111 141 5 136 452 3 449 3,635 75 3.560 161 138 115 104 113 92 141 140 139 122 204 184 163 136 180 141 160 158 185 138 680 622 460 421 376 346 503 503 356 317 5,345 4,825 3 875 3,415 3,680 3,110 4,130 4,105 3, 745 3,085 115 115 115 134 15 119 178 27 151 475 34 441 133 133 133 125 10 115 160 16 144 464 19 445 4,155 450 3,705 3,905 270 3,635 194 181 126 103 100 99 103 100 107 104 125 119 125 114 107 100 312 292 188 152 159 156 176 171 153 148 145 137 152 135 161 149 578 557 426 402 427 421 408 401 391 375 366 348 475 408 388 6,070 5,740 4.010 3,485 3,640 3,580 3,730 3,640 3,470 3, .350 3,365 3,190 3,970 3,670 3,610 3,390 FOOD CONSUMPTION. 183 Table 37. — Foreign and American dietaries — Continued. 334 a 134 h 135 136 137 138 Dietaries. CONNECTICUT — Continued. Family of a carpenter— Continued. Spring dietary, May — rood purchased Food eaten Average of ISTos. 127 to 134; wage- work- ers- Food purchased Waste Food eaten PENNSYLVANIA. Miscellaneous families in poorest part of Pliil- adelphia. Dietaries of 25 families: Average Minimum (negro) Maximum (German) = ft irxiNOis. Miscellaneous families in poorest part of Chi- cago. Dietaries of 26 families: Average Minimum Maximum United States army ration . United States navy ration . Nutrients. Grams. 115 111 114 8 106 109 66 202 119 86 168 120 143 Grams. 125 122 157 11 146 108 68 206 141 100 204 161 184 Grams. 346 336 409 16 393 435 181 608 398 213 626 454 520 Calories 3, 055 2,905 3,605 200 3,405 3,235 1, 630 5, 235 3.425 2, 195 4,950 3, 850 5,000 1: 5.5 5.5 6.7 6.2 5.4 5.3 6 4.6 11.3 6.8 7.5 Nos. 1 to 3, Playfair, Chem.News, 1865 (XI), 221. Nos. 4 and 5, Jiirgensen, Ztschr. Biol., 1886, 489. Nos. 6 to 8, Hultgren and Landergren, No. 6, Untersuchnng iiber die Ernahrung bei frei gewahlter Kost, Hygiea, 1889; Festband No. 11, and Nos. 7 and 8, Untersuchung iiber die Ernahrung scliwedi- Bcher Arbeiter, Stockholm. 1891. Nos. 9 to 11, Erismann, Arch. Hyg., 1889 (9), 23. Nos. 12 and 13, Sarin, Ibid., 34. No. 14, F. Hofmann, Ztschr. physiol. Chem., VI (1882), 372. Nos. 15 to 23, Meinert, Armee und Volks-Ernalirung, II, 189-221. No. 24, Bohm, Meinert, II, 186. No. 25, Forster, Untersuchung der Host, 211. No. 26, Von Eechenberg, Die Ernahrung der Handweber, Leipsic, 1890. Nos. 27 and 29, Schuster, Untersuchung der Kost, 165, 146. Nos. 28 and 30, Richter, Ibid., 174. Nos. 31 and 32, Forster, Ibid., 189. 191; Ztschr. Biol., 1873, 401. No. 33, Pettenkofer and Voit, Ztschr. Biol ., 1860 (2) , 459. Nos. 34 and 35, Beneke, Zur Ernahrungslehre d. ges. Mensch., Cassel, 1878, 290. Nos. 36 and 37, Eanke, Die Ernahrung d. Menschen, 193, 230. No. 38, For.ster, Untersuchung der Host, 213. Nos. 39 and 40, For.ster, Ztschr. Biol., 1873, 389, 390. No. 41, Cramer, Ztschr. physiol. Chein., VI (1882), 346. No. 42, For.ster, Untersuchung der Kost, 208. No. 43, Hoch, Dissertation. Rostock, 1888 ; Eef. Handbuch der Hygiene, Weyl., Ill, 1, 84 No. 44, Voit. Ztschr. Biol., 1889, 232. No. 45, Voit, Untersuchung der Kost, 28. Nos. 46, 49 and 51, report of Royal Bavarian special commission, see Memert, II, 225. Nos. 47 and 48, Forster, Ztschr. Biol., 1873, 387, 388. No. 50, Steinheil, Ztschr. Biol., 1877, 415. No. 52, Ranke, Ibid., 130. No. 53, Prausnitz, Arch. Hyg.-, 15 (1892), 387. No. 54, Holier, Der Isarwinkel, Munich, 1891,63-72. No. 55, Holler, Ibid., and Liebig, Meinert, II, 224 ; Sitzungsbcr. d. bayr. Acad., II, 403, 1869; Reden u. Abhandl., 121. Nos. 56 to 59, Meinert, Armee und Volks-Ernahrung, I, 276-287; and Konig, third edition, I, 156. No. 60, Ohlmiiller, Ztschr. Biol., 1884, 393 Nos. 61 and 62, Manfredi, Arch. Hyg., 17 (1893), 552. Nos. 63 to 65, Albertoni and Novi, Arch. Physiol., 1894, 213. No. 66, Moleschott, Razione del Soldato Italiano, Rome, 1883. No. 67, Beaunis, Recherches Exp6r., Paris, 1884, 4; Ref. Handbuch der Hygiene, "Weyl., Ill, 1, 84. 184 CHEMISTRY AND ECONOMY OF FOOD. I*ros.68to71, Forster, Ztsclir. Biol.,9 (1873), 381. Camerer, Ibid., 1880, 24; 1882, 220; 1884,556; 1888, 141; 189.i, 227, 308. Uffelmaim, Ibid., 1882, 584. Hasse, Ibid., 1882, 553. No. 72, Voit, Untersncbiing der Kost, 125. , No. 73, Schroder, Arcb. Hyg., 4 (1866), 89. No. 74, Prausnitz, Ibid., 15 (]892), 387. Nos. 75, 76, and 80, Eijlinian, Ztscbr. Biol.. 1889, 106. Nos. 77, 81, and 82, Tawara, Ibid., 1889, 107 ; Arch. Hyg., 1888, 102. No. 78, Kellner and Mori, Ztsohr. Biol.».1889, 102. No. 79, Soheube, Arch. Hyg., 1883, 352. No. 83, Atwaler and associates. Nos. 84 to 115, Atwater and assistants. Food consumption; Seventeenth Annual Report Ma.ssa- ohusetts Bureau of Statistics of Labor. Report of Storrs (Conn.) Experiment Station for 1891, 106. Nos. 116 to 134, and 137 and 138, Atwater and associates. Reports of Storrs (Conn.) Experiment Sta- tion, 1891, 106; 1892,135; 1893,174. Nos. 135 and 136, Shapleigh. A Study of Dietaries ; Partial Report of Datton Fellow, College Settle- ments Afssociation, 1892-93. COMMENTS UPON DIETAKIES SUMMARIZED IN TABLE 37. In tlie belief that tlie figures of Table 37 will be best understood by statement of some of the more important details, an attempt to reca- pitulate the latter is made in the pages which follow. English dietaries. — Nos. 1, 2, and 3 are those estimated by Sir Lyon Playfair from the actual weights of the food consumed by individuals; Playfair speaks of the engineers (soldiers) of No. 11 as "laborers in time of peace actively occupied either in the construction of field works, or pursuing their avocations as artisans/' and regards the dietary as "the most complete evidence we possess [at the time, 1864- 1865] of the requirements of food for laboring men doing a fair but not excessiA'^e amount of work in 24 hours; when these soldiers are at light labor they are found to take less." The sailors of No. 1 and weavers of No. 2 were prisoners in the Wakefield Gaol. The details of food consumption were very carefully observed, and are published by Dr. E. Smith.' Danish and Sicedish dietaries. — Nos. 4 and 5 are reported by Jiirgesen. No. 4 is that of a physician in Stockholm, 37 years old. The food in this case, as in No. 5, consisted of milk, meat, fish, bread, cheese, butter, and beer. The investigation was made in January and February. No. 5 is that of the wife of the physician just named, 35 years old, XJrincipal of a girls' school ; time of investigation, May. The food actually eaten was weighed and its composition estimated from the compilations of Konig and Almen. Nos. 6, 7, and 8 are reported by Hultgren and Landgren. The food materials were carefully weighed as used; the composition was estimated from analyses published by Konig and Almen. For substances of whicb no reliable figures for compo.sition were available, as pastry, etc., special analyses were made. No. 6 represents the average of 5 dietaries of as many medical students in Stock- holm, from 22 to 27 years of age, busily engaged in study and laboratory work. The examinations were made in the winter. The experimental periods ranged from 8 to 16 days; the protein per person per day from 103 to 163 grams, and the energy from 2,800 to 3,375 calories. No. 7 represents the average of 6 dietaries of 4 healthy men, a metal worker, a blacksmith, a carpenter, and a farm laborer, from 28 to 46 years of age, at moderately hard work and earning good wages. The food included meat, fish, milk^ etc., and alcohol in beer or stronger spirits. The alcohol averaged 22 grams per man per day, and is estimated as equivalent in fuel value to 37.8 grams of carbohydrates. The protein ranged from 105 to 166 grams and the energy from 2,895 to 3,510 calories per. man per day. The diet of this group of men is regarded by the authors as charac- teristic in respect to nutrients and energy for Swedish laboring men at moderate work (mittlere Arbeit). No. 8 represents the average of 5 dietaries of 5 vigorous men, a stone mason, a bricklayer, a carpenter, a wood sawyer, aud a farm laborer, from 31 to 54 years of 'Phil. Trans., voL 151, 747. FOOD CONSUMPTION. 185 age, at very hard work, and earning good wages. The food was similar to that of No. 7. The alcohol averaged 24.2 grams per man per day. It was estimated as equivalent to 41.3 grams of carbohydrates, and included in the estimates of carbo- hydrates and energy as in No. 7. The protein ranged from 128 to 246 grams, and the energy from 3,65.5 to 5,580 calories per man per day. The authors regard the diet of this group of men as fairly reiirescntative of that of Swedish workingmen at severe work. Eussian dietaries. — Nos. 9, 10, and 11 are dietaries of factory operatives in the neighborhood of Moscow, reported by Erismann. It is the general custom of Eus- sian factory operatives, such as are represented in these studies, to board in clubs of their own organization. The purchasing of food, etc., is delegated to a committee, which also keeps a careful account of the number of meals eaten by each member of the club. These accounts are kept with .the greatest care, as all the bills are paid by the owners of the factory, and a sum proportional to the number of meals eaten by each member of the club deducted from his wages. The statistics upon Avhich these dietaries are based are derived from these accounts, and represent the quantities of ibod purchased during periods of from two to three months in length. Their food consists principally of black bread, buckwheat grits, and sauer- kraut, and during those parts of the year when fasts are not observed, meat and ani- mal fats. During the fasts, which cover a considerable part of the year, vegetable oils are used to a considerable extent. The composition of the food was estimated principally from previous analyses by Eussian observers, otherwise according to Kouig's compilations. Nos. 12 and 13 are dietaries of peasants in the same locality, by Sarin. Each study occupied one week The food actually eaten by each person at each meal was care- fully weighed; the composition was estimated. German dietaries. — No. 14 is the dietary of the family of an intelligent laboring man, who had not been able to obtain work for several months, and was almost des- titute at the time of the inquiry. The study was made by F. Hofmaun. Nos. 15 to 23 are dietaries of laboring people of the poorer classes, living, No. 23 near, and the rest in the city of Leipsic, Saxony. The inquiry was conducted in part, at least, arid presumably the whole, in 1878-1880, by Dr. Meinert, with the purpose of learning something of the conditions of life, and especially the food of people of small incomes in Germany. It was evidently conducted with no little care and thoroughness. For each dietary the food was weighed during a period of five or seven days, with such detail as to show the amounts of each food material per meal. Allowance was made for the waste in one case, at any rate, as stated in the report and presumably for all, so that the quantities given appear to be those actually consumed. No statement is made of analyses especially executed for the investigation, and it is to be inferred that the composition of the food was estimated from standard analyses. The quantities of nutrients and costs of food are estimated per adult per day. In the cases where there were children the equivalent number of adults was assumed for the calculations. The amounts of food of ditterent kinds eaten per meal and per day, the amounts and costs of the several kinds of food, and of the whole food of each dietary, the incomes of the i)eople, and their ways of living, were observed and reported. While the quantities of nutrients imply straitened circumstances in most of the cases, the details in some are decidedly pathetic. The space here will allow only a brief summary of some of the more important points. No. 15, girl in cigar factory, 25 years old, earning an average of 5 marks per week, and boarding with her mother, who earned 3 marks per week by washing. Their food consisted mainly of bread, jiotatoes, a little rice, occasionally vegetables, meat 2,50 grams for 2 persons twice a week, or half a pound a week for each person, and coffee. In lack of fuel for heating the cott'ee, hot water from a neighboring fiictory was used. The description says ''it is not strange that with food so poor in x>rotein both mother and daughter are frail and sickly, nor that, as the girl told me in tears, 186 CHEMISTRY AND ECONOMY OF FOOD. they often went supperless to bed. * * * The girl is the mother of a child 6 months old. * * * Yot board and lodging of herself and child she pays 3^ marks per week, and thus has left from her wages for clothing and other expenses for herself and child 1^ marks per week, a sum which, while it does not justify, explains her increasing it by other means." The amounts and composition of the food are computed for the young woman aud her mother, so that the figures repre- sent the average for the two. No. 16, girl working in a printing office. She was 29 years old, her wages aver- aged 5 marks per week, she lived with another girl and a child of the latter in a room 10 feet square. In the three winter months of 1879-80, she had only bread and butter aud coffee, and for dinner daily from IJ to 2^ cents' worth of sausage, and even on this fare used up $5.50 of previous savings. The amount, composition, and cost of the food were estimated for the two girls together, so that the figures repre- sent the average. "What wonder," says Dr. Meinert, "that young women, whose moral energy and intellectual powers are reduced by such a starvation diet, are unable to withstand temptation." No. 17, widow, with five children, aged 5^, 8, 10, 12, and 14 years, respectively. She supported herself and children by plaiting straw and taking boarders. The food consisted of bread, beef fat, potatoes, vegetables, and occasionally meat. Family estimated equivalent to 4 adults. Nos. 18 and 20. No. 18, girl, 24 years old; in paper factory ; wages, 9 marks ; sister, 21 years; seamstress; wages, 8 marks per week. No. 20, brother of preceding, 28 years old ; printer ; wages, 18 marks per week. These persons lived with their invalid mother in a fifth-story apartment, consisting of a living room, a sleeping room, and kitchen. Dr. Meinert says that with their earnings these people might have had much better food. "The appearance of the two girls, however, explained the scanti- ness of their diet. Their clothing, esi^ecially that of the seamstress, was much finer than their position and income warranted, and formed a sadly striking contrast to the appearance of the mother and the pitiable dwelling in which the people lived. The food included meat daily. Account was taken of the food of the man and of that of the women separately, the man having more than the women. Nos. 19 and 21. No. 21, family of cabinetmaker, consisting of father and 6 chil- dren, aged i, 3, 7, 9, 11, and 14 years, and father's sister (No. 19), a girl of 18, work- ing in a bookbindery. The cabinetmaker earned 18 marks and the sister 9 marks per week. The 9 persons lived in an apartment consisting of 2 rooms and a closet holding a cook stove. The sister paid for lodging, breakfast, and dinner 3^ marks (84 cents ] per week and purchased bread and butter extra. The wife and children were undersized, pale, and weakly. No. 22, family of druggist's clerk, consisting of father, mother, and 2 daughters, aged 16 aud 12. They are spoken of as thoroughly good people. The annual income was 1,180 marks. Their food was better than the preceding. It included more variety ; vegetables, butter, and meat were eaten daily ; indeed the family had meat, eggs, or cheese once and often twice a day. As the man's labor was light. Dr. Meinert regards his diet as sufficient for his needs. No. 23, family of farm laborer near Leipsic, consisting of father, mother, and 4 children, from 5 to 14 years old. The 6 persons are accounted as equivalent to 4 adults. The food consisted mainly of bread, beef fat, and potatoes, with a little milk, and for one meal in the week, Sunday dinner, meat. FOOD CONSUMPTION. 187 The final statistics are summarized in the following table: Food materials and costs per adult per day. Dietariei. Girl in cigar factory Girl in priiitin<; oltice Woinan at straw ])laiting Girl in paper factory and soam stress Girl in bookbindery Printer Cabinetmaker Druggist's clerk Farm laborer Food mate- rials. awrs. ,202 , 504 842 , 0112 ,195 ,271 ,129 ,394 Nutrients. Protein. Total. Grams. 52 C5 72 56 61 87 77 71 80 Diges- tible. Grams. 42 ■ 54 56 47 49 73 62 59 61 Fata. Grams. 53 39 56 51 41 64 57 69 37 Carboliy drates'. Grams. 301 303 440 229 347 366 466 351 504 Cost. Pfennig. 34 43 40 86 36 48 46 47 30 Cents. 8.2 10.3 9.6 11.5 11 11.3 7.2 No. 26, hand weavers in Zittan, Saxony. For detailed description see pp. 164-177. No. 27 to 30 are dietaries of prisoners in Munich reported by Schuster, and in Brandenburg, Prussia, by Richter. No. 27 is that of a house of detention and No. 28 of a house of correction in Munich; in the latter the terms of service were 3 years or longer with labor. No. 29 is tbe ration served to prisoners without work, and No. 30 that of inmates of a house of correction, with labor, iu Brandenburg. In all the prison dietaries the food was mostly vegetable, and in Munich it was notably insufficient in quantity. In Nos. 27 and 28 the rations were carefully weighed and analyzed. In Nos. 29 and 30 the rations were weighed as prepared for cooking, but no analyses were made. Nos. 31 and 32 are reported by Forster, and are the dietaries of inmates of infirm- aries in Munich for aged and infirm persons in part or wholly incapable of self sup- port. In Nos. 31 and 32 and in all of Forster's dietaries all the food was carefully weighed and samples taken for a more or less complete analysis. When actual analy- ses were not made the composition was estimated from analyses by Voit and others. No. 33 is the average of three tests in the respiration apparatus made by Petten- kofer and Voit. The subject was a watchmaker in Munich, 28 years of age, and weighing 70 kilograms (152 pounds). During the exi^eriments he did no muscular work and lived upon an ordinary mixed diet. The quantities of nutrients are those actually metabolized. Nos. 34 and 35 represent observationsby Professor Benecke, ofthe University of Mar- burg, upon himself. He was in decidedly active mental and light physical work^ had about 3 hours' exercise in the laboratory and 8 hours' sleep. With a mixed diet of meat, milk, bread, etc., containing the nutrients of No. 34, his weight decreased 451 grams (1 pound) during an experiment of 14 days. From determinations of nitrogen in food and excreta, he estimated that the dietary of No. 35 would have sufficed for his needs. Nos. 36 and 37 represent the dietaries of Professor Eanke, of the University of Munich, in experiments upon himself, in which the total income and outgo were deter- mined with a respiration apparatus. "With very little physical exercise these quan- tities just sufficed him for the maintenance of his body without gain or loss. Nos. 38 to 40 were reported by Forster. The Munich lawyer, No. 38, was in moder- ate circumstances, but able to have all the food that health demanded. The quanti- ties here given are one-third of those consumed by a family of three adults. One- fourth of the carbohydrates of the food ofthe physician was taken iu beer. Nos. 34 to 40 were the dietaries of professional men in comfortable circumstances. Their food differed from that of tbe preceding and most of the succeeding dietaries in that it had much more of meat and other animal foods, and was hence more com- pletely digestible; and that it had more variety, which made it more palatable. No. 41. In contrast with these six dietaries of professional men, Nos. 35 to 40, which 188 CHEMISTRY AND ECONOMY OF FOOD. were composed largely of animal food, may be cited that of an official of high rank in the German civil service, reported by Cramer. The official vras 64 years of age, and had been a vegetarian for 11 years. He was in good health and possessed of a great deal of physical endurance. The character of the food in this dietary differs considerably from that in No. 44, as the official was not a so-called strict vegetarian, but used milk, eggs, and warm food. The food was weighed and its comx)osition determined by analysis. Digestibility was also determined. No. 42 was rej)orted by Forster. This ]uechanic was connected with a laboratory, was in very comfortable circumstances, had considerable animal food, and did very light muscular Avork. No. 43 is the dietary of a shoemaker in Eostock. observed by Hoch. No. 44 is the dietary of an upholsterer, 28 years of age, in Munich. He was a strict vegetarian, and had lived for 3 years upon an exclusively vegetable diet, containing no warm food, and consisting of bread, fruit, and oil. The man was normally devel- oped, appeared to be well fed, and weighed 57 kilograms (125 pounds). This dietary is reported by Voit, and the food was weighed and analyzed. The digestibility of the food was also determ ined. No. 45 represents the average result of examinations by Voit of the food of 3 well- paid mechanics in Munich. It consisted of meat, bread, other vegetal)le food, and beer. The quantities and composition of the food were estimated. No. 46 is the average of 2 dietaries of locksmiths, 7 of carpenters, and 3 of coopers in Bavaria, given in a royal Bavarian commission report. Nos. 47 and 48 were also reported by Forster. No. 49 is the average of 5 dietaries of Bavarian farm laborers reported by the same commission referred to in No. 46. No. 50 is the average result of examinations by Steinheil of the food of miners near Ems, Prussia, at severe work. The food included meat, bread, potatoes, beans, and other vegetables in considerable variety, and butter. It is probable that actual weighings of the food were made; its composition was estimated presumably from Voit's compilations. No. 51 is the average of 6 dietaries of Bavarian brewery laborers, reported by the Bavarian commission above mentioned. Their work is very severe, and they are noted for consuming large amounts of food, of which beer furnishes a considerable proportion of the carboliydrates. The figures for the individual dietaries of which Nos. 46, 49, and 51 express the averages, are as follows : The protein in the mechanics' dietaries Agarics from 47 to 183 grams, and the energy from 1,690 to 5,285 calories. I have not the original" data at hand, but the source would seem to vouch for their reliability. The rauge is very wide, but I am inclined to think not wider than might be found among people of similar 43Ccupation in ordinary communities. Dietaries of worMngmen in Bavaria. Locksmith Do :.. Carpenter Do Do Do Do Do Cooper Do Do Average of 11 dietaries of meoLauics Nutrients. Protein. Fats. Carbohy- drates. Potential energy. Grams. Grams. Grams. Calories. 309 41 407 2,495 78 12 331 1,790 149 25 974 4,835 163 30 1,058 5,285 ]73 59 513 3,360 183 52 761 4,355 65 22 228 1,405 99 52 585 3,290 ]24 22 651 3,380 47 7 350 1,690 147 50 409 2, 745 122 34 570 3,150 FOOD CONSUMPTION. Dietaries of ivorlchuimen in Bavaria — Continued. 189 Nutrients. Proteiu. Fats. Carbohy- drates. Poteutial energy. Grains. 131 123 189 95 U7 Grams. 61 61 63 33 59 Grams. 609 557 683 304 559 Caloriei. 3,600 3, 355 4,160 1,940 3,445 Do .. Do Do Do 137 55 542 3,300 197 122 85 116 223 63 34 32 61 113 897 674 728 566 009 5,070 3,580 3, 630 3, 365 5, 690 Do Do Do Do 149 61 755 4,270 No. 52 is the dietary reported Iby Eanke of a large number of Italian brickniakers working near Munich during the summer. Some three hundred were in charge of a superintendent, who provided them with food which consisted of maize meal and cheese, with occasionally a small amount of brandy. The labor was decidedly severe. The amounts of food materials were based upon statistics furnished by the superin- tendent. The composition was estimated by Eanke, but his assumed composition of maize evidently does not represent the maize of this region. The amounts of nutri- ents given in the table are recalculated, using for the composition of maize the aver- ages of analyses of maize grown in southern and southwestern Europe.' No. .53 is the dietary of machinists, etc., employed in the Krupp gun works at Essen, reported by Prausnitz. It has been for many years the endeavor of this firm to do all in its power to improve the food and quarters of its emjiloyees. The board- ing houses (menage)-were establislied in the interest of the unmarried workmen and those whose families lived at a distance, the purpose being to furnish them with suitable board and comfortable lodging. They were opened in 1856 with 200 members ; this number gradually increased with the extension of the works, until at the time of the investigation in 1890 it had reached about 800. Since 1884 all unmarried working- men, except those receiving high wages for special work and those living with their relatives, have been obliged to live in the company's boarding houses, a regulation which has been advantageous to both boarding houses and boarders. The price for dinner and supper together ifs 80 pfennigs (19 cents) per day. This does not include bread, but each man receives one-eight kilogram of coffee and one-fourth kilogram of butter per week. At dinner and supper the meat is served in individual portions; the men are allowed to take as much as they choose of all other dishes. The average quantities of nutrients furnished in the dinner and supper are 115 grams protein, 81 grams fats, and ^80 grams carbohydrates per day. In addition to this an allowance of 400 grams bread and 36 grams butter is made for the breakfast, which brings the total nutrients up to the amounts stated in the table. Prausnitz regards these figures to be the minimum estimate, as the daily amount of bread is placed very low, and milk, sugar, and beer are not included ; this would fully balance all food wasted in preparation and at meals. I'he quantities of food materials are estinjated on the basis of the bills of fare and their composition from Konig's aver- ages. No. 54. This represents the average of 6 dietaries examined by Holier of farm laborers in the district of Tolz, in upper Bavaria. The dietaries are included in a very interesting description of the region and the people. The author says, in speaking of the peasants of the district and their very unusually ample nourishment: 1 Kcinig, Chem. d. mensch. Nahr. n. Genuss-Mittel, third edition, 1, 559. 190 CHEMISTRY AND ECONOMY OF FOOD. "The influence of their food upon their bodily development is very noticeable. The people are tall, estt'emely strong, and sinewy ; they are not fat, but their organic albuminoids (muscular as distinguished from fatty tissue) are well developed. * * * Eeally 'fat' men, that is to say, men with large deposits of fat in the body, are rare among the peasantry of this region. They have large and muscular frames and are among the best bviilt men in the army enlistment rolls. * * * Aside from their severe work, a still further reason for the peculiarity of their food (large total amount and especially large quantities of fat) is found in the climate. * * * xhe low temperacure and the constant wind make the large amounts of fat a necessity. * * * People who have to endure such ranges of temperature as prevail here, without especial protection by clothing, and not sufli'er in health, must be enabled fco regulate the bodily warmth by large supplies of easily combustible fats and car- bohydrates in the food." The food consists of bread, flour, potatoes, more or less garden vegetables, milk, cheese, grease, and butter. The protein, outside that of the bread and flour, comes mainly from milk, cheese, and curd, the fats from grease and butter which are con- sumed in large quantities, and the carbohydrates from wheat, barley, and potatoes. Sugar is little used because of its cost. The description does not state how the dietaries were estimated, bufc only gives the quantities of nutrients as stated beyond. No. 55 is the average of 3 dietaries of lumbermen — 1 from Tolz, as reported by Hofler, and 2 from other parts of upper Bavaria, as reported by Liebig. These are in size and amounts of fat and of energy entirely exceptional among the European dietaries of which I have been able to find record, and rank even with the larger, though they are far from approaching the largest, of the American dietaries given in the previous pages. Of the peasantry in the region where the 2 dietaries of lum- bermen by Liebig were taken, Professor Ranke says: *'In contrast to the conditions prevalent elsewhere in Germany, the food of the country people in the Bavarian highlands and mountains is very ample, and although potatoes have not become the principal food material here, the food is chiefly vege- table. The famous peasant of the Bavarian mountain region, the genuine 'Haber- feldtreiber,' as he proudly calls himself, eats meat, in accordance with time-honored usage, only on the four great holidays of the year. He lives upon ' Schmalzkost,' that is to say, simple preparations of flour with which large quantities of fat are incorporated. To these he adds such materials as sauerkraut and dried apples or peas. The food of these powerful peasants is so generous as to explain their herculean development of muscle, their enviable vigor, and their consciousness of strength, which often leads to excess. * * * It is likewise a current observation by people in the Tegernsee Mountains that the lumbermen can do the more work the larger their appetites are." In comparing the dietaries of the Bavarian lumbermen, as reported by Liebig, with other European dietaries, I have sometimes, in my own mind, questioned whether the figures were entirely reliable as exponents of the eating habits of the class to which the men belonged. In matters of larger importance some of Liebig's doctrines have been doubted, only to be confirmed by the results of later inquiry. In this minor though interesting matter of detail the teaching of the great master is substantiated by the figures which Hofler cites. It would certainly be a valuable contribution to the science of nutrition if a number of these peasant dietaries could be thoroughly studied. FOOD CONSUMPTION. The table lierewitli summarizes the data of the dietaries just mentioned. Dietaries of men in Bavarian liitjliUtnds. 191 Occupation and. locality. FARM LABORERS. Jaehenau, Tolz, average of 3 estimates (Kofler) Gaissach, Tolz. average of 2 estimates (Hofler) Ejrchliichl, Tolz, one nieasuremeut (Holier) Average of 3 dietaries of farm laborers (Hoflor) LUMBERMEN Jaehenau, Tolz (Hofler) Eeichenliall Mountains (Liebig) Oberaudorfer Mountains (Liebig) Average of 3 dietaries of lumbermen Nutrients. Potential Protein. Pats. ^^^- ''''''''■ Grams. 161 166 85 137 144 112 135 Grams. 195 201 210 Grams. 467 734 438 358 309 208 606 691 876 Calories. 4,390 5, .'■.60 4,095 4,680 6,405 6,165 6,080 724 6, 215 No. 56 to 59. Army rations, like other dietaries, are decidedly variable. The figures here are borrowed from very extensive coniijilations by Meiuert. No. 56 is the aver- age of 4 estimates by Voit, Artmann, Hildersheim, and Meinert, respectively. No. 57 is the average of 3 estimates by Artmann, Hildersheim, and Meinert. No. 58 is an extraordinary ration for soldiers in active service in the field. German army management, from Frederick the Great to William and Moltke, has recognized the fundamental principle that soldiers to fight well must be well fed. No. 59 is therefore especially interesting as a ration ordered shortly after the out- break of the Franco-German war, at the time of the terrible marching and fighting which brought the victories at Worth, Metz, and Sedan. Anstria. — No. 60 represents the average daily food consumption of 15 farm laborers in Central Transylvania as observed by Ohlmuller. The men were engaged in the severe work of harvesting from 4 o'clock in the morning until evening; their food consisted exclusively of maize meal and beans, and their only drink was water. The amounts of nutrients were estimated by Ohlmiiller, who used the same composi- tion for maize which Eanke used iir No. 52 (Italian brickmakers). The nutrients are, therefore, recalculated, the same composition being assumed for maize as in No. 52. Italian dietaries. — Nos. 61 and 62 are the dietaries of people of the poorer class in Naples, as observed by Manfri'di and described above. No. 61 is the average of 5 dietaries of men, 2 shoemakers, a carpenter, a mason, and 1 without employment. No. 62 is the average of 3 dietaries of women (servants). Nos. 61 and 62 are described in detail on pages 173-177. Nos. 63 to 65 are the average dietaries of a peasant 39 years of age, his wife, and son 14 years of age— a shoemaker — who lived in the neighborhood of Ferrara. They were studied by Albertoni and Novi. The family Avas in good health but very poor; their combined yearly earnings amounted to only $97, of which $81 was expended for food. Their food in winter was mainly maize and chestnut meal, macaroni, beans, fish, and lard. In summer the maize meal Avas in part replaced by bread. The food was accurately weighed and analyzed, as were also the urine and feces. Each of the 3 dietaries represents 2 periods of observation of 3 days each, one in March and the other in August. No. 66 is the average of 4 Italian army rations, 2 for infantry and 2 for cavaJrj^, in time of peace, as calculated by Moleschott. France. — No, 67 was reported by Beaunia. 192 CHEMISTRY AND ECONOMY OF FOOD. Children {Germany, Russia, and Switzerland). — Nos. 68 to 71 are averages of indi- vidual dietaries of cliildren, with one or two exceptions in well-to-do private fami- lies. Of the 38 dietaries included in these averages 2 were observed by Forster, 3 by Uffelman, 10 by Hasse, and 23 by Camerer, all physicians. Forster's dietaries were those of 2 infants. One was in a laborer's family ; it was 7 weeks old and was fed on a porridge made of milk, flour, and sugar. The other belonged to a well-to-do family ; it was between 4 and 5 montlis old and was fed condensed milk. Both ^lese children probably lived in Munich. Uffelman observed the dietaries of his own boys, from 2 to 15 years of age, in Rostock ; only those of the three younger ones are included in these averages. Plasse made two series of studies of the dietaries of 4 girls, daughters of a well-to-do family in St. Petersburg; their ages ranged between 2 and 11 years. They were very well developed and their dietary consisted largely of animal food. The food was carefully weighed and its composition in parts deter- mined by direct analysis and in part estimated from Konig's compilations. Hasse also observed the dietaries of tAvo girls, aged 2 and 4 years, in a well-to-do family of Russian descent in Zurich, Switzerland. The food was essentially the same as that of the children in St. Petersburg and the method of the investigation the same. In all of Hasse's dietaries the period of observation ranged from 3 to 6 days. Camerer made all told 7 series of dietaries of his own children, 4 girls and 1 boy, from 1878 to 1892. In 1878 the ages of the girls were 2, 3i, 9, and 11 years, and that of the boy 5^ years. In 1892 those of the girls were 15, 16, 22, and 24 years and that of the boy 18 years. The general plan of these investigations consisted in observing the food of each child for 6 periods (in a few cases a less number), of 4 days each during each year. The 6 dietaries thus obtained were averaged together for the dietary of the child for the year, and these average (annual) dietaries are the ones included in the averages in the table. Except in one of the 7 annual series weighings were made of the food actually eaten and its composition in parb determined by analysis and in part estimated from Konig's compilations. In addition to these data the weights of the children were observed from day to day, the urine was collected and the urea determined and the feces collected, weighed, and analyzed. These studies were made in Riedlingen and Urach, in Wiirtemberg. During the period between 1878 and 1892, 31 of these average annual dietaries were made, representing approximately 37 observations for each child or 186 for the five children. Only those dietaries of the children up to 14 years of age are here included. Of these there were 23 annual dietaries representing approximately (6x23) 138 observations of 4 days each. It should be added that the chiklren were healthy and tlieir growth was normal, although the girls who had attained the ages of 15 to 20 before the end of the study were somewhat smaller than the average. These are by far the most extensive and valuable observations upon the food consumption of children which have been reported. No. 68 is the average of the 2 dietaries reported by Forster, referred to above, and 1 by Camerer, that of a child not in his own family. This girl was 1 year and 2 months old and weighed 23 pounds. Her food was cows' milk, toast, gruel, beef tea, etc. The food was weighed and its composition in part determined by analysis and in part estimated from Konig's compilations. The average age of these 3 chil- dren was 8 months and their average weight 16 pounds. No. 69 is the average of 14 dietaries, 9 of which are those of girls and 3 of boys from 2 to 6 years of age. Of the girls' dietaries 6 were reported by Hasse and 5 by Camerer. Two of the 3 boys were Uffelman's and the other Camerer's. The average age of these 14 children was 3 years and 10 months and their average weight 33 pounds. No. 70 is the average of 8 dietaries, 6 of girls and 2 of boys from 6 to 10 years of age. One of the girls' dietaries was reported by Hasse. All the other dietaries are FOOD CONSUMPTION. 193 those of Camerer's children. The average age of the 8 children was 8 years and 5 months and their average weight 53 pounds. No. 71 is the average of 13 dietaries, 10 of girls and 3 of boys between the ages of 10 and 14. Eight of the girls' and 2 of the boys' dietaries were observed by Camerer, those of the other two girls by Hasse, and that of the boy by Uifelman. The average age of the 13 children was 11 years and 8 months and their average weight 70 pounds. No. 72 is the dietary of chiklren 6 to 15 years old, inmates of an orplian asylum in Munich reported by Voit. who pronounced the food satisfactory both as regards quality and quantity. The food was weighed as prepared for cooking, but no men- tion is made of actual analyses. No. 73 is a dietary studied at a home for children in Gehlsdorf, near Eostock, con- taining 38 boys between 8 and 15 years of age. They wore healthy and normally developed, and occupied in study and light work. The study was made by Schroder. The food was weighed as prepared for cooking and its composition was estimated. The rules of the institution did not jjermit waste of food at the table. No. 74 is the dietary of girls from 14 to 19 years of age (average, 15|^ years') in the Krupp training school for girls. This school represents one jihase of the effort which has been made by the Messrs. Krupp to elevate the condition of their employees. The city of Essen, which has nearly 70,000 inhabitants, depends mainly upon the Krupp cast steel works, which employ some 10,000 workmen in the shops and 8,000 outside. While this establishment is of supreme interest to the mechanical engineer, the efforts of the Messrs. Krupp to promote the welfare of their employees are scarcely less so to the student of sociology. The girls' training school has for its object not only the general education but instruction in those things which pertain to the care of the household and the duties of the wife and mother. The course in these latter branches lasts for 3 months, and includes purchasing of food, cooking, preserving and care of provisions, management of the kitchen garden, washing, ironing, mangling, knitting, darning, and all kinds of housework. In instruction in food economy the pupils are taught what quanti- ties of food materials are required for a given number of persons and how much should be prepared for each meal. Each pupil is expected to provide for 10 others for a number of days. She must weigh out the necessary food materials and prepare and cook them. She must keep an exact account of what is used for each meal and the cost and quantities of the several materials employed. At the end of the course each girl talies her own account book, which makes a very valuable guide for her later in life, in that it tells her how a nutritious and at the same time varied diet may be furnished at a comparatively small expenditure. This dietary study was made in connection with No. 53, by Prausnitz. The quantities of food materials were taken from the girls' account books mentioned. The composition was estimated from Konig's compilations. Japanese dietaries. — According to Mori 3 general classes of dietaries are common among the Japanese, namely, (1) that of the rural population of the interior. This is almost exclusively vegetable ; fish is eaten but once or twice a month and meat but once or twice a year; (2) that of the population of the coast, who eat fish in con- siderable quantities, and (3) that of the city population and of well-to-do families, who eat both meat and fish to a considerable extent. Eice is the principal article of vegetable food, but, in addition to this, barley, wheat, various kinds of millet, and buckwheat are eaten in considerable quantities. Tubers and roots, such as turnips and radishes, are staple articles of food, and pump- kins, cucumbers, etc., are much used. The legumes are little eaten in their natural state, but form the basis of a number of prejiared foods and relishes, such as miso, tofu, and shoyu, all of which are made from the soja bean. The miso is prepared from cooked beans, which are rubbed to a thick paste and fermented with the ferment used in the preparation of the rice wine. Tofu, or bean cheese, is essentially the 8518— No. 21 13 194 CHEMISTRY AND ECONOMY OF FOOD. legumin of the soja beau, which is first extracted with water aud then precipitated bytlie addition of the mother liquor (magnesium chlorid), obtained from the evapo- ration of sea water in the manufacture of salt. The cheese is eaten fresh. The shoyu sauce is prepared from a mixture of cooked and pulverized soja beans, roasted and pulverized wheat, wheat flour, salt, aud water. The mixture is fermented with the above-mentioned rice ferment for 1^ to 5 years in casks. This sauce is used very largely by all classes. Nos. 75 and 76 are dietaries of prisoners in Tokyo, observed by Eijkman. The food was exclusively vegetable, and consisted mainly of a mixture of one part of rice and one and one-half parts of barley cooked together. All of Eijkman's dietaries, Nos. 7.5, 76, aud 80, were published in Japanese. Kellner and Mori and Nakahena in referring to them state that the food was in all cases weighed and its moisture con- tent determined. No. 77 is that of the employees in a large retail store in Tokyo, reported by Tawara. The period of observation covered only 3 days, but during this time no animal food was eaten; the food was essentially rice and salted radish. Tawara's dietaries, Nos. 77 81, and 82, are also published in Japanese, but are cited by the writers above referred to, who state that the food was weighed aud its composition esti- mated upon the basis of numerous analyses of Jai^anese food materials by Tawara and others. No. 78 is the dietary of Mori, an assistant at the University of Tokyo. It was observed by himself, and he regards it as representative of the food of people in well-to-do circumstances and students in the higher institutions. It is materially modified by European influences (more meat and more protein), but on account of its expense has gained little footing among the majority of the people. The food was beef, rice, potatoes and other vegetables, and milk. The test was continued for 6 consecutive days, during the last 3 of which the food materials and also the urine and feces were analyzed. The amounts given are, however, those actually eaten. No. 79 gives the average of the dietaries of two students in the University of Kioto, as observed by Scheube. Meat and fish were eaten daily, aud eggs, bean cheese (tofu), and green vegetables were also used. Each test was continued for 5 days. The food was weighed and its composition estimated. No. 80 is the dietary of a military school in Tokyo, reported by Eijkman. The observations cover a period of several nonconsecutive days. Meat was served daily. No. 81 is that of the inmates of a Government school in Tokyo, from 17 to 2,5 (aver- age, 20) years of age. The cost of the food was $4 per month per pupil. Meat was served once a day, and fish was eaten in considerable quantities. The period of observation covered 10 consecutive days. No. 82 is the dietary of the pupils in a private school, also in Tokyo. Their ages ranged from 11 to 21 years. Meat was served only twice a week in this school, but. fish was eaten regularly. The price of the food was about $2.25 per month per pupil. Their food consumption was observed during one week. Nos. 81 and 82 are reported by Tawara. In the opinion of Kellner and Mori the quantities of food served to these pupils, of whom a considerable number were children, were some- what excessive, and doubtless there were uneaten residues, especially of rice, which were not taken into account in estimating the amounts of nutrients. This would appear to be the case especially in No. 82. Java. — No. 83. In connection with the study of the food of some of the interest- ing people from the less-known countries at the World's Fair, made under the auspices of the World's Columbian Commission, ^ an opportunity was furnished to observe with exactness the food consumption of several inmates of the Java village. One of the houses was set apart for the purpose, and 2 families, including 2 women 1 A report of these investigations, which were conducted under the direction of the author, will, it is expected, appear with other reports of the World's Fair. FOOD CONSUMPTION. 195 and 3 men, were assigned to live in it for a period of 10 days. Tliey were enjoined to eat nothing except what was served in the honse, and the cooks were charged to provide tlie fullest opportunity for collecting the data desired. The men were engaged to a certain extent in the light occupations incident to the care of the village and in sewing. The women seemed to have no special occupation outside of the very small amount involved in the care of the house. The food consisted mainly of rice and lean beef, the former furnishing nearly seven-tenths and the two together nearly jive-sixtlis of the total actual uutriimts. In addition, chicken, tisli, eggs, bread, green vegetables, and fruits were eaten in small quantities. So far as could be ascertained this did not differ very greatly from the home diet. The investigations covered a period of 10 days during Septemlier, 1893. The food was carefully weighed as prepared for the table, and its composition in part deter- mined by analysis and in part estimated. DIKTARIKS IN THE UNITED STATES AND CANADA. Massachusetts and Canada. — Nos. 84 to 115 were described on pages 14.5-156. above. Connecticut. — In 1886 and later several dietaries of students, laborers, and one of a well-to-do private family in Middletown, were examined in connection with the study of Nos. 84 to 115. Nos. 117, 121, 122, 124, and 126 are selected from the group. The method employed is indicated in the text beyond. In general it was the same as that used in the Massachusetts dietaries, except that account was taken of the quantities of food rejected in the kitchen and table waste, and the amounts actually eaten were computed by subtracting these from the food purchased. In 1890 and later these investigations were renewed at Middletown in cooperation with the United States Department of Labor and as a part of the work of the Storrs Station. Nos. 116, 118 to 120, 123, 12.5, and 127 to 134 belong to the group thus studied. Tlie method employed has been esseiitially that described on pages 200-204. Dietaries of well-to-do ■private families in Middletown and Storrs. No. 116 is the dietary of the family of a chemist in Middletown. During the month of April, 1891, the food actually eaten in the family of a chemist in Middle- town was carefully weiglied, and while no analysis was made of the food or of the table waste, it is believed that the figures given below are quite reliable. The family consisted of 1 man, a chemist, 34 years old and weighing 230 pounds, his wife, and a maidservant, who were at home during the entire month; also 1 man, a chemist, 27 years old and weighing 175 pounds, and an elderly woman were at the table about one-half of this period. The food materials used were mostly of such a nature that their composition is fairly well known from the averages of other analyses. The waste was reduced to a minimum, and it is probably fair to assume that no very considerable error was introduced by neglecting it. As both of the station chemists lived in the family and the wife of one of them was very much interested in the experiment, a very careful account of the weights of food used was kept. For the most part the food was weighed just before using, on a scale sensi- tive to 1 gram, Avith a charge of 10 kilograms. No. 117, dietary of a professor's familj^ in Middletown. The weighings and esti- mates for this dietary were made by Mr. Rockwood, assistant in the chemical labo- ratory of Wesleyan University. On the 1st day of January accurate account was taken of all the food materials in the house. The quantities of food brought to the house during January, February, and March were estimated from the grocer's, butcher's, and other bills. During tlie same period all the food left unconsumed, i. e., the kitchen and table refuse, was carefully kept, weighed, and its composition estimated. On the 1st day of April the food materials remaining in the house were weighed. In estimating the quantities of nutrients the method employed for tho^e of the Massqichusetts and Canadian dietaries was used. 196 CHEMISTRY AND ECONOMY OF FOOD. The smalJuess of the waste is explained by tlie fact that the mistress of the house was a particularly careful housekeeper. Nos. 118 aud 119 are the dietaries of a professor at the Storrs Agricultural College. In the dietary made in the winter of 1893 the family consisted of the man, 32 years of age, his wife, and a maidservant; in that of the summer of 1893 the fsimily was the same, except that the servant was absent and a child 1 year old included. No. 120 is the dietary of the family of a retired jeweler. The family consisted of the father, 70 years of age, at very light work; his wife; their son, a chemist, 23 years old, with moderate exercise, and their daughter. The study was made during the month of September, 1891. Dietaries of college and prof essional students in Middletoxon. Nos. 121 to 123, three dietaries of a college students' club. A large number of the students in Wesleyau University board in clubs. The club, which may have any num- ber of members up to 30, chooses one of its number as steward, aud arranges with a matron to cook and serve the food which he purchases. Many of the members have to pay their way through college; the majority are obliged and the rest are content to have the cost of their board made low, even at the sacrifice of delicacies. While their diet is substantial and wholesome, thej-^ regard it as plain and economical. They are mostlj^ from the Eastern States, and coming from the class of families whose sons go to college, it seems fair to assume that their habits of eating formed at home would not differ materially from those of the more intelligent classes of people in that part of the country. While the habits of many are sedentary' rather than active, they nevertheless take considerable muscular exercise. In this respect they are very much like the students of other Eastern colleges. They are given to athletic sports in pleasant weather. Out of 250, sometimes 70 or more may be seen at once on the campus playing tennis and baseball. They could hardly be credited with as much muscular exercise on the average as laboring men doing moderate work, and they would therefore, without doubt, require somewhat less of protein as well as of the other nutrients in their food. Their requirements doubtless approach closely to those of the man with moderate exercise. From the accounts of one of these clubs for a period of 3 mouths in 188G, the amounts of the several kinds of food materials purchased and the quantities of nutri- ents were computed. The results are given in No. 121 of the table. The figures thus obtained represent what the students paid for, rather than the amounts actually consumed. The steward aud some of the members of the club were of the opinion, however, that the amount of waste — that is to say, the material thrown away — was very small. It costs too miich. But on investigating the matter more closely it appeared that a portion of the material served was left upon the plates and found its way into the garbage barrel or was given away. The rejected food was, therefore, collected during 1 week and weighed. Its composition was estimated and the amount of waste calculated. The following term an examination of the dietary of the same club was made by Mr.Videon. Another steward Avas then in charge. He had learned of the excessive amounts of food in the former dietary, and planned to reduce the quantities. This was done largely by diminishing the meats. He states that he did not apprise the club of the change, and that it was not noticed. As he put it, "The boys had all they wanted, and were just as well pleased as if they had had more." The quantities of nutrients in both dietaries were estimated by the method already described. The waste in the second dietary was estimated with some care. In this, as in the first, it is assumed that the difference between the food purchased and the waste represents the actual consumption. In the spring of 1893 the dietary was examined for a third time (No. 123). The observations were much more accurate, that is to say actual weighings and analyses were made of the food consumed. FOOD CONSUMPTION. 197 No. 124 is the dietary of a second students' club. The memhers of the club were iu moderate circuinstauces and felt the necessity of economizing, but at the same time intended to have an abundance of wholesome food. The observations were made by one of the members who was an advanced student in the chemical labora- tory and much interested in these studies. The food materials were actually wcio'hed and also the waste. The attention of the club had been called to the waste in the dietaries of the other clubs, lu all probability this is the explanation of the smallness of the waste here. No. 125 is the dietary of the members of a boarding club iu a divinity school. The details are not yet published. The method was essentially that described beyond on pages 201-213. No. 126, dietary of a college football team. This dietary was examined at a time when the team was in active training and boarding in a club by themselves. The observations were made at the same time and by the same i)erson (Mr. C. S. Videon) , as those of Nos. 122 and 121. Their exercise was vigorous and at times severe, but the examination was made near the close of the football season, when, in the judg- ment of members of the club, they were eating rather less heartily than they had done earlier in the season. Mechanics, etc., in Middletown. — No. 127 is the dietary of a boarding house. The dietary commenced with supper, October 20, 1890, and continued until after dinner of November 19, a period of 30 days. During most of the time the family consisted of 13 men and 7 women. It very rarely happened that all of the family took all three meals at the house any given day. There were occasional visitors, and in this way once or twice the total number of meals taken per day was larger than the family alone would have required. The sex, approximate age and occui:»ation of each member of the family, as it was constituted most of the time, were as follows: Meu: Machinists, 30 to 40 years of age 4 Machinist, about 35, after October 25 1 Harness maker, about 70 1 Hired meu about the stable, one old, the other middle aged 2 Proprietor of the house, about 70 1 Manufacturers, one about 60, the other about 30 2 Chemist, about 27 1 Reporter for newspaper, about 20, after October 27 1 Total 13 Women : Housekeeper, about 30 1 Cook, about 45 1 Table girl,about 20 1 Doing no manual labor, about 30, 55, 55, and 70 4 Young lady at house 4 days, doing no labor 1 Total 8 Of the 13 men, 3 were counted as "hearty eaters," and 6 more as haviug decid- edly good appetites. No. 128 is the dietarj^ of the famil'y of a machinist, consisting of the father, born in Germany, 50 years of age, his wife, and 3 daughters, from 14 to 20 years of age. The period of observation was 30 d.ays during November and December, 1891. No. 129 is that of the family of a blacksmith and consisted of the father, a Cana- dian, about 40 years old, his wife, aud 2 boys, 8 and 10 years of age. The study was made at the same time as No. 128. Nos. 130 and 131 are 2 dietaries of the family of a stone masou. The father, born in Sweden, was about 28 years of age; the mother was also a Swede aud had been in 198 CHEMISTRY AND ECONOMY OF FOOD. the United States only about 3 years; the other member of the family was a child 7 months old. The first study was made in November and December, 1892, and con- tinued 28 days; the father was at work during 3 of the 4 weeks. The second study was made in April, 1893, under approximately the same conditions as tiie former one. No. 132 is the dietary of the familj' of a carpenter. The family was of American birth and consisted of the father, who was about 25 years of age, the mother, and a boy 2 years of age. The study was made in November and December, 1892, and covered a period of 28 days. Nos. 133 and 134 are 2 dietaries of another carpenter's family, also American, and consisting of the father, about 35 years, his wife, and a boy 11 years of age. The first dietary covered a period of 2,8 days in November and December, l?^92, and the second a period of the same length in April and May, 1893. Pennst/lvania. — No. 135 gives the average minimum and maximum of 25 families in the poorest part of Philadeli)hia. With a single exception all of these families ^ wore either foreign or of foreign descent. Illinois. — No. 136 gives the average minimum and maximum of 26 families in the pooi'est part of Chicago. Nos. 135 and 136 were made in 1892-93 by Miss Amelia Shapleigh, Dutton Fellow, of the College Settlements Association. Complete and exact accounts of food bought and eaten by 55 families in Philadelphia and Chicago, representing as many nation- alities as possible and selected at random from the neighborhood of the settlement, were collected. The estimates ("amounts of food actually bought and put on the table") were made "after close questioning, observation, and iu case of food not bought by the pound, careful weighing." Ten per cent of the total was deducted for rejected and undigested residues. No analyses of food materials were made and the basis upon which the amounts of nutrients was estimated is not stated. United States Army and Navy rations. — It is difficult to compute exactly the food consumption by soldiers in the United States Army, because the men have more or less of opportunity to select or add to their food by commuting purchase or other- wise, so that the food actually used varies more or*less from the regulation rations. The best data for calculations I have found are those contained iu Circuhir No. 8 of the Surgeon-General's Ofitice, United States Army. From these Mr. Woods has com- puted the nutrients and energy as stated in Nos. 137 and 138. SUaGESTIONS REGAKDINa STUDIES OF DIETARIES. The following statements are gathered from the experience of the writer and his associates, sux^plemented bj^ their reading of the reiDorts of the work of others. The object of a dietary study is to determine the kinds and amounts of food materials and of nutriments consumed by one or more persons during a given period and under known and definitely stated condi- tions. The first essential is accuracy in the collecting of the original data. If these are indefinite, unreliable, or incomi^lete, the defects can not be comijensated by the most accurate and painstaking chemi- cal analysis, by elaborate treatment of the results, or even by a large number of observations. This accuracy is needed even in the smallest details; no part of the study of a dietary calls for more thought and care than the collection of the statistics regarding the food materials consumed, the people who consume them, and the proportions actually > 1 American, 3 Irish, 6 German, 6 Jewish, 3 Italian, and 6 Negro. POOD CONSUMPTION. 199 eaten and not eaten. When these preliminary data have been properly- collected, and the s])eoimens have been secured for analysis, the work up to the writing of the results is largely a matter of routine whicli can be carried out in any well-ordered laboratory which is equipped for this kind of investigation. The reporting and especially the inter- preting of the results requires not only an understanding of chemistry and physiology, but also an appreciation of some of the fundamental facts and principles of economics and sociology. The philosophical study of food consumption requires the skill and the training of the chemist, the physiologist, the statistician, and the sociologist. I. Qualifications of the observer. — For these reasons the person who collects the statistics should have a thorough scientific training and a clear idea of the questions involved and the imijortance of the task. Besides the technical knowledge, a goodly amount of tact is indispen- sable and the best success requires a certain symi)athy with the people among whom the work is done, especially when they are in moderate circumstances or belong to the poorer classes. Food and household expenses are delicate subjects. A housewife or mistress of a boarding house may object to having her kitchen and account book subjected to critical examination unless it is done with tact. Perfect frank- ness and an explicit statement of the nature of the statistics, at the beginning of the study, is the safest rule. Often the offer of a small sum of money in compensation for the trouble caused by the inquiry will materially help the observer. The questions, often very direct, which the observer is obliged to ask, and the close watch which he must keep over even the smallest details of food purchased and wasted during the course of the investigation, are liable to i^lace him in situations where deference is needed, for the good will and interest of the family must be kept at any cost, inasmuch as the observer is entirely depend- ent upon the subjects of his investigation for so much of his statistical information. Whether the observer had better be a man or a woman depends upon the individual and the circumstances of the case. II. Selection of persons for study. — Whether the dietary to be studied is that of an individual (man, woman, or child), of a family, or of any other group of persons, as a boarding house or club of people of like class and occupation, the person or persons should be typical of a class, and normal in respect to health, development, and age. [a) Health. — Families or groups containing invalids are not appro- priate for the study of normal dietaries; neither should persons whose occupations or general habits exert an abnormal influence upon their dietary habits be selected, except in cases where special studies of the effect of such conditions are to be made. (6). Development. — Greatly oversized or undersized persons should not be selected or included, and when children (either in families or 200 CHEMISTltY AND ECONOMY OF FOOD. individual experimeuts) are included or selected, height and weight as well as age should be ofu'efully noted. (c) Age. — Families or groups containing extremely old persons are hardly desirable. Studies of the food consumption of children or of aged people are best made with such iDcrsons by themselves. Other conditions being the same, the greater the number of persons included in a dietary study the more valuable are the results as repre- senting a class. There is, however, a limit in this direction which is set by the amount of labor which such a study involves. Accuracy and thoroughness must never be sacrificed, and the dietary of 1 person thoroughly studied is worth much more than that of a group of 20 or 30 studied indifferently. The number of imperfect studies is already con- siderable, and although they are valuable for the preliminary reconnois- sance, the demand now is for a more accurate form of inquiry, which shall bring to light exact and not merely approximate facts. An experienced investigator with good laboratory facilities and plenty of assistance for the analyses, and especially for the preparation of samples of food materials and wasted food, may undertake the study of the dietary of a club of 25 or 30 persons, but it would be hardly advisable to undertake so large a study, even with all needed help, until consider- able experience had been gained in the study of dietaries of individuals and families. The errors of my own early exj)erience are the reason for the emphasis of this statement. III. Length of period of observation. — One of the most serious criti- cisms to be made of a number of otherwise admirable dietary studies is that the period of observation has been too short. The demands of the organism for food may vary considerably from day to day. Changes in occupation, differences in the temperature and in the state of the weather in general, and minor ailments resulting from fatigue, exposure, or mental condition have a considerable effect upon the appetite j so that differences from one day to another may amount to a considerable por- tion of the total quantity of food consumed. For example, in a recent Italian dietary (No. 63 of Table 37) the period of observation covers 3 consecutive days, during 2 of which the subject was at work, while the third was a day of rest. On one of the working days he ate one-fourth more than on the other, and one-third more than upon the day of rest. This is by no means an extreme or exceptional case. For this reason studies of dietaries, either of individuals or families, covering a period of less than one or two weeks are not to be recommended unless they are to be frequently repeated, as was done by Camerer (see page 192). One month is a much more desirable length. Even for larger groups the time of observation should not be much less, inasmuch as, other conditions being the same, the longer the period of observation the more reliable the result. IV. Food — 1. Collection and measurement of food materials. — At the beginning of the study of a dietary a careful Inventory should be taken FOOD CONSUMPTION. 201 of food materials^ in stock in tlie bitclien, pantry, and cellar. The materials should in all cases be weighed rather than measured, and this applies not only to such materials as meats and flour, but also to such as milk, molasses, potatoes, beans, and other vegetables. Like accurate weighing should be made of all food materials purchased dur- ing the period of observation. Each should be carefully weighed wheu received; it is not safe to trust to purchase weights; in the case of meats, for instance, the cut may be trimmed at the market after weigh- ing. At the end a second inventory should be made with the same i^re- cautious as observed at the beginning. The sum total of the food materials at the first inventory and of those received during the study, less the amonnt indicated by the final inventory, shows how much has been used during the period of observation. 2. Deseriptiori of food materials. — The description of the various food materials, including that of each portion, e. g., each cut of each kind of meat, should be detailed, whether a sample is taken for analysis or not. The economic value would be increased by statements of price and quality. This is particularly to be observed in case of the meats; not only the kind, but the exact cut should be mentioned. • 3. Sampling for analyses. — Samples of all food materials which form any considerable part of the dietary should be analyzed. This list usually includes all the meats, samples of which should be taken with each individual purchase, the lard, milk, butter, flour, oatmeal, and other vegetable foods, including canned vegetables and sugar. ■ The procuring of representative samples of meats is less simple than one wicliout experience would suppose. To obtain fairly representative samples of steaks, chops, roasts, or ham is comparatively easy, as alter- nate or adjacent slices are readily procured at the time of purchase, but in the case of the miscellaneous cuts which form such a large pro- portion of the meat used in many kitchens, the problem of getting fair samples is often very perplexing. The matter is, however, one of fore- most importance, and the only safe rule is to obtain samples at each and every purchase. To illustrate by a concrete example: In New England the custom of serving veal and mutton stews is very common. The meat selected for this purpose consists usually of the odds and ends of veal or mutton which happen to be in the market at the time, an assortment which it is impossible to duplicate. The best expedient we have found is to have these miscellaneous pieces cut into smaller ones — as small as possible without injuring the appearance of the meat — and iln the studies of dietaries certain articles of food and drink are not, as a rule, included in the category of food materials. Tliey are such as tea, coffee, salt, spices and condiments in general, including beef extract. Beverages containing nutritive material, e. g., beer, should he taken into account with food. Alcohol when consumed in small quantities, should be included (1 gram alcohol is approximately equivalent to 1.7 gxams carbohydrates in fuel value) ; if alcohol is taken in large quantities the subject would not be iittod for observations upon normal nutrition. 202 CHEMISTRY AND ECONOMY OF FOOD. to select for analysis pieces rex)reseutative of the whole lot as regards proportion of meat and bone and lean and fat. The practice of buying meat from the butcher's cart, instead of at the market, is a common one in many localities and makes the getting of samples for analysis very difficult, unless previous arrangements are made by which the piece of meat purchased shall be large enough for the use of the family and for the sam^jle to be analyzed. The observer should always be at the market or meat wagon when purchases are made if this is possible, and must in any event attend to the taking of the sample for analysis whether at the market or in the kitchen; the market is generally the most convenient place for taking the sample. Samples of flesh of large fish, such as halibut, salmon, etc., may be taken in the same manner as samples of meats, but with smaller fish which are sold by the piece and likewise with shellfish and also i30ultry and eggs, one or more samples similar in size and general appearance to those purchased for food should be selected for analysis. Milk should be thoroughly mixed before sampling, and butter and cheese should be samjpled as recommended by the Association of Offi- cial Agricultural Chemists.^ Lard may be sami)led in the same way as butter. The obtaining of representative samples of vegetable foods, such as flour, cereals, and vegetables, is comparatively easy, as is also the case with canned foods, whether animal or vegetable. Too much care, how- ever, can not be taken to make sure that the samples for analysis shall be representative, as otherwise the accuracy of results will be greatly- diminished. 4. Analyses. — Meats vary so much in proportion of refuse and edible portion and in the composition of the edible portion that it is necessary to analyze every piece if the work is to be exact. Indeed, we have felt compelled in late dietary studies to chop all the meat and take a small sample of each lot for analysis. This, of course, interferes with the cooking, but it makes more accurate sampling i)ossible. With fish and l)Oultry the necessity of repeated analysis is perhaps not so great. Milk should be analyzed very frequently, but the number of analyses may be considerably lessened by combining several samples taken upon different days. Butter should be analyzed at each purchase. Granu- lated sugar is usually free from moisture and mineral matter, but the moisture content of soft sugars and of molasses should be determined. 5. Waste. — From the economic standpoint the waste of food in Ameri- can households is a serious matter, and it is desirable that exact statis- tics should be obtained and published. In the dietaries which we have studied the quantities of actual nutrients which have found their way to the garbage barrel have frequently amounted to a tenth, and in one 1 See proceedings of tlie aunual conventiona of this association. U. S. Dept. Agr., Div. Chem. FOOD CONSUMPTION. 203 case rose to a sixtli of tlie wliolc food ])nicliased. The real waste -was Avorse than these figures imply, because the lejectcd material came very largely from animal food in which the nutrients are more costly than in the vegetable food materials. In the reports of dietary studies by the writer and his associates the term " waste" has been applied to all of the so-called " edible portion " of food which may for any reason be rejected. It includes all uneaten residues of the cooked food, e. g'., meats, vegetables, bread, cake, and i)astry, except, of course, the bone and other j)arts of meats and fish which would be classed as "refuse" in food analysis. It also includes all portions of food materials which are rejected before cooking, except those which belong to the refuse. Such materials as the parings of potatoes and turnips are reckoned as belonging to refuse, and are not included in the waste; they are, how- ever, weighed, and their weights compared with the whole weight of the food material in order to determine the proportion of refuse. Collection of ivaste. — The collecting of the waste is always difficult, as there are so many avenues through which it may be lost, and unless the observer can personally superintend its collection at each meal, the most explicit directions for the care of the garbage barrel and soap- grease bucket are necessary. When once collected the waste food materials should be carefully looked over, and bones (from which all adhering meat must be removed) and all hard substances, such as fruit pits, etc., which may have been accidentally included, should be removed. The waste is then to be dried for analysis. Sampling. — The waste when thus partially dried is exposed to the air of the room for 28 to 48 hoiu'S and then weighed, chopped into l^ieces about the size of a pea, and carefully sampled. This sample, which should weigh about a kilogram, is very finely chopped, aud a final sample of the customary size taken for the actual analysis. When the amount of waste is very large samples should be taken compara- tively often, but in the case of an ordinary family the waste food for a period of 4 weeks will not present any special difficulty in obtaining a representative sample. When several samples are taken they may, of course, be combined, if care be taken that the amount of each partic- ular sample which enters into the composite one shall be proportional to the quantity of waste which it represents. Analysis. — The waste usually contains little crude fiber and only determinations of moisture, nitrogen, ether extract, and mineral matters are necessary. 6'. Digestihiliii). — The ideal dietary study would include a digestion experiment. That is to say, the solid excreta from the food woukl be collected, weighed, and analyzed. This has been done in some of the recent work in Italy, German}-, and Japau.^ AVork in this direction in the United States is much to be desired. 1 See detailed account of Nos. 44, 61 to 65, and 78, and special description of studies by Manfiedi,pp. 173, 188, 191, 194. 204 CHEMISTRY AND ECONOMY OF FOOD, Y. Data as to persons, length of period of ohservation, and climate. — The most important of these data are the sex, age, weight, and occu- pation of the persons and the length of time during which their food consumx)tion is observed. 1. Sex. — The number of persons of each sex must be noted. The estimation of comparative food consumption of men, women, and children and the number of men to which the number of women and children would correspond is explained beyond. 2. Age. — The exact age of each person, and especially of each child, should be recorded. 3. Weight. — The weight of each individual, or the average of all, should be noted — this especially to be borne in mind with children, statements of whose development, both weight and height, are also desirable. 4. Occupation. — The occupation of each person should be stated in detail. The relation between food consumption and the kind and amount of work done is as yet too little understood, and data bearing upon it much to be desired. It would obviously be misleading to com- pare the dietaries of professional men with those of men at muscular labor, and those of men at muscular work of different degrees of severity, without taking the nature of the labor into account. Of course these estimates of the severity of different kinds of labor can not be definite, but they should be described as accurately as possible. 5. Time of ohservation. — The exact times during which the food con- sumption of each person is observed must be carefully noted. This is most easily done by keeping an exact account of the number of meals eaten by each person during the period of observation. The number may be expressed in terms of days by dividing the total number of meals by the number of meals per day. This procedure is to be recommended, because members of the family or other groups are apt to be absent more or less from meals, and other persons are often present at meals. 6. Climate, season, temperature. — If the people spend their time in well- warmed houses, differences of climate and season may perhaps have little influence upon food consum]3tion. Otherwise these factors may be most important. But little is certainly known as to their actual effect, and data are most desirable. 7. Supplementary statistical and sociological data. — In addition to the statistical data above referred to, certain other information is needed to give the results their full meaning. Nationality, home life, environ- ment, health, income, and expenditures are among the data to be especially considered. VI. Calculation of results. — The statistics of food consumption in dietaries are usually reduced to terms of nutrients consumed per man per day. Data as to total amounts of food materials of different kinds and of food wasted and the composition of each are obtained in the man- ner mentioned above. From these we may calculate the total amounts FOOD CONSUMPTION. 205 of protein, fats, and carboliydrates. Dividing these quantities by tlie total number of days' food for 1 person gives the quantities ^>er_per,s'o?i per day. This, however, is not sufficiently accurate, for it is necessary to distinguish between persons of different classes. It would be obvi- ously unfair to compare the amounts of nutrients consumed by a child 5 years of age with those consumed by an adult man. It is therefore desirable to express the food consumption of men, women, and children in equivalents of per man per day. To do this we must find the ratio whicb the food consumption of children of various ages and of women bears to that of the man. The ratios used iu the dietary studies by the writer and his asso- ciates are the same as were explained on page 148. It may prove desirable to change them later. I hope to revert to this in a future discussion of standards for dietaries. Dietary habits are numerous and complex, and a dietary studied without taking these elements into account is thereby deprived of its real significance. CLASSES OF PEOPLE AND LOCALITIES FOR DIETARY STUDIES. The studies which, have so far been made are limited in locality to several towns and cities in Massachusetts and Connecticut, and to Phil- adelpbia and Chicago. In New England these studies include dietaries of professional men and students, factory operatives, mechanics, such as blacksmiths, carpenters, masons, and machinists, and also various classes of less skilled laborers, such as brickmakers, etc. They are very likely, so far as they go, typical of the town population of the ISTew England States. In Philadelphia and Chicago only the food con- sumption of families of the poorer classes of society, mostly foreigners, has been studied. It now seems' desirable that these studies should be extended in two ways. They should include a number of classes of people and cover a larger territory. They can be advantageously carried on with the aid of colleges and experiment stations, although other organizations, as labor bureaus and benevolent societies, might most advantageously cooperate. Among the classes that need to be studied are : First, people in pro- fessional and business life; those whose labor is intellectual rather than muscular. These would include the families of business and profes- sional men, and likewise students. Second, farmers and their families in the country districts. Third, mechanics of different classes, and with, muscular work of different degrees of severity, as carpenters, masons, blacksmiths, etc. Fourth, Victory operatives. Fifth, ordinary laborers of various classes. Sixth, people of the poorer classes in tlie large cities. Seventh, inmates of hospitals and prisons. Eighth, children of different ages. CHAPTER X. STANDARDS FOR DIETARIES. Various standards have been x3roposed by physiologists and chemists for daily dietaries for persons of different age, sex, and occupation, and in different conditions of life. They are usually estimated in terms of the three classes of nutritive ingredients, protein (or albuminoids), fats, and carbohydrates. Our best information regarding dietary standards has come from Germany where studies have been made by numerous investigators, such as Liebig and especially Yoit and his followers of the Munich school of physiologists. Voit's standards are the ones most commonly followed in estimates of dietaries. Outside of Germany the names of Playfair in England, Payen in France, and Moleschottin Italy, deserve especial mention as contributors to the knowledge of the subject. It is a noteworthy fact, however, that very little attention appears to have been paid in either the United States or England to the results of the latest and best research in this direction. Even the text-books on chemistry and physiology in the English language which are looked upon as most authoritative ai'e ai)t, when they treat of the matter, to do so most superficially.^ Unfortunately, in the treatment of this subject there is much con- fusion as to the real significance of the term dietary standard and the basis upon which the standards may be estimated. The same confu- sion obtains in still greater degree in the discussions of standards of rations for domestic animals. METHODS OF ESTIMATING DIETARY STANDARDS. A standard for a ration or a dietary may be based upon either; (1) The observed facts of consumption. Thus the standards of Play- fair, Molescliott, and Voit for a laboring man at moderate work are based mainly upon the quantities actually consumed by persons whose food consumption they had learned from their own or other observations. iThe subject is Avell liaudled in a number of Gei-man works including the follow- ing, in Avhich references to tbe original investigations may be found: Voit. Physiologie des allgemeinen Stoifwechsels und der Ernitbrung, Vol. V, of Hermann's Handbucb der Physiologie, 1881. Foster. Ernahrung und Nahrungsniittel in Vol.1, of Pettenkofer and Ziemssen's Handbucb der Hygiene, 1882. Konig. Chemie der menschlichen Nahr'ungs- und Genussmittel, 3d edition, Vol. I. 1891. Hammersten. Physiologische Chemie, 1891. 206 -• STANDARDS FOR DIETARIES. 207 (2) The actual need and available or most economical supply. Stand- ards estimated on this basis would take into account not only the actual demands of the body for nourishment, but also the kinds of food that are to be had and the pecuniary cost of the nutricMits in different food materials. (3) The x^hysiological demand. By this is meant the quantities of nutrients Avliich are most appropriate for the particular individual or class. The basis here would be found in the actual facts of normal metabolism. The data of this sort now at hand are too few to make estimates reliable. Standards estimated upon the first basis would correspond to actual practice. Those upon the second would take into account both pecun- iary and hygienic economy. Those of the third would consider only what was intrinsically most fitting. The current standards for daily dietaries for men and daily rations for domestic animals have been based maiuly upon the considerations in the first class. In the feeding- of domestic animals and in the nutrition of people who are limited in respect to either the supply of food to which they have access or their means for imrchasing their food the data of the second class would be appropriate. But for people in moderate and comfortable circumstances in most parts of Europe and the United States, where commerce brings a large variety of food materials to every market and incomes are large enough to warrant use of properly selected food, data of the third class are the ones to be taken into consideration. EUROPEAlSr AND AMERICAN DIETARIES AND STANDARDS. The pages which precede have outlined, though very incompletely, the data now available regarding the actual food consumption, and have indicated in a general way those which have been thus far obtained by experimental inquiry regarding the physiological demand. I hope, in a future publication, to discuss this subject more fully and to indi- cate what appear to be the inferences to be derived from the knowl- edge now at our disposal and what are the lines of inquiry which are needed to make that knowledge more nearly adequate. Meanwhile, I venture to quote the following from a j)revious article upon the .subject.' It will be observed that this discussion is based upon the assump- tion that the body requires for its nourishment — (1) Enough of protein to make up for the protein and muscle and other nitrogenous substances consumed in the body. (2) Enough energy to supply the demand for heat and muscular work. The estimates for energy are based upon Rubner's factors (4.1 calories for each gram of protein, the same for each gram of carbohydrates, 1 Report of Storrs (Conn.) Experimeut Station for 1891, pp. 145-119. 208 CHEMISTRY AND ECONOMY OF FOOD. Chart 3.— DIETARIES AND DIETARY STANDARDS. Quantities of nutrients and energy in food for man per day. [Amounts of nutrients in pounds. Fuel value in calories.] Protein. Fats. Carbohydrates. Fuel value. Nutritive ingredients (a ctual nutrients) - . Ib.s. Potential energy (fuel va l ue) calories ACTUAL DIETARIES. Underfed laborers, Italy Students, Japan - - Lawyer, Germany - - Physician, Germany "Well-paid mechanic, Germany Well-fed blacksmith, England German soldier, peace footing - German soldier, war footing Frencli-Canadian families Glass blower, Cambridge, Mass College students, N. and E. States Well-to-do families, Connecticut Mechanics and factory hands, Massachusetts. - Machinist, Boston, Mass Hard-worked teamster, Boston, Mass U. S. Army ration DIETARY STANDARDS Man at moderate work ( Voit) Man at hard work (Voit) Man at light work ( Atwater) Man at moderate work (Atwater) Man at hard work (Atwater) 2000 4000 6000 8000 STANDARDS FOR DIETARIES. 209 and 9.3 for each gram of fats). It is further assumed that in serving as fuel the fats aud carboliydrates may replace one another in propor- tion to their potential energy, so that it is not necessary to lay down specific quantities of either, provided the sum of the two is sufficient for the purpose. The fitting of the food to the demands of the palate and the digestive apparatus are, of course, factors of the utmost importance, but can not be discussed here. European dietary standards.— The standards in Table 38, compiled from European sources, are intended to represent roughly the needs of average individuals of the classes named in England and Germany. Nos. 1 to 8 are based upon observations of Voit and his followers. For Nos. 1 aud 3 the results of numerous estimates by Dr. Camerer of the food of his own childi-en, and by Voit and Forster of the food con- sumed by a number of other children, are used. No. 2 was calculated by myself from the data of Nos. 1 and 3. The figures given represent means between smaller quantities for the younger and larger for the older children. The data collated in Table 37 above seem to call for a revision of the standard for children as well as those for adults. Nos. 5 and 6 are based upon observations chiefly by Forster. Nos. 7 and 8 are by Voit, and based both uj)on quantities consumed by individuals under experiment, and upon observed dietaries of a much larger number of persons in Germany. No. 7 is the one so frequently quoted as Voit's standard for a "mittlerer Arbeiter," a laboring man at moderate -work.' These figures represent the average needs of ordinary mechanics and laboring meu at their ordinary work, as estimated from the food consumed by such meu in Germany and especially in the region of Munich. For men not engaged in muscular labor Voit regards it as better to use less carbohydrates, not over 350 grams per day, and supply the remaining need with fat. In other words, the food of well-to-do people, with intellectual rather than muscular labor, may advantageously contain more meat, butter, and other animal foods rich in fat, than the largely vegetable food of the German working people sup- plies. Voit would have somewhat over half of the 118 grams of protein of the food of the average laboring man at moderate work supplied by meat and other animal foods. It will be borne in mind that these quantities, like those in the tables of this article, generally refer to the total rather than the digestible nutrients of the food. Such dietaries as A^'oit proposes would contain approximately the following amounts of digestible nu trients : Protein. Fats. Carbo- hydrates. For laboring man at moderate work For laboring man at hard work Grains. 116 130 G-raiiis. 53 95 Grams. 450 402 No. 9 is by Moleschott, whose earlier scientific life was spent in Germany, but who has lived for many years in Italy. It may therefore be called either Italian or Ger- man. " No. 10 is German. Nos. 11 to 15 are dietaries estimated by Playfair, an Englishman, from the data cited in Table 37 and others.- The figures for No. 11, subsistence diet, are based upon dietaries of reconvalescents in hospitals, of people in prison, and of laboring people in Eugland, and in the so-called "cotton famine '? of 1862-63. For No. 12, diet in quietude, the dietaries of soldiers in time of peace, aud for No. 13, diet of adult in full health, army dietaries (English and continental) in war were employed. The estimates for active laborers, No. 14, were based upon 1 Physiologic des Stoffwechsels und der Erntihrung, 519-523. 2 Chem. News, XI, 1865, 222. 8518— No, 21 14 210 CHEMISTRY AND ECONOMY OF FOOD. observations of the food of meu at moderately active work, who would correspond in demand for nutrients to the "mittlerer Arbeiter" for which the dietaries of Voit, Moleschott, and Wolif, Nos. 1, 9, and 10, were calculated. The figures of No. 15 were based upon observations of food of jlien in England at harder work, such as those of Nos. 7, 8, and 9 of Table 38. Table 38. — European standards for daily dietaries for people of different classes. Children : 1 to 2 years, average 2 to 6 years, average 6 to 15 j'ears, average Aged womau Aged man Woman at moderate work Man at moderate work (Voit) Man at liard work (Voit) Man at moderate work (Molesoliutt) Man at moderate work ( Woltf) Subsistence diet (Playfair) Diet in quietude (Playfair) Adult in full health (Playfair) Active laborers (Playfair) Hard- worked laborers (Playfair) ... Nutrients. Protein. Grams. 28 55 75 80 100 92 118 145 130 125 57 71 no 156 185 TTats. Ch'ams. ■ 37 40 43 50 68 44 56 100 40 35 14 28 51 71 71 Carbo- hydrates. Grains. 75 200 325 260 350 400 500 450 550 540 341 341 531 568 568 Total. Gi'ams. 140 295 443 390 518 536 674 695 720 700 412 440 701 795 824 Potential energy. Calories. 765 1,420 2,040 1,860 2,475 2, 125 3,055 3,370 3,160 3,030 1,760 1,950 3,140 3,630 3,750 It is hardly necessary to exi)lain that the standards of this table represent only general averages. Thus Voit, Playfair, and the other physiologists named assume that for an ordinary laboring man, doing an ordinary amount of work, the amounts of nutrients stated in Nos. 7, 9, 10, and 14 will suffice; that with them he will hold his own, and that any considerable excess above these quantities will be superfluous. No one expects any given man to adjust his diet exactly to either of these standards. He may need more, and may perhaps get on with less. He may eat more fats and less carbohydrates, or he may consume more protein, if he is willing to pay for it. If, however, he has much less protein and keeps up his muscular exertion, he will be apt, sooner or later, to suffer. Of course, different individuals, under like conditions, will both require and con- sume different quantities of nutrients. In general, the larger the jierson, that is to say the bulkier the machinery in his organism, the more of protein and other nutri- ents will be consumed. Hence, men need, on the average, more than women and children. The requirements vary with the muscular activity. A man at hard work requires more nutrients than one at lighter work or at rest. Aged people, who are generall}^ less active than those in the prime of life, require less food. The four dietaries by Voit, Moleschott, Wolff, and Playfair, just mentioned (Nos. 7, 9, 11, and 14), have long been accepted by physiologists and chemists as expressing about the average quantities of nutrients which a man doing moderately hard, mus- cular work would need in his food each day. They vary considerably from each other, however. That of Moleschott, for instance, calls for 130 grams of protein; that of Voit, only 118. There are similar differences in the quantities of fat and carbohydrates. But no one adjusts his food exactly to chemical standards. Differ- ent people consume very different foods, and yet they get on very well, and it is perfectly clear that either of these standards may be right enough. And different as they are, a remarkable agreement between them has lately come to light. When these standards were proposed experimental science had not taught how to measure the fuel value of food by the potential energy of its constituents. Late research has told how this may be done. Tlie energy is measured in heat units, for which calories are here used. A gram of protein or of carbohydrates is assumed to contain 4.1 and a gram of fats 9.3 calories. Ap]Dlying this measure to these dietaries, the extreme variation in the four is only from 3,032 to 3,160 calories. That is to say, STANDARDS FOR DIETARIES. 211 four of the most prominent investigators, Play fair in England, and the others in Gei'many and Italy, working with different peojile and by more or less different methods, arrived at estimates which vary somewhat in the proportions of the nutri- eilts, but when the different standards are reduced to terms of potential energy they agree almost exactly. The closer scientific scrutiny, which tlie latest and most painstaking research has made practicable, serves only to bring the apparent dis- crepancies into accord and thus confirm, in an unexpected and most striking way, the correctness of the standards. To doubt the conclusions of such eminent authorities, when these conclusions are based upon such diversified experience and experiment and are substantiated in so striking a way as that just described, may seem presumptuous. I venture, never- theless, to urge that these standards do not represent the qiiantities of nutritive material that the average mechanic or other Avorkingman needs in order to do a fair day's work; that the allowance is too small for what such a man ought to do and can well do. The reasons for this A'iew are found in the teachings of later experi- mental research, especially that of Voit, and others who have been associated with him, regarding the functions of food and its nutritive ingredients, and in the studies of American dietaries above described and the inferences which they seem to war- rant. The kernel of the whole question is found in the fact that the European standards are based upon the food consumption of people whose plane of living is low in comparison with that of the people in the United States. The thesis which I attempt to defend is that to make the most out of a man, to bring him up to the desirable level of productive capacity, to enable him to live as a man ought to live, he must be better fed than he would be by these standards. This is only part of the story, but it is an essential part. The princijjle is one that reaches very deep into the philosophy of human living. American v. European standards. — In the passage just quoted empha- sis is laid upon the fact that the current European dietary standards are based mainly upon the facts of actual food consumption. Thus, Volt's standard for a laboring man at moderate work is based chiefly upon his observations of the quantities of food actually consumed by manual laborers, mostly mechanics, in Munich and other places in Bavaria, who were reasonably well paid and reasonably well fed, as judged by the standards of wages and living which obtained in these places at the times when the observations were made, twenty years or more ago. In the same way Play fair's estimates were based chiefly upon the conditions which he observed in England some thirty years ago. If either «ne had used such data as he would find in New Eng- land to-day he doubtless would have made his dietary standards cor- respond. The most cursory examination of Table 37 shows that the American standard in this respect would be much higher than the European. My own belief is that the American standard is a much more desirable one. The scale of living or "standard of life" here is much higher than it is in Europe. People in Massachusetts and Con- necticut are better lioused, better clothed, and better fed than in Bavaria or Prussia, they do more work, and they earn higher wages. While the statistics are not as full as is to be desired, there appears to be a consensus of those who have observed most closely that the facts lie in this direction. Very likely what Voit reckons as hard or severe mus- cular work would count here as only moderate work. 212 CHEMISTRY AND ECONOMY OF FOOD. Considering the body as a macliine, the American workingman lias a more strongly-built macliine and more fuel to run it tlian lias liis European brother. While it is not absolutely i)roven, it seems in the highest degree probable that the higher standard of living, the better nutrition, the larger product of labor and the higher wages go together. It is in view of such considerations as these that I have ventured to suggest more liberal standards for dietaries than those which have been proposed by the Euroi)ean authorities above quoted. The following standards are from the article above referred to:^ SUGGESTIONS FOU DIETARY STANDARDS. In Table 39, I venture to suggest certain proportions of i^rotein and energy which may be appropriate as averages for dietaries for people of diiferent forms of activity. In the method by which the estimates are made, these agree with those of Voit and Playfair in that the pro- X)ortions assumed to be needed are inferred empirically from those con- sumed in observed cases. They differ from the ones referred to in the use of the experience that has accumulated during the not far from two decades since the latest of the latter, those of Voit, were i)roposed; a period of no little activity of research in the science of nutrition. But the principal reason for the wide differences in the quantities is that the results of the inquiries regarding American dietaries have been taken into account in the estimates here given. Concerning the quantities of protein, it must be confessed that the experimental data do not yet sufi&ce for at all exact estimates even for average persons of different classes. The proportions here given are such as seem to me reasonable in the light of the present knowledge. The same may be said regarding the figures for energy. The estimates in Table 39 are expressed simply in terms of protein and energy. There is really little ground for giving quantities of fats and carbohydrates in such standards, since the two are mutually replace- able, and the quantities must vary with the conditions of consumption. Eegarding the standards of Table 38, a few additional remarks will suffice. It will be observed that the quantities are in a well-nigh regularly ascending scale. The lowest are such as have been found to suffice amply for men of sedentary life. The highest accord with the larger, but not the largest, of the American dietaries quoted above. The quantities in No. 1 are about the same as were found ample for the German jJ^ofessors and lawyers above referred to, who were men of decided mental activity. They might be small for the average man of like occupation with us, in which case such proportions as those of No. 2 would be more appropriate. The standard for a man at moderate work, which Voit places at 118 grams of protein and 3,050 calories, and ^ Report of Storrs (Conii.) Experiment Station, 1891, p. 160. STANDARDS FOR DIETARIES. 213 PlayfaJr aud other authorities at very nearly the same figures, I have phiced at 125 grams of protein and 3,500 of energy. These are smaller than the averages of the American dietaries, but I have assumed that the waste in the latter would count for considerable and that the quan- tities actually eaten would not be so very far above these figures, par- ticularly as the allowance here for a man at active muscular work is 150 grams of i^roteiu and 4,000 calories of energy. It lias been assumed a woman requires on the average eight-tenths as much as a man for corresponding muscular activity. I have assigned the dietary of a man with light exercise to a woman at moderate work, and that of a man with very little physical exercise to a woman at light work, thus jDroviding for a woman rather more than eight-tenths as much as a man. Very likely eight-tenths would accord more nearly with the actual needs. It is quite possible that the quantities of nounitrogenous nutrients necessary to furnish the energy called for in the following standards would be large in comparison, with the amounts of protein; in other words, that the nutritive ratios are too wide for normal nutrition. In this respect they are a compromise between the currently accepted European standards and the actual dietaries observed in Xew England. Table 39. — Standards for daily dietaries {American). Protein. Fuel value. Kutritive ratio. Woman with light muscular exercise Grams. 90 1 100 112 125 150 Calories. 2,400 2,700 3.000 3,500 4,500 1: 5 5 Woman with moderate muscular work 5.6 5 5 5 S 6.3 CHAPTER XI. ERRORS IN OUR FOOD ECONOMY.^ JFortunately, euougii information has already been gained to indicate in a general way wliat are the principal mistakes in the food economy of people in the United States, even though we are not yet certain as to all the details. Scientific research, interpreting the observations of practical life, imj)lies that several errors are common in the use of food : First, many people purchase needlessly expensive kinds of food, doing this under the false impression that there is some peculiar virtue in the costlier materials, and that economy in our diet is somehow detrimental to our dignity or our welfare. And, unfortunately, those who are most extravagant in this respect are often the ones who can least afford it. Secondly, the food which we eat does not always contain the proper proportions of the different kinds of nutritive ingredients. We con- sume relatively too much of the fuel ingredients of food, such as the fats of meat and butter, the starch which makes up the larger part of the nutritive material of flour and potatoes, and sugar and sweet- meats. Conversely, we have relatively too little of the protein of flesh- forming substances, like the lean of meat and fish and the gluten of wheat, which make muscle and sinew and which are the basis of blood, bone, and brain. Thirdly, many people, not only the well-to-do, but those in moderate circumstances, use needless quantities of food. Part of the excess,»iiow- ever, is simply thrown away with the wastes of the table and the kitchen; so that the injury to health, great as it may be, is doubtless much less than if all were eaten. Probably the worst sufferers from this evil are well-to-do people of sedentary occupations — brain workers as distinguished from hand workers. Finally, we are guilty of serious errors in our cooking. We waste a great deal of fuel in the preparation of our food, and even then a great deal of the food is very badly cooked. ' A reform in these methods of cooking is one of the economic demands of our time. ^ The statemeuts in this chapter~are taken mainly from articles by the author in the Century Magazine, The Forum, and the Eeport of the Storrs (Conn.) Experiment Station for 1892. 214 ERRORS IN OUR FOOD ECONOMY. 215 CHEAP V. DEAR FOOD. We can not judge of the nutritive value of food by the quantity. This fact is brought out clearly by the figures in Table 10 on page 139. There is as much nutriment in a pound of wheat flour as in '6^ quarts of oysters, which weigh 7 pounds. There is still less conncc- nectiou between nutritive value and price. In buying at ordinary mar- ket rates we get as much material to build up our bodies, repair their wastes, and give strength for work, in 5 cents' worth of flour or beans or codfish, as 50 cents or $1 will pay for in tenderloin, salmon, or lobsters. Bound steak at 15 cents a pound is just as digestible and is fully as nutritious as tenderloin at 50. Mackerel has as high nutritive value as salmon, and costs from an eighth to half as much. Oysters are a delicacy. If one can aflbrd them there is no reason for not having them, but 25 cents invested in a pint would bring only about an ounce of protein and 230 calories of energy. The same 25 cents spent for flour at $G a barrel, or a cents a pound, would pay for nine-tenths of a x)ound of protein and 13,700 calories of energy. When a day-laborer buys bread at 7^ cents a iiound the actually nutritive material costs him three times as much as it does his employer, who buys it in flour at $6 a barrel. FOOD OF THE POOR. Illustrations of the prejudice of people, especially those in moderate circumstances, against the less expensive kinds of food are very common. Mr. Lee Meriwether, who has given much attention to this special subject, cites a case in j)oint, that of a coal laborer who boasted: "Ko one can say that I do not give my family the best of flour, the finest of sugar, the very best quality of meat." He paid 1156 a year for the nicest cuts of meat, which his wife had to cook before 6 in the morning or after half past 6 at night, because she worked all day in a factory. When excellent butter was selling at 25 cents a pound he paid 29 cents for an extra quality. He spent only $108 a year for clothing for his family of 9, and only $72 a year for rent in a close tenement house, where they slept in rooms without windows or closets. He indulged in this extravagance in diet when much less expensive food materials, such as regularly come upon the tables of men of wealth, would have been just as nutritious, just as wholesome, and in every way just as good, save in the gratification to pride and palate. He was committing an immense economic blunder. Like thousands of others, he did so in the belief that it was wise and economical. The sad side of the story is that the poor are the ones who practice the worst economy in the purchase as well as the use of food. The Massachusetts Bureau of Labor, in collecting the dietaries above referred to, made numerous inquiries of tradesmen regarding the food of the i)Oor in Boston, meaning by poor ''those who earn just enough to keep themselves and familes from want." The almost universal testimony was, " They usually want the best and pay for it, and the 216 CHEMISTRY AND ECONOMY OF FOOD. most fastidious are those who can least afford it." The costliest kind of meat, the finest flour, and very highest priced butter were demanded, and many scorned the less expensive meats and groceries such as well-to-do and sensible people were in the habit of buying. I have taken occasion to verify these observations by personal inquiry in Boston markets. One intelligent meat man gave his experieuce with a poor seamstress, who insisted on buying tenderloin steak at 60 cents per pound. He tried to persuade her that other parts of the meat weie just as nutritive, as they really are, but she would not believe him ; and when he urged the wiser economy of using them she became angry at him for what she regarded as a reflection upon her dignity. '■ ' My wealthy customers," said he, "take our cheaper cuts, but I have got through trying to sell these economical meats to that woman and others of her class." I am told that people in the poorer parts of New York City buy the highest priced groceries, and that the meat men say they can sell the coarser cuts of meat to the rich, but that people of moderate means refuse them. I hear the same thing in Washington and other cities. ONE-SIDEDNESS OF OUR DIETARY. I have said that our diet is one-sided, that the food which we actu- ally eat has relatively too little protein and too much fat, starch, and sugar. In other words, it is relatively deficient in the materials which make muscle and bone and contains a relative excess of the fuel ingredients. This is due partly to our large consumption of sugar and partly to our use of such large quantities of fat meats. In the sta- tistics of dietaries above referred to the quantities of fat in the Euro- pean dietaries range from 1 to 5 ounces per day, while in the American the range is from 4 to 16 ounces. In the daily food of well-to-do professional men in Germany, who were amply nourished, the quantity of fat is from 3 to 4J ounces per day, while in the dietaries of Ameri- cans in similar conditions of life it ranges from 5 to 7^ ounces in the food purchased. The quantities of carbohydrates in the European dietaries range from 9 to 24 ounces, while in the corresponding Ameri- can dietaries the carbohydrates were from 24 to 60 ounces. It is customary to estimate the proportion of fuel ingredients to pro- tein in what Is called the nutritive ratio. In this estimate 1 part, by weight, of fats is counted as equivalent to 2^ of carbohydrates. Adding the two together gives the amount of the fuel ingredients. In the American dietaries the proportion of fuel ingredients to 1 part of protein ranges from 6.6 to 8.7, and even higher. In the Euro- pean dietaries of well-nourished people and in the dietary standards which express the average needs according to the teachings of the best physiological observations it is from 4.1 to 6, or thereabout. The rejection of so much of the fat of meat at the market and on our plates at the table is not mere willful wastefulness, it is in obedience to nature's protest against a one-sided and excessive diet. ERRORS IN OUR FOOD FX'OXO.MY. 217 OVEREATING — INJURY TO HEALTH. But the most remarkable tiling about our food consumption is tbe quantity. The American dietaries examined in the inquiry mentioned above were of people living at the time in Massachusetts and Connect- icut, though many came from other parts of the country. It would be "wroug to take their eating habits as an exact measure of those of peo- ple throughout the United States. For that matter, a great deal of careful observation will be needed to show precisely what and how much is used by persons of different classes in different regions. Just this kind of study in different parts of the country is greatly needed. But such facts as I have been able to gather seem to imj)ly that the figures obtained indicate in a general way the character of our food consumption. Of the over 50 dietaries of reasonably well-to-do people thus far exaraiued the smallest is that of a mechanic's family. In this the potential energy per man per day was about 3,000 calories. The next smallest was that of the family of a chemist who had been studying the subject and had learned something of the excessive amounts of food which many people with light muscular labor con- sume. This dietary supplied 3,200 calories of energy per man a day. The largest was that of brickmakers at very severe work in Massachu- setts. They lived in a boarding house managed by their emx)loyers, who had -evidently found that men at hard muscular work out of doors needed ample nourishment to -do the largest amount of work. The food supplied 8,850 calories j)er day. Yoit's standard for a laboring man at moderate work, which is based upon the observation of the food of wage workers who are counted in Germany as well paid and well fed, allows 118 grams of protein and 3,055 calories of energy. The standards proposed by myself in which the studies of American dietaries have been taken into account allow 125 grams of protein and 3,500 calories of energy for a man at moderately hard muscular work. The dietaries of Massachusetts and Connecticut factory operatives, day laborers, and mechanics at mod- erate work averaged about 125 grams of protein and 4,500 calories of energy. For a man at " severe '" work, Yoit's standard calls for 115 grams of protein and 3,370 calories of energy. The Massachusetts and Connecticut mechanics at "hard" and " severe" work had from 180 to 520 grams of protein and from 5,000 to 7,800 calories of poten- tial energy, and in one case it rose to the 8,500 just quoted. In the dietary standards proposed by myself it did not seem to me permis- sible to assign less than 4,000 calories to that for a working man at "hard," and 5,700 for a man at " severe"' work. Just what compounds in food are required for the nutriment of the brain, physiological chemistry has not yet told us; but it is certain that people with little muscular exercise require less food than those at hard muscular labor. Many men whose work and strain are inental 218 CHEMISTRY AND ECONOMY OF FOOD. ratlier than physical suffer from overeating. In a number of dietaries of professional men in Germany, Denmark, and Sweden, including a university professor, a lawyer, physicians, and students, all of whom were in comfortable circumstances, in good health, and amply nour- ished, the energy varied from 2,180 to 3,035 calories; the mean was about 2,600 calories. The average of the dietaries of professional men and students from the Northern and Eastern States, residing in Mid- dletown, Conn., was 4,155 calories. The range was from 3,205 in the family of the chemist to whom I have referred, to 5,345 in a students' boarding club. These figures, like the others of the American dietaries cited, refer to the food purchased. The average of the food eaten was 3,705 calories. In the students' dietary the food eaten supplied 4,825 calories. ISTow it is not easy to see why these men required so much more than was sufficient to nourish abundantly men of like occupation, but unlike temptation to overeating, in Europe. Difference in climate can not account for it. We are a little more given to muscular exercise here, whicli is very well for us, but it cannot justify our eating so much. In the German army, where especial attention is given to diet, and it has been an axiom since the time of Frederick the Great, that soldiers to march well and tight well must be well fed, a ration for time of peace has been computed at 2,800, and one for time of war at 3,095 calories. During the last Franco-German war, shortly before the battle of Sedan, an order was issued by King, afterwards Emperor, William, which provided an extraordinary war ration, which is estimated at 3,985 calories. If a man with a tremendous physical and nervous tension, required in such terrible service as the German soldier was called upon to render in his victorious contests with the Frenchman, is well sup- plied by a ration of less than 4,000 calories of energy, and German professional men in their quiet but active and successful intellectual work at home are «mply nourished with 2,700 calories and less, how happens it that men of mental rather than muscular occupation here consume food with 4,000 calories and more? I think the answer to this question is found in the conditions in which we live. Food is plenty. Holding to a tradition which had its origin where food was less abundant, that the natural instinct is the measure of what we should eat, we follow the dictates of the palate. Living in the midst of abundance, our diet has not been regulated by the restraints which obtain with the great majority of the people of the Old World, where food is dear and incomes are small. Indeed, the very progress which we are making in our civilization brings with it increased temptation to overeating. The four quarters of the earth are ransacked to suiiplyus with the things which will most tempt our appetites, and the utmost effort of cooks and housewives is used in the same direction. It is all the more fitting, therefore, that information as to our excesses and the ways of avoiding them should 3ome at the same time. ERRORS IN OUR FOOD ECONOMY. 219 How much liarin is done to health by our one-sided and excessive diet no one can say. Physicians tell us that it is very great. Ot the vice of overeating, Sir Henry Thompson, a noted English physician and authority on this subject, says : I have come to the couclusion that more than half the disease which emhitter.s the middle and. latter part of life is due to avoidable errors iu diet^ s * * ^,^mj that more mischief in the form of actual disease, of impaired vigor, aud of shorteued life accrues to civilized mau * * * iu England aud throughout central Europe from erroneous habits of eating than from the habitual use of alcoholic drink, considera- ble as I know that evil to be. This is in the fullest accord with the opinions of physicians and hygienists who have given the most attention to the subject, and these opinions are exact! j'^ parallel with the statistics here cited. WASTE OF FOOD IN AMERICAN HOUSEHOLDS. The direct waste of food occurs in two ways, in eating more than is needed and in throwing away valuable material in the form of kitcheu and table refuse. That which is thrown away does no harm to health, and in so far as part of it may be fed to animals or otherwise utilized, it is not an absolute loss. That which we consunie in excess of our need or nourishment is worse than wasted because of the injury it does to health. A few instances taken from the investigations mentioned above will help to illustrate the waste of food. One of the dietaries examined by the Massachusetts Labor Bureau was that of a machinist in Boston who earned $3.25 per day. In food purchased the dietary furnished 182 grams of protein and 5,640 calories of energy per man per day, at a cost of 47 cents. One-half the meats, fish, lard, milk, butter, cheese, eggs, sugar, and molasses would have been represented by 57 grams of protein, 1,650 calories, and 19 cents. If these had been substracted the record would have stood at 125 grams, 3,990 calories, and 28 cents. This family might have dispensed with one-half of all their meats, fish, eggs, dairy products, and sugar, saved 40 per cent of the whole cost of their food, and still have had all the protein and much more energy than is called for by a standard which is supposed to be decidedly liberal. In the instance just cited no attempt was made to learn how much of the food purchased was actually consumed and how much was rejected. In some of the dietaries published by the Massachusetts bureau such estimates were made. That of a student's club in a Kew England col- lege will serve as an example. The young men of the club, some 25 in number, were mostly from the Northern aud Eastern States, and, coming from the class of fami- lies whose sons go to college, it seems fair to assume that their habits of eating formed at home would not differ materially from those of the more intelligent classes of people in that part of the country. While the diet of the club was substantial and wholesome, it was plain, as was, indeed, necessary, because several of the members were dependent upon 220 CHEMISTRY AND ECONOMY OF FOOD. tlieir own exertions and the majority had rather limited means. Though fond of athletic sports, they could hardly be credited with as much muscular exercise as the average "laboring man at moderate work." The matron, a very intelligent, capable New England woman, had been-selected because of her especial fitness for the care of such an establishment. The steward who purchased the food was a member of the club, and had been chosen as a man of business capacity. He thought that very little of the food was left unconsumed. "All of the meat and other available food that was not actually served to the men at the table," said he, "was carefully saved and made over into cro- quettes. Men who work their way through college can not afford to throw away their food." But actual examination showed the waste to be considerable. The estimates of the quantities of nutrients were based upon the quantities of food materials for a term of three months and upon the table and kitchen refuse for a week. The results were as fol- lows: In food purchased, protein, 161 grams; energy, 5,345 calories. In waste, protein, 23 grams ; energy, 520 calories. In food consumed, pro- tein, 138 grams; energy, 4,825 calories. One eighth of the protein and one tenth of the energy were simply thrown away. During the succeeding term a second examination of the dietary of the same club was made. Another steward was then in charge. He had learned of the excessive amounts of food in the former dietary, and planned to reduce the quantities. This was done largely by diminish- ing the meats. He stated that he did not apprise the club of the change, and that it was not noticed. As he put it, "The boys had all they wanted, and were just as well pleased as if they had had more." Esti- mates as before, but with more care in determining the waste, showed in food purchased, protein 115 grams; energy, 3,875 calories. In waste, protein, 11 grams; energy, 460 calories. In food consumed, jjrotein, 104 grams; energy, 3,415 calories. One- tenth of the nutritive material of the food this time was thrown away. The young men were amply nourished with three-fifths of the nutrients they had purchased in the previous term. How much food is required on the average by men whose labor is mainly intellectual is a question to which physiology has not yet given a definite answer, but it is safe to say that the general teaching of the specialists who have given the most attention to the subject would call for little more than the 304 grams of protein and very much less than the 3,400 calories of energy in the food estimated to be actually con- sumed by these young men when the second examination was made. They could have dispensed with half of all the meats, fish, oysters, eggs, milk, butter, cheese, and sugar purchased for the first dietary and still have had more nutritive material than they consumed in the second. l^Tot only was one-tenth or more of the nutrients thrown away in each of the two cases, but what makes the case still worse pecun- iarily, the rejected material was very largely from the animal foods in which it is the most expensive. ERRORS IN OUR FOOD ECONOMY. 221 Tlie estimates of tlie quantities of food in tlie two dietaries just quoted were made from tradesmen's bills and tlie comijosition was cal- culated from analyses of similar materials rather than of tLose actually used. The figures are therefore less reliable than if the food and wastes had been actually weighed and analyzed. In some dietaries lately examined in Middletown, Conn., all the food has been carefully weighed and portions have been analyzed, and the same has been done with the table and kitchen refuse. The results therefore show exactly how much was purchased, consumed, and thrown away. One dietary so inves- tigated w^as that of a boarding house. The boarders were largely mechanics of superior intelligence and skill, and earning good wages j the mistress was counted an excellent housekeeper and the boarding house a very good one. About one-ninth of the total nutritive ingredi- ents of the food was left in the kitchen and table refuse. The actual waste was worse than this i)roportion would imply, because it consisted mostly of the i^rotein and fats, which are more costly than the carbo- hydrates. The waste contained Diearly one-fifth of the total protein and fat, and only one-twentieth of the total carbohydrates of the food. Or, to put it in another way, the food purchased contained about 23 per cent more protein, 24 per cent more fats, and 6 per cent more carbohy- drates than were eaten. And, worst of all for the pecuniary economy, or lack of economy, the wasted protein and fats were mostly from the meats which supply them in the costliest form. In another dietary, that of a carpenter's family, also in Middletowu, Conn., 7.6 per cent of the total food purchased was left in the kitchen and table wastes. The total waste was somewhat worse than this pro- portion would imply, because it consisted mostly of the protein and fats, whicli are more costly than the carbohydrates. The w^aste con- tained about one-tenth of the total protein and fat, and only one twenty- fifth of the total carbohydrates of the food; or, to put it in another way, the food purchased contained nearly 10 i^er cent more protein, 12 percent more fat, and 5 per cent more carbohydrates than were eaten; and here again the wasted protein and fats were mostly from the meats, which supplied them in the costliest form. At the rate in which the nutrients were actually eaten in this dietary, the protein and fats in the waste would have each supplied one man for a week, and the carbohydrates for three days. These cases are probably exceptional; at least it is to be hoped that they are. Among 8 dietaries lately studied in Middletowu those above named showed the largest proportion of material thrown away. In the rest it was much less. In two cases there was almost none. It is worth noting, however, that the people in these two had the largest incomes of all. In other words, the best-to-do families were the least wasteful. Tliisform of bad economy is not confined to the kitchen, but begins in the market. In buying meat in the retail markets it is a common practice to have the bone and considerable of the fat cut out and left. 222 CHEMISTEY AND ECONOMY OF FOOD. In tlins removing' tlie 'trimmings" tlie butclier is apt to cut out con- siderable else than tlie bone and fat. In a piece of roast beef weigliiug- 16 pounds, the 'Hrimmings," which consisted of the bone and the meat cut out with it, and which were left for the butcher to sell to the soap man, or get rid of as he might otherwise choose, weighed 4^ pounds. The butcher said that he sold this sort of beef largely to the ordinary people of the city — mechanics, small tradesmen, and laborers. The 4| pounds of " trimmings " consisted of, approximately, 2J pounds of bone and one-half pound of tendon ("gristle"), which would make a most palatable and nutritious soup, and If pounds of meat, of which 1 pound was lean and three-fourths pound fat. It is estimated that the nutritive materials of meat thus left unused, saying nothing of the bone and tendon, contained some 15 per cent of the protein and 10 per cent of the potential energy of the whole. The price of the beef was $2.21. Assuming the nutritive value of the ingredients of the "trimmings "to" be 12 J per cent of the whole, 28 cents worth of the nutritive material, besides the bone and tendon, was left at the butcher's. Dr. S. A. Lattimore, professor of chemistry in the University of Roch- ester, ]!»r. Y., tells me that while a member of the board of health of that city he directed the officer in charge of the collection of garbage to note the character of the waste material. It was ascertained that from the streets inhabited by the well-to-do classes, where the culinary affairs were largely left to the servants, the amount of waste thus col- lected was enormous, and that a considerable x^roportion of the food purchased was literally thrown away by careless servants. A surpris- ingly large amount of this waste consisted of good bread. Among the people in moderate circumstances this waste was less. The common saying that "the average American family wastes as much food as a French family would live upon" is a great exaggeration, but the statistics cited show that there is a great deal of truth in it. Even in some of the most economical families the amount of food wasted, if it could be collected for a month or a year, would prove to be very large, and in 'many cases the amounts would be little less than enormous. O COLUMBIA UNIVERSITY This book is due on the date indicated below, or at the expiration of a definite period after the date of borrowing, as provided by the rules of the Library or by special ar- rangement with the Librarian in charge. DATE BORROWED DATE DUE DATE BORROWED DATE DUE 1 i.ifiU H o ZW L sO^3 02 M Huv u 9 '-^ ■ - C£e!638)MS0 COLUMBIA UNIVERSITY LIBRARIES QP141 At9 Atwater aethods end r^f of i-^^^^Jsat^j' ;„ thechemistry and economy of food u \^ J-i 0\a^^ , vV