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WORKS OF ELLEN H. RICHARDS 
 
 PUBLISHED BY 
 
 JOHN WILEY & SONS 
 43-45 East Nineteenth Street, New York 
 
 Laboratory Notes on Industrial Water Analysis: A 
 Survey Course for Engineers. 
 8vo, 52 pages. Cloth, 50c net. 
 The Cost of Cleanness. 
 
 l2mo, v + 109 pages. Cloth. $1.00. 
 
 The Cost of Living as Modified by Sanitary Science. 
 
 Third Edition, Revised. 12mo. 164 pages. Cloth. 
 $1.00. 
 Air, Water, and Food; From a Sanitary Standpoint. 
 
 By Ellen H. Richards and Alpheus G. Woodman, 
 Assistant Professor of Food Analysis, Massachusetts 
 Institute of Technology. Third Edition, Revised 
 and Enlarged. 8vo. 278 pages. Cloth. $2.00. 
 
 The Cost of Food : A Study in Dietaries. 
 12mo. 161 pages. Cloth. $1.00. 
 
 The Dietary Computer. 
 
 By Ellen H. Richards, Instructor in Sanitary Chem- 
 istry, Massachusetts Institute of Technology, assisted 
 by Louise Harding Williams. $1.50 net. Pamphlet 
 separately, $1.00 net. 
 
 The Cost of Shelter. 
 
 12mo. vi + 136 pages. Illustrated. Cloth. . $1.00. 
 
 " Cost of Living " Series. 
 
 1. Cost of Living. 2. Cost of Food. 3. Cost of 
 Shelter. 4. Cost of Cleanness. 12mo. Cloth. 4 
 vols, in a box. $4.00. 
 
 Published by WHITCOMB & BARROWS 
 Huntington Chambers 
 
 The Chemistry of Cooking and Cleaning. 
 
 By Ellen H. Richards and S. Maria Elliott. 158 
 pages. Cloth. $1.00. 
 Food Materials and their Adulterations. 
 
 183 pages. Cloth. $1.00. 
 
 Home Sanitation. 
 
 Revised Edition. Edited by Ellen H. Richards and 
 
 Marion Talbot. 85 pages. Paper. 25c. 
 Plain Words about Food. 
 
 The Rumford Leaflets. Illustrated. 176 pages. 
 
 Cloth. $1.00. 
 First Lessons on Food Diet. 
 
 52 pages. Cloth. 30c net. 
 The Art of Right=Living. 
 
 50 pages. Cloth. 50c net. 
 
 Sanitation in Daily Life. 
 
 82 pages. Cloth. 65c. net. 
 
AIR, WATER, AND FOOD 
 
 FROM A SANITARY STANDPOINT. 
 
 BY 
 
 ELLEN H. RICHARDS AND ALPHEUS G. WOODMAN. 
 
 Instructor in Sanitary Chemistry. Assistant Processor of Food Analysis, 
 
 Massachusetts Institute of Technology. Massachusetts Institute of Technology. 
 
 "These cannot be taken as sufficient ... in these times whei) 
 every word spoken finds at once a ready doubter, if not an opponent. 
 They are. however, specimens, and will serve to- make* comparisons 
 in time to come." — Angus Smith. 
 
 "The ideal scientific mind, therefore, must always be held in a 
 state of balance which the slightest new evidence may change in one 
 direction or another. It is in a constant state of skepticism, knowing 
 full well that nothing is certain."— Henry A. Rowland. 
 
 THIRD EDITION, REVISED AND ENLARGED. 
 
 FIRST THOUSAND. 
 
 NEW YORK: 
 JOHN WTLEY & SONS. 
 
 London : CHAPMAN & HALL, Limited. 
 
 1909. 
 
V 
 
 X ** 
 
 Copyright, 1900, 1904. 1909, 
 
 BLLBN H. RICHARDS and ALPHEUS G. WOODMAN. 
 
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 LC Control Number 
 
 tmp96 028456 
 
PREFACE TO THE THIRD EDITION. 
 
 The great increase of attention to the relations of 
 physical environment to mental and moral welfare leads 
 the authors to hope that this revised and enlarged edition 
 will meet with approval by the body of seekers after truth 
 along these lines of study and investigation. 
 
 More clearly than any one else they recognize the omis- 
 sions and shortcomings of any book dealing with so compre- 
 hensive a subject under the limitations of a short school 
 course. Therefore a suggestive rather than a complete 
 treatment has been adopted, and a certain conservatism 
 has governed the discussion of some subjects which to 
 treat fully would require too much space as well as a 
 previous training impossible to assume. 
 
 The chapters on analytical methods have been con- 
 siderably enlarged; the character of the matter added 
 tends to make the work more adapted to the needs of 
 the chemical and sanitary engineer as well as to the general 
 student and householder. In a subject so rapidly advanc- 
 ing the printed page can hardly hope to keep fully abreast 
 of the times, but all the methods have been reviewed or 
 modified, and tentative ones have been retained or dropped 
 as experience has indicated their value. 
 
 The bibliography has been revised and brought up to 
 date. 
 
CONTENTS. 
 
 :haptsr page 
 
 I. Three Essentials of Human Existence i 
 
 II. Air: Composition, Impurities, Relation to Human Life 10 
 
 III. The Problem of Ventilation 19 
 
 IV. Methods of Examination -. 27 
 
 V. Water: Source, Properties, Solvent Power, as a Carrier. 57 
 VI. The Problem of Safe Water and Interpretation of Analy- 
 ses 76 
 
 VII. Methods of Examination 96 
 
 VIII. Food in Relation to Human Life, Definition, Sources, 
 
 Classes, Dietaries 142 
 
 IX. Adulteration and Sophistication of Food Materials 157 
 
 X. Methods of Food Analysis 167 
 
 Appendices, Tables, Reagents 235 
 
 Bibliogp.aphy .- 263 
 
AIR, WATER, AND FOOD, 
 
 CHAPTER I. 
 
 THREE ESSENTIALS OF HUMAN EXISTENCE. 
 
 Air, water, and food are three essentials for healthful 
 human life. Sanitary Chemistry deals with these three com- 
 modities in their relation to the needs of daily existence: 
 first, as to their normal composition; second, as to natural 
 variations from the normal; third, as to artificial variations — 
 those produced directly by human agency with benevolent 
 intention, or resulting from carelessness or cupidity. A 
 large portion of the problems of public health come under 
 these heads, and a discussion of them in the broadest sense 
 includes a consideration of engineering questions and of 
 municipal finances. This, however, is beyond the scope of 
 the present work. 
 
 The following pages will deal chiefly with such portions 
 of the subject of Sanitary Chemistry as come directly under 
 individual control, or which require the education of indi- 
 viduals in order to make up the mass of public opinion 
 which shall support the city or state in carrying out sanitary 
 measures. 
 
 A notable interest in the subject of individual health as 
 
■2 AIR, WATER, AND FOOD. 
 
 a means of securing the highest individual capacity both for 
 work and for pleasure is being aroused as the application of 
 the principles governing the evolutionary progress of other 
 forms of living matter is seen to extend to mankind. 
 
 Will power may guide human forces in most economi- 
 cal ways, and may concentrate energy upon a focal point so 
 as to seem to accomplish superhuman feats, but it cannot 
 create force out of nothing. There is a law of conservation 
 of human energy. The human body, in order to carry on 
 all its functions to the best advantage, especially those of the 
 highest thought for the longest time, must be placed under 
 the best conditions and must be supplied with clean air, safe 
 water, and good food, and must be able to appropriate them 
 to its use. The day is not far distant when a city will be 
 held as responsible for the purity of the air in its school- 
 houses, the cleanliness of the water in its reservoirs, and the 
 reliability of the food sold in its markets as it now is for the 
 condition of its streets and bridges. Nor will the years be 
 many before educational institutions will be held as respon- 
 sible for the condition of the bodies as of the minds of the 
 pupils committed to their care; when a chair of Sanitary 
 Science will be considered as important as a chair of Greek 
 or Mathematics; when the competency of the food-purveyor 
 will have as much weight with intelligent patrons as the 
 scholarly reputation of any member of the Faculty. Within 
 a still shorter time will catalogues call the attention of the 
 interested public to the ventilation of college halls and dor- 
 mitories, as well as to the exterior appearance and location. 
 
 These results can be brought about only when the stu- 
 dents themselves appreciate the possibilities of increased 
 mental production under conditions of decreased friction, 
 such as can be found only when the requirements of health 
 are perfectly fulfilled. 
 
THREE ESSENTIALS OF HUMAN EXISTENCE. 3 
 
 Of the three essentials, air may well be considered first, 
 although its office is to convert food already taken into heat 
 and energy. Its exclusion only for a few minutes causes 
 death, and in quantity used it far exceeds the other two. 
 Again, so important is the action of air that the quality of 
 food is of far less consequence when abundant oxygen is 
 present, as in pure air, than when it is present in lessened 
 quantity, as in air vitiated by foreign substances. 
 
 Individual habit has much to do with the appreciation 
 of good air, and as our knowledge of the value of an abun- 
 dance of this substance in securing great efficiency in the 
 human being increases, we shall be led to attach more im- 
 portance to the sufficiency of the supply. 
 
 In northern climates air is not free to all in the sense of 
 costing nothing, for the coming of fresh air into the house 
 means an accompaniment of cold which must be counter- 
 acted by the consumption of fuel. A mistaken idea of econ- 
 omy leads householders, school boards, and college trustees 
 to limit the size of the air-ducts as well as of the rooms. It 
 is therefore necessary to emphasize the facts which science 
 has fully established, in order to secure the survival of the 
 fittest of the race under the present pressure of economic 
 conditions, which take so little account of the highest wel- 
 fare of the human machine. 
 
 Air, water, and soil are the common possessions of man- 
 kind. It is impossible for man to use either selfishly without 
 injury to his neighbor and without squandering his inheri- 
 tance. Primitive man could leave a given spot when the 
 soil became offensive, and neighbors were then too few to 
 require consideration; but neither man nor beast could with 
 impunity foul the stream for his neighbor who had rights 
 below him. The soil is permanent; one knows where to look 
 for it and its pollution. Air is abundant and is kept in con- 
 
4 AIR, WATER, AND FOOD. 
 
 stant motion by forces of nature beyond human control, so 
 that, save in the neighborhood of an exceptionally offensive 
 factory, man does not often foul the free air of heaven; it is. 
 only when he confines it within unwonted bounds that it 
 becomes a menace. 
 
 Water is the next precious commodity of the three. 
 Without it man dies in a few days; without it the soil is bar- 
 ren; without it air in motion parches all vegetation and 
 carries clouds of dust-particles; without it there is no life. 
 As population increases it becomes necessary to collect as 
 much of the rainfall as possible, to store it until needed, and 
 to use it with discretion. After use it is often loaded with 
 impurities and sent to deal death and destruction to those 
 who require it later, and yet, in nature's plan, it is the carrier 
 of the world, and rightly treated and carefully husbanded 
 there is enough for the needs of all. Its presence or absence 
 has been the controlling force in determining the habitations 
 of men. In its office of carrier it not only brings nourishment 
 in solution to the tissues of the human body, but also carries 
 away the refuse material. It is a cardinal principle in all 
 sanitary reforms to get rid of that which is useless as soon as 
 possible. Too little water allows accumulation of waste 
 material and a clogging of the bodily drainage system. 
 
 The average quantity needed daily by the human body is 
 about three quarts. Of this a greater or less proportion is 
 taken in food, so that at times only from a pint to a quart 
 need be taken in the form of water as such. 
 
 Next in importance to quantity is the quality, dependent 
 somewhat upon the uses to which it is to be put. As a rule, 
 the moderately soft waters are the best for any purpose. 
 For drinking purposes water must be free from dangers to 
 health in the way of poisonous metals, decomposing matters, 
 and disease-germs. For domestic use economy requires; 
 
THREE ESSENTIALS OF HUMAN EXISTENCE. 5 
 
 that it should not decompose too much soap. Manufactur- 
 ing interests require that it should not give too much scale 
 to boilers; for agriculture there should not be too much 
 alkali. 
 
 From the nature of things, no one family or city can have 
 sole control of a given body of water. Those on the high- 
 lands may have the first use of the water, which then perco- 
 lates to a lower level and is used by the people on the slopes 
 over and over before it reaches the sea to start again on 
 its cycle of vapor, cloud and rain, brook and river. Al- 
 though receiving impurities each time, there are many 
 beneficent influences at work to overcome the evils resulting 
 from this repeated use. That which is dissolved from one 
 portion of earth may be deposited on another. As the plant 
 is the scavenger of the air, withdrawing the carbon dioxide 
 with which it would otherwise become loaded, so the water 
 lias also its plant life, purifying it and withdrawing that which 
 would otherwise soon render it unfit for any use. 
 
 Pure water is found only in the chemical laboratory; the 
 most that can be hoped for is that human beings may secure 
 for themselves water which is safe to drink, which will not 
 impair the efficiency of the human machine. 
 
 The importance of the third essential for human life, 
 food, and the close interdependence of all three, may be 
 clearly shown. Of little use is it to provide pure air and 
 clean water if the substances eaten are not* capable of com- 
 bining with the oxygen of the air or of being dissolved in 
 the water or the digestive juices; of less use still is it to par- 
 take of substances which act as irritants and poisons on the 
 tissues which they should nourish, and thus prevent healthful 
 metabolism and respiratory exchange. 
 
 And yet a large majority of those who have acquired 
 some notion of the meaning and importance of pure air and 
 
6 AIR, WATER, AND FOOD. 
 
 are beginning to consider it worth while to strive for clean 
 water pay not the least attention to the sanitary qualities of 
 food; the palatable and aesthetic aspects only appeal to 
 them. 
 
 Steam-power is produced by the combustion of coal or 
 oil. Human force is derived by releasing the stored energy 
 of the food in the body. The delicately balanced mechansm 
 of the human body suffers even more from friction than the 
 most sensitive machine, and the greatest loss of potential 
 human energy occurs through ignorance, carelessness, and 
 reckless disregard of nature's laws in regard to food. 
 
 It is necessary to know, first, what is the normal compo- 
 sition of a given food-material. This is found by analyses 
 of many typical samples. Second, is the sample under con- 
 sideration normal? To answer this requires an analysis of it, 
 and a comparison of the results with standards. If it is not 
 normal, in what way does it depart from the standard both 
 in healthfulness and in quality? Third, if a food-substance 
 is normal, what are its valuable ingredients and in what pro- 
 portions are they to be used in the daily diet? 
 
 In regard to meat, milk, and fish, the sanitary aspect for 
 the chemist resolves itself into two questions: Is the sub- 
 stance so changed as to become a possible source of poison- 
 ous products? Or has anything in the nature of a preserva- 
 tive been added to it? If so, is it of a nature injurious to 
 man? 
 
 There is, however, a great range of quality in some of the 
 most abundant foodstuffs, such as the cereals, especially in 
 the nitrogen content. This is most important to the vege- 
 tarian and to institutions where economy must be practised. 
 The following variations in the composition of leading cereals 
 will illustrate: 
 
THREE ESSENTIALS OF HUMAN EXISTENCE f 
 
 ,, T ■ Nitrogenous Crude Carbo- i?;w;«. a„v, 
 
 Water - Substance, rat. hydrates. Flbre " Ash ' 
 
 Oats, maximum. ..... . 20.80 18.84 10.65 64.63 20.08 8.64 
 
 " minimum 6.21 6.00 2. 11 48.69 4.45 1.34. 
 
 «• American hulled. 12. 11 13.57 7-68 63.37 1.30 2.03 
 
 Corn, maximum 22.20 14.31 8.87 52.08 7.71 3.93 
 
 " minimum. .. 4- 6 § 5-55 i-73 72-75 0.99 o.Sz 
 
 One sample of wheat flour may contain 14 per cent, of nitro- 
 genous substance, another may yield only 9. A day's ration, 
 500 grams, will give 70 grams of gluten, etc., in the one 
 case and only 45 in the other. This difference of 25 grams, 
 would be a serious factor in the dietary of an institution 
 where little additional proteid is given, and it alone might 
 be the cause of dangerous under-nutrition. 
 
 The next step would naturally be to determine how 
 definitely these varying percentages mean varyine nutrition.. 
 To this end a study of vegetable nitrogenous oroducts in 
 their combination or contact with cellulose, starch, and min- 
 eral matter is needed. Much work remains to be done 
 before these questions can be even approximately answered. 
 
 At the low cost of one cent a pound, common vegetables 
 yield only about one-fifth as much nutriment as one cent's- 
 worth of flour, yet they contain essential elements and de- 
 serve to be carefully studied. 
 
 Dried fruits and nuts are much undervalued as articles of 
 food, as are rice and lentils. (See table, page 150.) 
 
 The discussion of food values will be found in Chapter 
 
 Yin. 
 
 Probably the widest field for the sanitary chemist to-day 
 is the study of the so-called predigested foods, infant foods, 
 " hygienic " preparations, two-minute cereals, and the count- 
 less proprietary packages, which, designed to meet the de- 
 mand for quick results, prove traps for the unwary. 
 
 Therefore the sanitary aspect of food demands a study 
 
8 AIR, WATER, AND FOOD. 
 
 of normal food and food value even more than of adulterants 
 or of poisonous food, ptomaines and toxines. The cultiva- 
 tion of intelligent public opinion is most important, and each 
 student should go out from a sanitary laboratory a mission- 
 ary to his fellow men. That is, the office of a laboratory 
 of sanitary chemistry should be so to diffuse knowledge as 
 to make it impossible for educated people to be deluded by 
 the representations of unprincipled dealers. Freedom from 
 superstition is just as important in this as in the domain of 
 astronomy or physics. So long as chemists are employed 
 by manufacturing concerns in making adulterated and 
 fraudulent foodstuffs, so long must other chemists be em- 
 ployed in protecting the people until the public in general 
 becomes wiser. A part of the common knowledge of the 
 race should be the essentials of healthful living, in order that 
 the full measure of human progress may be enjoyed. 
 
 There is needed a greater respect for food and its func- 
 tions in the human body, a better knowledge of its effect on 
 the daily output of energy, its absolute relations to health 
 and life, and the enjoyment of the same. The familiarity 
 with these facts which is given by a few hours' work in the 
 laboratory will make a lasting impression and will enable the 
 student to benefit his whole life, even if he never uses it pro- 
 fessionally. It is purely scientific knowledge, just as much 
 as that derived from a study of the phases of the moon or the 
 formulae of integration. 
 
 The variety of operations in such work, calling for great 
 diversity of apparatus and methods, is an educational factor 
 not to be overlooked in laboratory training. 
 
 For all detailed discussions and methods the reader *s 
 referred to such works as those of Wiley, Allen, Leach, etc., 
 but for the student who needs to study, as a part of general 
 education, only typical substances, and such methods as can 
 
THREE ESSENTIALS OF HUMAN EXISTENCE. 9 
 
 be carried out within the limits of laboratory exercises in 
 a college curriculum, the following pages are written. Not 
 enough is given to frighten or discourage the student, but 
 enough, it is hoped, to arouse an interest which will impel 
 him at every subsequent opportunity to seek for more and 
 wider knowledge. 
 
 Food is too generally regarded as a private, individual 
 matter rather than as a branch of social economy; it is, 
 however, too fundamental to the welfare of the race to be 
 neglected. Society, in order to protect itself, must take 
 cognizance of the questions relative to food and nutrition. 
 
 Formerly each race adapted itself to its environment and 
 trained its digestion in accordance with the available food 
 supply. In America to-day the question is not how to get 
 food enough, but how to choose from the bewildering variety 
 offered that which shall best promote the health and develop 
 the powers of the human being, and, what is of equal im- 
 portance, how to avoid over-indulgence, which weakens the 
 moral fibre and lessens mental and physical efficiency. In 
 spite of all preaching, few really believe that plain living 
 goes with high thinking. Professor Patten says that the 
 ideal of health is to obtain complete nutrition. Over-nutri- 
 tion as well as under-nutrition weakens the body and sub- 
 jects it to evils that make it incapable of survival. 
 
 Xo other form of social service will give so full a return 
 for effort expended as the help given toward better diet 
 for children and students. Fortunately help is coming fast. 
 The United States Government is giving much study to 
 food problems, and by publications is making available the 
 work of other countries. The later bulletins listed in the 
 bibliography at the end of this volume are especially valu- 
 able. What is now needed is a general recognition of the 
 importance of the subject. 
 
CHAPTER II. 
 
 air: composition; impurities; relation to human- 
 life. 
 
 The average adult human being makes about eighteen 
 involuntary respirations per minute. The tidal volume of 
 air is from 300 to 500 cubic centimeters (30 cu. in.), about 
 2800 cubic centimeters (170 cu. in.) remaining in the lungs 
 unless voluntarily expelled by deep breathing. The total 
 volume expelled is often called the vital capacity, and is about 
 3400 cubic centimeters for men and 2500 for women. Even 
 when at rest a volume of 7000 to 12,000 liters (250 to 420 
 cu. ft.) of air passes through the lungs of each individual in 
 twenty-four hours. Under conditions of exercise more or 
 less prolonged or violent this volume may be doubled. The 
 composition of the normal inspired air by volume is approxi- 
 mately: nitrogen and argon 79 per cent., oxygen 20.9 per 
 cent., other constituents 0.1 per cent. The air as it leaves 
 the lungs contains nitrogen 79.5 per cent., oxygen 16.0 per 
 cent., carbon dioxide 4.4 per cent., and is saturated with 
 water-vapor. There has therefore taken place an inter- 
 change of gases (called the respiratory exchange), by which 
 oxygen has passed into the fluids of the body, and carbon 
 dioxide into the air contained within the lung-cells. Only 
 about one-fifth of the total oxygen is abstracted during each 
 tide. 
 
 If the composition of the inspired air varies from the 
 
air: relation to human life. ii 
 
 normal, this exchange is disturbed, owing to the difference 
 in gaseous pressure and in rate of absorption which this 
 variation causes. So delicate is the balance of the active 
 forces that serious disturbance of the functions of the living 
 organism occurs if the percentage of oxygen is lessened by 
 one or two tenths, or if the pressure is raised or lowered by 
 a fraction of an atmosphere. It is true that, like a tree 
 bending before the wind, the organism soon adapts itself to 
 changed circumstances, provided the change is not too great 
 nor too suddenly made; but, like the exposed tree, the living 
 being is never quite so vigorous and symmetrical as it would 
 have been without the effort to overcome disadvantageous 
 conditions. 
 
 That a permanent or habitual lowering of the oxygen in 
 inspired air must be harmful will be readily seen from a con- 
 sideration of the office of this gas in the body. To Lavoisier 
 and Laplace we owe the knowledge that animal heat is de- 
 rived from a process of combustion. Lavoisier held, how- 
 ever, that the seat of this combustion was in the lungs, and 
 it is to Pfliiger and his pupils that we are indebted for the 
 proofs that it is in the tissues themselves, while the lungs 
 serve as a clearing-house or centre qf exchange. 
 
 By the union of the oxygen with the substances found in 
 the tissues and brought to them by the circulating fluids of 
 the body from the digested food, the heat necessary for the 
 life and work of the body is produced. This heat is needed 
 to keep the tissues at the temperature at which they can best 
 accomplish their work, to give mechanical power for the in- 
 voluntary action of heart and lungs, for the processes of 
 assimilation, and to furnish the energy for all voluntary work 
 and thought. Thus both water and food are intimately con- 
 cerned in the processes in which air is an essential factor. 
 The statement made in the first sentence of Chapter I is 
 
12 AIR, WATER, AND FOOD. 
 
 therefore justified, namely, that air, water, and food together 
 are three essentials of human existence. A certain relation 
 between the three means health, and any disturbance of this 
 relation means unhealth, by which term may be designated 
 a condition of less than perfect health not yet so serious as 
 to be called sickness. 
 
 Air being a mere mixture of the gases nitrogen and oxy- 
 gen, in no definite atomic proportions, and carrying varying 
 amounts of other substances, gaseous and suspended parti- 
 cles, no definite composition can be given. The difference 
 between the air over sea or forest plateau and that of city 
 streets or of crowded tenements seems only slight if expressed 
 in per cent. From 20.98 per cent, of oxygen in the first to 
 20.87 an d 20.60 in the last; from .022 per cent, of carbon 
 dioxide in the purest air to .045 in cities and .33 in rooms, are 
 the common variations; and yet the effect of these apparently 
 small differences on human beings subjected to them is very 
 noticeable. It is customary to enhance these differences by 
 expressing the results in parts per 10,000. 
 
 That the carbon dioxide is of itself a disturbing factor is 
 indicated by the observed fact that air which has had the per 
 cent, of oxygen reduced by combustion to a point at which 
 a candle will no longer burn may be made again a supporter 
 of combustion by the removal of the cafbon dioxide. 
 
 A practical application of this principle is made in the 
 devices used in diving and in entering mines filled with irre- 
 spirable gases. 
 
 There is a sensible effort in breathing, and a feeling of 
 discomfort is usually experienced, if the carbon dioxide ac- 
 cumulates to ten times the normal amount, or 40 parts per 
 10,000 instead of 4. This is probably due to its solubility 
 and to its interference with the respiratory exchange, since 
 the interchange of gases is influenced by their " partial pres- 
 
air: relation to human life. 13 
 
 sures." Each gas forming part of a mechanical mixture 
 
 exerts a partial pressure proportional to its percentage of the 
 
 mixture. For example, if atmospheric air, containing 20.81 
 
 per cent, of oxygen, is at 760 millimeters barometric pres- 
 
 20.81 
 sure, the partial pressure of the oxygen would be X 
 
 760=158.15 millimeters. The following partial pressures 
 of oxygen and carbon dioxide in inspired air and in the lung- 
 cells show the extent of variation in different parts of the 
 respiratory tract: 
 
 Inspired Air. Lung-cells. 
 
 Oxygen 158.15 mm. 122 mm. 
 
 Carbon dioxide 0.30 mm. 38 mm. 
 
 Gas will always tend to diffuse from the region of high- 
 est to that of lowest pressure. Hence the reason for the 
 great influence of pressure in causing the diffusion of oxygen 
 from the inspired air into the lung-cells and for the converse 
 movement of carbon dioxide. That variation in pressure 
 has much to do with the discomfort is shown in the so-called 
 mountain-sickness, experienced at high altitudes in rarefied 
 air, and in the so-called caisson-disease, developed in men 
 working in compressed air. If the passage from the caissons 
 to the open air is made gradually, there is little trouble, but 
 a quick change is often dangerous. A sort of mountain- 
 sickness is experienced by many on entering a close room 
 from the outside air. Usually this passes away in a measure 
 as the organism accommodates itself to the new conditions. 
 Even if the symptoms are not severe, there is a dulness or 
 an irritability which is not conducive to the best apprehen- 
 sion of a difficult subject or to the fullest enjoyment of an 
 entertainment. 
 
 This lessening of mental capacity is especially to be de- 
 
14 AIR, WATER, AND FOOD. 
 
 plore'd in the case of school-children, who are at an age when 
 respiration is most frequent and the need of pure air the 
 greatest, and also when economy of effort is most demanded. 
 
 It has been said that from the study of the physiological 
 effects of close air it seems to be indicated that the evil is 
 due to the change in the respiratory quotient and to the con- 
 sequent change in blood-pressure, which interferes with the 
 circulation. The respiratory quotient is obtained by divid- 
 ing the volume of carbon dioxide given off by that of the 
 oxygen absorbed, and indicates how much of the oxygen has 
 combined with carbon to form carbon dioxide, since one vol- 
 ume of oxygen combines with caroon to form one volume of 
 carbon dioxide. The rate of exchange is influenced by 
 questions of pressure, exposure, temperature, and water- 
 vapor or moisture, muscular activity, and the like. 
 
 Water-vapor is the most variable constituent, due to the 
 changing capacity of air for moisture at different tempera- 
 tures and to the character of the earth's surface. Whether 
 over land or water, cultivated or forest region, air at o° C. 
 contains only 4.87 grams of water per cubic meter, while air at 
 6o° F. (15 C.) can take up 12.76 grams, and at 90 F. holds 
 33.92 grams. Since the human body is constancy giving off 
 moisture from skin and lungs, and since this exhalation is an 
 important factor in the bodily economy, the presence of ex- 
 cessive moisture in the air exercises a decided effect. 
 
 On clear, invigorating days the moisture in the air may 
 be only 30 or 50 per cent, of that required for complete satu- 
 ration at the given temperature, and although the ther- 
 mometer reading may indicate 85 ° F. on a hot day, little 
 discomfort follows; but let the humidity rise to 90 or 95 per 
 cent, while the' temperature remains the same, and oppres- 
 sion, restlessness, or languor results. Much the same effects 
 are seen in the case of close rooms and crowded halls. The 
 
air: relation to human life. 15 
 
 watery vapor given off (about 20 grams per person per hour) 
 soon saturates the air, and the consequent drowsiness and 
 headache usually attributed to carbon dioxide will be felt; 
 while if this moisture is removed, the same proportion of 
 carbon dioxide would hardly inconvenience the occupants. 
 A relative humidity of 60 per cent, is said to be the most 
 comfortable for house temperature. 
 
 In normal man, exposure to cold increases the respiratory 
 exchange; but if he represses shivering and keeps still by 
 force of will, it apparently does not. Politely sitting still in- 
 creases the probability of taking cold. A high temperature 
 lessens the production of carbon dioxide and therefore saves 
 food. This may in part account for the oppressiveness felt 
 by well-fed and warmly clothed persons in public places none 
 too warm for those with a more restricted diet. 
 
 Muscular activity increases respiratory exchange and 
 causes a demand for food. A class of students passing across 
 the campus, up several flights of stairs, into a lecture-room 
 vitiate the air for the first ten minutes at a rate higher by 
 one part of carbon dioxide per 10,000 than half an hour later. 
 The exchange is also stimulated by a meal. Not only the 
 oxidation of the food itself, but the muscular activity of the 
 alimentary canal and probably other accompanying activities 
 call for an expenditure of energy which is supplied by in- 
 creased heat production. 
 
 Sodium sulphate is said to increase the various respira- 
 tory activities, and some have held this, fact to be one reason 
 for the beneficial effects of certain mineral waters. 
 
 The amount of carbon dioxide expired is estimated by 
 Pettenkofer .at .006 to .012 cubic foot per pound of body 
 weight, according to the degree of exertion. Rubner con- 
 siders that, in general, metabolic processes depend also upon 
 the proportion of superficial area to the total volume of the 
 
1 6 AIR, WATER, AND FOOD. 
 
 body, hence the smaller the animal the greater the surface to 
 the whole mass. Children give off in proportion to their 
 body weight about twice as much carbon dioxide as adults. 
 Another estimate gives the output of carbon dioxide as 
 .0027 gram per hour per square centimeter of surface. 
 
 Ammonia is also a constant component of the air of in- 
 habited places and is washed out by rain and snow, as will 
 be shown in Chapter VI. 
 
 Of the occasional impurities, probably the most fatal is 
 carbon monoxide arising from leaking gas-fixtures or de- 
 fective furnaces. This gas has 250 times the affinity for 
 haemoglobin and therefore forms with it a more stable 
 compound than does oxygen, and hence its presence causes 
 a deficiency of the latter gas in the blood, giving symp- 
 toms like those observed in mountain-climbing or bal- 
 loon ascensions. When the blood-corpuscles become about 
 one-third saturated the effect becomes sensible; but if the 
 quantity of gas is considerable, the symptoms are hardly 
 noticeable before insensibility occurs. For this reason, glow- 
 ing charcoal and open gas-jets are the favorite forms of 
 cowardly self-destruction. 
 
 In the neighborhood of factories, smelting-works, ore- 
 heaps, and of cities burning soft coal there is a noticeable 
 amount of sulphurous and sulphuric acids, sometimes so con- 
 siderable as to destroy vegetation. 
 
 In places where gas is burned, oxides of nitrogen are 
 formed in small quantity, the effect of which is known to be 
 harmful. Minute quantities of hydrogen sulphide and of com- 
 pounds of carbon and hydrogen and of other gases may be 
 present, especially in houses with defective plumbing or in the 
 neighborhood of barns, cesspools, and filthy back yards. 
 These may reach dangerous proportions, but, like carbon 
 
air: relation to human life. 17 
 
 monoxide, should not be permitted in or near any well-regu- 
 lated household. 
 
 Soot, being insoluble, accumulates in the lungs, as a post- 
 mortem examination of persons who have lived for some time 
 in a smoky city proves; nevertheless no definite ill effects 
 have been as yet attributed to this cause. This again con- 
 firms the inference that it is the gaseous constituents, and the 
 varying temperature and pressure, which seriously affect the 
 respiratory exchange 
 
 The following results, obtained on the air of a large man- 
 ufacturing city, will be of interest in this connection: * 
 
 GRAMS PER 1,000,000 CUBIC METERS OF AIR.f 
 Soot. H 2 S0 4 . FreeNH 3 . Alb. NH 3 . HNO,. HN0 2 . 
 
 1000 to 40000 7000 to 63000 1 100 to 1000 97 to 557 45 to 1063 o to 155 
 
 1 Partly H a SO s . 
 
 It is probable that much of the danger ascribed to sewer- 
 air arises from other causes. Since the atmosphere in sewer- 
 pipes is always moist, the only probable source of organisms 
 is the splashing of the water. Only about one-half as many 
 organisms have been found in the air a'bove flowing sewage 
 as in out-door air. Professor Carnelley and Dr. Haldane 
 found only one-half as much carbon dioxide and one-third 
 as much organic matter in such air as in that of the streets 
 above. 
 
 Beyond individual control, and in a measure beyond gen- 
 eral control, there exists suspended matter in the air: fine 
 volcanic dust, pollen, spores of moulds and algae, dried bac- 
 teria, diatoms, small seeds of plants, soot and the finely 
 pulverized earth from roads and cultivated and barren lands. 
 To this portion of the air we owe beautiful sunsets and dis- 
 agreeable fogs. To it manv affections of the throat and 
 
 * Mabery: /. Am. Chem. Soc, 17 (i8qs). 105. 
 
 f See also Bailey: " The Air of Large Towns," Science, Oct. 13, 1893. 
 Irwin: "The Soot Deposited on Manchester Snow,"y. Soc. Chem. bid* 
 (1902), 533. 
 
18 AIR, WATER, AND FOOD. 
 
 eyes are due, and by it disease may be transmitted. Some 
 kinds of dust lodge in the air-cells and by irritation render 
 tke individual liable to disease, as statistics of the mortality 
 in dust-producing trades show. In the air of houses this 
 impurity increases a thousand-fold by means of the wear of 
 furnishings and the accumulation on them of deposited par- 
 ticies, by means of furnace-ashes and dried debris of all 
 kinds. Only recently have the dangers of this part of the 
 air we breathe been distinctly pointed out. 
 
 Aitken * estimated that a cubic inch of air may carry 
 2000 dust-particles in the open country, 3,000,000 and more 
 in cities, and 30,000,000 in inhabited rooms. Among these 
 millions there may be found from ten to several hundred 
 micro-organisms, moulds, and bacteria, and, under certain 
 conditions, pathogenic germs. 
 
 As methods of culture become more satisfactory and tests 
 more universal, it may be demonstrated that many old or 
 long-inhabited buildings furnish several varieties of patho- 
 genic germs constantly to the air. 
 
 According to some authorities, the most dangerous con- 
 tamination of the air is the " crowd-poison," or organic 
 matter given off with the carbon dioxide and moisture in the 
 breath. References will be found in the bibliography to dis- 
 cussions of the subject. No evidence has ever been found 
 in the course of investigations in this laboratory, covering a 
 period of twenty-five years, that the healthy human lung gives off 
 any toxic substance. The same conclusion is reached by Dr. 
 Emanuel Formanek of the Hygienic Institute at Prague after 
 a long series of critical experiments.f 
 
 * Nature, 31 (187 o), 265; 41 {1886) t 394. 
 f Archlv fur Hygiene, 38 (igoo), 1. 
 
CHAPTER III. 
 
 THE PROBLEM OF VENTILATION. 
 
 From the preceding chapter it will be seen how impor- 
 tant is the purity of the air to human well-being, and how 
 essential is the diffusion of the knowledge of the methods 
 by which it can be secured. It is often said that artificial 
 ventilation is a modern necessity. Remains of aqueducts 
 and sewers have testified to the sanitary intelligence of his- 
 toric peoples, but the ventilating fan does not seem to have 
 been included, although natural ventilation by shafts and flues 
 has been practised since man came out of cave-dwellings. It 
 is true that customs have changed as to many items of daily 
 life. In cities more people live on an acre of ground, thus 
 fouling the air above and the ground beneath ; more factories 
 are belching smoke; more coal is burned; houses are built 
 with smaller rooms and less pervious walls; schools and 
 lecture-halls are more crowded; people are better fed, con- 
 sequently there is more garbage; streets are macadamized, 
 allowing finely ground particles to fill the air with every puff 
 of. wind; gas-pipes traverse the walls of every house and 
 pass under every street; carpets, draperies, and much passing 
 in and out cause an accumulation of dust unknown fifty 
 years ago. Kerosene lamps require more oxygen than manv 
 candles. Besides, people -are becoming less hardy and more 
 sensitive physically, so that well-ventilated living-spaces are 
 a modern necessity if human efficiency is to be maintained. 
 
 19 
 
20 AIR, WATER, AND FOOD. 
 
 As we have seen, the air of open spaces presents only 
 very slight variation at the same level or for several thousand 
 feet above it. The movement of the air caused by the wind 
 is usually so rapid, and the reservoir of air for many miles 
 above the earth is so immense in comparison with the thin 
 vitiated layer, that there are only to be considered enclosed 
 spaces in which human beings remain for a period of time. 
 
 To supply the 7000 to 12,000 liters (250 to 430 cube feet) 
 of tidal air per person in maximum purity, there must be 
 brought to the person at rest some 1800 cubic feet of air per 
 hour. If he were in an air-tight chamber 12 feet square and 
 8 feet high, a man would reach the limit of purity in 38 
 minutes; but no ordinary room is air-tight, and when the 
 difference between inside and outside temperature is consid- 
 erable, a rapid exchange is taking place even with doors and 
 windows shut. 
 
 To secure the passage of this large volume of air through 
 a small space without causing a draft that will be objected to 
 by the abnormally sensitive victim of modern luxurious 
 habits is the problem of ventilation — one not yet satisfactorily 
 solved. 
 
 The sanitary engineer is expected to design the appara- 
 tus and to aid the architect in so placing and proportioning 
 flues, inlets, and outlets as to accomplish the desired results. 
 Unfortunately it is too common, especially in the case of 
 school and college buildings, to economize in the first cost 
 by dispensing with the services of the expert and to leave to 
 the builder and " practical " architect all such details. In 
 any case, it often becomes necessary to call in the chemist to 
 prove the need of reform, or to show by the composition of 
 the air whether or not the ventilating plant is doing its work 
 efficiently. 
 
 The sanitary inspector, whose business it is to decide 
 
air: the problem of VENTILATION. 21 
 
 upon the legal questions connected with tenements and fac- 
 tories, must often rely upon chemical examinations of the 
 air. The validity of these depends not only upon the per- 
 fection and delicacy of apparatus and methods used, but also 
 upon the judgment and intelligence with which the samples 
 are taken. 
 
 Many errors in the construction of buildings have been 
 perpetrated because of an ignorance of the physical proper- 
 ties of air and, consequently, a mistaken notion of the be- 
 havior of a vitiated atmosphere. The lecturer on popular 
 science who some forty years ago enlightened (?) the com- 
 munity on the chemistry of daily life was accustomed to use, 
 as a striking illustration, a glass jar in which a small lighted 
 candle was instantly extinguished on pouring into the jar a 
 tumblerful of carbon dioxide which had been collected for 
 the purpose. The inference was plain: carbon dioxide was 
 heavier than air, therefore it falls to the floor and must be 
 allowed to flow out as if it were a stream of water. Further 
 confirmation of this inference was found in the frequently 
 observed fact that a candle lowered into a well often went 
 out just before the water was reached. 
 
 Hence for many years the habits of thoughtful persons 
 were formed on a belief in the heaviness of carbon dioxide or 
 " bad air," and in its tendency to go to the bottom of the 
 room and into any holes it could find. This is only another 
 instance of danger in half a truth. When do we find cold 
 carbon dioxide generated in living-rooms? And how warm 
 must the gas be in order to be lighter than the ordinary air? 
 How quickly does diffusion take place? Until within a very 
 few years the almost unanimous belief among the so-called 
 educated classes was that the bad air could be let out by 
 opening a window at the bottom, and, in spite of the lessons 
 w 7 hich might have been learned by any observant person in 
 
22 AIR, WATER, AND FOOD. 
 
 hanging pictures or Christmas greens, the common practice 
 in private houses, churches, and schools is to open the win- 
 dows at the bottom. 
 
 All ordinary vitiation of the air proceeds from a heated 
 source. Human breath and warm air are lighter than cold 
 air and rise even with their burden of carbon dioxide. It is 
 only when they impinge on a very much colder surface, as on 
 the window-pane on a very cold day, that they become suffi- 
 ciently chilled to fall without mixing with the neighboring 
 air. The freedom with which the gases of the air mix, as 
 well as the rapidity of the action, may be illustrated in a 
 variety of ways. Open a bottle of any volatile and pungent 
 substance, as ammonia or hydrogen sulphide, in one corner 
 of a room, and almost instantly it may be perceived in the 
 most distant part. 
 
 In natural ventilation we have only to avail ourselves of 
 these characteristic properties of gases; and whether we wish 
 to get rid of the light gases escaping from furnace, stove, or 
 gas-pipe, or of the specifically heavier carbon dioxide, or of 
 the most dangerous dust, we must furnish an outlet at the 
 place to which the fleeing enemy first arrives, lest it turn and 
 rend us for our ignorance. 
 
 It is usually sufficient to furnish this opportunity, the 
 current caused by this willing escape drawing in sufficient 
 fresh air to take its place except in very crowded rooms, and 
 even these might be so ventilated provided the whole roof 
 were one large ventilating flue. If, however, the air is to be 
 drawn from the bottom of the room, its unwilling current 
 must be pulled by a superior force, as by an open fire on the 
 hearth, which heats the air above it so that, in rushing into. 
 the free air above, it draws after it all things movable within 
 reach. Then, indeed, even the top of the room becomes 
 quickly cleared and no corner can escape; but if the fire be 
 
air: the problem of ventilation. 23 
 
 long gone out and the chimney cold, the reverse takes place 
 and cold, heavy air sinks to the floor, helping to confine the 
 bad air at the top of the room. 
 
 What the cold chimney cannot accomplish the mechani- 
 cally driven fan can do, namely, by a slight compression 
 force a draught even up a cold chimney. In this case the 
 very unwillingness of the air to take the prescribed path 
 helps in the result as water forced through a miil-wheel de- 
 velops mechanical work. The warmed fresh air forced in 
 near the top of the room loses its velocity as it mingles with 
 that already present, and finds its way along the line of least 
 resistance to the opening provided at the bottom of the 
 room, into the flue, but only in case there is no easier way. 
 
 Open doors or windows interfere with the prescribed 
 course, and blindness to this fact on the part of the occupants 
 of mechanically ventilated buildings has caused unjust com- 
 plaints of the system. The necessity of regulating the con- 
 sumption of fuel and admission of fresh air in accordance 
 with variations of temperature, as well as the great care and 
 trouble this involves, renders the " natural " system of ventila- 
 tion practicable only in less crowded dwelling-houses where 
 intelligence can control the varying factors. For schools, 
 lecture-halls, or any enclosed spaces occupied by numbers of 
 persons at one time, some form of mechanical ventilation 
 offers the only hope of good air in cold climates. What 
 form that shall take is for the engineer to decide. The chem- 
 ist's part is to devise means of readily determining whether 
 the persons in charge of the apparatus are using it to gain 
 the results designed by the expert. 
 
 As a test of how nearly practice approaches the theoreti- 
 cal value, carbon dioxide is taken as the indicator, since it is 
 present in a thousand times larger quantitv than any other 
 impurity and since it is easily determined. If the air has 
 
24 AIR, WATER, AND FOOD. 
 
 only the normal amount of carbon dioxide, it is but rarely 
 that it contains enough of anything else to be harmful. The 
 presence of hydrogen sulphide or of coal-gas is betrayed by 
 the odor. Where the gas-supply is " water-gas," contain- 
 ing 30 to 40 per cent, of carbon monoxide, there is greater 
 danger; but if legal restrictions are complied with, the pres- 
 ence of this can be detected in the same way, viz., by the 
 odor. 
 
 Danger may also arise from the presence of so-called 
 " sewer-gas," which, however, is not a single gas, but a most 
 complex and variable mixture of the more volatile products 
 of decomposition. For the detection of " sewer-air " chemi- 
 cal tests are of little value, since it contains no constituent 
 in sufficient quantity and with sufficient regularity to 
 serve as an index of its presence. Ill-smelling gases are 
 given off only when sewage is about eighteen hours old, 
 hence dirty house-pipes are the chief cause of foul air. The 
 delicate sense of smell is of value here. Indeed, an edu- 
 cated nose is most essential in all examinations of house- 
 air. " Crowd-poison," if it exists, keeps company with the 
 increase of the products of respiration, and if the incoming 
 air is strained or taken from a place free from dust, the par- 
 ticles added to the air which is in the rooms will also be re- 
 moved with the carbon dioxide. 
 
 From nearly all points of view, carbon dioxide is an indi- 
 cator of the efficiency of ventilation, especially if combined 
 with observations of temperature and moisture. It is an in- 
 dicator also readily understood and accepted by the public. 
 
 The principles of ventilation may be readily illustrated to 
 a class by means of simple apparatus. Such an apparatus, 
 using candles and designed to illustrate the section of an 
 ordinarv room, is shown in Fig. I. 
 
 In testing the efficiency of ventilation of any room or 
 
AIR: THE PROBLEM OF VENTILATION. 
 
 25 
 
 building, it is necessary to determine first the direction of the 
 air-currents, for there can be no ventilation without currents. 
 If the architect who designed the building, or the engineer 
 who advised the architect, is responsible, then the chemist 
 has only to follow directions in taking the samples; but fre- 
 quently the chemist, as well as the sanitary engineer, is called 
 
 Fig. 1. — Apparatus to Illustrate the Principles of Ventilation. 
 
 upon to make tests of rooms and buildings of which no plans 
 are available. 
 
 In the examination of such rooms, then, the position of 
 flues or conduits, both inlets and outlets, which were intended 
 to convey air or which serve without such intention, should 
 first be located. Possible avenues of ingress and egress by 
 means of loose windows, cracks around doors, etc., are to be 
 considered. When there is great difference of temperature 
 between outer and inner air, these allow of quite rapid change 
 of air. Some means of rendering visible these currents is de- 
 sirable, such as smouldering paper, magnesium powder, or 
 fumes of ammonium chloride. 
 
26 AIR, WATER, AND FOOD. 
 
 When the direction and intensity of these air-currents 
 have been determined, the places from which the air-samples 
 are to be taken may be chosen. It will be evident in what 
 part of the room stagnation occurs and where eddies are 
 formed, also where the air escapes. 
 
 In a room or building without artificial ventilation the 
 air-currents are seen to be ascending until they become 
 chilled, when they fall. An empty room will not show so 
 decidedly the rise of air-currents as will an occupied one in 
 which the vitiated air, being much warmer, rises more rap- 
 idly and cools less quickly. In taking the samples all acci- 
 dental means of contamination must be avoided and the 
 occupants must be quiet, for the moving of persons causes 
 disturbance in the air-current. There is room for great in- 
 genuity in this part of the examination, as circumstances 
 greatly modify the method of procedure. A fair sample, or 
 a sufficient number of samples to give a fair average, must 
 be taken. 
 
 Having secured and analyzed the samples of air, the de- 
 cision as to the efficiency of ventilation must be rendered. 
 
 If the room examined is a study- or recitation-room, the 
 stratum of air at the level of the students' heads should not 
 contain over 8 or 9 parts per 10,000 of carbon dioxide, should 
 not show a temperature of over 70 F., nor a humidity of 
 over 35 or 50 per cent., and these conditions should be main- 
 tained for hours at a time. 
 
 For lecture-halls and spaces occupied for only one hour 
 at a time, with ample time between occupation, it is admis- 
 sible to allow 9 to 11 parts. If fan ventilation is used, the 
 outlet should give the average degree of contamination. If 
 no system is used, the air at the top of the room is first 
 vitiated; only at the end of twenty minutes to half an hour 
 do the lower layers begin to show it. 
 
CHAPTER IV. 
 
 ANALYTICAL METHODS. DETERMINATION OP CARBON 
 
 DIOXIDE. 
 
 General Statements. — Since the earliest crude attempts 
 at the determination of carbon dioxide all chemical methods 
 have been based on its absorption by alkalies or alkaline 
 earths. It may be the -diminution in volume of the air 
 through absorption of the carbon dioxide that is measured ; 
 the carbon dioxide may be separated as barium carbonate 
 and weighed ; the reduced alkalinity of the absorbing liquid 
 may be determined ; or the carbon dioxide may be set free 
 from the absorbing solution and its volume determined 
 directly ; all of these methods have been used with more or 
 less success. For determining with great exactness the 
 amount in out-door or " fresh " air it is customary to aspirate 
 large quantities of air, sometimes as much as 600 liters, 
 through the absorbing solution. For determining the 
 amount in the air of rooms a much smaller sample, collected 
 in calibrated vessels, of from one to eight liters, is preferable. 
 
 Where it is necessary to absorb large quantities of the 
 gas in a slight volume of solution, potassium or sodium hy- 
 droxide is used. For nearly all of the " popular tests " cal- 
 cium hvdroxide, lime-water, is used because of its harmless 
 nature and the ease with which it can be obtained from the 
 corner drug store, or from the quicklime procured from the 
 mason's barrel. For volumetric methods barium hydroxide 
 is generally preferred, because of the less solubility of the 
 
 27 
 
28 AIR, WATER, AND FOOD. 
 
 barium carbonate, it being only about two-thirds as soluble 
 as the calcium salt. The very avidity with which these 
 substances take up carbon dioxide is a hindrance to the 
 preparation of standard solutions in an atmosphere already 
 rich in it. When once prepared the solution must be pre- 
 served with especial care, since contact with the hands or a 
 whiff of the breath will reduce its strength and vitiate the 
 results. All such solutions are best kept in bottles well pro- 
 tected from the air by tubes filled with soda-lime and de- 
 livered from a burette, as described on page 36. 
 
 Pettenkofer Method. — The method which for many years 
 was generally employed for the estimation of carbon dioxide 
 in the air of rooms is some modification of that originally 
 devised by Pettenkofer.* 
 
 Principle.— In principle this consists in absorbing the 
 carbon dioxide from a known volume of air in barium hy- 
 droxide solution and titrating the excess with standard 
 sulphuric acid. It is essential for the complete absorption of 
 the carbon dioxide that the barium hydroxide be largely in 
 excess, so that not more than one-fifth of it is neutralized ; 
 furthermore, the absorbing solution must be shaken up with 
 the air for a considerable time. 
 
 Collecting the Samples.- — The samples are collected in four- 
 or eight-liter bottles, the volume of which is accurately 
 known, the bottles having been calibrated by weighing them 
 filled with water. These bottles are provided with a rubber 
 stopper carrying a glass tube over which a rubber nipple 
 is slipped. They are filled with the air to be tested by 
 means of a pair of nine-inch blacksmith's bellows, fitted 
 with valves so arranged as to draw the air cut of the bottle. 
 The bellows is connected with a three-quarter-inch brass 
 
 * Pettenkofer: Annalen, 2, Supp. Band (1862), p. 1. Gill: Analyst, 17 (1892), 
 184. 
 
AIR: ANALYTICAL METHODS. 29 
 
 tube reaching nearly to the bottom of the bottle ; fifteen or 
 twenty strokes should be sufficient to replace the air in a 
 four-liter bottle. At the time of collecting the samples the 
 following observations should be recorded: Room, date, 
 time, weather, place in room, number of people present, number 
 of gas-jets or lamps burning, condition of the doors, windows, 
 and transoms; in short, everything that would tend to affect 
 the amount of carbon dioxide in the air,, or to cause currents or 
 eddies. The bottles should be distinctly labelled and their 
 volumes recorded. If the temperature at the point where 
 the samples are collected should be essentially different from 
 that of the laboratory, the bottles should be allowed to 
 stand in the laboratory for half an hour, or until they have 
 attained its temperature. 
 
 Directions for Laboratory Work. — The solutions of barium 
 hydroxide and sulphuric acid which are used are approxi- 
 mately of equal strength; but since it is impracticable to 
 prepare exact solutions of barium hydroxide and to keep 
 them without change, the exact value of the barium hy- 
 droxide solution must be found by titration against the 
 standard sulphuric acid, which is made of such a strength 
 that 1 cubic centimeter is equivalent to exactly 1 milligram 
 of C0 2 . This standardization, as well as the subsequent 
 titration, is best made in a small flask to lessen the error 
 from absorption of carbon dioxide from the air. It will be 
 found most generally satisfactory to measure into the flask 
 about 25 c.c. of the barium hydroxide, add. a drop of phen- 
 olphthalein solution, and titrate with the sulphuric acid to 
 the disappearance of the pink color. In all cases the first 
 end-point should be taken as the correct one, because the 
 pink color will sometimes return on standing. This is due 
 to the presence of minute quantities of potassium or sodium 
 hyd^.'^ide in the solution. The alkali sulphates will react 
 
30 AIR, WATER, AND FOOD. 
 
 with any barium carbonate which may be suspended in the 
 liquid with the formation of alkali carbonates which give a 
 pink color with phenolphthalein.* The standardization 
 should be repeated until consecutive results are obtained 
 which check within 0.2 per cent, of each other. 
 
 Determination. — Remove the cap from the tube in the 
 stopper of the bottle, insert the tube-tip of the burette so 
 that it projects into the bottle, and run in rapidly 50 c.c of 
 barium hydroxide from the burette. Replace the cap and 
 spread the solution completely over the sides of the bottle 
 while waiting three minutes for the burette to drain. In 
 doing this take care that none of the solution gets into the 
 cap. Note carefully the temperature and barometric 
 pressure. Place the bottle on its side and roll or shake it 
 at frequent intervals for forty-five minutes, taking care that 
 the whole surface of the bottle is moistened with the solution 
 each time. At the end of this time thoroughly shake the 
 bottle to mix the solution, remove the cap, and pour the 
 solution into a stoppered bottle of hard glass of 40 c.c. 
 capacity, taking care that the solution shall come in contact 
 with the air as little as possible. Under these conditions a 
 full well-stoppered bottle may safely stand for days before 
 titration. For the titration, measure out with a pipette 
 25 c.c. of the clear liquid into a 7 5 -c.c. flask and titrate it 
 with the sulphuric acid as in the standardization. The differ- 
 ence between the number of cubic centimeters of standard 
 acid required to neutralize the total barium hydroxide 
 before and after absorption gives the number of milligrams 
 of dry carbon dioxide in the sample tested. The results 
 may be expressed in parts per 10,000, by volume, under 
 
 * This action can be largely prevented by including a small amount of barium 
 chloride when making up the barium hydroxide solution (see p. 247.) 
 
air: analytical methods. 31 
 
 standard conditions (o° and 760 mm.), saturated with 
 moisture (Method 1) or dry (Method 2). Tables for this 
 purpose will be found in Appendix A.* 
 
 Example. — Data: Standardization, I c.c. Ba (0H) 2 = 
 1.020 c.c. H 2 S0 4 volume of bottle = 8490 c.c; Ba(OH);j 
 used = 49.9 c.c. ; H 2 S0 4 used = 21. 1 c.c. ; temperature and 
 pressure = 21 and j66 mm. 
 
 Before absorption 
 
 49.9 c.c. Ba(OH) 2 = 49.9 X 1.020 = 50.90 c.c. H 2 S0 4 . 
 After absorption 
 
 49.9 c.c. Ba(OH) 2 = 42^2. x 21. 1 = 42.12 c.c. H 2 S0 4 . 
 
 . '. (8490 — 49.9) = 8440. 1 c.c. air contain 50.90— 42. 12 = 
 
 8.78 mg. C0 2 . 
 
 Method 1. — I c.c. C0 2 saturated with moisture at 2 1° and 
 
 766 mm. weighs 1.79624 mg. (Table II, Appendix A). 
 
 8 78 
 .-. 8.78 mg. = —7 — =4.887 c.c. C0 2 saturated with 
 
 moisture. 
 
 tt r ■ 1 4.887 
 
 Hence in 10,000 c.c. of air there are -^ — X 10,000 = 
 
 8440. 1 
 
 5.79 parts C0 2 . 
 
 Method 2. — In this method the volume of air is reduced 
 to standard conditions of temperature and pressure, under 
 which conditions the weight of a cubic centimeter of dry C0 2 
 is a constant quantity. 
 
 Thus v' — v{\ + o.oo366(/ / — *°)]. 1/ = 8440.1, f = 21 , 
 t° = o° ; hence v = 7837.7 c.c. 
 
 * Dietrich's Table, the one in general use, is not absolutely correct, the 
 weight of a cubic centimeter of carbon dioxide at o° C. and 760 mm. being 
 somewhat different from that given at present by the best authorities, but 
 it is sufficiently close for any but the most exacting work. 
 
32 AIR, WATER, AND FOOD. 
 
 Also, v : v"=H"\H> or 7837.7 : ^=760: (766— 18.5). 
 
 (18.5 = tension aqueous vapor at 21 .) 
 
 Then v" = 7709 c.c. = volume of air at o° and 760 mm. 
 
 1 c.c. CO2 at o° and 760 mm. weighs 1.9643 mg. 
 
 8.78 4-469 
 
 = 4.469 c.c. CO. — X 10,000 =5.79 parts 
 
 1.9643 " * 7709 
 
 C0 2 per 10,000. 
 
 Two samples are to be taken, closely following the notes, 
 and the results calculated by both methods before collecting- 
 more samples. Then some one room may be taken and the 
 quality of the air determined for the different hours of the 
 day, or a comparison of different rooms may be made, or a 
 building may be tested as a whole. All data and results ob- 
 tained should be arranged in tabular form on a separate page 
 of the note-book. 
 
 Notes. — This method of collecting the air in a large bottle 
 possesses a decided advantage over the method of slowly 
 drawing the air through barium hydroxide contained in a long 
 tube, in that a sample represents the condition of the air at 
 a given time and not its average condition for a period of an 
 hour or so. 
 
 In collecting samples, care must be taken to avoid cur- 
 rents of air or the close proximity of people. Duplicate 
 samples can be obtained only in empty or nearly empty 
 rooms. Even two sides of the same room will probably 
 show differences, but two samples taken carefully side by 
 side ought to agree within 0.05 part per 10,000. 
 
 While the Pettenkofer method is convenient, and for a 
 long time has been the favorite, it is now quite generally 
 recognized that it contains inherent sources of error which 
 can be obviated only by the use of complicated apparatus 
 and extreme skill in manipulation. That the method can 
 be employed to obtain results of the highest degree of accu- 
 
AIR: ANALYTICAL METHODS. 33' 
 
 • racy has been shown by Letts and Blake* in an exhaustive 
 study of the question. The refinements found necessary, 
 however, place their modification out of consideration for 
 ordinary use. 
 
 The principal source of error lies in the necessity for 
 titrating the alkaline liquid within the "area of contamina- 
 tion," the exhaled breath containing on an average from 
 50 to 100 times as much carbon dioxide as the air under 
 examination. Other important sources of error which have 
 been found to lead to erroneous results are the action of 
 the caustic alkali on the glass of the large bottle, and the 
 presence of small amounts of the precipitated barium car- 
 bonate in the solution during the titration. It should 
 therefore be borne in mind that results obtained by this 
 method may be too high even though agreeing closely 
 among themselves. 
 
 The small bottle to which the solution is transferred for 
 settling should be of such a size (40 c.c.) that the volume 
 which drains readily from the large bottle when the glass 
 tube is flush with the stopper shall a little more than fill it. 
 That is, no air-space should be left to serve as a medium for 
 transpiration from the surrounding air if the bottle stand 
 for some hours. On the other hand, there should be a 
 sufficient excess over the 25 c.c needed to ensure the filling 
 of the pipette at the first trial. This pipette is globular in 
 shape, with a stem of small diameter above and below the 
 bulb. The last drop is taken off by touching the neck 
 of the flask after counting ten from the time it is 
 empty. It is then set upright to drain; the drop which 
 collects is gently shaken out before the next titration. 
 The error is less than if it were rinsed with water each time. 
 
 All rubber stoppers which are used should first be boiled 
 
 * Proc. Royal Dublin Sec., 9, 107 (iqoo). 
 
34 AIR, WATER, AND FOOD. 
 
 in dilute caustic soda, then in a dilute solution of potassium 
 bichromate and sulphuric acid and thoroughly washed. 
 
 Walker Method. — A comparatively simple method in 
 which the errors inherent to the Pettenkofer process are 
 avoided has been proposed by Walker.* 
 
 The method has been carefully studied in this laboratory f 
 and found to be capable of great accuracy 
 
 Principle. — To a definite volume of air, usually i to 2 
 liters, is added a measured amount of standard barium 
 hydroxide, care being taken to avoid contact of the solution 
 with the air. After the absorption of the carbon dioxide, 
 the solution is filtered under reduced pressure through as- 
 bestos and the clear barium hydroxide received into a 
 known excess of standard hydrochloric acid. The absorp- 
 tion vessel is rinsed out with water free from carbon dioxide. 
 The excess of acid is then determined by titration with 
 barium hydroxide. 
 
 Reagents and Apparatus. — The standard solutions used 
 are N/50 hydrochloric acid, and barium hydroxide, approxi- 
 mately N/100, its exact strength relative to the acid being 
 found daily by titration. It will be found advantageous 
 to use solutions of this strength, somewhat more dilute than 
 those recommended by Walker, on account of the increased 
 accuracy with air nearly free from carbon dioxide. The 
 decreased range of usefulness is readily compensated ' by 
 the employment of smaller samples of the impure air. 
 
 The barium hydroxide, which is usually made up in 
 quantities of 8 liters at a time, is preserved with especial 
 care. The hard-glass bottle containing it, placed on a high 
 shelf so that the measuring apparatus can be filled directly 
 .by gravity, is heavily coated on the inside with barium 
 
 * J. Chem. Soc, jj t IIIO {iqoo). 
 
 ■f Woodman : /. Am. Chem. Soc, 25, 150 (iqoj). 
 
air: analytical methods. 
 
 35 
 
 carbonate. The bottle is closed by a rubber stopper 
 with two holes, one of which carries the siphon tube dip- 
 ping to the bottom of the bottle and supplying the meas- 
 uring burette, while the other carries a fairly large glass T 
 (Fig. 2). 
 
 A 
 
 I 
 
 W 
 
 Fig. 2. 
 
 From one-half the horizontal arm of this projects a glass 
 tube carrying the device for protecting the solution. This 
 device is shown drawn on a somewhat larger scale in the 
 same sketch. The horizontal tube enters the T tube far 
 
36 AIR, WATER, AND FOOD. 
 
 enough to support the apparatus. Connection is made, 
 by a closely fitting rubber tube. The longer tube, reaching 
 nearly to the bottom of the test-tube, carries a fairly good- 
 sized "calcium chloride tube" which contains soda-lime, 
 enclosed in the usual manner by pings of cotton. The test- 
 tube contains 5 to 10 c.c. cf dilute (about N/50) caustic 
 potash colored with phenolphthalein, the whole serving to 
 indicate the efficiency of the soda-lime. From the other 
 end of the horizontal arm of the T projects in the same way 
 a long tube bent at right angles fitting by a rubber stopper 
 into the top of the burette, thus making the whole a closed 
 system, much after the manner of Blochmann.* Any air 
 entering the bottle when the solution is drawn from the 
 burette or when the burette is filled again must have come 
 through the protecting apparatus. This will be found 
 efficient if care is taken in the selection or preparation of 
 the soda-lime. t 
 
 The burette used for the barium hydroxide is a glass- 
 stoppered one, differing somewhat from the ordinary form. 
 The lower portion below the graduations is narrowed and 
 bent at right angles. This horizontal part is fitted with an 
 ordinary glass stop-cock. This gives no trouble when kept 
 well vaselined. The tip of the burette is kept covered with 
 a little rubber cap when not in use to prevent clogging from 
 the formation of carbonate. The apparatus could easily be 
 arranged with a special pipette for the delivery of a definite 
 charge of baryta solution if desired. 
 
 The bottles used for the collection of samples are of 
 hard glass of about 2 liters capacity, the exact volume being 
 determined in each case to a cubic centimeter. The bottle 
 
 * Ann. Chem. (Liebig), 237, 39 (1887). 
 
 f Directions for preparing a good quality of soda-lime are given by Benedict 
 and Tower: /. Am. Chem. Soc, 21, 396 (i8qq). 
 
AIR: ANALYTICAL METHODS. 
 
 37 
 
 is olosed by a rubber stopper through which pass two glass 
 tubes about 7 mm. in diameter. The longer tube reaches 
 almost to the bottom of the bottle; the shorter tube ends 
 internally just flush with the stopper. Both tubes project 
 externally about two inches and are provided with stop- 
 
 Fig. 3. 
 
 cocks at slightly different levels so as to permit of convenient 
 manipulation. There is permanently attached to the upper 
 end of the longer tube a piece of rubber tubing 1 inch in 
 length which serves to connect it with the tip of the baryta 
 burette. The stop-cocks may be replaced by rubber tubing 
 and Mohr pinch-cocks if desired. 
 
38 AIR, WATER, AND FOOD. 
 
 The apparatus used for filtering off the barium carbonate 
 is shown in Fig. 3. 
 
 To the base of a ring-stand is firmly clamped an ordinary 
 filter-bottle of about 250 c.c. capacity closed by a rubber 
 stopper with two holes. Through one of these passes a tube 
 leading to the suction-pump, through the other the tube of 
 a Gooch filtering-funnel, the upper part of which is cut off 
 so that the remainder above the constriction is about an 
 inch long. The tip projecting into the bottle is bent so that 
 the liquid shall flow down the side and not spatter. A 
 rather close coil of stout platinum wire placed above the 
 narrow portion serves as a support for the asbestos filter, 
 or can be removed if it is desired to use a cotton plug instead. 
 In the upper part of the tube is tightly fitted a rubber 
 stopper through which passes a narrow glass tube extending 
 to within one-eighth inch of the asbestos layer and provided 
 above the stopper with a stop-cock. Connection is made 
 with the short tube of the inverted bottle by means of a 
 rubber tube about 8 inches in length. 
 
 Procedure. — (a) The Absorption. — Insert the tip of the 
 baryta burette into the short piece of rubber tubing and run 
 in approximately 50 c.c. with both stop-cocks open. Close 
 the outlet cock, pinch the rubber tube with the fingers, 
 detach it from the burette and insert a bit of glass rod to 
 keep out the air. Finally close the stop-cock. Drain the 
 burette three minutes and take the reading as usual. 
 Carry out the absorption of the carbon dioxide as described 
 in the Pettenkofer method, except that 25-30 minutes is 
 ample for the absorption. 
 
 ib) The Filtration. — While the absorption is in progress 
 prepare the filter. Apply slight suction and add enough 
 asbestos fiber suspended in water to form a felt about a 
 sixteenth of an inch thick over the platinum coil. Wash it 
 
air: analytical methods. 39 
 
 once or twice with distilled water. If properly done the 
 water should flow from the filter-tube in a continuous 
 stream when the pump is running at good speed, but should 
 drop only slowly when the suction is slight. 
 
 Prepare also about ioo c.c. of " wash- water " by adding 
 to distilled water i c.c. of a 10 per cent, barium chloride 
 solution and three drops of phenolphthalein, then titrating 
 with the barium hydroxide to a faint permanent pink. Keep 
 in a stoppered flask until wanted. 
 
 Measure into the filter-bottle 25 c.c. of the hydrochloric 
 acid. 
 
 The arrangement of the bottle and filter during filtration 
 is shown in the figure. 
 
 Open the stop-cock of the shorter tube and turn on the 
 pump. Now slowly open the filter stop-cock and control the 
 flow of liquid entirely with this cock. The barium carbonate 
 remains on the asbestos, and the clear baryta solution which 
 passes through is at once neutralized by the hydrochloric 
 acid. When all the liquid has passed through allow the 
 pump to act for a few minutes to partially exhaust the 
 bottle, then close the filter-cock. 
 
 Pour some of the wash-water into a small beaker, dip 
 the end of the longer tube into it, .and by opening the stop- 
 cock allow about 20 c.c. to flow into the bottle before again 
 closing it. Unclamp the bottle and shake thoroughly while 
 held horizontally and still attached to the filter. Clamp it 
 in place again, turn on the pump, and drain off the wash- 
 water. Repeat this twice. Generally at the third washing" 
 the wash-water is no longer turned pink, showing that the 
 barium hydroxide has been completely removed. Remove 
 the stopper and cock from the filter-tube and draw the re- 
 mainder of the wash-water through the filter to wash down 
 the sides of the tube. 
 
40 AIR, WATER, AND FOOD. 
 
 (c) The Titration. — Transfer the acid solution tea 6-inch 
 porcelain dish and run in barium hydroxide to the produc- 
 tion of a distinct pink color. Return the solution to the 
 filter-bottle and pour it again into the dish. One or two 
 drops of the alkali solution will suffice to finish the titra- 
 tion. 
 
 Note. — It will be seen that in this method the errors of 
 the other are largely avoided. The alkali solution is made 
 weaker, and its time of contact with the glass of the bottle 
 is shorter; the barium carbonate is entirely removed if the 
 filtration is properly conducted ; the titration is not carried 
 out in an alkaline solution, but in one that is acid. 
 
 For a discussion of the results obtained the papers cited 
 above may be consulted. 
 
 Strong potassium hydroxide is undoubtedly the best absorb- 
 ent for carbon dioxide and in all cases where delicate manipula- 
 tion and expensive apparatus are not hindrances, some form 
 of gas absorption apparatus is best. The measurement of the 
 gas should be made over mercury and in a finely calibrated 
 tube. Eimer and Amend now supply a modification of 
 the Petterson and Palmquist apparatus which gives good 
 results. 
 
 General Tests. — In addition to the above methods for 
 determining carbon dioxide just described, there are general 
 tests which can often be used with advantage. If within the 
 space of a few hours some fifty or more tests are to be made, and 
 comparative results rather than great accuracy are required, 
 some simpler form of apparatus is desirable. 
 
 Such an apparatus, to be satisfactory, should meet, so 
 far as possible, the following requirements: 
 
 (i) It should be sufficiently compact and portable to be 
 carried in the hand from place to place. 
 
air: analytical methods. 41 
 
 (2) It should be as simple in construction as possible, 
 and its use should not involve delicate measurements. 
 
 (3) If possible, the apparatus should be made entirely 
 of glass, avoiding prolonged contact of corks or of rubber 
 connectors with any dilute solution which may be used. 
 
 (4) It should be so constructed as to protect the solution 
 at all times from the carbon dioxide of the air, especially 
 while the determination is being made, because of necessity 
 such an apparatus must be used within the area of contami- 
 nation. 
 
 (5) The complete apparatus should be sufficient for fifty 
 or more determinations. 
 
 (6) It must be capable of giving results of a reasonable 
 degree of accuracy, say within 0.5 part of carbon dioxide in 
 10,000 parts of air, in the hands of persons having little or 
 no chemical knowledge and minimum skill in manipula- 
 tion. 
 
 (7) If a solution be used in the apparatus it should be 
 one which can be prepared easily from chemicals readily 
 obtained; the solution must maintain its efficiency for a 
 reasonable length of time, if protected from external influ- 
 ences; and the solution should be one that is not at all 
 dangerous or obnoxious to use. 
 
 Simplicity of apparatus is much to be desired, but it 
 should not be gained at too great sacrifice of accuracy. Even 
 when no greater precision is required than is necessary to 
 meet the demands of practical work, it is out of the question 
 to measure the test solution by means of an ordinary pipette 
 or to preserve it for any length of time in stoppered vials; 
 the strength of the solution is almost certain to be reduced 
 by contamination with the breath, by contact with rubber 
 or cork. 
 
42 
 
 AIR, WATER, AND FOOD. 
 
 It must ever be borne in mind that extreme care is 
 necessary in the preparation and rise of these very dilute 
 solutions, the strict observance of conditions which might 
 well be neglected in ordinary analytical procedures being 
 here an essential factor of success. 
 
 For the preservation and measuring of the test solution 
 the authors have devised an apparatus which appears to 
 answer the above requirements, and in actual practice has 
 been found satisfactory.* 
 
 The essential feature of this apparatus consists of an 
 automatic pipette for measuring the test solution. This is 
 a modified form of the pipette first pro- 
 posed by G. P. Vanier and in use in this 
 laboratory for a number of years. A gen- 
 eral idea of it may be had from Fig. 4. 
 The manner of using it is extremely simple. 
 The test solution is preserved in a 1 -liter 
 bottle of hard glass provided with a doubly 
 perforated rubber stopper. Through one 
 opening passes the siphon tube of the pi- 
 pette, which is sufficiently long to reach to 
 the bottom of the bottle ; through the other 
 passes a glass tube ending just below the 
 stopper and connected with a small bottle 
 containing fresh soda-lime. By means of 
 the three-way cock the solution is allowed 
 to flow into the small inside pipette until 
 it overflows. The stop-cock is then turned 
 and the solution allowed to flow out 
 at the lowest point. The pipette is 
 made of such a size as to deliver exactly 
 10 cubic centimeters. The entrance of atmospheric car- 
 
 * Air Testing for Engineers. A. G. Woodman and Ellen H. Richards: Tech. 
 Quar., 14, 94 ^9 01 )- 
 
 Fig. 4. — Automatic 
 Pipette. 
 
AIR: ANALYTICAL METHODS. 43 
 
 bon dioxide as the solution flows out is prevented by the 
 small tube containing soda-lime or bits of caustic potash, 
 The excess of liquid which accumulates in the overflow 
 reservoir may be drawn off when desired. The bottle and 
 pipette are contained in a wooden case about 20X8x7 inches, 
 outside dimensions, and with the solution weigh about 8 
 pounds. The case is furnished with a handle at the top so 
 that it may be carried readily in the hand from place to 
 place. The bottle is fastened to the case, and the lower 
 end of the pipette is clamped to a wooden support to keep 
 it from swinging. The stopper should be firmly fastened 
 to prevent loosening. 
 
 The bottle should be thoroughly cleaned and washed 
 with potassium bichromate and sulphuric acid, and it is 
 best also to steam it for half an hour or so. As a further 
 measure of precaution the rubber stopper is boiled with 
 dilute caustic potash and thoroughly washed, although the 
 solution can come in contact with it only through splashing 
 while the case is being carried. 
 
 This measuring apparatus may be used with a variety of 
 methods and with various strengths of solution. 
 
 The general tests are based on two fundamental principles. 
 For instance, the Fitz and Wolpert methods are carried out 
 by shaking a small quantity of dilute lime-water, colored pink 
 by phenolphthalein, with successive portions of air until the 
 solution is decolorized. The greater the amount of carbon 
 dioxide in the air the less will be the volume of air required 
 to neutralize the lime-water, and vice versa. That is, the amount 
 of lime-water remaining constant, the amount of carbon 
 dioxide will vary in a certain inverse ratio to the volume of 
 air. 
 
44 AIR, WATER, AND FOOD. 
 
 The method of Cohen and Appleyard* is based upon the 
 fact that if a dilute solution of lime-water, slightly colored 
 with phenolphthalein, is brought in contact with a sample 
 of air containing more than enough carbon dioxide to com- 
 bine with all the lime present, the solution will be gradually 
 decolorized, the length of time required depending upon 
 the amount of carbon dioxide present. That is, the quantity 
 of lime-water and the volume of air remaining the same in 
 each case, the rate of decolorization will vary inversely with 
 the amount of carbon dioxide. The method is scientific in 
 principle because it recognizes the fact that the absorption 
 of carbon dioxide by dilute alkali solutions is a time- 
 reaction. 
 
 The method of preparation of the solutions and the 
 manner of making the tests which have been found to give 
 the best results will be described in detail, since experience 
 has shown that these directions cannot be too minute. 
 
 Preparation of the Test Solution. — The solution used is 
 a dilute solution of lime-water colored with phenolphthalein. 
 To freshly slaked lime add twenty times its weight of water 
 in a bottle of such size that it is not more than two-thirds 
 full. Shake the mixture continuously for 20 minutes, and 
 then allow it to settle over night or until perfectly clear. 
 The resulting solution is the stock lime solution, or "satu- 
 rated lime-water." If made in the manner indicated, each 
 cubic centimeter of it ought to be very nearly equivalent 
 to 1 milligram of carbon dioxide. If, however, it is desired 
 to know the strength of it more exactly, it may be deter- 
 mined by standard acid. 
 
 To prepare the "test solution," pour into the 1 -liter 
 bottle of the testing apparatus 1 measured liter of distilled 
 
 * Chem. News, 70, (1894), in. 
 
air: analytical methods. 45 
 
 water, and add 2.5 ex. of a solution of phenolphthalein (made 
 by dissolving 0.7 gram of phenolphthalein in 50 c.c. of 
 alcohol and adding an equal volume of water). Stand the 
 bottle on a sheet of white paper and add the "saturated 
 lime-water " drop by drop from a pipette, shaking the bottle 
 thoroughly after each addition until a faint pink color is 
 produced which is permanent for one minute. Now add 
 6.3 c.c. of the " saturated lime-water," shake, and imme- 
 diately connect the bottle again to the apparatus. 
 
 For accuracy in testing air which is high in carbon dioxide, 
 it is found advantageous to use a solution twice as strong as 
 the above. This double solution is prepared in precisely the 
 same way, using 5.0 c.c. of the phenolphthalein solution and 
 12.6 c.c. of the " saturated lime-water." 
 
 While this procedure does not give an exact volume of 
 solution, it is believed to be the best for the preparation 
 of this dilute test solution, since it obviates the necessity 
 for pouring the prepared solution from the measuring-flask 
 into the bottle in which it is kept; 12.6 c.c. of the stock 
 lime solution is added rather than 10 c.c, in order to keep 
 the values obtained with the resulting solution more nearly 
 comparable with the older values calculated on the suppo- 
 sition that 10 c.c. of " saturated lime-water " was equivalent 
 to 12.6 milligrams of carbon dioxide. 
 
 Method of Making the Test. — The Fitz shaker or appara- 
 tus for measuring the volume of air used, consists of a tube 
 of about 30 cubic centimeters capacity, closed at one end, 
 and graduated for a distance of 20 cubic centimeters from 
 the closed end. In this tube, by means of a rubber collar, 
 slides a smaller tube which is contracted at the outer end 
 so as to be more readily closed by the finger. The appa- 
 ratus is shown full size in Fig 5. 
 
4 6 
 
 AIR, WATER, AND FOOD. 
 
 See that the inner tube of the shaker slides readily in 
 the outer one, moistening the rubber collar slightly if 
 necessary. Have the inner tube pressed down to the 
 
 bottom of the larger one, and 
 measure into the apparatus 10 
 cubic centimeters of the test solu- 
 tion from the automatic pipette, or 
 from a burette, as in Fig. 2. Pull 
 the inner tube up to the 5-c.c. mark 
 (the bottom of the inner tube serv- 
 ing as the index) and close the end 
 of the tube with the finger. Hold 
 the apparatus horizontally, and 
 shake it vigorously for exactly 30 
 seconds. 
 
 The amount of air that is thus 
 brought in contact with the solution 
 is equivalent to approximately 30 
 cubic centimeters, as there are 25 
 cubic centimeters of air above the 
 liquid when the small tube is forced 
 to the bottom of the larger. Re- 
 move the finger, press down the 
 small tube again to the bottom of 
 the larger and draw it up to the 
 20-c.c. mark. Shake the apparatus 
 again for 30 seconds. The amount 
 of air brought in contact with the 
 solution is now 30 + 20 = 50 c.c. 
 Repeat the shaking, using 20 c.c. 
 of fresh air each time, until the 
 pink color is discharged. The amount of carbon dioxide 
 corresponding to the number of cubic centimeters of air 
 used will be found in Table A. 
 
 10 
 
 Fig. 5-— Fitz Shaker. 
 Full Size. 
 
air: analytical methods. 
 
 47 
 
 Acting on the same principle is the Wolpert shaker shown 
 in Fig. 50. This cylinder is easier to manipulate and results 
 obtained with it by students are more 
 consistent than those obtained with the 
 Fitz. 
 
 TABLE A. 
 
 Double 
 
 
 Standard Test 
 
 Solution. 
 CO2 in 10,000. 
 
 Cubic Centimeters 
 of Air. 
 
 Solution. 
 CO2 in 10,000. 
 
 22.2 
 
 5° 
 
 15-6 
 
 18.O 
 
 70 
 
 12.4 
 
 I5- 1 
 
 90 
 
 10.2 
 
 13.O 
 
 no 
 
 8.7 
 
 "•3 
 
 13° 
 
 7-5 
 
 9.9 
 
 15° 
 
 6.6 
 
 8.8 
 
 170 
 
 5-8 
 
 8.0 
 
 190 
 
 5- 2 
 
 7-3 
 
 210 
 
 4.8 
 
 6.8 
 
 230 
 
 4-5 
 
 6-3 
 
 250 
 
 4-3 
 
 5-9 
 
 270 
 
 4.1 
 
 5-6 
 
 290 
 
 3-95 
 
 5-4 
 
 310 
 
 3-8 
 
 5-i 
 
 33° 
 
 H 
 
 4.8 
 
 35° 
 
 3.6 
 
 4-7 
 
 31° 
 
 
 4-5 
 
 39o 
 
 
 4.4 
 
 410 
 
 
 4.2 
 
 45° 
 
 
 4.0 
 
 490 
 
 
 3-9 
 
 53o 
 
 
 I 
 
 The following notes and precautions feiV - 
 
 apply to both forms of the shaker. 
 Care should be taken that the finger 
 used to close the end of the tube is 
 perfectly clean, since on a warm day FlG " 5a ' 
 
 the free acid in the perspiration might easily vitiate the 
 results. Some may find the use of a rubber stopper prefer- 
 able. 
 
 If greater accuracy is desired, the shaker should be filled 
 \rith the air to be tested before running in the test solution. 
 
48 AIR, WATER, AND FOOD. 
 
 This may be done readily by filling the shaker with water 
 and emptying it. 
 
 The apparatus should be shaken vigorously and contin- 
 uously during the 30 seconds in order to absorb practically 
 all of the carbon dioxide in the enclosed air. The number 
 of shakings ought not to be less than 100 during this time. 
 
 Care should be taken not to contaminate the air while 
 the sample is being taken. The breath should be held momen- 
 tarily while the air in the apparatus is being replaced, and the 
 sample should be collected as far to one side of the body as 
 possible. It ought not to require over 10 seconds to replace 
 the air, and the entire test, with air containing, say, 8 parts 
 of carbon dioxide per 10,000, should not require over 6 
 minutes. 
 
 If less than 90 c.c. of air is required to discharge the pink 
 color, the test should be repeated, using 10 c.c. of air each 
 time after the first 30 c.c. 
 
 It is not necessary to rinse out the shaker after making 
 each test, but it should be carefully washed and dried after 
 using, and the parts kept separate when not in use. 
 
 The " double solution " is used in exactly the same manner 
 and amount as the regular test solution, reference being made 
 to the appropriate portion of the table. 
 
 For the Cohen method the same solutions may be used 
 and measured from the same apparatus. The samples are 
 collected in white, glass-stoppered bottles of one-half liter 
 capacity. This may be done by aspirating the air with a bel- 
 lows, or the bottles may be completely filled with water, which 
 is then emptied at the place where the air is to be tested. 
 
 A convenient modification of this is the water siphon method. — 
 Two bottles (diameter one-third the height) of nearly equal 
 capacity are fitted with rubber stoppers carrying small glass 
 tubing, connected by several feet of rubber connector with 
 
air: analytical methods. 
 
 49, 
 
 clamps (Fig. 6). One bottle is completely filled with water, 
 nearly free from carbon dioxide. 
 
 The pair of bottles is taken to the place from which the air 
 is to be collected. The inlet tube may be long to reach to near 
 
 Fig. 6. 
 
 the ceiling, or short; if long, the first siphoning should be 
 rejected, to secure filling the inlet tube with the air desired, 
 the stoppers exchanged, and the sample taken. The air-filled 
 bottle is stoppered and taken to the laboratory; or the test 
 solution is at once added, the bottle stoppered and shaken, 
 noting minutes and seconds. One bottle of water with a small 
 
.5° 
 
 AIR, WATER, AND FOOD. 
 
 reserve will serve for a number of takings before absorbing a 
 deleterious amount of C0 2 . (See Fig. 6.) 
 
 A method involving more preparation but less trouble in 
 the field is the steam vacuum method. The steam is supplied 
 by a 500 c.c. flask serving as a boiler with a Tirrill burner to 
 
 Fig. 7. — Steam- Vacuum Apparatus. 
 From the thesis of Carl E. Hanson, 1908. 
 
 supply the heat. The flask (Fig. 7) is fitted with a rubber 
 stopper carrying a No. 6 glass tube bent so that one end extends 
 within one half-inch of the bottom of the bottle when placed in 
 position on the stand. The bottles used are of about 500 c.c. 
 capacity, made for a ground-glass stopper but fitted with a 
 rubber stopper. 
 
air: analytical methods. 51 
 
 To prepare the jet, the water in the flask is allowed to boil 
 for five minutes in order to expel completely the air in the 
 water and the flask. The pressure should be sufficient to throw 
 the vaporized steam at least one foot above the exposed end 
 of the tube. 
 
 The empty bottle is placed on the stand in an inverted 
 position and allowed to remain for three minutes. In the mean- 
 time a thin coating of vaseline is applied half way up the sides 
 of the stopper. The vaseline acts as an unguent, reducing 
 the coefficient of friction to such an extent that the principal 
 resistance is due to the reaction of the stopper against com- 
 pression. This enables one to force the stepper in far enough 
 t:o bring the glass and rubber into intimate contact, which is 
 essential. The vaseline also fills the interstices between the 
 rubber and the glass, which makes leakage impossible. 
 
 Protecting the hand with a cloth, the bottle is raised from 
 the stand, and the instant it clears the end of the tube the 
 stopper is inserted while the bottle is still inverted. The 
 stopper may be pushed in more securely by pushing it against 
 the table with a few pounds pressure while the bottle is still 
 in the inverted position. The stopper is kept in under this 
 pressure for a few minutes until the vacuum begins to form, 
 after which the atmospheric pressure will keep it in place. 
 
 All the bottles required are treated in the same way. The 
 rubber stoppers should be at least one size larger than would 
 ordinarily be used for the bottles, and should project three- 
 eighths of an inch or more to be easily removed when the sample 
 is to be taken. 
 
 Sample bottles may be tested for completeness of vacuum 
 by holding them in an inverted position under water at 70 
 F., free from carbon dioxide, and removing the stopper. After 
 the water has replaced the vacuum, the stopper is inserted and 
 the bottle removed. 
 
5 2 
 
 AIR, WATER, AND FOOD. 
 
 In making the test 10 c.c. of the test solution are run in 
 from the automatic pipette, or from a burette as in Fig. 2, 
 the time noted, and the bottle shaken continuously and 
 vigorously with both hands until the pink color vanishes. 
 From the time required the amount of carbon dioxide in the 
 air may be found by referring to Table B. 
 
 TABLE B. 
 
 Double Solution. 
 
 Time, 
 Minutes and 
 
 "Test Solution.' ' 
 
 Double Solution. 
 
 Time. 
 Minutes and 
 
 CO2 in 10,000. 
 
 Seconds. 
 
 CO2 in 10,000. 
 
 CO2 in 10,000. 
 
 Seconds. 
 
 .... 
 
 O.15 
 
 .... 
 
 4.0 
 
 5-45 
 
 
 
 O.30 
 
 15-6 
 
 
 6.00 
 
 
 
 o-45 
 
 12. 1 
 
 3-9 
 
 6.15 
 
 16.O 
 
 1. 00 
 
 9.9 
 
 
 6.30 
 
 i3-i 
 
 i-i5 
 
 8.4 
 
 3*8 
 
 6-45 
 
 11.4 
 
 1.30 
 
 7.2 
 
 
 7.00 
 
 IO.I 
 
 i-45 
 
 6.3 
 
 
 7-i5 
 
 9.1 
 
 2.00 
 
 5-5 
 
 3-7 
 
 7-3° 
 
 8-3 
 
 2.15 
 
 4.9 
 
 
 
 7.6 
 
 2.30 
 
 4.4 
 
 
 
 7.0 
 
 2.45 
 
 4.0 
 
 
 
 6-5 
 
 3.00 
 
 3-8 
 
 
 
 6.1 
 
 3-i5 
 
 3-7 
 
 
 
 5-7 
 
 3-3° 
 
 3-6 
 
 
 
 5-4 
 
 3-45 
 
 
 
 
 5-i 
 
 4.00 
 
 
 
 
 4.9 
 
 4-i5 
 
 
 
 
 4-7 
 
 4-3° 
 
 
 
 
 4-5 
 
 4-45 
 
 
 
 
 4-3 
 
 5.00 
 
 
 
 
 4.2 
 
 5-*5 
 
 
 
 
 4.1 
 
 5-30 
 
 
 
 
 Carbon Monoxide. — The detection and estimation of 
 carbon monoxide in the very minute quantities in which 
 it is found in the air of ordinary rooms is a problem of 
 considerable difficulty. 
 
 Detection. — Probably the most convenient test for detect- 
 ing small quantities is the blood test. Dilute a large drop 
 of human blood, freshly drawn by pricking the finger, to 10 
 c.c. with water. Divide the solution into two equal portions, 
 and shake one portion gently for ten minutes in a bottle 
 containing about 100 c.c. of the air to be tested. Compare 
 the tints of the two portions by holding them against a well- 
 
air: analytical methods. 53 
 
 lighted white surface. The presence of carbon monoxide is 
 indicated by the appearance of a pink tint in the blood which 
 has been shaken with air. One part in 10,000 can be de- 
 tected in this way.* The delicacy of the test can be increased 
 by examining- the blood, after shaking with the air, with 
 a spectroscope. By collecting the sample in an 8-liter bottle 
 and examining it in this way 0.01 part m 10,000 may be detected. 
 Determination. f — Principle. — Oxidation of the carbon 
 monoxide to carbon dioxide by iodine pentoxide, iodine 
 being liberated according to the following equation: 
 
 I 2 5 + 5 CO = I 2 + $co 2 . 
 
 N 
 
 The iodine is titrated with sodium thiosulphate. 
 
 1000 r 
 
 Directions. — Place 25 grams of iodine pentoxide, free from 
 
 iodine, in a small U tube which is suspended in an oil-bath 
 
 and connected with a small absorption-bulb containing 0.5 
 
 gram of potassium iodide dissolved in 5 c.c. of water. Heat 
 
 the oil-bath to 150 C, and pass the air, previously drawn 
 
 through U tubes, — one containing sulphuric acid and the 
 
 other solid potassium hydroxide, — through the apparatus at 
 
 the rate of a liter in two hours. Titrate the liberated iodine 
 
 N 
 
 bv sodium thiosulphate and starch. 
 
 J 1000 l 
 
 Notes. — The temperature and barometric pressure should 
 be noted and all volumes reduced to o° C. and 760 mm. pressure. 
 
 Using 1000 c.c. of air, it is possible to determine in this 
 way 0.25 part per 10,000, by volume, of carbon monoxide. 
 
 The use of tubes containing sulphuric acid and potassium 
 hydroxide is to free the air from unsaturated hydrocarbons, 
 hydrogen sulphide, sulphur dioxide, and similar reducing gases. 
 
 * Clowes: " Detection and Estimation of Inflammable Gas and Vapor in 
 Ihe Air," p. 138. 
 
 t Kinnicutt and Sanford: Jour. Am. Chem. Soc, 22 (1900), 14 
 
54 AIR, WATER, AND FOOD. 
 
 Nitrites- — The determination of the amount of nitrites 
 
 or nitrous acid in the air can be readily made as follows: 
 
 Collect a sample of the air in a calibrated eiodit-liter bottle, 
 
 as in the determination of carbon dioxide. Add ioo c.c. of 
 
 N 
 approximately — sodium hydroxide solution. (This should 
 
 be free from nitrites and is best made by dissolving metallic 
 sodium in redisti led water.) Shake the bottle occasionally 
 and let it stand for about twenty-four hours. Take out 50 
 c.c. of the solution and determine the amount of nitrites as 
 directed on page 108. 
 
 Micro-organisms. — For the quantitative determination 
 of the number and distribution of the micro-organisms in air, 
 the method employed by Tucker * in the examination of the 
 air of the Boston City Hospital answers very well. The 
 apparatus used consists essentially of three parts: (1) a 
 special glass tube called the aerobioscopc, in which is placed 
 the filtering material; (2) a stout copper cylinder of about 
 sixteen liters capacity, fitted with a vacuum-gauge; (3) an 
 air-pump. The filtering medium which is used to retain the 
 micro-organisms is a narrow column of sterilized granulated 
 sugar about four inches long. 
 
 In using the apparatus, the required amount of air is first 
 drawn from the cylinder by means of the air-pump. A 
 sterilized aerobioscopc is then attached to the cylinder and the 
 air is slowly drawn through it, leaving its germs in the sugar- 
 filter. After the air has been drawn through, the aerobioscopc 
 is taken to the culture-room and the sugar dissolved in 
 melted sterilized nutrient gelatine. The ge'atine is con- 
 gealed in an even film on the inside of the tube, where, after 
 
 * Report State Board of Health, Mass., 1889, 161. 
 
air: analytical methods. 55. 
 
 'four or five days, the colonies will develop, and can be 
 counted by the aid of squares engraved upon the glass. 
 
 This method possesses several peculiar advantages. The 
 use of a vacuous cylinder allows a known volume of air to be 
 readily aspirated, and the rate of flow through the filter is 
 easily controlled. Another great advantage is the use of a 
 soluble filter (sterilized granulated sugar), since insoluble 
 substances seriously interfere with the counting. Further- 
 more, the removal or transference of the filter and its germs 
 is avoided. The apparatus is portable, and the method, as 
 compared with others, is exceedingly rapid of execution. 
 
 Organic Matter. — In regard to the presence of organic 
 matter in the air there is at present considerable variance of 
 opinion. While some investigators have obtained results- 
 which indicate the presence of such organic matter, it has 
 been found also that the amount which is obtained is very 
 much less when the dust of the air is first removed by filtra- 
 tion. The quantity of organic matter is therefore closely re- 
 lated to the amount of dust, and there is strong evidence that 
 this dust in the air is the source of the greater part, if not all,, 
 of the organic matter, unless there are present persons with 
 decayed teeth, diseased lungs, etc. 
 
 The methods of determination that are in general use 
 may be divided into two groups. In the first group are 
 those methods in which the organic matter is converted into 
 ammonia and determined by Nessler's reagent. In the sec- 
 ond group the organic matter is oxidized by boiling with 
 dilute potassium permanganate, the excess being titrated 
 with oxalic acid. No one method gives results which are 
 wholly satisfactory, the chief difficulties being to secure an 
 absorbing material which shall itself be free from organic 
 matter, and to avoid the introduction of minute particles of 
 organic matter or dust during the analytical process. 
 
56 AIR, WATER, AND FOOD. 
 
 Remsen * and Bergey f recommend the use of freshly- 
 ignited granular pumice-stone contained in a narrow glass 
 absorption-tube. After aspirating a known volume of air, 
 the pumice-stone is transferred to a flask, the ammonia dis- 
 tilled off from alkaline permanganate and estimated by Ness- 
 ler's reagent. Experience with the method in this labora- 
 tory has shown that it is practically impossible to prepare the 
 pumice-stone so that it shall be absolutely free from organic 
 matter, and that the mere act of transference of the absorb- 
 ing material resulted in a considerable error. Miss Talbot J 
 iound, furthermore, that all of the organic matter is not con- 
 verted into ammonia by a single distillation, but that a second 
 and third redistillation of the distillates uniformly gave 
 higher results. She found it preferable to draw the air 
 directly through the boiling permanganate, having the ap- 
 paratus so arranged that the condensed steam was returned 
 to the flask. In this way the particles of organic matter were 
 returned again and again to be acted upon by the perman- 
 ganate. 
 
 Experience with all these methods is well summed up by 
 Professor Remsen when he says: " It would be useless to 
 have examinations of air made by any but the most careful 
 workers. It would be time thrown away to have such an- 
 alyses made by the average practical chemist.'* 
 
 Dust and Soot — The dust in the air may be estimated by 
 drawing a measured volume through tubes packed with cot- 
 ton and noting the increase in weight. Soot may be deter- 
 mined by drawing the air through combustion-tubing partly 
 filled with ignited asbestos, and then determining the carbon 
 by the ordinary methods of combustion. 
 
 * National Bd. Health Bulletin, I, 233; II, 517. 
 
 f Mis. Coll. of Smithsonian Institution, No. 1037 (1896). 
 
 X Tech. Quart., 1 (1887), 29. 
 
CHAPTER V. 
 
 WATER : ITS SOURCE, PROPERTIES, AND RELATION TO LIFE 
 
 AND HEALTH. 
 
 {From the Householder' s Standpoint.) 
 
 The metabolism which produces human energy is depen- 
 dent upon the presence of water in the tissues. This water 
 is derived in part from food which, as eaten, contains from 
 30 to 95 per cent.; in part from boiled water, as in tea and 
 coffee; or raw from well or city tap. The total daily supply 
 per person for this purpose from all sources is five or six 
 pints. 
 
 Water is also necessary to all forms of vegetable and 
 animal life, even the lowest types, including those inim'cal 
 to human health. Man has always used water as his beast of 
 ourden: to carry ships to the ocean, to turn mill-wheels, to 
 generate electrical power. He has also forced it to be his 
 scavenger, carrying the refuse of his activities out of his sight. 
 Unless compelled by legal restrictions, he has given little 
 thought to the effect on his neighbor of this treatment of 
 their common property. 
 
 In common law, water is held to be a gift of nature to 
 man for use by all, and therefore not to be diverted from its 
 natural channels for the pleasure or profit of any one to the 
 exclusion of the rest. Neither has one the right to return 
 to the channel water unfit for the use of his neighbor farther 
 
 down the stream. That is, there is no private ownership in 
 
 57 
 
5« 
 
 AIR, WATER, AND FOOD. 
 
 surface-waters flowing in natural channels. But this inter- 
 pretation of eminent jurists has not always been strictly fol- 
 lowed. Many cases have been decided, especially since the 
 rapid growth of large cities, in direct contradiction to this 
 law. As population increases, cities need to go farther and 
 farther into the country for their water-supply, and they 
 often take from the few settlers found there the right to the 
 water which passes their doors, for the benefit of far-away 
 thousands. 
 
 The law in regard to that portion which never enters, or 
 which escapes from visible channels, is less clear. It is usu- 
 ally held that this water goes with the soil, and that rights 
 to it may be bought and sold: that wells may be driven and 
 drains dug, even if a neighbor's supply is cut off; but it is 
 always maintained that no man has a right to place any sub- 
 stances on or in the ground which shall render his neighbor's 
 well unfit for use. 
 
 The changes in conditions of life have rendered impera 
 tive a careful study of the ways and means of practically com- 
 plying with the law's demand without a serious restraint upon 
 the progress of civilization. 
 
 The daily quantity required for each person has increased 
 from the two ^o four gallons drawn by bucket from the farm- 
 house well to thirty or forty gallons taken from the town sup- 
 ply by the turning of a faucet, and in cities where much is used 
 for manufacturing purposes, for running elevators and 
 motors, the daily amount may reach ioo gallons per inhabi- 
 tant. This constantly increasing use of water for other than 
 cleansing purposes has enormously increased the difficulty 
 of securine dean water for domestic use. Not only is a 
 larger quantity of polluting material deposited in the water, 
 but it is carried farther from its source by the dilution. 
 This fact, as well as the demand for higher standards of 
 
water: source, properties, and relation to life. 59 
 
 purity, has made the abandonment of private water-supplies 
 a necessity, and has demanded from municipalities the best 
 scientific knowledge and the most careful supervision of the 
 quality of the public supply. 
 
 A city or town is under as strict obligation to furnish a 
 safe supply of water as it is to provide safe roads. To this 
 end, the proper construction and maintenance of reservoirs 
 and a sufficient police surveillance of the watershed is as im- 
 portant as abundance of supply. 
 
 Education of the people at large is still necessary, not 
 only that those who depend in whole or in part upon springs 
 and wells may know how to protect themselves, but also that 
 the necessary cost of the larger public (municipal) supply 
 may be cheerfully paid for by the citizens. 
 
 Leaving out of the present discussion such considerations 
 as belong only to the engineer and specialist, the problem of 
 potable water will be treated in this chapter from the point 
 of view of the intelligent citizen and educated individual who 
 cannot afford to remain ignorant of so important a factor in 
 the general welfare. The reason why this education is needed 
 lies in the fact that primitive habits of thought, influencing 
 action in every-day life, survive long after the race has passed 
 beyond the original conditions. In no respect is this more 
 true than in regard to water. 
 
 The ideal drinking-water of most persons is the dear,, 
 colorless, sparkling water of a spring, refreshing in its cool- 
 ness and satisfying the aesthetic sense by its suggestion of 
 purity. So strong a hold has this ideal that it is most diffi- 
 cult to convince the average person that any water which has 
 these characteristics can be other than wholesome and, con- 
 versely, that w r ater lacking in any of these qualities is suitable 
 for human consumption. Early man drank clear cool water 
 
60 AIR, WATER, AND FOOD. 
 
 wherever he found it. If there was not a spring at hand, he 
 scooped out a hole in the sand. Pioneer settlers dug the 
 well as near the kitchen door or the barnyard as they could 
 find water, with a blind faith in the protecting power of 
 mother earth, not wholly misplaced so long as the require- 
 ments of the household did not exceed two or three gallons 
 per person daily, and so long as the nearest neighbor was 
 half a mile away. So persistent is this confidence in nature 
 that in the light of this day a majority of intelligent people, 
 even, will quaff at a roadside well or drink freely at a country 
 hotel or go to live in a city without ever taking thought for 
 the quality of the water. Water is water, and he who pauses 
 with his glass half-way and asks whence comes the supply is 
 scouted as a weak-minded crank. So, too, when town au- 
 thorities have spared no pains or expense to secure a safe 
 supply from a distant lake, and have guarded it by all means 
 known to science, the primitive habit of thought requiring 
 colorless water of an even coolness of temperature leads 
 those who can afford it to purchase " spring "-water in jugs 
 and bottles, with the blind faith of the savage that what comes 
 out of the ground must be good. 
 
 Fundamental race-habits are taken advantage of by the 
 dealer in spring-waters as well as by the vendor of patent 
 medicines — the missionary has no chance against him. 
 From the schools and colleges there should, however, 
 be sent out a generation of more intelligent persons who, 
 learning to weigh evidence, will not take chances and 
 will help to develop a public opinion on sanitary matters, 
 especially in regard to water-supplies. For not until 
 there is an intelligent public can the present reckless use of 
 water and ground be stopped. While no^ everv man may 
 be a chemist, he can have that modicum of knowledge which 
 will enable him to understand the need of chemical tests of 
 
water: source, properties, and relation to life. 6i 
 
 water and to distinguish between the work of the expert and 
 the amateur. 
 
 However safe this ideal of clear, colorless water may have 
 been in early times, it must now be relegated, with the un- 
 barred door and unwatched treasure, to the mountain fast- 
 nesses. As the country becomes settled, appearance and 
 taste are no longer sufficient guides; therefore scientific tests 
 must be applied and the results interpreted by trained ob- 
 servers to whom the individual subordinates his private 
 judgment. 
 
 The ideal water should be above suspicion, for if it has 
 once been contaminated, who can tell how soon it will find 
 bad company again? Not the analyst in his laboratory. In 
 fact, the laboratory verdict is worth very little without a 
 knowledge of outside conditions and without a keen detec- 
 tive insight which scents out the most unlikely causes. 
 Nevertheless the evidence given by analytical results is 
 needed to procure conviction. 
 
 Although " pure " water is found only in the laboratory, 
 " safe " water, that which is reasonably free from objection- 
 able substances, mineral and organic, may be obtained with 
 sufficient care and knowledge. 
 
 A clear understanding of the problem requires a close 
 study of the circulation of water on the earth. Let us trace 
 the course of water from sky to ocean, in view of its availa- 
 bility for domestic use, and note the dangerous properties it 
 may acquire, considering also the changes in condition which 
 it may undergo in its course from mountain to sea. 
 
 Water-vapor rising from sea and land is condensed in the 
 upper air, then falls to the earth, absorbing, as it does so, 
 ammonia, carbon dioxide, sulphur oxides, and other soluble 
 gases, if present, and washing the air free from dust-particles, 
 mineral and organic. 
 
62 AIR, WATER, AND FOOD. 
 
 This meteoric water (rain or snow), although nearly free 
 from dissolved mineral substances, is therefore by no means 
 pure. Furthermore, rain falling on insoluble rocks, bare or 
 lichen-covered, or on loose, sandy soils, washes them also, 
 giving up to the vegetation the ammonia and taking in re- 
 turn carbon dioxide and dissolved albuminoid ammonia. 
 
 Water thus enriched has increased solvent power on cer- 
 tain rocks and soils. This rain-water soon forms rivulets 
 which, passing down from the highlands into the forest, spread 
 over the moss-covered area, soaking the leaves and peaty soil 
 and extracting organic substances. Mountain brooks, as well 
 as lowland streams, draining a region free from limestone, are 
 thus colored brownish-yellow and furnish " meadow-tea/' as 
 Thoreau happily named it. As the stream flows on it re- 
 ceives contributions of many kinds — the overflow of springs, 
 the under-drainage from cultivated fields, the surface-wash 
 from pasture and meadow. Scavengers are, however, con- 
 stantly at work. Brought as dust by the ever-passing air- 
 currents, seeds of tiny plants freely sprout in the water and 
 grow rapidly whenever a quiet pool or lake gives oppor- 
 tunity. The products of organic decay and the ammonia of 
 the rain may be thus removed and the water pass on to the 
 reservoir clear and soft and as nearly pure as nature furnishes. 
 It is, however, becoming rare to find even a mountain stream 
 or forest brook which has not been subjected to modification 
 by human agencies. Three kinds of contamination may take 
 place. First: A farmhouse high up on the hillside lays trib- 
 ute for drinking purposes upon that water finding its way 
 beneath the sand which appears in the form of a spring. The 
 overflow is made into a duck-pond, or passes through the 
 watering-trough by the roadside before it joins other water 
 tumbling over the rocks as a rapid stream. The brook thus 
 grown larger widens out a little below the farmhouse into a 
 
water: source, properties, and relation to life. 63 
 
 shallow pool, in which one or two cows frequently seek com- 
 fort. The water has become rich in organic matter and sup- 
 ports a thick growth of tiny plants; the stones, even, may be 
 coated with green slime. This vegetation serves as a warning 
 to the hunter and the woodsman, who wisely drink only of 
 water from clear pools with bottom of shining sand. The 
 heavy material stirred up by the cattle soon settles, leaving 
 the water in the stream below clear, although probably a little 
 yellow in color. It still tastes well and looks all right, and 
 may be used by human beings with probable impunity. 
 
 Second: The little stream next passes other farm build- 
 ings, where the privy is put over it to save the trouble of 
 cleaning, or, even if not so close, is placed in such a way as to 
 allow of a possible wash into it, especially in times of sudden 
 rain. 
 
 A case of typhoid fever develops at this farm. No pre- 
 caution is taken to disinfect the discharges, and a portion of 
 the dangerous material is carried into and along with the 
 water. Some two or three miles below, another farmhouse, 
 having no spring, uses this same little stream for its supply, 
 perhaps damming it up into a little pond or pumping it into 
 a tank. All unconscious of what has happened above, or 
 ignorant of consequences, this water with a history is freely 
 used, and perhaps the whole family come down with the dis- 
 ease, perhaps only the delicate one may have it. It may be 
 that they will all escape, owing to the fact that they were 
 particularly robust, or that they drank no water raw, or that 
 the conditions on the stream have been favorable to purifica- 
 tion of the water by storage and consequent growth of the 
 green plants, which are our friends in such cases; but if the 
 water were pumped into a covered tank and used soon after, 
 the chances are nine to one that some deleterious results 
 followed. 
 
64 AIR, WATER, AND FOOD. 
 
 Third: A part of the water sinks through the sand, and by 
 this filtration becomes freed from all suspended matter and 
 consequently from the germs of disease, if present. In its 
 course if it is intercepted and collected in a shallow well it 
 may again be of great organic purity and free from danger, 
 but it will surely bear the telltale marks of its progress in 
 the increase of chlorine and solids which will have escaped 
 all the agents of purification, and in the nitrates, the result of 
 the process. 
 
 It will be noticed that it is only after contamination with 
 the " waste of human life " that danger comes to other human 
 beings and that many circumstances modify that danger. 
 The chances are about equal to those of fire; and as most 
 householders think it worth while to insure against possible 
 fire, so they should hold the chemist's certificate as a sort of 
 water insurance; but since the fire policy does not protect 
 from carelessness, the knowledge that the water-supply is 
 once good does not absolve the householder or the citizen 
 from the greatest care in protecting his premises. Duty to 
 his neighbor should lead him to see that this coin of the 
 world is passed on in as good condition as possible, and he 
 should at least give notice of danger when he knows that it 
 exists. 
 
 But this general movement of water on and near the sur- 
 face is not all the story. From 25 to 40 per cent, of the 
 annual rainfall, in temperate regions, soaks at once into the 
 ground, and passing downward through the soil to hard-pan, 
 to clayey or impervious layers, or to rock surface, thence 
 through crevices, broken joints, or glacial drift-deposits to 
 the water-table, flows along the slope for many miles, until 
 it finds its way again to the surface, either from the bottom 
 of a lake, the bed of a river, the side of a hill, supplying wells 
 or appearing as a spring free from all organic and suspended 
 
water: source, properties, and relation to life. 65 
 
 matter but often rich in gases. In any one of these courses 
 it may be intercepted by man and caught or pumped for his 
 use. Such water may never have been far from the surface;, 
 it may have been used and returned to the ground many 
 times; it may have appeared as surface-water and again dis- 
 appeared to great depths. It has been estimated that water 
 moves in the ground at rates varying from 0.2 to 20 feet per 
 day. This long contact with rocks will, of course, bring min- 
 eral substances into solution which may be precipitated as 
 new rocks are reached or other streams encountered, so that 
 the same gallon of water may have had many stages in its 
 course and may have held many different substances in solu- 
 tion. An example of how much can be so held is found in 
 the waters of the alkali belt (page 241). 
 
 It is no wonder that so active a solvent as water should 
 take with it much substance whenever it remains long in con- 
 tact with soil or rock, for it may be many months before that 
 which has once sunk out of sight again appears. In fact, great 
 rivers are supposed to flow into the sea from under the sur- 
 face. 
 
 Then, too, the acquisition of dissolved gases favors the 
 solution of many substances; for instance, water carrying 
 carbon dioxide dissolves limestone as well as lead and cop- 
 per, and when at low temperature and containing ammo- 
 nium carbonate water may dissolve ferric iron. 
 
 Water carrying organic acids dissolves among other sub- 
 stances iron compounds which may or may not be in the 
 ferrous condition, and therefore may or may not be precipi- 
 tated on coming to the surface. And as we have seen that 
 the ground below a certain level is permeated with moving 
 water, whatever is buried in the earth is likewise liable to enter 
 the watercourses in one form or another. 
 
 An understanding of this movement of water under- 
 
66 AIR, WATER, AND FOOD. 
 
 ground, with the accompanying changes in its character, 
 cannot be too strongly insisted upon, for the lack of com- 
 prehension of it is at the root of most of the troubles from 
 well-waters. For example, the leaching cesspool, the primi- 
 tive " septic tank," delivers its more or less filtered water rich 
 in nitrogen compounds into the general circulation at a 
 depth below the most efficient action of the nitrifying or- 
 ganisms, hence it may permit the passage of organisms of 
 putrefaction into underground streams or into the well, when 
 access is direct. Even when filtration is perfect, the products 
 of decay are yet carried with it and so tell the story of the 
 past. The difficulty is to determine the state of the filter 
 which may be on a neighbor's land many hundred feet away, 
 and to be sure that its action is uniform. Experience with 
 artificial filters shows how difficult it is to maintain efficiency 
 with rapid use; hence heavy rains or wet years may cause a 
 state of danger not ordinarily existing. 
 
 The relation of water to human health must be consid- 
 ered chiefly in the light of the changes which go on in the 
 substances held suspended or dissolved in it, and the effect 
 of these changes on the wholesomeness of the water. The 
 suspended matter may be either inert, as clay or sand; dead 
 vegetable, as fragments of plants; living vegetable, as plants 
 floating on the surface, diatoms, desmids, a'gse, etc.; dead or 
 living animal, as infusoria, small crustaceans, etc. 
 
 Wherever these occur there are found the lower orders 
 of vegetable organisms, fungi, moulds, bacteria, ready to do 
 the necessary work of decomposition preparatory to solu- 
 tion. The mere presence of these forms of living matter 
 does not of itself mean danger to those using the water, but 
 among these may be found pathogenic organisms which are, 
 at present, considered as liable to cause disease. Such mi- 
 crobes do not find in water a congenial habitat, and, fortu- 
 
water: source, properties, and relation to life. 67 
 
 nately, do not thrive on the vegetable diet and in the cool tem- 
 perature of natural waters, hence the other organisms soon 
 overpower them; danger decreases not only in proportion to 
 distance, time, and dilution, but also, probably, to the abun- 
 dance of other vegetable life. Under favorable circum- 
 stances the danger is, however, a very real one. 
 
 The presence of certain living plants may, moreover, give 
 rise to unpleasant, if not dangerous, tastes and odors, due to 
 the presence of extremely pungent oils or other aromatic 
 substances formed in the process of growth. When these 
 plants are decaying putrefactive odors are also present, some- 
 times rendering the water too offensive for use. These or- 
 ganisms are described in Whipple's " Microscopy of Drink- 
 ing-water," and in Chapter VII a short list of those which 
 give characteristic odors will be found. 
 
 The presence of much decaying vegetable matter in 
 drinking-water is to be avoided, since it is not known what 
 effect it may have upon the general health of the individual, 
 rendering him perhaps more susceptible to disease. 
 
 Food-supply is a necessary condition for life, and there 
 cannot be abundant growth in a water without a correspond- 
 ingly large amount of dissolved substances furnishing the food 
 for this living fauna and flora. As has been stated, water 
 usually carries considerable mineral substance and is often 
 supplied with organic and gaseous compounds, while nitro- 
 gen is furnished from many sources, most abundantly from 
 sewage, so that it is not strange that water-life is so abundant, 
 but rather that it is not more so. Most of the difficulties in 
 securing a satisfactory water-supply are connected with the 
 cycle of nitrogen in its relation to organic life. 
 
 This may be briefly stated as follows: Nitrogen is found 
 as an essential constituent of all living matter. When thus 
 combined, it is the so-called organic nitrogen, and is found 
 
68 AIR, WATER, AND FOOD. 
 
 in undecomposed vegetable or animal substances. As soon as 
 dead, these substances may become food for micro-organisms 
 and the nitrogen then appears in a form from which it can be 
 obtained as ammonia; for instance, from decaying beans, from 
 putrefying broth, and from fresh sewage. This process takes 
 place with or without much air and may be accompanied by 
 very bad odors. As soon, however, as the nitrogen has passed 
 from the insoluble organic form into the soluble compounds 
 from which ammonia is obtained, then, if oxygen is present, 
 and only then, another set of micro-organisms take up the 
 work and nitrites appear; when still another set have done 
 their work the nitrogen is found only in combination as ni- 
 trates, fully oxidized and mineralized, no longer organic or 
 capable of sustaining the life of the lower forms of vegetation, 
 but, on the other hand, the most valuable food for chlorophyll- 
 bearing plants which convert nitrates again into organic 
 nitrogen. This cycle may be arrested or broken at certain 
 stages. If the soluble ammonia compounds are set free out 
 of contact with air or below the layers of soil containing the 
 nitrifying organisms, they may remain indefinitely un- 
 changed. If nitrates have been carried below the reach of 
 the roots of the chlorophyll-bearing plants, or if they are con- 
 fined in a space deficient in oxygen, then an access of decom- 
 posable organic matter with micro-organisms will cause a, 
 reduction of the nitrates to nitrites and free nitrogen, through 
 the action of these lower plants which, in the absence of 
 air, take the little oxygen they need from mineral com- 
 pounds. 
 
 These micro-organisms are not the only ones at work, 
 however. In any sudden prominence of one factor others 
 are apt to be overlooked; thus in the present case the in- 
 finitely small has so powerfully affected men's minds tha f r 
 partly because the micro-organisms are beyond their range 
 
WATER: SOURCE, PROPERTIES, AND RELATION TO LIFE. 69 
 
 of vision, such forms of life as are evident to the naked eye 
 or with low powers of the microscope have been overlooked 
 to an extent. 
 
 As agents of putrefaction and of decay the micro-organ- 
 isms have their work to do, but the final purification — the 
 finishing up of the work — belongs to another order of life. 
 The still minute but visible green plants — those which float 
 free in water or attach themselves to larger growths — have 
 now their part to play. The life-history of these forms has 
 been little studied, and the work they do in the actual puri- 
 fying of polluted water has been almost overlooked. The 
 impression left on reading most books is that when foul mat- 
 ter has been dissolved and converted into ammonia, carbon 
 dioxide, and nitrates the work is done, but these compounds 
 only furnish food for the next class, and these again for in- 
 fusoria, tiny crustaceans, etc. 
 
 In some cases these organisms succeed each other with 
 great rapidity; in one case the fauna and flora of a given 
 pond varied each week of a season, certain rare forms being 
 found only once. 
 
 There is needed, almost more than anything else, a con- 
 secutive study of the green plants found in water-supplies, 
 since by their cultivation greater purity might be attained 
 and possibly a way might be found of exterminating the dis- 
 agreeable ones. The most unexpected results may follow 
 the long study of a single organism, such as has been given 
 to Oscillaria prolifica of Jamaica Pond for a period of fifteen 
 years. Weekly, sometimes daily, observations have been 
 made for several years.* 
 
 It is organisms of this class which give tastes and odors 
 to water, and which, if enough were known concerning them, 
 
 * Trans. A. A. A. S., 1898. Technology Quarterly, 14 {igoi) t 302; 15 
 <{jgo2) y 308. 
 
JO AIR, WATER, AND FOOD. 
 
 would probably give perfectly trustworthy evidence as to the 
 past history or source of contamination. 
 
 The two classes of organisms work in opposite directions, 
 and so long as food is present for either, life will increase with 
 proportional rapidity. This connection of cause and effect 
 should be made familiar to the intelligent citizen. When a 
 ground- water free from all organic matter but rich in 
 nitrates is exposed in an open basin the rich growth of 
 chlorophyll-bearing algae follows as a matter of course; later, 
 decay sets in and products of decomposition abound, the air 
 above being the source of a constant supply of spores of all 
 kinds. 
 
 When a house- or barn-drain empties into a small slug- 
 gish stream, it soon becomes filled with green plants thriving 
 on the ammonia, and it is often possible to trace the source 
 of pollution of a large lake by the line of green anabaena 
 leading to the insignificant ditch. 
 
 A curious blindness on the part of managers of water- 
 works to the movements of water and its action in transport- 
 ing material is seen not only in the almost universal proximity 
 of cemeteries to reservoirs, but also in the common practice 
 of dressing the sloping banks of turf with a heavy coating of 
 manure. Even if this was derived from clean stables and 
 was not liable to be contaminated with night-soil, the abun- 
 dant food for plants which inevitably finds its way into the 
 reservoir occasions as fruitful results in the water as on the 
 banks, and is undoubtedly the cause of much of the trouble 
 in storage basins. 
 
 It is evident, therefore, that a once polluted water cannot 
 be said to be purified so long as food for green plants re- 
 mains, for the moment the temperature and other conditions 
 be^nf favorable growth will begin. The term "purifica- 
 tion" f aken in a chemical sense, should not be looselv used. 
 
water: source, properties, and relation to life. 71 
 
 Complete purification can take place only when all traces of 
 former impurity, in any form, have been removed. Chemical 
 precipitation of sewage leaves the soluble ammonia, and sand 
 filtration leaves nitrates to serve for abundant life and sub- 
 sequent decay in the streams into which the effluents flow. 
 Such effluents are clarified and the organic matter may have 
 been mineralized, but this is not purified water. Only when 
 growing plants have removed this food and have themselves 
 been removed can the water approach a purified condition. 
 
 The effect of storage of water containing high nitrates 
 in open tanks or reservoirs exposed to the collection of dust 
 will be that spores of chlorophyll-bearing algae, diatoms, 
 desmids, etc., will soon develop and will increase as long, as 
 the food (nitrates, mineral matter, etc.) lasts. Only by pro- 
 tection from dust and light can such water be kept free 
 from unpleasant accumulations of suspended organisms or 
 from disagreeable tastes. Unpolluted surface-waters, on the 
 other hand, improve on storage, as a general rule, if the basin 
 is a clean one. The storage of polluted or clarified water is 
 thus forbidden, since not infrequently the first indication of 
 the pollution of a surface supply is given by the appearance 
 of some member of that richly nitrogenous group of algae 
 called cyanophycecc, or " blue- greens," from the presence of 
 blue or purple coloring matter along with the yellow-green 
 chlorophyll. Since this group of plants contains from seven 
 to eleven per cent, of nitrogen, while other groups contain 
 only one or two, it is evident that, if it is to flourish, more 
 nitrogenous food must be supplied. This may be derived 
 from fertilized fields, from decay of other vegetable life, as 
 well as from the richer source of direct sewage; but, in anv 
 case, the growth of these plants is a sign of abundant food- 
 supply which must be cut off if they are to be starved out, as 
 they must be unless they are removed while fresh by strain- 
 
72 AIR, WATER, AND FOOD. 
 
 ing or skimming, for the odor of their decay is so intolerable 
 as to preclude the use of the water. In some cases the odor 
 accompanying their growth renders the water quite objec- 
 tionable, and neither natural nor artificial filtration is able to 
 remove it. 
 
 Either natural or artificial basins may have a collection of 
 vegetable matter on the bottom which slowly decomposes 
 in summer, and since the bottom water is colder, the resulting 
 ammonia remains until the late fall overturn, when it is 
 brought to the surface, where it favors the growth of diatoms 
 and other cold-water plants. Certain diatoms, as asterio- 
 nella, cause disagreeable odors. Such basins show the least 
 ammonia in early October and the most in late November. 
 
 In order to make any predictions as to the pro'bable de- 
 velopment of this flora and fauna of water, experience and 
 at least a year's watching of any given supply are required 
 until more is known of the life-history of these forms of life. 
 Nothing is more needed to-day than work along these lines. 
 When may disagreeable odors and tastes be expected? 
 What precaution or measures may be taken in each case to 
 prevent them? These are the questions the water-works 
 superintendent, equally with the consumer, is asking, for the 
 most part vainly as yet. 
 
 As has been stated, surface-waters often carry stable or- 
 ganic matter in connection with color, so that while the 
 organic nitrogen shows high, no free ammonia or nitrates are 
 formed on standing. These weak meadow-teas are now 
 largely used for town supplies, and a word as to the source 
 of the color may not be amiss. Many carbonaceous sub- 
 stances, sugar, for example, when partially broken up become 
 caramelized and give a brown solution, the color being due 
 to substances richer in carbon; this color is deeper as the 
 decomposition is more complete. There is no reason to sup- 
 
water: source, properties, and relation to life. 73 
 
 pose that such compounds have any deleterious effect on 
 health. Indeed, experience has proved that such waters are 
 more reliable than many others. 
 
 The chlorine of unpolluted natural waters is derived from 
 the sea in past or present times. Waves breaking on a 
 rocky shore send finely divided salt-spray high into the air; 
 dust-particles becoming coated with it carry their burden of 
 salt around the world. The rain brings to earth now more, 
 now less of this salted dust, each region receiving in the 
 course of the year an amount fairly proportional to its dis- 
 tance from the seacoast and to the rainfall. No mountain 
 lake or stream has yet been found free from this element. 
 Where evaporation and rainfall nearly balance, the normal 
 chlorine will be that of the rain for the year, but where evapo- 
 ration is in excess it may exceed that for any given year. In 
 the absence of salt-springs and industries using much salt, 
 the source of chlorine in excess of the normal is the do- 
 mestic life of man. Mr. F. P. Stearns has estimated that the 
 chlorine in the annual drainage of any watershed is increased 
 one-tenth part per million by 20 inhabitants per square mile. 
 
 Chlorine may serve to prove not only the presence but 
 the amount of sewage pollution in any case where the other 
 factors are known. Otherwise chlorine has no sanitary 
 significance. 
 
 Of the mineral constituents in waters there is little to 
 say except that, like climate, water is to be taken as It is 
 found — hard, high in mineral matters if derived from a lime- 
 stone region, soft if from archean formations. Physicians are 
 not agreed as to the effects of hard water, or of the brown 
 soft waters. 
 
 Fortunately the human system possesses remarkable 
 adaptability, so that if slowly accustomed to a given condi- 
 tion, as we have seen in the case of air, and as we shall have 
 
74 AIR, WATER, AND FOOD. 
 
 occasion to remark when food is considered, it can safely 
 bear what would be a serious shock if suddenly encountered 
 from an opposite condition. Natives of a hard-water region 
 are made ill on coming to a soft-water region, and vice versa. 
 Inhabitants of a city with a polluted water-supply seem to 
 acquire a certain immunity. 
 
 The safety from organic contamination secured by the 
 use of distilled water has brought up the question of a pos- 
 sible danger in too little mineral contents for the best cellular 
 interchange wherein lies life. 
 
 With the superabundance of mineral salts in ordinary 
 diet, there would seem to be little cause for alarm; but if the 
 food were poor in these substances, it is quite conceivable 
 that evil results might follow a free use of distilled water. 
 
 A word as to the care of water in the house may not 
 seem amiss, in view of the tendency it has to absorb gases, 
 to collect dust, to favor chemical and vital changes, to dis- 
 solve metals. 
 
 Too great care cannot be taken in all these directions to 
 secure water freshly drawn from the main pipe beyond the 
 lead or brass house-pipes and to avoid thos,e traps for the un- 
 wary householders — faucet filters. 
 
 When the water-supply is cafe, but warm and flat to the 
 taste, ice is frequently used to cool it. 
 
 Much has been said about the dangers of ice when used 
 in drinking-water and on or about food. The latter is prob- 
 ably the most serious danger, since people are not so careful 
 about the quality of ice for that purpose. 
 
 Certain rules may be broadly stated as guides to the 
 householder: 
 
 Crystal-clear ice, free from crevices, bubbles, etc., is 
 probably pure, for it has been formed from slow freezing in 
 a thin layer, over a deep mass of water, as 20 to 30 inches of 
 
water: source, properties, and relation to life. 75 
 
 ice in a pond 40 or 60 feet deep. In this case the impurities 
 have been excluded. This crystal ice is impermeable to air 
 and therefore to what air carries, and of course to water 
 and what it carries. 
 
 An equally safe rule is to discard all "snow-ice" made 
 from snow saturated with water. 
 
 The increasing difficulty of obtaining safe water has 
 caused an increasing use of distilled water obtained either 
 from domestic stills or in bottles or carboys from manu- 
 facturers. The latter is often a desirable source of drink- 
 ing-water if the glass does not scale off from the bottles. 
 A very little common salt may be added if the consumer 
 prefers, or even a drop or two of the druggists' "lime- 
 water." 
 
 The domestic still, if made from a poor quality of metal, 
 may bring an evil second only to that of polluted water. 
 Lead should not enter into its construction. 
 
CHAPTER VI. 
 
 THE PROBLEM OF SAFE AND ACCEPTABLE WATER AND THE 
 INTERPRETATION OF ANALYSES. 
 
 {From the Chemist's Standpoint.) 
 
 From what has been said it will be evident that the prob- 
 lem of safe water for domestic use is not so much concerned 
 with the water itself as with its property as a carrier and its 
 part in chemical changes. 
 
 We have seen how a great variety of vegetable and ani- 
 mal matter finds its way into the water of a settled region; 
 and as it is constantly being transformed from one form to 
 another by the agency of multitudes of organisms, it is evi- 
 dent that the exigencies of modern life render impossible the 
 exclusive use of water of great organic purity. It is useless, 
 therefore, to fight over again the battles of the past as to the 
 source and kind of " organic matter " in water. 
 
 We have also seen that it is not the mere presence of 
 compounds of carbon, hydrogen, and nitrogen in drinking- 
 water which gives the element of danger. It is not even 
 the fact that these have taken part in animal life; fish and 
 frogs continually die in ponds and streams, to say nothing 
 of countless cyclops and mosquito larvae. Well authenti- 
 cated cases are on record in which one drink of a polluted 
 water has proved fatal; while, on the other hand, it is equally 
 sure that highly contaminated water has been used with ap- 
 parent impunity. 
 
 76 
 
water: the problem of SAFE WATER. J7 
 
 When water has received excreta of diseased human 
 beings, disease-germs are very likely to be conveyed by it 
 to other human beings. In a city there are. always cases of 
 disease, therefore all city sewage is to be considered danger- 
 ous. But besides the living germs there are other accom- 
 paniments of decaying organic matter which, when in con- 
 centrated form, sometimes show toxic properties. Certain 
 facts and many conjectures lead to the conclusion - that a 
 water is " safe " only when free from decaying substances. 
 
 Along with the millions of harmless micro-organisms 
 engaged in the work of conversion there may be a few score 
 inimical to the health of man, and for the education of the 
 still skeptical public it is often advisable to speak somewhat 
 strongly of the possible dangers from water-borne disease- 
 germs. -\ •„ 
 
 Nitrogen as the Essential Element in Living Matter. — All 
 organisms from the lowest to the highest thrive only in the 
 presence of food; therefore only that organic, matter which 
 serves to support life or which, as a product of life, may be 
 deleterious to man is rightly to be held as dangerous. The 
 element common to both kinds is nitrogen; therefore the 
 water-analyst seeks evidence not only of its presence or ab- 
 sence, but of the forms in which it is found and their relation 
 to one another. It may be assumed that any water which 
 shows no change in the relative amount of its nitrogenous 
 compounds at the end of a week either does not contain the 
 organisms necessary to effect this change or is wanting in 
 the food upon which they can thrive. As, however, it is 
 inconvenient to wait a week before deciding this point, other 
 methods are used. The so-called a 1 buminoid ammonia is 
 supposed to indicate the amount of decomposable nitrogen- 
 ous matter, but, as a matter of fact, taken by itself it gives 
 little information of value. While its absence is conclusive, 
 
j8 AIR, WATER, AND FOOD. 
 
 its presence is not equally so; but a proof of its variability 
 from- day to day is really valuable. Whether used in the final 
 interpretation or not, " organic nitrogen " (or that portion 
 of it appearing as albuminoid ammonia) is always deter- 
 mined, together with the other forms, as soon as the sample is 
 received. 
 
 A nitrogenous organic compound is dangerous from one 
 of two causes: first, because it is already decaying and har- 
 bors pathogenic germs or is giving off toxines; or, second, 
 because it will furnish food for a further development of bac- 
 terial life. 
 
 As to its derivation from animal or from vegetable mat- 
 ter, there need be little discussion, especially since the recog- 
 nition of the high nitrogenous content of the blue-green 
 algae and the nitrogenous character of " soil-humus " and 
 the close approximation of animal and vegetable protoplasm. 
 But it is most important to know if it is stable, since one of 
 the best aphorisms ever contributed to the literature of water- 
 analysis is given by Dr. Drown's statement, " A state of 
 change is a state of danger." 
 
 Results of the Decay of Nitrogenous Organic Matter. — The 
 products of the first stage of decay of this class of organic 
 matter are carbon dioxide and ammonia. It is to the 
 latter that we turn for the proofs sought, by reason of the 
 methods at hand for detecting such small amounts as one 
 part in a billion parts of water, and because it is for the nitro- 
 gen compound that we seek. 
 
 The mere presence of free ammonia is not a sufficient in- 
 dication of recent pollution from human sources. Rain-water, 
 as shown in Table III, contains considerable quantities; 
 decaying blue-green algae furnish it in still larger amounts, 
 and moreover it offers acceptab!e food to plant-life and may 
 therefore disappear in the form of combined nitrogen. 
 
water: the problem of safe water. 79 
 
 Nevertheless, it is to be held as one of the chief witnesses, for 
 it is found in sewage in a thousand times the quantity in 
 which it occurs in ordinary potable water. While putrefac- 
 tive decay takes place by stages, the lines of division are not 
 sharply drawn, and nitrites, the result of the second stage, may 
 be and usually are found in polluted waters together with 
 ammonia. So frequently is this the case that it is considered 
 circumstantial evidence sufficient to convict when both am- 
 monia and nitrites are found together. (See Tables V and 
 VI, p. 241.) 
 
 The reason is not far to seek. Both are not only prod- 
 ucts of decay, but both are in that unstable condition which 
 indicates active processes, and which therefore means the 
 presence of micro-organisms. Certain exceptions will be 
 noted later. 
 
 The fourth form of nitrogen, that found in nitrates, is no 
 longer classed as organic; it is now become food for green 
 plants and cannot nourish the class to which bacteria and 
 pathogenic germs belong, hence it is fair to presume that for 
 lack of food the latter have succumbed or have been other- 
 wise removed. The value of this test is the proof it sometimes 
 furnishes of previous sewage pollution, since the nitrogen 
 present in excess of that brought down by rain must have 
 been furnished either by fertilizers, by decaying matter, or by 
 sewage. (See Tables V and VI, p. 241.) 
 
 Organic Carbon. — Since by far the largest constituent of 
 organic matter is carbon, some fifty per cent., it might seem 
 as if this was the best indication of pollution. Indeed, it was 
 formerly so considered, and many methods have been de- 
 vised to show its presence quantitatively. As our knowledge 
 of the slight differences between many forms of animal and 
 vegetable substances grows, the probability of any conclusive 
 evidence from this source, either as to past history or present 
 
8o . AIR, WATER, AND FOOD. 
 
 condition, decreases. In short, although for many years 
 water-analysts have been striving to perfect methods of de- 
 tecting certain substances and certain organisms, it would 
 seem as if they were no nearer a discovery of one simple de- 
 cisive test, but, in most cases, were driven to a somewhat 
 elaborate examination in which one test only furnishes one 
 link in the chain of evidence. 
 
 Sanitary Analysis. — The examination of a water to deter- 
 mine its safety for domestic use is called a sanitary analys's, 
 in distinction from that examination which determines its 
 fitness for manufacturing purposes, for use in steam-boilers, 
 or its medicinal value. 
 
 Four points are to be determined: First, the amount, if 
 any, of organic matter in a living or dead condition, sus- 
 pended or dissolved in the water; second, the amount and 
 character of the products of decomposition of organic mat- 
 ter, and their relative proportions to one another; third, the 
 stability of the undecomposed organic substances; fourth, 
 the amount of certain mineral substances dissolved. From 
 these results we draw conclusions as to the present condition 
 and past history of the water. These conclusions are not in- 
 fallible, but there are enough unavoidable risks in human 
 life without taking unnecessary ones; and if pollution is 
 proved, the cause should be removed or the supply aban- 
 doned. 
 
 Preliminary Inspection. — So long as the eye can re-enforce 
 the other tests and the whole course of the water may be 
 clearly traced, it is comparatively easy to judge of the charac- 
 ter of a supply and of its safety for human use; but when a 
 hole in the ground is the visible source, or the actual history 
 of the water is hidden in unknown distances and depths, the 
 diagnosis is more difficult. 
 
 First, the geological horizon and superficial soil must be 
 
water: the problem of safe water. 8r 
 
 studied; the direction and flow of underground water, not the 
 slope of the surface only; the possible sources of danger, 
 occasional as well as constant, within at least a quarter of a 
 mile radius. The composition of unpolluted water of the 
 same region should always be at hand for consultation. 
 
 Safe Water. — As has been said, we can no longer require 
 pure water; the most that we can demand is that the supply 
 shall be safe. To the uninitiated one sample of clear, color- 
 less water seems very like any other. The safe, colored or 
 muddy water of a stream or pond seems less desirable than 
 the clear, cold water of a badly polluted well. 
 
 A water may be normally safe and yet, from exceptional 
 circumstances, be for a time a source of danger. In one case 
 the mouth of a well at a factory was overflowed by a con- 
 taminated brook raised above its usual level by a heavy 
 shower for half an hour only. Some thirty cases of typhoid 
 fever resulted, so close to one another and so suddenly ceas- 
 ing as to leave no doubt of the fact that for only a few hours 
 was the water unsafe. How, then, shall a chemist tell if at 
 some past time a water may have been or at some future time 
 may become a source of disease? Only by carefully weigh- 
 ing all the testimony attainable — ocular, chemical, biological, 
 bacteriological — in the light of past experience. 
 
 The day of the vest-pocket sample, usually in a flavoring- 
 extract bottle, cork and all, is nearly past, but that of the 
 fruit-jar, with a sticky rubber ring and corroded zinc top, is 
 still with us. That admiration for chemical knowledge and 
 belief in chemical clairvoyance which expects the chemist to 
 decide from a sample while you wait if a certain water caused 
 the death of a person a month since in a distant town under 
 unknown conditions is very trying to the man who knows his 
 own limitations. 
 
 The market value of an analysis cannot well be appre- 
 
82 AIR, WATER, AND FOOD. 
 
 dated until a juster estimate of the professional training of 
 the analyst is a part of common knowledge. 
 
 Safe and Acceptable Water. — It is not enough that a 
 supply shall be free to-day from disease-germs; it should re- 
 main free from changes for a reasonable period of time. 
 Therefore the advice desired by the towns seeking for sup- 
 plies implies much more than mere analysis; it includes esti- 
 mates of future changes, of variations due to possible further 
 developments, and of the effect of these variations on accept- 
 ability as well as safety. 
 
 To be fully acceptable, a water should be free from color, 
 odor, turbidity, sediment, and of a uniform temperature so 
 low as to admit of use without ice. Only such water as has 
 been earth-filtered and earth-cooled can meet this demand, 
 but the supply of this class is becoming drawn upon to its 
 limit; besides there are difficulties in the conveyance and 
 storage of ground-water which offset many of its advantages. 
 
 From the foregoing paragraphs it will be seen not only 
 that waters carry every possible degree of safety or danger 
 according to the country they drain, the num'ber and habits 
 of the people living on the watershed, and the presence or 
 absence of factories, slaughter-houses, etc., but that many 
 elements enter into the judgment of a water-supply, and how 
 different these elements are in different waters. Safe water 
 is that which carries neither seeds of disease nor such sub- 
 stances as are deleterious in any way to mankind in general. 
 
 A brown water may yield 20 parts per million organic 
 matter and show 10 parts oxygen consumed, and yet be a 
 safe and wholesome water. A ground-water may show 5 
 parts nitrates, and yet for ten or twenty years prove a safe 
 supply. 
 
 Since, however, water is so universally made a carrier of 
 refuse, it is difficult to find a stream or well which fulfils the 
 
water: the problem of safe water. 83 
 
 above exacting requirements, and a compromise is made 
 which sets certain arbitrary limits and so keeps the chances 
 small. Such limits are very misleading of themselves, espe- 
 cially if used over a wide extent of territory. The English 
 standards, for instance, are not applicable to eastern North 
 America. Only a study of all local conditions and a wise in- 
 terpretation of all results can make standard figures of any 
 significance. This is true, also, of bacterial results in surface- 
 waters. In the natural condition of lakes and streams there 
 are so many varieties of bacteria present and in such varying 
 numbers, according to wind and rain and watershed, that 
 taken alone the numerical count gives no more convincing 
 proof than is found in chemical figures. 
 
 While it is quite within the limits of possibility that a 
 culture-tube of typhoid bacilli might be emptied into the 
 middle of a river or be washed into a reservoir, and chemical 
 analysis give no sign, yet no continuous natural means of 
 contamination is known which is not accompanied by sub- 
 stances readily detected by suitable chemical examination. 
 In either case an epidemic may or may not result, dependent 
 upon causes other than the mere presence or absence of the 
 micro-organisms. 
 
 If drainage from a house or barn is seen entering a 
 stream, it does not need a dozen plate-cultures to prove that 
 there is possible danger. Such tests may, however, when 
 used with skill, serve to trace contamination back to its 
 source, and is another means at the service of the trained 
 water-works superintendent whereby he can keep a close 
 watch over the character of his supply. 
 
 As a means of control of the efficiency of filter-plants the 
 bacterial examination is invaluable, and as a knowledge of 
 the forms which accompany pathogenic germs becomes more 
 certain the value of these tests will increase, even if the 
 
84 AIR, WATER, AND FOOD. 
 
 classification and identification is not perfected to scientific 
 accuracy. 
 
 It is one of the penalties of living in a large city that the 
 water-supply must of necessity be surface-water which has 
 been caught and stored at a distance or that which has been 
 filched from a stream, filtered and made passable. Conse- 
 quently education must take the place of instinct, and custom 
 must make that acceptable which circumstances render 
 necessary. 
 
 THE INTERPRETATION OF ANALYSES. 
 
 Experience in cutting through glacial moraines for rail- 
 ways or in driving levels for mining operations does not 
 qualify a man for exploration of a Babylonian or prehistoric 
 mound. Human occupations have left upon the sand and 
 clay evidences which, although so slight as to be unnoticed 
 by the casual observer, are like an open book to him who 
 patiently acquires a knowledge of the meaning of the dis- 
 placements, discolorations, and enclosed fragments. Flowing 
 water, like sand and clay strata, bears evidences of its previous 
 history no less intelligible to him who has the key to the 
 cipher and who adds to the keen eye of the detective and 
 ready wit of the interpreter the sound judgment of the engi- 
 neer. Reasoning upon insufficient premises will as often 
 fail in the one case as in the other, while lucky guesses fre- 
 quently encourage superficiality in both. 
 
 After the analyst has entered on the blank (page 141) the 
 six to ten records needed for a ground-water, or the fifteen 
 to twenty for a surface-water; after the columns headed 
 Bacteria, Diatoms, Algae, etc., have been filled in, there still 
 remains the summing up of the case by the judge. The 
 correct interpretation of results means a knowledge of 
 the source, geological horizon, surroundings, probable 
 
water: the interpretation of analyses. 85 
 
 changes, and the significance of each item in this particular 
 case. Each class of water has its own characteristics. The 
 presence, in quantity, of any given element is interpreted 
 according to the kind of water under consideration. Spring- 
 water is, of course, colorless; lake-water of equal safety is 
 probably colored. Spring-water must be, as a rule, free from 
 ammonia; lake-water may at times contain considerable 
 amounts without detracting from its good character. 
 
 Classification of Waters. — To facilitate examination, 
 therefore, w r aters may be divided Into three classes: first, 
 cistern, brook, pond, and river water — so-called surface- 
 water; second, spring and deep-well water; and third, shal- 
 low wells and sewage effluents. 
 
 Water of the last two classes has been for greater or less 
 periods of time in contact with rock and filtered through 
 sand, hence is designated as ground-water. 
 
 A few examples taken from the different kinds of water 
 showing the varying conditions to which they are subjected 
 may serve to make the rules of interpretation clearer. 
 
 Surface-Waters. — When rain-water falls on slated or 
 shingled roofs and is conducted into cisterns, it carries with 
 it whatever deposits lave collected, the pollen of forest-trees 
 or disease-germs from city slums many miles away; from 
 metal roofs it takes either the metal itself or the pain" used 
 to protect the surface. In all cases, lower forms of animal 
 life, small insects, and soot from chimneys may be present. 
 These foreign substances should be at once filtered out with- 
 out allowing time for organic decay, unless there is an auto- 
 matic device for wasting the first washings of the collecting 
 surface. There are still substances in solution which would 
 be better away; therefore the water is allowed to stand 
 quietly in order that the changes may have time to take 
 place — to ferment, as it is often technically expressed. After 
 
86 AIR, WATER, AND FOOD. 
 
 this season of purification the water is again filtered and 
 stored ready for use. There is usually color and a little am- 
 monia, but rarely nitrates. The soluble meta's, if once pres- 
 ent, still remain. It goes without saying that all such 
 cisterns must be absolutely impervious to surface drainage. 
 For lack of one or all of these precautions, cistern-water has. 
 often been found to be contaminated from cesspools, from 
 leaden or painted roofs, or from decaying organic mat er. 
 
 Brook-water. — The rain that falls on mountain slopes of 
 granitic or other insoluble rocks washes from them whatever- 
 loose earth may have fallen there, and from the firmly fixed 
 lichens the small insects and other animal forms which they 
 harbor. These are transported in brooks to the lower lands 
 where the organisms decay, the heavier earthy particles fall- 
 ing out by the way. 
 
 If the upland rocks and soil yield a portion of mineral 
 salts to the water, it may come out clear and colorless even if 
 it has not penetrated to an appreciable depth. 
 
 The water from these forest brooks, after remaining im- 
 pounded in a clean lake or reservoir, exposed to sunlight and 
 air, often becomes the safest source of supply. As with cis- 
 terns, so with reservoirs, filtration, natural or artificial, may 
 take place previous or subsequent to storage, or both before 
 and after. 
 
 Lake or Mixed Water. — Lakes are fed by springs as well 
 as by brooks, or by that portion of rainfall which passes a few 
 inches below the surface, and is filtered before reaching the' 
 main body. If the banks are sandy and uninhabited, the 
 water will show good effects from this filtration; but if the 
 seepage-water comes from a settled country, it will bring 
 either ammonia or nitrates. The analysis will quickly show 
 this if the water sample can be taken before it has mixed 
 with that bearing the spores of plants which are fed by 
 
water: the interpretation of analyses. 8y 
 
 nitrates. Often the very presence of these plants furnishes 
 the proof sought. 
 
 River-waters. — A large stream, especially a muddy one, 
 may receive the drainage of half a dozen cities a hundred miles 
 distant and yet not give conclusive evidence of dangerous 
 contamination, while a small river with a rapid current may 
 become unsafe from the presence of a few villages a dozen 
 miles away. 
 
 Northeastern America is so well supplied with uninhab- 
 ited high lands for collecting-grounds, and with basins in the 
 glacial drift for storage in natural or artificial lakes, that very 
 few rivers need to be used after they have become polluted. 
 The Merrimac and the Hudson are, however, so used. In 
 other parts of the country the use of rivers is an increasing 
 necessity, requiring municipal filter plants. 
 
 From every point of view organic matter should be kept 
 as far as possible out of running streams which may at any- 
 time be needed for public supplies, or the natural purifica- 
 tion by algae should precede the final filtration and storage. 
 It is quite probable that this double treatment may be more 
 frequently required as unpolluted water becomes more 
 scarce. 
 
 What the method of filtration shall be depends upon the 
 character of the water, whether clear or turbid with clay, 
 whether certainly polluted or only with a remote possibility 
 of contamination. Each problem must be studied by itself 
 without prejudice in favor of any one method. It is the re- 
 sult which must be kept in mind, namely, the furnishing of 
 safe and acceptable water to the community. 
 
 Effect of tJie Storage of Surface-water. — In interpreting 
 his results, the analyst should take into acccunt the influence 
 which the keeping of water in basins has upon its character. 
 Storage of surface-water is of utmost importance in all cases- 
 
gg AIR, WATER, AND FOOD. 
 
 of doubt. Most disease-germs find such water an unfavor- 
 able medium for prolonged life, since exposure to sunlight 
 soon destroys the darkness-loving bacteria, and a certain 
 sterilizing effect results from the growth of green alg?e, so 
 that water considerably polluted becomes purified if given 
 time for the various agents to do their work; but time is 
 essential. 
 
 Odors. — For surface-waters one of the links in the chain 
 of evidence is found in the odor, cold and hot, which to the 
 trained and sensitive nose often gives convincing testimony. 
 A musty odor, unmistakably different from a mouldy vege- 
 table smell, betrays sewage contamination even when the 
 chemical analysis might not be convincing. This odor is not 
 always taken out. by filtration, neither is that of certain or- 
 ganisms growing in stored water, notably Anabcena and 
 Synurd. A study of these organisms is invaluable to the 
 routine observer who watches the seasonal and annual 
 changes in his reservoir. 
 
 Turbidity and Sediment. — The determination of turbid- 
 ity and sediment, added to the odor, tells much to the expert, 
 but very little to the inexperienced student. Turbidity may 
 be due to drainage contamination, to growth of bacteria, to 
 clay, to iron, to swarms of micro-organisms. Sediment may 
 be sand, zooglea, fragments of plants or animals, or ferric 
 oxide. 
 
 Filtration. — The subject of filtration has been so exten- 
 sively treated elsewhere that the student is referred to the 
 bibliography on page 263. There are cases in which it is 
 preferable to run the risk of too much alum in the drinking- 
 water, and too much sulphuric acid in boiler feed-water, 
 rather than of too many micro-organisms with the accom- 
 panying organic matter. 
 
 It will have been noticed that the ideal natural water is 
 
water: the interpretation of analyses. 89 
 
 that which has been earth-filtered, and thus all suspended 
 matter, including microbes, has been removed. This sup- 
 poses that sufficient time has elapsed so that all decomposing 
 organic matter has been destroyed. Man tries to imitate 
 nature's processes, but expects to accomplish it in moments 
 instead of months. 
 
 The era of house-filters, those admirable culture-grounds 
 for bacteria, is happily nearly past. Taxpayers are becoming 
 convinced that a good original water-supply in competent 
 hands is worth paying for. Where straining only is needed, 
 a flannel bag washed daily is as efficient as any faucet-filter. 
 If the latter takes out color as well, it should be closely 
 watched. Water should not be first boiled and then filtered, 
 but first filtered and then boiled. 
 
 Summary. — Surface-water. — In general it may be said 
 that the waters of the first class found in New England are 
 generally more or less colored, and contain more or less sus- 
 pended organic life and its debris, which often impart a de- 
 cided odor to the water. These waters, draining for the most 
 part wooded and sparsely populated regions, are low in free 
 ammonia, nitrates, and nitrites; low, also, in mineral salts, 
 and with only a slight excess of chlorine over the normal. 
 They are usually high in organic matter and albuminoid am- 
 monia even when entirely free from pollution. 
 
 In other parts of the United States surface-waters may be 
 low in color, but with much suspended clay and silt, and may 
 hold in solution notable quantities of mineral salts. The 
 latter aid greatly in the clarification by artificial filtration, 
 which is so often rendered necessary by the excessive turbid- 
 ity even if not by sewage contamination. 
 
 In Table IV, page 239, will be found examples showing 
 at a glance how profoundly the character of a water is affected 
 by the geological horizon, whether its source is in the glacial 
 
90 AIR, WATER, AND FOOD. 
 
 drift of the Appalachian region, or in the limestone of the 
 Hudson River Valley, or in the saline deposits of the sub- 
 sided areas. 
 
 Deep Wells and Springs. — The waters of the second class 
 are derived from the depths of the earth, far below any pos- 
 sible surface contamination, and have long been imprisoned 
 in the dark and cold, and often subjected to great pressure, 
 The influence of pressure on organisms has not been entirely 
 worked out, but from what is known it is probably very un- 
 favorable to the life of the lower organisms. The results of 
 many bacterial examinations have been vitiated by the diffi- 
 culty of securing a sample from great depths without con- 
 tamination by surface exposure — pipes open to the air har- 
 boring many forms of life. 
 
 Deep wells, 700 feet and more, are not likely to be dan- 
 gerous. They may often contain ammonia from prehistoric 
 coal-fields or tertiary deposits, but rarely nitrates. This is 
 accounted for by the fact that " the result of the changes of 
 the nitrogenous organic substances which fall into the earth 
 is, without doubt, frequently the formation of gaseous nitro- 
 gen." Also, that " salts of nitric acid on penetrating into 
 the depths of the earth give up their oxygen." * 
 
 Owing to their long sojourn in the depths of the earth, 
 these waters are higher in mineral substances than surface- 
 waters. Since their origin is unknown, the chlorine cannot 
 be correctly gauged, especially as there are saline waters deep 
 down in rock cavities in all parts of the world. 
 
 It is usually believed that these deep wells furnish a safe, 
 palatable water when the kind and amount of mineral matter 
 is not objectionable. 
 
 Shallow Wells. — It is not to be wondered at that waters 
 
 * Mendeleeff : "Chemistry," p. 223. 
 
water: the interpretation of analyses. 91 
 
 of the third class — ground-water, taken from just beneath 
 the surface layers of the soil — should contain many sub- 
 stances foreign to the waters about them as well as to those 
 at greater depths. The shallow wells, which are practically 
 more or less diluted sewage effluents, present the greatest 
 variety. They may be clear and colorless and show as great 
 organic purity as the best mountain spring. In other cases, 
 the overworked filter permits the passage of organisms and 
 undecomposed material. In either case there will be found 
 those compounds which, being soluble and stable, are car- 
 ried with the water as signs to be read by him who knows the 
 language. A complete history of each specimen of this class 
 of ground-water is desirable, and with sufficient patience 
 and care it may be obtained with reasonable accuracy, if the 
 principles governing the circulation of water and the changes 
 of the organic matter it carries be kept well in mind. 
 
 It is certain at once that absence of color, of organic mat- 
 ter in any form, and of odor should be insisted upon, for 
 ground-water is filtered water and the filter should be doing 
 its work. 
 
 A modicum of geological knowledge is essential, as the 
 presence of shaly or slaty rock will permit the passage into 
 underground water of surface drainage with less purification 
 than will a granite or sandstone region. A clayey soil is a less 
 efficient filter than a sandy loam and permits the pollution 
 to travel farther. 
 
 Nitrogen in Well-water — It may be taken as an axiom 
 that the only form of nitrogen permissible in a good ground- 
 water is that of nitrates, a fully oxidized or mineralized food 
 for green plants. If nitrites are also present, a source of 
 pollution is at hand, for, as has been said, nitrites indicate 
 either a stage of oxidation not completed or one of reduction 
 from nitrates in the presence of organic matter. If free am- 
 
92 AIR, WATER, AND FOOD. 
 
 monia be present, it is safe to say that the source is not only 
 near but in actual contact, since but a few hours' time is 
 needed to oxidize the ammonia in any soil not waterlogged. 
 It may also be pretty safe to assume that bacteria are present, 
 since ammonia is the first stage of that decomposition which 
 they accompany. It is the part of prudence, therefore, to 
 avoid any water which contains both free ammonia and 
 nitrites above .200 or .300 parts per million of the first, and 
 .020 or .030 of the second. 
 
 The absorption of nitrogen by plants is rarely complete, 
 so that it usually appears in far larger quantities in contami- 
 nated ground-waters than could be obtained from purified 
 rain-water. The leaching cesspool discharges its liquid con- 
 tents below the zone of green-plant life; fertilized soil also 
 yields a portion of its food value to the lower layers. A 
 small portion of the nitrogen of vegetable origin may appear 
 as nitrates, but only as a derivative of soil rich in humus is it 
 likely to play any considerable part. In eastern America 
 nitrates above 0.5 parts per million would arouse suspicion, 
 ;and above 5 parts would in most cases prove previous por- 
 tion. 
 
 It is evident that in the use of nitrogen as an indicator of 
 the conditions of a water we are limfted, by the changeful 
 character of the compounds, to certain not-to-be-mistaken 
 amounts, and that in the majority of cases the evidence given 
 is not decisive. v 
 
 Chlorine in Well-water. — Fortunately there is another ele- 
 ment not so eagerly sought for by plants and not liable to so 
 many transformations. Thanks to the great solubility of its 
 common compounds and to their stability, chlorine, once a 
 constituent of a given body of water, is not extracted there- 
 from and remains as a telltale to reveal the past history of a 
 stream or spring. If a man is judged by the company he 
 
./? J 
 
 vnt 
 
 y># 
 
STATE BOARD OF HEALTH 
 MAP OF THE 
 
 STATE OF MASSACHUSETTS. ^^£^1 
 
 SHOWING The ** 
 
 NORMAL CHLORINE. 
 
WATER: THE INTERPRETATION OF ANALYSES. 93 
 
 keeps, much more a water-supply. From sewage all the 
 nitrogen may be removed and the chlorine still remain. 
 
 But in order to use this information with any degree of 
 certainty the normal chlorine of the locality must be known. 
 If a map showing isochlors has been made of the region or 
 State, and if there are no geological deposits to interfere, this 
 is easy; but if the chemist or engineer has an unknown coun- 
 try to report upon, it will be necessary to examine the local 
 conditions and to choose six, eight, or ten samples of prob- 
 able freedom from contamination and to test them for com- 
 parison. The sources of the excess of chlorine over the 
 normal are usually the sink-drain with its burden of salted 
 water from domestic operations; the house-drain, with its 
 chlorine-containing excreta; and the stable-drain, with a 
 slight chlorine content in comparison with the other two. 
 
 Mineral Substances. — Since water Is a universal solvent, 
 it is not surprising to find considerable amounts of mineral 
 matter in the two columns " Total Solid Residue on Evapo- 
 ration " and " Hardness." How much calcium sulphate or 
 magnesium chloride or other soluble mineral is allowable in 
 a potable water is for the physician rather than the chemist 
 to say. As has been said, the human system possesses great 
 adaptability, not only for different foods, but for mineral sub- 
 stances water-carried. Not so the steam-boiler or the laundry- 
 tub, which reacts very sensitively and affects the pockets 
 of the consumers. In a region of soft water, high solids 
 with chlorine and nitrates indicate sewage pollution. 
 Silica is much more commonly present even in surface- 
 waters than is often supposed. What its effect may be is 
 unknown. Iron is not uncommonly found in combination 
 with organic matter in either surface or imperfectly filtered 
 waters in contact with soils poor in calcium salts. It is fre- 
 quently accompanied by free ammonia, which causes an 
 
94 AIR, WATER, AND FOOD. 
 
 abundant growth of Crenothrix. It is also present in deep 
 wells in the form of carbonate, which precipitates on exposure 
 to warm air. 
 
 In a considerable number of cases of public water-supply 
 there is a mixture of surface and ground water which com- 
 plicates the verdict, requiring a most delicate balancing of 
 probabilities. The mineral contents often aid in this deci- 
 sion. Well-waters, too, are often exposed to surface-wash 
 because of poor protection at the mouth. Cyclops or other 
 surface-water organisms often indicate this. 
 
 Water-pipes. — After all, if the pipes conveying the water 
 are of lead or brass, an additional danger appears. Gen- 
 erally speaking, the purer the water the greater the risk. 
 No common metal seems to withstand the action of soft 
 water; six to eight years being the average age of galvanized 
 pipe, and eight to ten of iron pipe. It would seem as if 
 wooden pipe must come into greater use until some kind 
 of glass is invented which will withstand this corrosive 
 action and yet admit of plumber's connections. 
 
 Value of Tests. — It is often asked if some tests cannot be 
 made by the ordinary person of average intelligence which 
 will enable him to tell the quality of a water as well as the 
 expert to whom he pays ten or twenty dollars for an opinion. 
 A careful perusal of the preceding pages will have answered 
 the question in the negative. There is no assay of water as 
 there is of gold and silver. Not one but ten or twenty tests 
 must be made. Not only must the tests be made with the 
 utmost care and cleanliness of person, utensils, and room, but 
 the results must be studied in the light of other experience 
 and other knowledge, geological and biological, and after 
 all this is done there is an array of circumstantial evidence 
 which must be carefully weighed by one whose judgment and 
 experience enable him to read clearly where another might 
 
water: the interpretation of analyses. 95 
 
 see nothing. The value of a water-analysis is in direct pro- 
 portion to the knowledge and experience of the one who 
 interprets it. Clinical skill in addition to theoretical knowl- 
 edge is required to interpret the figures obtained in the course 
 of a water-analysis, as in the symptoms of a disease: and the 
 analogy goes still further, for as some diseases are clearly 
 defined, others are so complicated that only those who have 
 had long experience can outline a safe course, of treatment; 
 so some waters bear the marks of their character so plainly 
 as not to admit of mistake, while others require most careful 
 study. For these reasons the value of water-analysis should 
 not be decried because the fears aroused by reports given by 
 unskilled analysts prove groundless, any more than the prac- 
 tice of medicine should be discarded because inexperienced 
 men make mistakes. 
 
 Is the water in any given case safe for drinking? To an- 
 swer this question there is needed a knowledge wider than a 
 chemist's of the relation of decaying organic matter and of 
 the germ-carrying power of water to outbreaks of disease. 
 There must be added the knowledge of the biologist, the en- 
 gineer, and the sanitarian. 
 
CHAPTER VII. 
 
 ANALYTICAL METHODS.* 
 
 General Statements. — Water-analysis cannot be carried on 
 in an ordinary laboratory. In order to obtain satisfactory 
 results it is necessary to have a room set apart for the pur- 
 pose, and to exclude rigidly all operations which tend to the 
 production of fumes or dust. Where such minute traces of 
 substances are dealt with as in water-analysis, too much care 
 cannot be taken to insure the absolute cleanliness of the ap 
 paratus and the surroundings. It is desirable that the room 
 be well lighted, and if possible the windows should face 
 toward the north. 
 
 The methods for the examination of water which are de- 
 scribed in this chapter by no means comprise all that are in 
 use. The directions are given for the use of students in our 
 own laboratory under the conditions obtaining, i.e., of large 
 classes and of several courses of study, with especial reference 
 to educational rather than purely technical needs, and in some 
 cases, no doubt, the traditions of thirty years may have unduly 
 persisted. The methods have been so selected as to intro- 
 duce a variety of apparatus and to illustrate principles. They 
 have also been subjected to a thorough test in meeting the 
 demands of practical work. 
 
 Collection of Samples.— -F or the collection of water sam- 
 ples, glass-stoppered bottles of about a gallon capacity are 
 best. Those used in this laboratory are of white glass, fifteen 
 inches high to the top of the stopper, five and a half inches 
 
 * See Report of Committee on Standard Methods of Water-analysis, Jour, of 
 Infectious Diseases, Supplement No. I, May, 1905. 
 
 96 
 
water: analytical methods. 97 
 
 in diameter, and weigh about three pounds. They have flat,, 
 mushroom stoppers, on which is engraved a number to corre- 
 spond with that on the bottle. The bottles, before being 
 sent out, are thoroughly cleaned with potassium bichromate 
 and sulphuric acid, washed with distilled water and dried. If 
 glass-stoppered bottles are not at hand, new demijohns fitted 
 with new corks may be used. A glass bottle or a demijohn 
 is much to be preferred to an earthenware jug, because, if for 
 no other reason, it is so much easier to be sure that the interior 
 is clean. It should always be borne in mind that in water- 
 analysis the question is one of very minute quantities of mate- 
 rial, and that the methods to be employed are extremely 
 delicate. Hence, in the case of many waters, careless hand- 
 ling of the sample would contaminate the water to a sufficient: 
 extent to render valueless the results obtained in the labora- 
 tory. In collecting samples, the following directions should 
 be closely followed: * 
 
 Directions for Collecting Samples for Analysis — From 
 a Water-tap. — Let the water run freely from the tap for a 
 few minutes 'before collecting the sample. Then place the 
 bottle directly under the tap and rinse it out with the waler 
 three times, pouring out the water completely each time. 
 Place it again under the tap; fill it to overflowing and pour 
 out a small quantity so that there shall be left an air-space 
 under the stopper of about an inch. Rinse off the stopoer 
 with flowing water; put it into the bottle while still wet and 
 secure it by tying over it a clean piece of cotton cloth. Seal, 
 the ends of the string on the top of the stopper. Under no 
 circumstances touch the inside of the neck of the bottle or 
 the stem of the stopper with the hand, or wipe it with a 
 cloth. 
 
 From a Stream, Pond, or Reservoir. — Rinse the bottle and. 
 
 * Ann. Rep. Mass. State Board of Health, 1890, p. 520. 
 
98 AIR, WATER, AND FOOD. 
 
 stopper with the water, if this can be done without stirring | 
 up the sediment on the bottom. Then sink the botlle, with 
 the stopper in place, entirely beneath the surface of the water 
 and take out the stopper at a distance of twelve inches or 
 more below the surface. When the bottle is fu 1 replace the 
 stopper, below the surface if possible, and secure it as directed 
 above. It will be found convenient, in taking samples in 
 this way, to have the bottle weighted so that it will sink be- 
 low the surface, and to remove the stopper by a cord. It is 
 important that the sample should be obtained free from the 
 -sediment at the bottom of a stream and from the scum on 
 the surface. If a stream should not be deep enough to admit 
 of this method of taking a sample, dip up the water with an 
 absolutely clean vessel and pour it into the bottle after the 
 latter has been rinsed. 
 
 The sample of water should be collected immediately be- 
 fore shipping by express, so that as little time as possible 
 shall intervene between the collection of the sample and its 
 examination. All possible information should be furnished 
 •concerning the source of the water and of possible sources of 
 contamination. For example, in the case of a well, the prox- 
 imity of dwellings, cesspools, or drains should be recorded, 
 and the character and slope of the soil, whether toward or 
 away from the well, should be noted. In the case of a sur- 
 face-water, mention any abnormal or unusual conditions; as, 
 for instance, if the streams or ponds are swollen by recent 
 heavy rains, or are unusually low in consequence of prolonged 
 drought, or if there be a great deal of vegetable growth in or 
 on the surface of the water. Record, in short, any circum- 
 stantial evidence which by any possibility may aid in the final 
 judgment. 
 
 The question of proper collection of samples is an impor- 
 tant one, and the chemist is perfectly justified in refusing to 
 
water: analytical methods. 99 
 
 give an opinion in regard to the purity of a water which he 
 has not himself collected. The ignorance and carelessness 
 shown by people who send samples for analysis are often- 
 times quite amusing. Samples have been received at this 
 laboratory in almost every kind of container imaginable, from 
 an imperfectly rinsed whisky-bottle to a discarded syrup-jug, 
 with about an inch of maple sugar in the bottom. One sam- 
 ple was sent all the way trom Georgia in a stone jug with a 
 corn-cob inserted for a stopper. Others are received with 
 the stopper carefully (?) protected by a mass of sealing-wax 
 or candle-grease. A favorite way is to send the sample in a 
 fruit-jar packed in sawdust or straw. Opinions evidently 
 differ greatly, too, in regard to the size of sample that is 
 needed. It is no uncommon occurrence to have a person 
 come into the laboratory with the remark, " Here is a sample 
 of water that I want analyzed," supplemented by the produc- 
 tion from a coat-pocket of a homoeopathic vial or a sample 
 of half a pint or so of water. Of course, in cases like these 
 practically nothing can be done. 
 
 Preparation of the Sample for Analysis. — Since changes 
 in the composition of a contaminated water are constantly 
 going on, the analysis of the sample should be begun without 
 •delay. The bottle is held under the tap, and the neck and 
 stopper are washed free from adhering dust. The stopper Is 
 rinsed off with some of the water from the bottle. Qualita- 
 tive tests should be made for ammonia, nitrites and chlorine. 
 With waters containing much suspended matter, and in the 
 case of surface-waters in which it is desired to distinguish 
 between the organic matter in solution and that in suspen- 
 sion, a portion of the water should be filtered. In most 
 cases the suspended matter can be removed by filtration 
 through paper. For this purpose only the best Swedish 
 filter-paper should be used, and the filters should be first 
 
IOO 
 
 ATR, WATER, AND FOOD. 
 
 thoroughly washed with ammonia-free water. With some 
 waters containing very finely divided clay in suspension, fil- 
 tration through paper will not be satisfactory, and the sample 
 must be filtered by suction through a cylinder of ung'azed 
 porcelain, such as an ordinary Chamberland-Pasteur hi er- 
 tube. In the filtered water it is customary to determine the 
 dissolved solids, the albuminoid ammonia, or the organic 
 nitrogen, and the color. 
 
 Determination of Free and Albuminoid Ammonia — 
 Apparatus* — The apparatus used for the determination of 
 
 ammonia is that shown 
 in Fig. 8. It consists 
 of a round-bottomed 
 flask of 900 c.c. capaci- 
 ty, with square shoul- 
 ders and a narrow neck 
 five inches long, and an 
 ordinary Liebig con- 
 denser fitted with an. 
 inner tube of block tin,, 
 3 / 16 of an inch in diame- 
 ter. The flask is closed 
 by a cork carrying a 
 glass tube bent nearly at 
 right angles, which 
 slips for some distance 
 within the tin tube cf 
 the condenser. A tight 
 joint is made by means 
 of a large cork, which 
 is shown in section in 
 Fig. 9. The large cork 
 serves the double purpose of making a tight joint with the 
 
 ScaleJHin.= lfoot. 
 Fig. 8. — Apparatus for Ammonia Dis- 
 tillation. 
 
 * A. H. Gill : /. Anal, and App. Chem., 6 {1892), 669. 
 
WATER: ANALYTICAL METHODS. 
 
 IOI 
 
 condenser and also as a convenient means for handling- the 
 small glass tube. In order to remove the cork from the dis- 
 tilling-flask, the glass tube carrying it is simply turned to one 
 side, using the large cork as a pivot. The flasks are heated 
 with the free flame of a Bunsen burner. 
 
 New flasks are treated with boiling dilute sulphuric acid 
 and potassium bichromate before they are used. New corks 
 should be steamed out for one or two hours. A good, sound 
 cork will last for several months with daily use. The dis- 
 
 ssssssssssssssssssss/ss/.'/ . n - 
 
 "~-.^'"-~~ ■ - , ■— 7-.,./. , ' — 
 
 CORK JO I NT 
 
 Full Size 
 
 Fig. 9. 
 
 tillates are received into small 50-c.c. flasks and poured into 
 Nessler tubes for nesslerization. The Nessler tubes are 11 
 inches long and f-inch internal diameter, the 50-c.c. mark 
 being about two inches from the top. It is desirable to so 
 arrange the apparatus as to collect the distillates directly in 
 the Nessler tubes and at the same time render the apparatus 
 more compact by having several condenser tubes run through 
 a common cooling tank. For class work, however, the appa- 
 ratus just described has been found most suitable. 
 
 Directions. — Free the apparatus from ammonia by dis- 
 tilling off the water in the flask, testing each 50-c.c. portion 
 of the distillate until no color is given with the Nessler re- 
 agent. When the distillate is free from ammonia, pour the 
 
102 AIR, WATER, AND FOOD. 
 
 water left in the flasks into the bottle marked " Ammonia- 
 free residues." 
 
 Shake the bottle thoroughly to mix the sample. For 
 determining the ammonia measure out in a calibrated flask a 
 portion, usually 500 ex., the amount taken depending upon 
 the result of the qualitative test. Pour this into the distilling- 
 flask, and distil over three portions of 50 c.c. each into Nessler 
 tubes or into the graduated flasks. 
 
 In dealing with sewage or sewage effluents, which are very 
 high in free ammonia, if the ammonia were collected in three 
 portions, so much would distil over in the first portion that 
 the color given with Nessler's reagent would often be too deep 
 to read or a precipitate might form. To avoid this the total 
 distillate of 150 to 175 c.c. is collected in a 200-c.c. graduated 
 flask, made up to the mark, thoroughly mixed by pouring, and 
 then 50 c.c. of it taken for nesslerization. In this way the 
 ammonia is distributed more evenly in the distillate and the 
 determination is not sacrificed. 
 
 Notes. — When the amount of ammonia shown by the quali- 
 tative test is high — i.e., shows a color equivalent to I. c.c. of the 
 standard ammonia solution — a less quantity than 500 c.c. should 
 be taken for the distillation, 100 c.c. or, in the case of sewage, 
 even 10 c.c. being diluted to 500 c.c. with water free from 
 ammonia. Sewage and soils may be distilled with steam in 
 the apparatus figured on page 106 under the Kjeldahl pro- 
 cess. 
 
 After the free ammonia has been distilled off, allow the 
 contents of the flask to cool slightly; then add 40 c.c. of alka- 
 line permanganate through a funnel, taking care that none of 
 the alkaline soluion touches the neck of the flask, and proceed 
 with the distillation of the albuminoid ammonia; that is to 
 say, the determination of the nitrogen of the undecomposed 
 organic matter. With colored surface-waters distil off five 
 
water: analytical methods. 103 
 
 portions of 50 c.c. each; with waters of low organic content 
 three or four portions will suffice. 
 
 In order to obtain about one half the total organic nitrogen 
 regulate the height of the flame so that the time of distilling 
 50 c.c. shall not be more than eight and not less than five 
 minutes. 
 
 It is impossible to convert all of the organic nitrogen into 
 ammonia by boiling with alkaline permanganate. The amount 
 of ammonia which is thus obtained depends not only upon the 
 character of the substances, but also upon the concentration 
 of the solution and the rate of boiling. In order that the 
 albuminoid ammonia in potable waters shall bear some definite 
 relation to the total organic nitrogen, it is necessary that these 
 conditions shall be duplicated as nearly as possible in different 
 determinations; that is, the alkaline permanganate must be 
 added to a definite volume of the water, and the boiling must 
 be carried on at a definite rate. Some of the highly colored 
 surface-waters give up their nitrogen very slowly by this treat- 
 ment; polluted waters, on the other hand, yield the ammonia 
 more rapidly, so that the observation of the relative amounts 
 found in the successive portions is of the utmost importance 
 in forming a judgment. 
 
 Have the Nessler tubes clean and thoroughly rinsed with 
 ammonia-free water. Unless permanent standards are used 
 prepare standards by adding to Nessler tubes nearly filled. 
 with ammonia-free water varying quantities of the standard, 
 ammonium chloride solution; for instance, 0.1, 0.3, 0.5, 0.7, 
 1.0, 1.3, 1.5, 2.0, 2.5, 4.0, 6.0 c.c. The standard ammonium 
 chloride solution contains .00001 gram N in one cubic centimeter. 
 
 Mix the contents of the tubes by rotating them between 
 the palms of the hands (never shake them like a test-tube or 
 stir them with a rod), allow them to stand for two or three 
 minutes, and add 1 c.c. of the Nessler' s reagent to the whole 
 
io4 
 
 AIR, WATER, AND FOOD. 
 
 set, and to the samples to be tested, as rapidly as possible. 
 At the end of ten minutes match the colors and record the 
 amount of ammonia. 
 
 As an example of a colored surface-water may be given 
 the following results from distilling 500 c.c: 
 
 
 Free Ammonia. 
 
 Albuminoid A 
 
 mmonia. 
 
 1st 
 
 50 C.C, 
 
 0.7 C.C. 
 
 1st 50 c.c, 
 
 4.5 c.c 
 
 2d 
 
 50 C.C, 
 
 0.3 C.C 
 
 2d 50 c.c, 
 
 2.8 C.C 
 
 3d 
 
 50 C.C, 
 
 0.0 c.c. 
 
 3d 50 c.c, 
 4th 50 c.c, 
 5th 50 c.c, 
 
 1.5 C.C. 
 1.0 C.C 
 0.5 c.c 
 
 1.0 c.c. 10.3 cc. 
 
 In this case the free ammonia would be 0.020 and the 
 albuminoid ammonia .206 parts per million. 
 
 In the case of water from suspicious wells and of sewage 
 effluents, about 0.5 gram of freshly ignited sodium carbonate 
 should be added before distillation, in order to make sure that 
 the reaction of the water is not acid, and to decompose any 
 urea which may be present. This will not be necessary with 
 ordinary surface-waters, as experience has shown that they 
 almost always have a slight alkaline reaction. 
 
 A depth of color given by 6 c.c. of the standard ammonium 
 chloride with the Nessler reagent is about the limit of satis- 
 factory comparison in the 11-inch 50 c.c. tubes. The color 
 given by 10 or 12 c.c. of the standard may be matched in the 
 100 c.c. tubes with a depth of 5 inches and a diameter of ij 
 inches. 
 
 For most cases where great exactness is not essential it is 
 possible to divide the 50 c.c. or the 100 c.c. into two equal 
 parts by pouring into a tube the exact counterpart of the 
 standard tube and matching the color. It is even possible to 
 closely approximate the correct result by the use of a foot rule. 
 The standard is, we will assume, 5 c.c. The height of liquid in 
 
water: analytical methods. 105 
 
 the tube to be tested, we will call 9 inches. If the height of 
 the column left which matches 5 c.c. is 3 inches, then the reading 
 was 15 c.c. of the standard. 
 
 The limit of solubility of the mercur-ammonium iodide is 
 reached at 25 or 30 c.c. of the standard in 50 c.c. The incipient 
 precipitate not only changes the color of the solution but causes 
 a slight milkiness or turbidity which prevents a sharp reading 
 of the color. 
 
 The test is an excellent example of quantitive color work 
 when carried out under strictly comparable conditions. 
 
 It should perhaps be stated that in both the ammonium 
 and nitrite determinations, as also in that of iron, dilution of 
 the sample in which the color is already developed does not 
 give a correct result. Therefore dilution if necessary must be 
 made before the reagents are added. 
 
 In order to secure the most accurate results it is impor- 
 tant that the temperature of the distillates to be nesslerized 
 and of the standards be the same, since the warmer solutions 
 give a more intense color with the Nessler reagent. 
 
 The compounds produced by the action of ammonia on 
 mercuric solutions are considered as substitutions of 1 Hg 
 for 2H in NH 4 , and are called mercur-ammoniums. Tetra- 
 mercur-ammonium iodide (NHg 2 I), the compound formed by 
 addition of the Nessler reagent, is a brown precipitate, sol- 
 uble in excess of KI in the presence of KOH with a brown- 
 ish-yellow color proportional within certain limits to the 
 amount of NH 3 : 
 
 NH 3 + (2HgI 2 + 2KI + 3KOH) = NHg 2 I + 5KI + 3H2O. 
 
 The " free ammonia " in all probability does not exist in 
 the water in a free state or as the hydroxide; it is probably 
 present in the form of carbonate or of chloride. When water 
 containing these or similar compounds of ammonia is boiled, 
 they are decomposed and free ammonia passes off with the 
 
io6 
 
 AIR, WATER, AND FOOD. 
 
 steam and is found in the distillate; hence the origin of the 
 name. 
 
 Determination of Total Organic Nitrogen by the 
 Kjeldahl Process — Directions. — Measure 500 c.c. of the 
 water into a round-bottomed flask of 750 c.c. capacity and 
 
 Fig. 10. — Apparatus for Distilling Ammonia by Steam. 
 
 boil until about 200 c.c. have been driven off. (The free 
 ammonia which is thus expelled may be determined, if de- 
 sired, by connecting the flask with a condenser.) Allow the 
 water remaining in the flask to cool, and add 10 c.c. of 
 pure concentrated sulphuric acid free from nitrogen. Mix 
 by shaking; place the flask in an inclined position on wire 
 
WATER. ANALYTICAL METHODS. IO7 
 
 gauze under the hood and boil cautiously until the water is 
 all driven off. Place a small funnel in the neck of the flask 
 to prevent the escape of acid fumes, and continue the heating 
 for at least half an hour after the sulphuric acid becomes 
 white. Meanwhile rinse out the distilling apparatus (see 
 Fig. 10), and free it from ammonia as usual. Then, after the 
 acid in the digestion-flask has cooled, rinse down the neck 
 of the flask with ioo c.c. of ammonia-free water and attach 
 the flask to the distillation apparatus. Add ioo c.c. of 
 potassium hydroxide solution through the separatory funnel 
 and distil off the ammonia by steam, receiving the distillate 
 in a 250-c.c. graduated flask. Conduct the distillation rather 
 slowly until the first 50 c.c. have distilled over, then distil 
 more rapidly until about 175 c.c. have been collected. Make 
 the volume of the distillate up to 250 c.c. with ammonia-free 
 water, mix it thoroughly and take 50 c.c. for nesslerization. 
 
 Notes. — The principles involved in the method consist in 
 the oxidation of the carbon and hydrogen of the organic mat- 
 ter by boiling sulphuric acid, the nitrogen being converted 
 into ammonia and held by the acid as ammonium sulphate. 
 The ammonia is then liberated and distilled off. from an alka- 
 line solution. The use of mercury and of. potassium per- 
 manganate to assist in the oxidation has been found to be 
 unnecessary, as the organic matter in natural waters is much 
 more easily oxidized than in other substances,- — flour, for in- 
 stance. The presence of nitrates and nitrites in waters has 
 not been found to interfere with the accurate determination 
 of the organic nitrogen. The error which has been found by 
 Kjeldahl and Warrington to be caused by the presence of 
 nitrates seems to disappear when the organic material is 
 diluted to the considerable extent that exists in natural 
 waters. The high chlorine found in some well-waters does 
 
108 AIR, WATER, AND FOOD. 
 
 not interfere with the method to any extent, but this deter- 
 mination does not possess much value in this class of waters, 
 which are low in organic nitrogen. 
 
 In carrying out the digestion with sulphuric acid, the 
 greatest care must be taken to prevent access of ammonia or 
 dust from any source. The acid solutions will absorb am- 
 monia from the air or from the dust of the laboratory if they 
 are allowed to remain uncovered for any length of time. 
 This source of error may in some instances be sufficiently 
 large to render a determination valueless, even in a room 
 which is to all appearances free from ammonia-fumes. 
 Hence the operation should, if possible, be carried to com- 
 pletion within twenty-four hours, and for every set of deter- 
 minations a blank analysis should be made with ammonia- 
 free water in order to make a correction for the ammonia in 
 the reagents, and for that accidentally introduced during the 
 process. 
 
 As the result of many hundred comparative determina- 
 tions of the organic nitrogen and of the albuminoid ammo- 
 nia in natural waters which take their origin in the glacial 
 drift, it has been found that the nitrogen given by the albu- 
 minoid-ammonia process as directed in the previous pages 
 is about one-half of the total organic nitrogen as given by the 
 Kjeldahl process; in the case of sewages and polluted waters 
 it is very variable owing to their irregular composition. 
 
 Determination of Nitrogen in the Form of Nitrites. 
 — Directions. — When the determination of the free and 
 albuminoid ammonia is well under way, the estimation of 
 nitrogen in the next stage of decay, that of nitrites, should 
 be begun. If the water is colorless, measure out the required 
 amount, usually ioo c.c, into a ioo-c.c. tube. If the water 
 possesses color which cannot be removed by simple filtra- 
 tion, it should be decolorized as follows: Thoroughly rinse 
 
water: analytical methods. 109 
 
 with the water a 250-c.c. glass-stoppered bottle; pour into 
 it about 200 c.c. of the sample, add about 3 c.c. of the milk 
 of alumina and shake the bottle vigorously. Let the bottle 
 stand for ten or fifteen minutes and filter through a small 
 plaited filter which has been thoroughly washed with water 
 free from nitrites. From this filtrate take 10 c.c. for nitrates 
 (see p. no). To 100 c.c. of the filtered sample or of the origi- 
 nally colorless water add 10 c.c. of sulphanilic acid in acetic 
 acid and 10 c.c. of naphthylamine acetate. 
 
 After standing 5 to 10 minutes, not longer, compare with 
 the standards made with the nitrite solution or, better, with 
 2x4 inch pieces of Milton Bradley's standard papers* the VR, 
 violet-red tint 2 which is an exact match for the color given 
 by 5 c.c. or VR, tint 1, which matches 10 c.c. of the stand- 
 ard nitrite solution in a ioo-c.c. Nessler tube with a depth 
 of 5 inches to the graduation. If 100 c.c. of the sample is used 
 this measures the nitrites in parts per million. Good waters 
 show considerably less than .005, suspicious waters between 
 .005 and .010, bad waters may show from .000 to .300 or even 
 more. The same use of the foot rule and aliquot part may 
 be made as above in the ammonia determination. 
 
 One cubic centimeter of the standard nitrite solution contains 
 0.0000001 gram N as nitrite. The determination must be 
 completed within half an hour, since the air of a room in which 
 gas is burned contains nitrites. f 
 
 Notes.— If the color obtained is more . than . that given by 
 20 c.c. of the standard solution, as it may. be in the case of 
 water from bad wells and sewage effiuents,. the water should 
 be diluted with nitrite-free water, 10 c.c. or even 1 c.c. being 
 made up to 100 c.c. before adding the reagents, since colors 
 
 * Mulliken's "Identification of Pure Organic Compounds,"' Sheet A, Color 
 Standard. 
 
 f Defren: Tech. Quart., g (1896), 238; Axson: loc. cit., 12 (1899), 219. 
 
IIO AIR, WATER, AND FOOD. 
 
 above 20 c.c. are too deep for accurate comparison. In many- 
 cases, however, it may be more convenient and sufficiently 
 accurate, where the colors are not very much greater than 
 20 c.c, to read the color in an aliquot part, as described in 
 the determination of ammonia on page 104. 
 
 The reactions which take place consist first in the diazotiz- 
 Ing of the sulphanilic acid by the nitrite present in acid solu- 
 tion, forming diazobenzenesulphonic anhydride. This reacs 
 with the naphtylamine hydrochlorate, forming azo-or-amido- 
 naphtylic parabenzol-sulphonic acid, which gives the pink 
 color to the solution, the amount formed depending upon 
 the amount of nitrite present. 
 
 ' N ■ N H 
 
 I: J i 
 
 H— C C— H H— C C C— H 
 
 II I I II I 
 
 H— C C— H H— C C C— H 
 
 v/ \/\// 
 
 c c c 
 
 I I I 
 
 SO3H NH a H 
 
 Determination of Nitrogen in the Form of Nitrates.* 
 
 — Directions. — Nitrogen in the fourth stage, that of nitrates, 
 is next determined. In the case of ground-waters, or sewage 
 effluents, measure 2 c.c. from the bottle with a capillary pipette, 
 into a three-inch porcelain evaporating-dish; for surface- 
 waters, always low in nitrates, take 10 c.c. from the portion 
 already decolorized in the determination of the nitrites. Place 
 the dishes on the top of the water-bath and let their contents 
 evaporate gently until one or two drops are left; then set them 
 away in a place free from dust, that the remainder may evapo- 
 rate spontaneously. Do not let them go quite to dryness on 
 the bath. 
 
 * Sprengel: Pogg. Ann., 121, 188. Grandval and Lajoux: CompL rend. y 
 101, 62. Gill: J. Am. Chent. Soc, 16 {1894), 122. 
 
water: analytical methods. hi 
 
 When the water is entirely evaporated, drop six drops of 
 phenol-disulphonic acid directly upon the dry residue and 
 rub it around with a glass rod to insure complete contact of 
 the acid and the residue in the dish. Dilute the acid with 
 7 ex. of distilled water and add 3 c.c. of ammonium hydrate 
 (1:1) or if only one laboratory is available KOH (1:3) since 
 no ammonium hydrate solutions should be allowed in a distilling 
 laboratory. 
 
 To prepare the standards to be matched in the small porce- 
 lain dishes, measure out the varying amounts of the standard 
 nitrate solution, for instance 0.5, 1.0 c.c. to 8 c.c, add enough 
 water to make the volume 10 c.c. and two or three drops of the 
 alkaline hydrate. 
 
 For very low or very high colors the matching is most 
 satisfactorily done in 50-c.c. Nessler tubes, diluting to 50 c.c. 
 or reading an aliquot portion. For matching the lowest colors, 
 which in this case is safely done, 5 or 6 inch high tubes cut 
 from broken Nessler tubes are very satisfactory. 
 
 To prepare standards in Nessler tubes. A portion of water 
 is made alkaline, and the standard is run in little by little until 
 it matches the lowest color. Then more is added until the next 
 color is matched, and so on to the highest color. 
 
 Notes. — It will be found that if 10 c.c. of a colored water 
 be evaporated directly, the color obtained with the reagents 
 will be much deeper as well as browner than that given by 
 the standards; hence the necessity for first decolorizing. 
 
 Chlorides interfere with the accuracy of the method, but 
 not to any extent when chlorine is present in less than 20 parts 
 per million. If the amount of chlorine be more than this, the 
 evaporation should be made in vacuo over sulphuric acid. 
 Nitrites do not interfere with the test. 
 
 The reaction is generally considered to consist in the 
 formation of picric acid. While this is not quantitatively 
 true, it offers the best explanation of the changes that occur. 
 
II 2 AIR, WATER, AMt> FOOD. 
 
 Trinitrophenol (picric acid) is formed by the action of the 
 nitrates in the cold, dry residue upon the phenol-disulphonic 
 acid with which it is moistened: 
 
 OH OH 
 
 l A 
 
 H— C C— SO,H NO,— C C— NO, 
 
 || | J- 3 HNO,= II | +2H,SO. 
 
 H— C C— H H— C C— H 
 
 \ // \ / + H,0 
 
 C C 
 
 I I 
 
 SO.H NO, 
 
 Phenol-disulphonic acid. Picric acid. 
 
 The addition of an excess of caustic alkali converts the 
 picric acid to the alkali picrate, which imparts an intense yel- 
 low color to the liquid. The best color is obtained by the 
 use of ammonia. 
 
 Large quantities of nitrates in colorless water may be de- 
 termined by reduction to ammonia by sodium amalgam, or 
 by any reaction which yields nitrogen, this being measured as gas. 
 
 Determination of the Carbonaceous Matter or " Oxy- 
 gen Consumed." 
 
 KubeVs Hot Acid Method. 
 
 Reagents. — Ammonium oxalate 0.888 gram in one liter 
 distilled water. One c.c. is equivalent to 0.0001 gram of 
 oxygen. Potassium permanganate 0.4 gram in one liter dis- 
 tilled water, standardize against the ammonium oxalate solution 
 and make the necessary correction. If exact, 1 c.c. is equivalent 
 to 0.0001 gram available oxygen. 
 
 Directions. — Measure 100 c.c. of the water into a 250-c.c. 
 flat-bottomed flask, add 10 c.c. of sulphuric acid (1:3) and 
 about 10 c.c. of the potassium permanganate. Place the flask 
 oh wife gauze and heat it quickly to boiling. Boil the solution 
 for exactly two minutes; remove it from the flame; let it cool 
 one minute, and add 10 c.c. of the ammonium oxalate. Titrate 
 
water: analytical method. 113 
 
 with the permanganate to a faint permanent pink color. Each c.c. 
 of the exact permanganate used in excess of the oxalate solution 
 used represents 0.0001 gram of oxygen consummed by the sample. 
 
 Notes. — For highly colored surface-waters 25 c.c. are 
 taken and diluted to 100 c.c. with water free from organic 
 matter; for sewages 10 c.c. are diluted in the same way. 
 
 The oxygen given up by the permanganate combines 
 with the carbon of the organic matter and perhaps to a cer- 
 tain extent with the hydrogen, but not with the nitrogen. 
 The amount of oxygen consumed bears some relation, there- 
 fore, to the amount of organic carbon present in the water r 
 but this relation certainly cannot be taken as a definite one 
 in every case, the results varying even with the time of 
 boiling. The method has its greatest value when it is 
 used to compare waters of the same general character and 
 having the same origin; for example, in making periodical 
 tests of the purity of the effluent from a filter. Furthermore^ 
 in order that the results shall have this comparative value, 
 it is absolutely necessary that the process shall always be 
 carried out in exactly the same way, even to the minutest 
 detail of quantity, time, and temperature. 
 
 In some cases it may be found advantageous to heat the 
 solution upon the water-bath for half an hour instead of boil- 
 ing it for five minutes. The results, however, will not be 
 exactly comparable with those obtained by boiling. 
 
 - Different kinds of organic matter behave differently with 
 various oxidizing agents, so that a comparison of the results 
 obtained with different oxidizing agents may throw light 
 upon, the character of the organic matter, as well as i f s 
 amount.* In waters from the watersheds of eastern Nor^h 
 America the color and the oxygen consumed have a certain, 
 though somewhat varying, relation, , I 
 
 < Determination of Chlorine, r^The chlorine is deter- 
 mined in natural waters by the method in general use; 
 
 * Woodman: /. Am. Chem. Soc, 20 (rSgS), 497. 
 
114 AIR > WATER, AND FOOD. 
 
 namely, titration with a solution of silver nitrate, using potas- 
 sium chromate as an indicator. Since the exact change of 
 color which constitutes the end-point will vary with the 
 sensitiveness of the eyes of different observers to red, each 
 person should standardize the silver nitrate solution for him- 
 self. To do this, measure into a six-inch porcelain dish 25 
 c.c. of distilled water; add 5 c.c. of sodium chloride solution 
 (1 c.c. — 0.001 gram CI) from the burette and three drops of 
 potassium chromate solution. Titrate with the silver nitrate 
 solution until the yellow color of the liquid assumes the faint- 
 est tinge of reddish brown. 
 
 Directions. — Waters which are high in chlorine, i.e., which 
 contain 20 or more parts per million, are titrated directly, 
 using 25 c.c. either with or without the addition of 5 c.c. of 
 the salt solution. Waters which are low in chlorine are con- 
 centrated before titration, 250 c.c. being evaporated to 25 c.c. 
 on the water-bath. Brown surface-waters should be decol- 
 orized as follows: Pour into a 750-c.c. flat-bottomed flask 
 about 500 c.c. of the water. Add 3 c.c. of the milk of 
 alumina; shake and heat the water quickly to boiling on an 
 iron plate. When the liquid comes to a full boil, at once 
 remove the flask from the plate to avoid loss by evaporation. 
 Place it in an inclined position to allow the alumina to settle. 
 Decant off 250 c.c. of the colorless water into a six-inch dish 
 for concentration to 25 c.c, using a flask calibrated for both 
 the hot and the cold solution. Before making the titration, 
 rub down the sides of the dish above the liquid with a small 
 quantity of distilled water free from chlorine, using a clean 
 feather. Rinsing alone will not always dissolve the chlo- 
 rides which adhere to the sides of the dish. 
 
 Notes. — For titration by this method the solution must 
 be as nearly neutral as possible If the water is alkaline to 
 .any extent, it should be neutralized with dilute sulphuric acid, 
 
water: analytical methods. 115 
 
 using phenolphthalein as an indicator. The solution will 
 then contain alkali only as bicarbonate, which does not 
 interfere with the titration. Acid water must be made neu- 
 tral by the addition of sodium carbonate. 
 
 It is important that the process be carried out essentially 
 as described, since it has been found that the results vary 
 with the volume of solution in which the titration is made, 
 the amount of chromate used, and the amount of precipitated 
 silver chloride present.* A correction for volume can be 
 made by means of the formula given by Hazen. 
 
 E. G. Smith t recommends titration in a volume of 
 100 c.c., making a correction of .1 c.c. more or less as found 
 for the error due to dilution of the reagents. 
 
 Color is removed by agitation with milk of alumina as 
 before described. 
 
 Determination of the Residue on Evaporation and 
 the Loss on Ignition. — Directions. — Ignite and weigh a 
 platinum dish. Measure into it 100 c.c. of the water (200 
 c.c. in the case of surface-waters), and evaporate to dryness 
 on the water-bath. When the water is all evaporated heat 
 the dish in the oven at the temperature of boiling water for 
 two hours, then let it remain in a desiccator over sulphuric 
 acid for several hours and weigh.J The increase in weight 
 gives the " total solids " or " residue on evaporation." If 
 from a ground-water, save the residue for the determination 
 of the iron. 
 
 In the case of surface-waters the residue should be ignited 
 and the loss on ignition noted. Heat the dish in a " radia- 
 tor," which consists of another platinum dish enough larger 
 to allow an air-space of about half an inch between the two 
 dishes, the inner dish being supported by a triangle of plati- 
 num wire. Over the inner dish is suspended a disk of 
 
 * Hazen: Am. Chem. Jour., 11 (iSSg), 409. 
 
 \ Trans. Wis. Acad. Sciences, Arts, and Letters, Vol. XIII, 359. 
 
 Jin some laboratories it is the practice to dry at no° or 130 C. 
 
n6 
 
 AIR, WATER, AND FOOD. 
 
 platinum-foil to radiate back the heat into the dish. The 
 larger platinum dish is heated to bright redness by a triple 
 gas-burner. Heat the dish in the radiator until the residue is 
 white or nearly so. Note any blackening or charring of the 
 residue and any peculiar " burnt odor " which may be given 
 off. After the dish has cooled, slightly moisten the residue 
 with a few drops of distilled water to secure weighing under 
 the same conditions. Heat the residue in the oven for half an 
 hour; cool in a desiccator and weigh. This gives the weight 
 of " fixed solids," the difference being the " loss on ignition." 
 
 Notes. — Before the introduction of modern methods of 
 water-analysis the determination of " loss on ignition " was 
 the only method for the estimation of organic matter in 
 water. In order, however, that the determination shall pos- 
 sess any real value, it is necessary to regulate carefully the heat 
 during the ignition, so as to destroy the organic matter with- 
 out decomposing calcium carbonate or volatilizing the alkali 
 chlorides. 
 
 This is what the use of the radiator is intended to accom- 
 plish, and in the case of surface-waters, with low mineral con- 
 tent and considerable organic matter, the method gives gen- 
 erally satisfactory results. But in the case of ground-waters 
 having little or no organic matter and high mineral content 
 the loss is often very great on account of the decomposition 
 of nitrates and chlorides of the alkaline earths and the loss of 
 water of crystallization. In waters of this class the determi- 
 nation of " loss on ignition " is, therefore, generally meaning- 
 less, although an approximation to the amount of organic 
 matter can be obtained by the addition of sodium carbonate to 
 the water before evaporating to dryness. By this means the 
 alkaline earths are precipitated as carbonates, the chlorine 
 and nitric acid are held by an alkaline base, and there is no 
 water of crystallization in the residue. Even with this modi- 
 fication the loss is considerable when magnesium salts are 
 present, owing to the loss of carbonic acid. ,0 - r; 
 
water: analytical methods. 
 
 117 
 
 The behavior on ignition is oftentimes significant. 
 Swampy or peaty waters give a brownish residue on evapora- 
 tion to dryness, which blackens or chars, and this black sub- 
 stance burns off quite slowly. The odor of the charring is 
 like that of charring wood or grain; sometimes sweetish, but 
 not at all offensive. Waters much polluted by sewage blacken 
 slightly; the black particles burn off quickly and the odor is 
 disagreeable. Any observations on this point should be re- 
 corded in the report (p. 141 ) under the heading " Change on 
 Ignition." 
 
 Determination of the Hardness. 
 
 1. By Soap. — Clark's Method. 
 
 Directions. — Measure 50 c.c. of water into a 200-c.c. clear 
 glass-stoppered bottle and add the soap solution from the 
 burette, two or three tenths of a cubic centimeter at a time, 
 shaking well after each addition, until a lather is obtained 
 which covers the entire surface of the liquid with the bottle 
 lying on its side, and is permanent for five minutes. The 
 number of parts of calcium carbonate corresponding to the 
 volume of soap solution used is found in the table in Appen- 
 dix A. 
 
 This will give the total hardness. If it is desired to find 
 the permanent hardness also, dilute 50 c.c. of the water to 
 about 200 c.c. and boil down to 50 c.c. in a beaker, cool and 
 determine the hardness as before. This will give the per- 
 manent hardness, and the difference will be the temporary 
 hardness. 
 
 Notes. — When potassium or sodium soap is added to 
 water containing calcium and magnesium salts, the soap is 
 decomposed, and insoluble compounds with the fatty acids 
 are formed. The importance of adding the soap in small quan- 
 tities cannot be too strongly emphasized, especially in the 
 presence of magnesium compounds. The presence of mag- 
 
Il8 AIR, WATER, AND FOOD. 
 
 nesium salts will be recognized by the peculiar curdy appear- 
 ance of the precipitate formed and by the occurrence of a 
 false end-point, the lather lasting about three minutes when 
 the titration is about half done. If much carbonic acid be 
 'liberated, it is better to follow Dr. Clark's original directions 
 and remove it by suction. 
 
 By reference to the table it will be observed that values 
 are not given fcr more than 16 c.c. of the soap solution. If 
 in any case the water under examination requires more than 
 10 c.c. of the standard soap solution, a smaller portion of 
 25 c.c, 10 c.c. or even 2 c.c, as the case may require, is meas- 
 ured out and made up to a volume of 50 c.c with recently 
 distilled water. If the volume of soap used is always about 
 7 c.c, this will keep the results comparable with each other, 
 although the element of dilution introduces an error. Potable 
 waters, in the eastern United States, at least, are rarely so 
 high in mineral matter as to require excessive dilution. In 
 the case of extremely hard waters, however, the acid 
 method is to be preferred. Distilled water itself, containing 
 no calcium salt whatever, requires the use of a considerable 
 quantity of soap to produce a permanent lather. The cause 
 for this seems to exist in the dissociation of the greater part 
 of the soap at the extreme dilution to which it is subjected,, 
 and the slow accumulation of a sufficient quantity of undis- 
 sociated soap to allow of the increase of surface tension to a 
 point at which soap-bubbles will persist. 
 
 By the temporary hardness of water is meant the hardness 
 which is removed by boiling. It is due to the carbonates of 
 calcium and magnesium held in solution by the carbonic acid 
 in the water, probably in the form of bicarbonates. Perma- 
 nent hardness is that which is not removed by boiling. It is. 
 caused by the presence of soluble salts of calcium and mag- 
 nesium, not carbonates, but chlorides and sulphates princi- 
 pally, held in solution by the solvent power of the water itself.. 
 
WATER: ANALYTICAL METHOD. II9 
 
 2. By Acid. — Hehner's Method* 
 
 ALKALINITY. 
 
 Directions. — For the determination of the " alkalinity," 
 
 measure ioo c.c. of the water into a clear bottle such, as is used 
 
 for the soap test, and add 2.5 c.c. of the erythrosine indicator, 
 
 0.1 gram of the sodium salt in 1 liter of distilled water, and 
 
 5 c.c. of chloroform neutral to erythrosine. Mix well by shaking 
 
 N . 
 
 and add — sulphuric acid from the burette in small quantities, 
 
 shaking thoroughly after each addition. The pink color grad- 
 ually grows lighter until the addition of a drop or two of the 
 acid causes it to disappear entirely. Each tenth of a cubic 
 centimeter of acid used represents one part of CaC0 3 in 1,000,000. 
 Make a correction for the indicator by carrying out a blank 
 determination with distilled water. 
 
 The alkalinity may be determined more quickly as follows. 
 Measure 100 c.c. of the water to be tested into a No. 6 evapo- 
 rating dish, add two drops of sensitive methyl orange and titrate 
 
 with the — sulphuric acid. Lacmoid and phenacetolin can 
 
 also be used in the determination of the alkalinity, but they 
 necessitate titration in a hot solution on account of their sus- 
 ceptibility to carbonic acid. 
 
 ■Notes.— This method is especially useful for waters which 
 require clarification by alumina and subsequent filtration. 
 
 i The use of chloroform is essential to secure a sharp end- 
 point. The non-ionized erythrosine formed by the addition 
 of the acid to its alkali salt is soluble in the aqueous solu- 
 
 * Hehner: Analyst, 1883, 8, 77; Draper, Chem. News, 1885, 51, 206: Ellms: 
 Jour. Am. Chem. Soc, 1899, 21, 239. 
 
120 AIR, WATER, AND FOOD. 
 
 tion with a slight rose color. It is, however, more soluble 
 in the chloroform, and when it is thus removed as fast as 
 formed the neutralization of the alkali becomes at once 
 apparent.* 
 
 If a water contains sodium or potassium carbonate, 
 there will not be any permanent hardness, and hence more 
 acid will be required for the filtrate than corresponds to the 
 amount of sodium carbonate added. From the excess 
 the amount of sodium carbonate in the water may be 
 determined. Any alkali carbonate present would be 
 calculated as temporary hardness by the direct titration; 
 hence it should be calculated to calcium carbonate and 
 subtracted from the results found by the direct titra- 
 tion. 
 
 Determination of Phosphates. f — Directions. — Evapo- 
 rate 50 c.c. of the water and 3 c.c. of nitric acid (sp. gr. 1.07) 
 to drvness in a 3 -inch porcelain dish on the water-bath. 
 Heat the residue in an oven for two hours at the tempera- 
 ture of boiling water. Treat the dry residue with 50 c.c. 
 of cold distilled water, added in several portions and poured 
 into the comparison-tube. It is not necessary to filter the 
 solution. Add 4 c.c. of ammonium molybdate (50 grams 
 per liter) and 2 c.c. of nitric acid, mix the contents of the 
 tube and compare the color, after three minutes, with stand- 
 ards made by diluting varying quantities of the standard 
 phosphate solution (1 c.c. =0.0001 gram P 2 5 ) to 50 c.c. with 
 distilled water and adding the reagents as above. Carry 
 out a blank determination on the distilled water used for 
 dilution, especially if it has stood for any length of time in 
 glass vessels. 
 
 * Ellms: /. Am. Chetn Soc, 21 (i8qq), 359. 
 
 fLepierre- Bull. Soc. Chim., 15 (1896), 1213 Woodman and Cayvan: 
 J. Am. Chem. Soc, 23 (iqoi), 96. Woodman- ibid. (1902), 735. 
 
WATER: ANALYTICAL METHODS. 12 1 
 
 Notes. — The method as described will be sufficient for 
 ordinary work. If a more exact determination of the phos- 
 phate is required, a slight correction should be made in each 
 case. For a table showing these corrections reference may 
 be made to the paper by Woodman and Cayvan previously 
 cited. 
 
 The evaporation and heating w T ith nitric acid is for the 
 purpose of removing silica, which gives with ammonium 
 molybdates a yellow color similar to that given by phos- 
 phates. 
 
 The determination of phosphates in a drinking-water is 
 a matter which has not received the attention from water 
 analysts that has been given to the estimation of various 
 other constituents. Any one who looks through the litera- 
 ture cannot help noticing how few are the published 
 results of quantitative estimations of the phosphate con- 
 tent of natural waters, apart from mineral waters. Yet 
 this determination, by reason of the conversion of 
 organic phosphorus compounds into phosphates through 
 the processes of decay, is one which might reasonably 
 be expected to throw considerable light on the question 
 of the pollution of natural waters by objectionable ma- 
 terial. 
 
 The reasons for this dearth of published data are not 
 far to seek. To be of value the amount of phosphate must 
 be known within rather narrow r limits. Qualitative tests 
 are not sufficient. The mere presence of phosphates is by 
 no means definite or even confirmatory evidence of organic 
 pollution. Rocks and minerals containing phosphates are 
 found nearly everywhere, and traces, at times even con- 
 siderable quantities, may be dissolved, especially by waters 
 rich in carbonic acid. This, however, does not constitute 
 
122 AIR, WATER, AND FOOD. 
 
 a serious objection to the utility of the determination. The 
 same is true of many if not most of the constituents upon 
 which reliance is placed in judging of the quality of a water. 
 Unpolluted waters often contain notable amounts of nitrates 
 and chlorides, and a true judgment can be rendered only 
 after comparison with samples from adjacent but unpol- 
 luted sources. 
 
 The chief reason, however, has been the lack of an accu- 
 rate and simple method, sufficiently delicate, and of enough 
 data to work out a standard for comparison. 
 
 This reason can hardly hold true now, for enough work 
 has been done on the colorimetric method to indicate its 
 value as another link (of which we have none too many, any- 
 way) in the chain of circumstantial evidence by which we 
 are often compelled to judge the purity of a water. 
 
 The amount of phosphate and its variation seem to fol- 
 low the same general line as the other mineral constitu- 
 ents which either accompany the polluting material or are 
 produced by its decay, especially the nitrates and chlorides. 
 It is not, however, so delicate an indicator as these. In 
 general it may be said that the amount (expressed as P 2 5 ) 
 in an unpolluted water will seldom be over i.o part per 
 million. 
 
 Determination of Iron.* — Directions. — Evaporate iooor 
 200 c.c. of the water to dryness in a platinum dish. (The 
 weighed residue from the determination of total solids may 
 be used if desired.) Treat the residue with 5 c.c. of hydro- 
 chloric acid (1:1), being careful to carry the acid to the edge 
 of the dish. In some cases it may be necessary to heat the 
 dish gently on the water-bath in order to bring all the iron 
 
 * Thomson: J. Chem. Soc, 67 (1885), 493. 
 
WATER: ANALYTICAL METHODS. 123 
 
 into solution. When all is dissolved with the exception of 
 silica, rinse the solution into a ioo-c.c. tube and make it up 
 to about 50 c.c. with distilled water. Add a solution of po- 
 tassium permanganate drop by drop until the solution re- 
 mains pink for 10 minutes. 
 
 Meanwhile prepare a blank standard with 5.0 c.c. of dis- 
 tilled water and about a cubic centimeter of hydrochloric 
 acid. Add 15 c.c. of potassium sulphocyanide solution to 
 the waters and to the blank standard. Add the standard 
 iron solution, in small quantities, .02 c.c. if necessary, from 
 a capillary pipette, mixing thoroughly by pouring the solu- 
 tion back and forth from one tube to another after each 
 addition, until the color of the standard matches that of 
 the water. One cubic centimeter of the standard iron solu- 
 tion is equal to 0.000 1 gram of Fe. 
 
 Notes. — In the case of some river-waters it will be fpund 
 necessary to add a few cubic centimeters of hydrochloric 
 acid to the water while evaporating, in order to facilitate 
 the solution of the iron. This should be done on a separate 
 portion from that used for the determination of total 
 solids. 
 
 The colors should be matched immediately after adding 
 the sulphocyanide, since the color fades appreciably on 
 standing. The highest standard should not contain more 
 than 3 c.c. of the iron solution, since the color then becomes 
 too deep for accurate comparison. 
 
 Determination of the Dissolved Oxygen. 
 
 Method of L. W. Winkler* 
 
 Collection of Samples. — The samples are collected in 
 glass-stoppered bottles of known capacity, holding about 
 
 * Berichte, 21 (1888), 2843. 
 
124 AIR » WATER, AND FOOD. 
 
 250 cubic centimeters. When water is taken from a faucet 
 the bottle is filled by means of a tube which passes to the 
 bottom of the bottle. A considerable amount of water is 
 allowed to pass through the bottle and overflow at the top. 
 It will be almost impossible to obtain duplicate samples 
 unless the bottles are filled at the same time by means 
 of a T tube, owing to variations in pressure in the 
 pipes. 
 
 In taking samples from a stream or pond, a stopper 
 with two holes is used. A tube passing through one of 
 these holes is sunk in the water to the desired depth, and 
 the other is connected with a larger bottle of at least four 
 times the capacity of the smaller one, and fitted in the same 
 way. From the larger bottle the air is exhausted by the 
 lungs or by an air-pump until it is nearly filled with water. 
 Unless the determination is to be made at once, the rubber 
 stopper of the smaller bottle is quickly replaced by the 
 glass stopper so that no air is left in the bottle. The 
 temperature of the water at the time of sampling should 
 be noted. 
 
 The apparatus which has been used in connection with 
 work in this laboratory for collecting samples at various 
 depths down to 75 feet is shown in outline in Fig. 11. A gal- 
 vanized-iron can of such size as to hold one of the gallon bot- 
 tles is weighted with lead and provided with ears at the top 
 for suspending. The bottle, which is securely wired in, is pro- 
 vided with a rubber stopper carrying two brass tubes, one 
 ending just below the stopper and projecting for about 8 or 
 9 inches above it, the other extending to the bottom of the 
 bottle and connected by heavy rubber tubing with the 
 sample bottle. This is held by brass brackets, which are 
 fastened by means of a wooden cleat to the side of the can. 
 The neck of the bottle is put into the slot in the .upper 
 
WATER: ANALYTICAL METHODS. 
 
 125 
 
 bracket and then it is firmly clamped by the thumb-screw 
 of the lower one. The arrangement of tubes in the sample 
 bottle is obvious. In using the apparatus it is quickly 
 
 Fig. 
 
 lowered to the desired depth by means of a rope marked off 
 in feet. The water enters the sample bottle and flows 
 through it into the other. When the bubbles cease to rise, 
 indicating that the larger bottle is full, thus replacing the 
 water in the sample bottle a number of times, the apparatus 
 is drawn to the surface. The temperature is read from a 
 thermometer fastened to the tube inside the gallon bottle. 
 The Determination. — Remove the stopper and add 2 c.c. 
 of manganous sulphate solution with a pipette having a 
 long capillary point reaching to the bottom of the bottle, 
 and in the same way add 2 c.c. of the solution of sodium 
 hydroxide and potassium iodide. Insert the glass stopper, 
 leaving no bubbles of air, and mix the contents of the bottle. 
 
126 AIR, WATER, AND FOOD. 
 
 f 
 
 Allow the precipitate to settle, and add 3 c.c. of strong 
 hydrochloric acid with another pipette ; add also one or two 
 small glass beads and again insert the stopper. When the 
 white portion of the precipitate is entirely dissolved, pour 
 out a part of the solution into a flask, put back the stopper 
 and shake the bottle vigorously. Then rinse out the con- 
 tents of the bottle into the flask and titrate the liberated 
 
 N 
 iodine with approximately — sodium thiosulphate until the 
 
 color becomes a faint yellow. Then add starch solution 
 and titrate to the disappearance of the blue color. The 
 first end-point should be taken, as the color will return on 
 account of the reducing action of the organic matter present. 
 
 OXYGEN DISSOLVED. 
 
 From Report on Standard Methods. 
 
 Sulphuric Acid. — Specific gravity 1.4 (dilution 1:1). 
 
 Sodium Thiosulphate Solution. — Dissolve 6.2 grams of 
 
 chemically pure recrystallized sodium thiosulphate in one 
 
 N - 
 liter of distilled water. This gives an — solution, each c.c. 
 
 40 
 
 pf which is equivalent to .0002 gram of oxygen or .1395 c - c - 
 
 of oxygen at o° C. and 760 mm. pressure. Inasmuch as 
 
 .this solution is not permanent, it should be standardized 
 
 N 
 "occasionally against an — solution of potassium bichromate 
 
 as described in almost any work on volumetric analysis. 
 The keeping qualities of the thiosulphate solution are im- 
 proved by adding to each liter 5 c.c. of chloroform and 1.5 
 grams of ammonium carbonate before making up to the 
 prescribed volume. . 
 r "Calculation of Results.— The standard method of ex- 
 
water: analytical methods. 127 
 
 pressing results shall be by parts per million of oxygen by 
 weight. 
 
 "It is sometimes convenient to know the number of c.c. 
 of the gas per liter of o° C. temperature and 760 mm. pres- 
 sure, and also to know the percentage which the amount of 
 gas present is of the maximum amount capable of being 
 dissolved by distilled water at the same temperature and 
 pressure. All three methods of calculation are therefore 
 here given: 
 
 Oxygen in parts per million 
 
 
 0.0002N X 1 
 
 .000,000 200N 
 
 
 V 
 
 
 ~ V 
 
 in c.c. 
 
 per liter 
 
 
 
 
 0.1395NX: 
 
 [OOO 
 
 i39-5 N 
 
 
 V 
 
 
 V 
 
 Oxygen in per cent, of saturation 
 
 200N X 100 2o,oooN 
 
 = vxo = "~vo 
 
 N 
 Where N = number of c.c. of — thiosulphate solution, 
 
 V = capacity of the bottle in c.c. less the vol- 
 ume of the manganous sulphate and potas- 
 sium iodide solution added (i. e., less four 
 c.c). 
 
 = the amount of oxygen in parts per million in 
 water saturated at the same temperature and 
 pressure." 
 
128 
 
 AIR, WATER, AND FOOD. 
 
 QUANTITIES OF DISSOLVED OXYGEN IN PARTS PER MILLION BY 
 WEIGHT IN WATER SATURATED WITH AIR AT THE TEMPERATURE 
 GIVEN. 
 
 Temp. C. 
 
 Oxygen. 
 
 Temp. C. 
 
 Oxygen. 
 
 Temp. C. 
 
 Oxygen. 
 
 Temp. C. 
 
 Oxygen. 
 
 o 
 
 14.70 
 
 8 
 
 11.86 
 
 16 
 
 9-94 
 
 24 
 
 8.51 
 
 I 
 
 14-28 
 
 9 
 
 11.58 
 
 17 
 
 9-75 
 
 2 5 
 
 8-35 
 
 2 
 
 13.88 
 
 10 
 
 II. 31 
 
 18 
 
 9.56 
 
 26 
 
 8.19 
 
 3 
 
 I3-50 
 
 11 
 
 11 05 
 
 19 
 
 9 37 
 
 27 
 
 8.03 
 
 4 
 
 13 14 
 
 12 
 
 10.80 
 
 20 
 
 9.19 
 
 28 
 
 7.88 
 
 5 
 
 12.80 
 
 13 
 
 IO-57 
 
 21 
 
 9 01 
 
 29 
 
 7-74 
 
 6 
 
 12.47 
 
 14 
 
 IO-35 
 
 22 
 
 8.84 
 
 30 
 
 7.60 
 
 7 
 
 I2.l6 
 
 15 
 
 IO.14 
 
 2 3 
 
 8.67 
 
 
 
 Notes. — This determination is a good illustration of an 
 indirect volumetric process. A precipitate of manganous 
 hydroxide is formed in the bottle by the reaction of the 
 manganous sulphate and the sodium hydroxide. This imme- 
 diately combines with the oxygen in the water to form a cer- 
 tain amount of manganic hydroxide. The hydrochloric acid 
 which is added reacts with the manganic hydroxide to form 
 chlorine, which in turn liberates iodine from the potassium 
 iodide, the amount thus set free depending primarily upon 
 the quantity of oxygen dissolved in the water. The presence 
 of considerable amounts of organic matter or of nitrites in- 
 troduces an error. In such cases the method must be modified 
 or a correction made. Details of the method used in such 
 cases are given in the paper by Winkler previously cited. 
 
 A correction is made for the volume of the reagents 
 added, but since the precipitated hydroxides had settled 
 before the acid was added, no allowance should be made for 
 the amount of acid, since the water it displaces contains 
 neither oxygen nor iodine. 
 
water: analytical methods. 12 o> 
 
 is a constant for any particular bottle, and its logarithm 
 may be recorded in a note-book or upon the bottle itself. 
 
 If water is collected in the ordinary way and transferred. 
 to the apparatus by pouring, there will inevitably be an ab- 
 sorption of oxygen unless the water is already saturated. 
 Thus a process which gives excellent results when the water 
 is nearly or quite saturated may fail entirely to give accurate 
 results when the dissolved oxygen is low or absent. The 
 water may be supersaturated with oxygen, in which case the 
 per cent, of saturation may be more than one hundred.* 
 
 Determinations of dissolved oxygen in ponds and 
 streams are best made on the spot, or at least the re- 
 agents should be added. The very simple apparatus re- 
 quired for the Winkler process can be packed in small space, 
 and the entire determination requires only a few minutes. 
 The absorption of the oxygen by the manganous hydroxide- 
 is complete almost at once, and it is unnecessary to allow it 
 to settle for a long time before adding the acid. The titra- 
 tion can be made with a small burette or pipette with accurate 
 results. 
 
 Determination of Free Carbonic Acid. — Reagent. — Stand- 
 
 N 
 ard — solution of sodium carbonate. Dissolve 2.41 grams of 
 
 dry sodium carbonate in one liter of distilled water which has 
 been freed from carbonic acid by cautious addition of dilute 
 solution of sodium carbonate. Add 5 c.c. of phenolphthalein 
 indicator (7 grams in a liter) to the distilled water before 
 neutralizing and measuring. Preserve this solution in bottles 
 of resistant glass, protected from the air by tubes filled with- 
 soda lime. One c.c. equals 0.001 gram of C0 2 . 
 
 ♦Gill: Tech. Quart., 5 (1892), 250. 
 
130 AIR, WATER, AND FOOD. 
 
 Procedure. — Measure 100 c.c. of the sample into a tall, 
 
 narrow vessel, preferably a 100 c.c. Nessler tube, and titrate 
 
 N 
 rapidly with the — sodium carbonate solution, stirring gently 
 
 until a faint but permanent pink color is produced. 
 
 N 
 The number of c.c. of — sodium carbonate solution used in 
 22 
 
 titrating 100 c.c. of water, multiplied by 10, gives the parts per 
 
 million of free carbonic acid as C0 2 . 
 
 Owing to the ease with which free carbonic acid escapes 
 irom water, particularly when present in considerable quanti- 
 ties, it is highly desirable that a special sample should be 
 collected for this determination, which should preferably be 
 made on the ground. If the analysis cannot be made on the 
 spot, approximate results from water not high in free carbonic 
 acid may be obtained from samples collected in bottles which 
 are completely filled so as to leave no air space under the 
 stopper. 
 
 Notes. — The reaction consists in the formation of acid 
 sodium carbonate: 
 
 Na 2 C0 3 + H 2 4-CO2 = 2NaHC0 3 . 
 
 The acid carbonate does not give a pink color with phenol- 
 phthalein. 
 
 Determination of the Color. — The amount of color is 
 generally determined by direct comparison of the water with 
 some definite standard of color. Various standards of color 
 have been proposed, the objection to most of them being 
 that they are not sufficiently general in their application, 
 Being adapted only for the color of some particular class of 
 waters. 
 
water: analytical methods. 131 
 
 Nesslerized Ammonia Standards .—The yellowish-brown 
 "tint of the surface-waters of the Atlantic watershed corre- 
 sponds, except in the lowest grades, very closely to that of 
 nesslerized ammonia, so that the standards for reading 
 ammonia can be used also for the determination of the 
 color. The comparison is made in the same kind of 50-c.c. 
 tubes that are used for the ammonia determinations, but 
 the tubes used for this purpose are kept separate from those 
 used for the ammonia, since the least amount of alkali re- 
 maining in a tube (from imperfect washing, for instance) 
 ■alters the color of the water. The scale used corresponds 
 quite closely with the amount of the standard ammonium 
 chloride solution in the standards. Thus a color of 1.0 is 
 nearly the same as that produced by the nesslerization of 1 
 c.c. of the standard ammonia; c.i is about the color pro- 
 duced with 0.1 c.c. of the ammonia solution. In the higher 
 grades of color, above 1.0 or 2.0, the tint varies considerably 
 from that of the nesslerized ammonia, and the degree of 
 color is then better determined in wider tubes and in less 
 depth. 
 
 The degree of correspondence of the ammonia standards 
 with the natural waters is dependent largely upon the sensi- 
 tiveness of the Nessler's reagent, a solution which is so sen- 
 sitive as to precipitate in two hours, matching the colors 
 more closely than one which will remain for twenty- four 
 hours. This is perhaps due to the reddish tinge given to the 
 solution by the incipient precipitation of the mercuric 
 iodide. 
 
 Natural Water Standards. — To avoid these variations in 
 •color, standards made from dark-colored water from swamps 
 by various degrees of dilution, and verified by direct com- 
 parison with suitably prepared nesslerized ammonia stand- 
 
132 AIR, WATER, AND FOOD. 
 
 ards, are used. They have the same hue as the waters to be 
 matched, as well as a degree of turbidity which corresponds 
 well with that of surface-waters ; once prepared, they will 
 keep for a fairly long time if protected from the light and 
 from the dust. These are the standards that are in use in 
 this laboratory. They are periodically standardized by 
 comparison with the permanent glasses of a Lovibond 
 Tintometer. 
 
 Platinum Standards. — For ground-waters which have 
 only very little color and considerable hardness, and for fil- 
 tered waters, the platinum color standards are convenient.*" 
 According to this scale, the color of a water is the amount of 
 platinum in parts per ten thousand, which, together with 
 enough cobalt to match the tint, must be dissolved to pro- 
 duce an equal color in distilled water. In practice, a stand- 
 ard having a color of 5.00 is prepared by dissolving 1.246' 
 grams of potassium platinic chloride (equivalent to .5 gram 
 platinum), 1.000 gram of cobalt chloride (equivalent to .25 
 gram cobalt), and 100 c.c. of strong hydrochloric acid in dis- 
 tilled water and diluting to one liter. 
 
 Dilute standards for use are made by diluting varying 
 amounts of this standard to 50 c.c. with distilled water. Thus, 
 by diluting 1 c.c, 2 c.c, and 3 c.c. to 50 c.c, colors of 0.1, 0.2, 
 and 0.3 are obtained. It is claimed that the platinum stand- 
 ards are permanent if protected from the dust. 
 
 Iodine Standards. — A standard for color which could be 
 made up at the moment when wanted and without the use of 
 costly apparatus would be a desideratum. Experiments made 
 in this laboratory indicate that an aqueous solution containing 
 a definite weight of iodine offers the best solution of the prob- 
 lem. Owing, however, to the volatility of iodine even in 
 dilute aqueous solution it is better to liberate it directly in 
 
 * Hazen : Am. Chem. /., 14 (1892), 300. 
 
water: analytical methods. 133 
 
 the comparison-tube itself. For this the following solutions 
 are required: Potassium iodide, 0.1 gram per liter; potas- 
 sium bichromate, 0.09 gram per liter; picric acid, 0.2 gram 
 per liter. 
 
 For a color of 5.0, 50 c.c. each of the iodide and of the 
 bichromate solutions are used; for lower colors proportional 
 amounts are taken and diluted to 100 c.c. with distilled water. 
 To each tube is added 1 c.c. of the picric acid solution, and 
 just before the colors are to be matched add 2 c.c. of strong 
 sulphuric acid. The color develops, as in the case of nessler- 
 ized ammonia, within ten minutes and can be relied upon 
 for about half an hour. A very slight milkiness aids in match- 
 ing the color; a great hindrance to the use of metallic solu- 
 tions being their clearness or brightness as compared with 
 natural waters. 
 
 The comparison-tubes which give the most satisfactory 
 results with colors from 5.0 to 0.5 on the natural water scale 
 are 15 / 16 inch wide and 9V4 inches high to the 100-c.c. mark, 
 For lower colors, narrower tubes, n /i6 mcn diameter and the 
 same depth, give closer readings. 
 
 Determination of the Odor. — Cold. — Shake violently 
 the sample in one of the large collecting-bottles when it is 
 about half or two-thirds full, then remove the stopper and 
 quickly put the nose to the mouth of the bottle. Note the 
 character and degree of intensity of the odor, if any. An 
 odor can often be detected in this way which would be en- 
 tirely inappreciable if the water were poured into a tumbler. 
 
 Hot. — Pour into a beaker about five inches high enough 
 water to one-third fill it. Cover the beaker with a well-fitting 
 watch-glass and place it on an iron plate which has been pre- 
 viously heated, so that the water shall quickly come to a boil. 
 When the air-bubbles have all been driven off and the water 
 is about to boil, take the beaker from the plate and allow it 
 to cool for about five minutes. Then shake it with a rotary 
 
134 AIR, WATER, AND FOOD. 
 
 movement, slip the watch-glass to one side and put the nose 
 into the beaker. Note the odor as before. The odor may or 
 may not be the same as that of the water when cold; it can 
 be perceived, as a rule, for only an instant. 
 
 Notes. — It is inevitable that a certain personal equation 
 should influence this test. Each laboratory will have its own 
 .standards for routine work, but a certain familiarity with the 
 more common odors will tend to allay public anxiety and to 
 aid in a more watchful habit on the part of consumers. Good 
 ground-waters do not give distinct odors unless they are de- 
 rived from clayey soil, but the odor often betrays a contami- 
 nated wei! more surely than any other test. Surface-waters 
 will nearly always yield a characteristic odor. This odor may 
 be due to the organic matter contained in the water, or to 
 the presence of minute plants or animal organisms. 
 
 Among the odors which are frequently met are the 
 " earthy," " vegetable," " musty," " mouldy," " disagree- 
 able," and " offensive." The " earthy " odor is that of 
 freshly turned clayey soil. u Vegetable " is the odor of 
 many normal colored surface-waters; it may be described 
 as swampy or marshy, pond-like, and is often strengthened 
 by heating. " Musty " can be likened to the odor of damp 
 straw from stables; it is fairly characteristic of sewage con- 
 tamination, and by the trained observer is distinctly distin- 
 guishable from the mouldy odor. " Mouldy " is the odor of 
 upturned garden or forest mould, or of a moist hot-house; 
 it is somewhat allied to the earthy odor. " Disagreeable " 
 is a term which is capable of wide variation among different 
 observers. It may include certain characteristic odors which 
 are peculiar to the growth or decay of certain organisms, as 
 the " pigpen " odor of Anabcena, the " fishy " or " cucum- 
 ber " odor of Synura, etc. The term " offensive " is generally 
 reserved for the sewages. These terms can be taken only as 
 broad illustrations of the character of the particular odor, 
 
WATER ANALYTICAL METHODS. 13$ 
 
 since the odor will very likely be described by different per- 
 sons in different ways, and each laboratory will have its own 
 characterization. The odor which often accompanies an 
 abundant development of diatoms is a good illustration of 
 this. It will be called by various inexperienced observers 
 offensive, rotten, fishy, geranium-like, aromatic, in one and 
 the same sample of water. 
 
 The terms generally used to signify the degree of inten- 
 sity of the odor are " very faint," " faint," " distinct," and 
 " decided." The exact value to be placed on each of these 
 terms will, as a matter of course, vary with the individual 
 analyst, but in a general way it may be said that the " very 
 faint " odor is one that would not be detected except by the 
 trained observer; the " faint " odor would be recognized by 
 the ordinary consumer if his attention were called to it; the 
 " distinct " odor is one that would be readily noticed by the 
 average consumer, but would not interfere with the use of 
 the water; while the " decided " odor is one which would, in 
 all probability, render the use of the water unpleasant. 
 
 Biological Examination — The close relation of the odor 
 to the living fauna and flora of the water makes it desirable 
 that the chemist shall be able to recognize the more common 
 forms of water plants and animals even if he makes no pre- 
 tensions to a knowledge of cryptogamic botany or of zo- 
 ology. Therefore a microscope and a concentration appara- 
 tus should be in every water-laboratory. A full description 
 will be found in Whipple.* 
 
 The bacteriological examination belongs to the expert 
 rather than to the student, certainly in the present state of 
 our knowledge of the lower organisms. It may be desirable 
 for the student to be familiar with the simpler methods of 
 plate and tube culture, and the water-works laboratory 
 should, as in the above case, be provided with means for plain 
 
 * " Microscopy of Drinking-water." 2d ed. N. Y., Wiley. 
 
H36 AIR, WATER; AND FOOD. 
 
 number counts, and directions for avoiding errors due to 
 variations in temperature, time of culture, etc., consult 
 Frankland's "Micro-organisms in Water"; "Manual of 
 Bacteriology," Muir and Ritchie; "Water Bacteriology," 
 Prescott and Winslow. 
 
 Determination of the Turbidity and Sediment — The 
 suspended matter remaining in the water after it has rested 
 quietly in the collecting-bottle for twelve hours, or more, is 
 called its turbidity, and that which has settled to the bottom 
 of the bottle, its sediment. 
 
 Good ground-waters are often entirely free from turbidity 
 and sediment, the suspended matters having been filtered out 
 during the subterranean passage of the water, but this is 
 rarely true of surface-waters. The turbidity is various in 
 character and amount, sometimes milky from clay or ferrous 
 iron in solution; usually it consists of fine particles, generally 
 living algae or infusoria. These often collect on the side 
 toward or from the light, and a practised eye can, not infre- 
 quently, recognize their forms. Some of the lower animal 
 forms can also be seen by the naked eye, and the larger En- 
 tomostraca are quite noticeable in many waters. 
 
 The sediment may be earthy or flocculent; in ttie latter 
 case it is generally debris of organic matter of various kinds. 
 The degree of turbidity is expressed by the terms " very 
 slight," " slight," " distinct," and " decided," and the degree 
 of sediment by " very slight," " slight," " considerable," and 
 " heavy." These determinations, again, are of value only to 
 the routine worker, and for him there are various methods in 
 use. The papers of Parmelee and Ellms * and of Whipple 
 and Jackson f should be consulted for a description of these. 
 
 Permanent standards, however desirable for a routine 
 laboratory where many samples are tested daily, are not 
 very reliable for students' work where the tests are made 
 
 * Tech Quart., 12 {1899), 145. \Ibid. t 283. 
 
waier: analytical methods. 137 
 
 only at intervals and for educational rather than technical 
 purposes. 
 
 Determination of Alum. — On account of the use of alum 
 or aluminum sulphate as a coagulant in the filtration of 
 water, a determination of alumina in the effluent water is 
 often necessary. This may be readily made by the log- 
 wood test.* 
 
 Directions. — The logwood solution is made as follows: 
 Take two grams of logwood chips and boil one minute in a 
 platinum dish with 50 c.c. of distilled water. Decant the 
 solution and boil again for one minute with 50 c.c. of water. 
 Decant this and similarly boil a third time with 50 c.c. of 
 water. Decant this into a platinum receptacle for use. 
 Take three drops for each test. Kept in platinum, the solu- 
 tion will last for several days at least. 
 
 Test the water as follows: Boil 50 c.c. of the water in 
 a platinum dish for a short time to expel carbon dioxide. 
 Add three drops of the logwood solution and continue boiling 
 for a few seconds to develop the color. Decant into a glass 
 flask and cool quickly under the tap (so as not to keep the 
 hot solution too long in the glass). Transfer to a No. 2 
 beaker and blow in carbon dioxide from the breath by means 
 of a glass tube until there is no further decolorization. Pour 
 the water into a Nessler tube for comparison with standards 
 similarly prepared. Allow them to stand several hours 
 before taking the final reading. No wash-water is used at 
 any of the decantations. The test shows one part of 
 aluminum sulphate in 8,000,000 parts of water. 
 
 A blank made with distilled water, if not completely 
 decolorized by the C0 2 , will show a tint perceptibly fainter 
 
 * E. H. Richards: Tech. Quart., 4 (1891), 194. A. H. Low, Tech. Quart., 
 15 (1902), 351. 
 
1 3$ AIR, WATER, AND FOOD. 
 
 than that produced by one part in 8,000,000 of aluminum 
 sulphate. 
 
 It should be noted that carbon dioxide must be kept 
 absent until the point prescribed. The solution is therefore 
 transferred to a beaker in order to keep the flask free from 
 carbon dioxide for the next test. 
 
 The main points are: 
 
 1. Any kind of logwood appears to answer. 
 
 2. The solution is good for several days, at least, if kept 
 in platinum. 
 
 3. The use of platinum instead of glass for boiling the test, 
 
 4. The use of carbon dioxide instead of acetic acid. 
 Aluminum hydrate, as pointed out by the late Professor 
 
 A. R. Leeds in 1893, will produce a tint almost as strong as 
 if it were in solution, but of a distinctly differing tint. 
 
 Mr. Low's method of procedure is as follows: First, 
 test the water as above described. If no tint, or none ex- 
 ceeding that of the blank, remains after standing several 
 hours or over night, that is sufficient. If, however, a tint 
 persists, or a colored precipitate settles out, it is necessary 
 to determine if this is due to aluminum hydrate. Pour a 
 sample of the water several times through a double Swedish 
 filter, and finally test the filtrate. If the tint produced is 
 weaker than that given by the unfiltered water, repeat the 
 operation on a fresh portion of the water, using the same 
 filter, and continue repeating with new portions of the 
 water and always using the same filter, until it is apparent 
 that no further diminution of the tint can be effected. 
 
 For a less delicate test in school laboratories where 
 platinum is not available, the following alternative method 
 may be used: 
 
 Dissolve about 0.1 gram pure hematoxylin in 25 c.c. 
 water ; this solution will keep for two weeks and works best 
 
water: analytical methods. 139 
 
 after being made several hours. To 50 c.c. of the water, 
 placed in a four-inch porcelain dish, add two drops of the 
 haematoxylin solution, allow the solution to stand for one 
 or two minutes, then add a drop of 20 per cent, acetic acid. 
 The standards are prepared at the same time, using 50 c.c- 
 of distilled water and the required amount of a stand- 
 ard alum solution. The comparison must be made imme- 
 diately, since the color fades on standing. In this way the 
 presence of one part of aluminum sulphate in five million can 
 be determined directly in the water and with ease. 
 
 Logwood may be used instead of the haematoxylin, the 
 solution being prepared as above. 
 
 Notes. — This test will show the presence of all soluble salts 
 of aluminum which enter into combination with the coloring 
 matter of the logwood to form a " lake." 
 
 The alkalies and alkaline earths give a purplish color with 
 logwood extract, hence the test for alum can be made only in 
 acid solution. 
 
 Determination of Lead. — Lead in the minute quantities 
 in which it ordinarily occurs in water is best estimated by 
 comparing the color of the sulphide with standards. 
 
 Directions. — If the water is colorless, acidify the clear solu- 
 tion, concentrated if need be, with two or three drops of 
 acetic acid, and pass in hydrogen sulphide to saturation. If 
 a color is produced, compare it in a 100-c.c. tube with the 
 color given by varying quantities of a standard lead solution. 
 
 If the water is too highly colored to estimate the lead di- 
 rectly, evaporate three or four liters in a porcelain dish to 
 about 25 c.c, add 10 c.c. of ammonium chloride solution and 
 a considerable excess of strong ammonia. Then add hydro- 
 gen sulphide water and allow the dish to stand some hours. 
 JBoil the contents of the dish for a few moments to expel the 
 
140 AIR, WATER, AND FOOD. 
 
 excess of hydrogen sulphide, and filter. The precipitate con- 
 tains all the lead, iron, and suspended organic matter, also 
 copper and zinc if present, while the soluble color goes into 
 the filtrate. Wash once with hot water, transfer the filter to 
 the original dish, and dissolve the sulphides by boiling with 
 dilute nitric acid (i part acid, sp. gr. 1.2, to 5 parts water). 
 Filter and wash; evaporate to 10-15 c.c, cool, add 5 c.c. con- 
 centrated sulphuric acid and evaporate until copious fumes 
 are given off". Then, if the original water contained less than 
 0.25 part iron per million, add acetic acid and ammonia, boil, 
 filter, and read the' amount of lead in the alkaline filtrate, 
 making the standards (page 260) also alkaline with ammonia. 
 
 If the water contained over .25 part iron, wash the lead 
 sulphate into a beaker with alcohol and water, and let it set- 
 tle overnight. Filter, wash free from iron with 50 per cent, 
 alcohol, dissolve the precipitate by boiling with ammonium 
 acetate, filter, and determine the lead as above. 
 
 Note. — If more than .25 part of iron is present, some of 
 the lead will be held by the precipitated ferric hydroxide; and 
 if 25 parts are present, all of the lead may be lost in this way; 
 hence the modification of the method in the presence of con- 
 siderable quantities of iron.* 
 
 When copper is also present it is detected by the blue 
 color given to the ammoniacal filtrate from the iron precipi- 
 tation. 
 
 Statement of Results — In reporting water analyses the 
 results are best expressed in milligrams per liter, which for 
 the majority of waters is equivalent to " parts per million." 
 Occasionally it may be desirable to express the results in 
 " grains per gallon." Parts per million may be converted into 
 grains per U. S. gallon by multiplying by 0.058. For con- 
 
 * Ann. Rep. State Bd. Health, Mass., 1898, 577. 
 
water: analytical methods. 
 
 141 
 
 venience the results should be arranged in tabular form, such 
 an arrangement being suggested below: 
 
 sanitary water-analysis. 
 
 (Parts per 1,000,000.) 
 
 
 Date. 
 
 Physical. 
 
 Residue on Evaporation. 
 
 No. 
 
 Color. 
 
 Turb. 
 
 Sed. 
 
 Odor. 
 
 Total. 
 
 Loss. 
 
 Fixed. 
 
 Change 
 
 
 Cold. 
 
 Hot. 
 
 Ignition. 
 
 X2I 
 
 3-9-'oo 
 
 .50 
 0.0 
 0.0 
 
 Dec. 
 
 None 
 
 Cons. 
 
 None 
 
 None 
 
 F. Veg. 
 
 None 
 
 42.5 
 
 64.0 
 
 9740.0 
 
 12.5 
 
 30.0 
 
 (Slight 
 \ black 
 
 "3 
 
 
 
 
 
 Nitrogen as 
 
 
 No. 
 
 Total 
 Organic. 
 
 Alb. Ammonia. 
 
 Free Am. 
 
 Nitrite. 
 
 Nitrate. 
 
 Ox. 
 
 Cons. 
 
 
 Total. 
 
 Sol. 
 
 Susp. 
 
 
 121 
 
 .598 
 
 .306 
 .014 
 .032 
 
 .170 
 
 .136 
 
 .056 
 .000 
 .560 
 
 .003 
 .000 
 .003 
 
 .220 
 .1.40 
 1. 14 
 
 4.83 
 
 •41 
 
 3.23 
 
 123 
 
 
 
 
 
 
 
 Hardness 
 
 Chlorine 
 as 
 Chlo- 
 rides. 
 
 Iron. 
 
 Biological (per c.c.) 
 
 No. 
 
 Bac. 
 
 Plants. 
 
 
 
 Diatoms. 
 
 Cyano- 
 phyceae. 
 
 Alg«e. 
 
 Animals. 
 
 
 20.0 
 
 23.0 
 
 560.0 
 
 1.8 
 
 6.3 
 
 1198.0 
 
 
 
 ■ 
 
 
 
 
 
 229 
 
 
 .01 
 
 .46 
 
 
 123 
 
 
 
 
 
 
 
 
 
 
 
 No. 121 is from a pond; 122 from a spring; 123 from an artesian well. 
 
CHAPTER VIII. 
 
 FOOD IN RELATION TO HUMAN LIFE: COMPOSITION, SOURCES, 
 
 DIETARIES. 
 
 Life itself is conditioned on the food-supply. Wholesome food 
 is a necessity for productive life. Man can and does exist on very 
 unsuitable, even more or less poisonous, food, but it is merely 
 existence and not effective life. This is true not only of the 
 wage-earner, but of the business-man, the professional man, the 
 scholar. To be well, to be able to do a day's work, is man's 
 birthright. Nevertheless a too large proportion of the American 
 people sells this most valuable possession for a mess of pottage 
 which pleases the palate for three minutes and weights the diges- 
 tive organs for three hours. With the products of the world ex- 
 posed in our markets, the restraints of a restricted choice, as well 
 as inherited instincts or traditions, lose their force. The buyer, 
 unless he has actual knowledge to guide him, is swayed by the 
 caprices of the moment or the condition of his purse, and often 
 fails to secure adequate return in nutritive value for the money 
 paid. The fact that so much manipulated material is put upon 
 the market renders this choice of food doubly difficult, since the 
 appearance of the original article is often entirely lost, and to 
 city-bred buyers even the natural product conveys little idea of 
 its money value. It is now even more necessary that an elemen- 
 tary knowledge of the proximate composition and food value of 
 the more common edible substances should be recognized as 
 
 an essential part of education. 
 
 142 
 
FOOD IN RELATION TO HUMAN LIFE. 1 43 
 
 Food: Definition and Uses. — Food is that which builds up the 
 body and furnishes energy for its activities: that which brings 
 within reach of the living cells which form the tissues the elements 
 which they need for life and growth. Only such available sub- 
 stances can be called food, no matter what their chemical compo- 
 sition may be. Soft coal contains carbon and hydrogen and is 
 food for the furnace, but is not available for the animal body. 
 
 This food which is taken into the body is used in various ways. 
 It forms and builds up new tissues, besides repairing and making 
 good the waste of tissues due to bodily activity; it is stored up in 
 the body to meet a future demand; it supplies the needed heat 
 by the transformation of its stored up or potential energy into the 
 muscular energy required by the body; it may be used to protect 
 the tissues of the body from being themselves consumed as food. 
 
 Composition of Food. — We determine what chemical elements 
 enter into the composition of the body by an analysis of the various 
 organs and tissues. We learn what combinations of these ele- 
 ments serve as food by determining those present in mother's milk 
 and in foodstuffs which experience has proved to furnish perfect 
 nutrition. From these studies it is apparent that about fifteen 
 chemical elements are constant constituents of the human body; 
 that about a thousand natural products are known to have food 
 value; that of these, one hundred are of world-wide importance 
 (see table, page 150), and that ten of them form nine-tenths of 
 the food of the world. 
 
 The composition of food, as shown by chemical analysis, is 
 not, however, the only factor that must be known to determine its 
 value. The digestibility of the material must be taken into account 
 as well. "We live not upon what we eat, but upon what we digest." 
 It is more important to know the amount of available nutrients 
 than the amount of total nutrients. 
 
 Food Principles. — W^hile the foodstuffs present great variety, 
 the food principles may be grouped under four headings; 
 
144 AIR, WATER, AND FOOD. 
 
 viz., nitrogenous substances or proteids, fats, carbohydrates, 
 and mineral salts. Each group contains many members with 
 minor but often essential differences. To make these sub- 
 stances available, there is needed an ample supply of air and 
 of water, — of water for solution and circulation, of air for the 
 oxygen needed to liberate the stored energy of the food in the 
 place where it will accomplish its purpose. 
 
 Nitrogenous Substances. — Since, in some way as yet un- 
 known to us, nitrogen is essential to living matter, such sub- 
 stances as contain this element in an available form are of the 
 first importance. Some, as albumen, are so closely allied to 
 human protoplasm that probably they need only to be dis- 
 solved to be at once assimilated. Others, as gluten and sim- 
 ilar vegetable products, undergo a greater change; while still 
 others, as gelatine, have a less profound but marked effect in 
 protecting the tissues from waste. 
 
 The enzymes, " ferments," in part, of the older nomencla- 
 ture, are also highly nitrogenous substances present in some 
 form in nearly all foodstuffs of natural origin. The nearer 
 the composition of the food approaches that of the protoplas- 
 mic proteid, presumably the greater its food value, since each 
 cleavage, each hydrolysis, each step in the breaking down of 
 the highly complex molecule, consisting of hundreds of atoms, 
 is supposed to liberate the stored energy. Therefore it is not a 
 matter of indifference in what form this essential is taken. So 
 little is known, however, with scientific accuracy that stu- 
 dents will find a fruitful field of research along these lines of 
 investigation. Also together with this element, nitrogen, go 
 others, in small quantity to be sure, but evidently of great 
 value. Such are sulphur, iron, phosphorus. One difference 
 between the several groups of proteids is seen in this com- 
 bination with the metallic elements which seems to carry with 
 it certain effects. Until greater progress has been made in 
 
FOOD IN RELATION TO HUMAN LIFE. 1 45 
 
 determining the availability in the organism of the various 
 known substances, we must be content with a wide margin 
 in the calculated quantities necessary for the daily efficiency, 
 except in the very few instances of nearly pure substances, as 
 white of egg. It is evident also that the manner of prepara- 
 tion and the kind of mixtures used in food will afreet most 
 profoundly so unstable and complex a class of substances. 
 One thing is certain, that the body cannot take nitrogen 
 from that which does not contain it. Therefore a cer- 
 tain quantity of highly nitrogenous food should form "a 
 portion of the daily supply. It is usually held that the body 
 seems to be sufficiently nourished when the food contains 
 an amount of digestible proteid equivalent to about ioo> 
 grams of dry albumen per day for the average adult, although 
 recent work has shown that this figure is probably too high. 
 An excess appears to have a stimulating effect and overloads 
 the system with the waste, since the end-products are not 
 purely mineralized substances, as are carbon dioxide and 
 water from the carbohydrates, but are compounds of an or- 
 ganic nature, as creatin, urea, and uric acid, which have 
 deleterious effects when accumulated in the system. A de- 
 ficiency of nitrogen is made good, to a limited extent, by the 
 protective agency of the other foodstuffs which offer them- 
 selves for all the offices except the final one of tissue-building. 
 Fats. — For this protective action, as well as for many other 
 purposes, the fats are most valuable, and if they occur in about 
 the same proportion as do the nitrogenous elements, the 
 needs of the organism seem to be well met. Thus, in mother's 
 milk, in eggs, and in meat from active animals these two are 
 in nearly equal proportions, while in the cereals the fat is less; 
 in nuts and in meat from fattened animals, as a rule, it is 
 higher than the nitrogen. Little is known as to the varying 
 food value of these fats from different sources. Certain 
 
146 AIR, WATER, AND FOOD. 
 
 physical conditions of solidity, melting-point, etc., seem to 
 have more influence than mere chemical composition. What- 
 ever the source, it is certain that the stored-up energy which 
 is to serve the organism in cases of loss of income from any 
 cause is in the form of fat, a form which is not subject to the 
 action of agents which so readily decompose proteids and 
 •carbohydrates and yet is readily converted into available food 
 whenever called for. That it is not absolutely necessary that 
 the food should contain fat as such seems to be proved by 
 experiment, but from the fact that all nearly natural food- 
 substances do contain it, and that it appears to be more 
 economical of human energy to take it from these foods than 
 to manufacture it from the proteids and carbohydrates, we 
 may safely assume fat to be an essential of the human dietary. 
 
 That the equality in amount of fat with nitrogenous com- 
 pounds is not essential is proved by the fact that the strong 
 draft animals, as horses and oxen, take food in which the per 
 cent, of fat is not more than half as much as of proteid; never- 
 theless it is present in the food of all animals and doubtless, 
 in its turn, is protected by an excess of the third class of 
 foodstuffs, the carbohydrates, characteristic of the vegetable 
 kingdom — a class which in the final decomposition yield clean 
 volatile products, water and carbon dioxide, and which, there- 
 fore, do not clog the system so readily as do urea and other 
 wastes. 
 
 Carbohydrates. — The number of more or less well-defined 
 substances under this head is legion: starches from scores 
 of plants, sugars from as many more, gums, pectins, and 
 dextrins, all with a certain food value, dependent prob- 
 ably upon the utilization of the various mixtures with 
 which they are taken into the alimentary canal. These 
 foodstuffs are very liable to " fermentation," that is, to an' 
 acid decomposition which prevents their absorption by 
 
FOOD IN RELATION TO HUMAN LIFE. 147 
 
 the delicate lining of the walls of the intestines and which 
 causes digestive disturbance. The sugars, which are very 
 soluble, and therefore liable to be present in excess, are es- 
 pecially subject to this change. This class of food-substances 
 is found in the diet of civilized man, free to choose, in an 
 amount about equal to the sum of the other two classes, with 
 a tendency to less rather than more. It may be said that 
 sugar and fat increase over starch in the diet of a people of 
 unrestricted choice, but it is not certain that the qualities of 
 body which make for hardihood and resistance to disease 
 are correspondingly increased. There is, indeed, much evi- 
 dence to show that power of digesting vegetable foods indi- 
 cates a general well-being of body conducive to long life. A 
 ready adaptation renders possible the changes of habitat re- 
 quired by civilization. Unless one is to be confined to a nar- 
 row range it is wise to cultivate a strength of digestion as 
 well as a strength of muscle, and for the best brain power we 
 believe it to be more essential. 
 
 Mineral Salts. — The fourth class, mineral salts, comes into 
 the food largely from the vegetable substances eaten, for in 
 these the union is an organic one readily assimilated. As we 
 have seen, certain elements go with the nitrogenous portion, 
 as, for example, in gluten and its congeners are found sul- 
 phur and phosphorus. Potassium, found in barley, is a con- 
 stant constituent of protoplasm, while sodium is found in 
 blood-serum. A lack of vegetable foods seems to impoverish 
 the blood-corpuscles. For children, a deficiency in lime 
 causes serious disease. Sugar, olive-oil, corn-starch, and 
 other prepared food-substances cannot take the place of 
 asparagus, cabbage, carrots, etc. 
 
 To sum up briefly, then, wu may say that the protein or nitro- 
 genous portion of the food forms tissue, such as muscle, sinew and 
 fat, and furnishes energy in the form of heat and muscular strength ; 
 
I48 AIR, WATER, AND FOOD. 
 
 the fats build up fatty tissue, but not muscle, and supply heat; the 
 carbohydrates are changed into fat and supply heat. Another im- 
 portant use of the nutrients is to protect each other from being used 
 in the body. The carbohydrates, especially, in this way protect 
 the protein, including muscle, etc., from consumption. 
 
 Change in Composition Due to Cooking. — The composition of 
 cooked food is in general not the same as the raw material on ac- 
 count principally of chemical and physical changes brought about 
 by the heat employed in the cooking process. The total nutrients, 
 calculated on a water-free basis, may be practically the same, but 
 the structure is often quite different. 
 
 Starch is hydrolyzed and rendered soluble by heating in the 
 presence of moisture, and at higher temperatures it may be con- 
 verted into the brown, soluble dextrin. The sugars are changed, 
 being, in the case of sucrose, partly converted into other forms, 
 such as invert sugar, by the heating, with the help of the organic 
 acids present in many foods. Some of the proteids tend to become 
 less soluble through heating and at higher temperatures may be 
 even partly decomposed with possible loss of food value. 
 
 Heat of Combustion. — Until a more definite knowledge of the 
 processes of metabolism (the transformations of matter and energy 
 in the animal organism) is obtained the potential energy of food is 
 calculated in terms of mechanical work — expressed in heat-units 
 or calories. 
 
 One calorie is the amount of heat required to raise the tempera- 
 ture of one gram of water one degree centigrade. A gram of fat, 
 as actually digested and oxidized in the body, affords enough 
 heat to raise the temperature of about 9000 grams of water one 
 degree. In like manner a gram of protein has an energy- 
 producing power expressed in calories of about 4000, and for 
 carbohydrates the average value is also 4000. 
 
 Allowance is made in these figures for the fact that to digest com- 
 pletely any part of our food results in a decrease of the amount of 
 
FOOD IN RELATION TO HUMAN LIFE. 1 49 
 
 energy to be derived from it, and this affects the protein more than 
 it does the other two. It is probably true that under favorable con- 
 ditions the fat and carbohydrates can be completely utilized in the 
 body and consequently their energy-producing power can be correctly 
 estimated from their heat-producing power outside the body, In 
 the case of protein, however, the digestion within the body is never 
 so complete as to furnish all the energy that would be obtained by 
 a complete combustion of these nitrogenous materials outside of 
 the body. 
 
 The fact remains, however, that all experiments yet made go 
 to show that within practical limits We are safe in using the heat 
 of combustion (expressed in calories) of any food-substance at a 
 controlling measure of food values. 
 
 Nutritive Ratio. — The requisite number of calories must, how- 
 ever, be obtained by the utilization of such substances as contain 
 all the elements needed by the body, and in such ratio as has been 
 found available for the balance of nutrition. In carrying on its 
 multifarious activities the body loses about 20 grams of nitrogen 
 per day, which must be replaced by the same element in the food 
 taken. Thus while the requisite number of calories may be fur- 
 nished by fat or starch, these substances alone will not suffice for 
 complete nutrition. The nutritive ratio, or the proportion of 
 nitrogeneous to non-nitrogenous food, must be maintained in the 
 proportion of 1 to 3, or at least 1 to 5. 
 
 The following table of one hundred common food-mate- 
 rials is arranged in the order of calorific or energy-giving 
 power, but in considering the food value of any one substance 
 its nitrogen content must also be considered, and such com- 
 binations made as will yield the requisite elements for a well- 
 oalanced ration. 
 
 From even a cursory examination of the table it will be 
 seen how widely some of the foodstuffs differ under differing 
 conditions of soil moisture, fertilization in the case of plants, 
 
J5o 
 
 AIR, WATER, AND FOOD. 
 
 COMPOSITION OF SOME COMMON FOOD-MATERIALS AS PURCHASED* 
 I. Fuel Value 3000-4000 Calories* per Pound. 
 
 Food -material. 
 
 Butter 
 
 Lard (refined) 
 
 Oleomargarine. . . . 
 
 Salt fat pork 
 
 Suet 
 
 Walnuts (shelled) 
 
 Refuse. 
 
 Per cent. 
 
 Water. 
 
 Per cent. 
 
 I I o 
 
 9-5 
 0.3 to 12.2 
 4.3 t° 21 9 
 
 3-5 
 
 Nitroge- 
 nous 
 Substances. 
 
 Per cent. 
 
 0.2 to 5.0 
 
 i.r to 7.5 
 
 16.6 
 
 Fat. 
 
 Per cent. 
 
 85.0 
 100.00 
 
 83.0 
 80.3 to 94.1 
 70.7 to 94.5 
 
 63.4 
 
 Carbo- 
 hydrates. 
 
 II. Fuel Value 2000-3000 Calories per Pound. 
 
 Bacon 
 
 Cheese (American pale). 
 
 Chocolate 
 
 Doughnuts 
 
 Mutton Hank (fat) 
 
 Peanut butter 
 
 Sausage (farmer) 
 
 8.7 
 
 3 9 
 
 10.4 
 31.6 
 ,5 to 10.5 
 o to 25.8 
 28.9 
 
 2.1 
 22.2 
 
 9-5 
 
 28.8 
 
 12.5 to 13.4 
 
 5.1 to 7.6 
 
 10.7 
 
 20 3 
 27.9 
 
 59-4 
 
 35-9 
 47.1 to 50.2 
 16.4 to 25.7 
 
 59.8 
 46.5 
 
 40.4 
 
 III. Fuel Value 1500-2000 Calories per Pound. 
 
 Barley (pearled) 
 
 Beans (dried) 
 
 Cake average (except fruit). 
 
 Candy 
 
 Cheese (Neuchatel) 
 
 Corn-meal 
 
 Corn-starch 
 
 Crackers (average) 
 
 Fat meats 
 
 Gelatin 
 
 Ham (smoked, medium fat) 
 Infants' and invalids' foods 
 
 Macaroni 
 
 Oats 
 
 Peanuts 
 
 Peas (dried) 
 
 Pop-corn 
 
 Rice 
 
 Rye flour 
 
 Sugar (granulated) 
 
 Wheat (entire) flour 
 
 Wheat flour (white bakers'). 
 
 Wheat (shredded) 
 
 Zwieback 
 
 11. 7 
 
 4.5 to 28.4 
 
 9.8 to 12.9 I 
 
 9.6 to 15. 5 
 
 19.9 
 
 4.0 
 
 42.7 to 57.2 
 
 8.8 to 17.9 
 10. o 
 
 6.8 
 
 38.3 
 
 13.6 
 27.3 to 42.5 
 2.4 to 12.3 
 
 7.0 to 12.3 
 
 7.8 
 6.9 
 
 6.9 to 15.0 
 
 4-3 
 
 9.1 to 14.0 
 11. 9 to 13 6 
 
 7.0 to 10. 1 
 
 19.9 to 26.6 
 
 6.3 
 
 6.4 to 13.1 
 lo.i to 13.3 
 7.2 to 10.7 
 5.0 to 7.7 
 
 * Including fibre. 
 
 15. 1 to 22.3 
 6.7 to 11.6 
 
 10.7 
 13.0 
 84.2 
 
 10.2 to 21.9 
 2.0 to 22.5 
 7.9 to 16.6 
 
 16. s 
 
 19. 5 
 20.4 to 28.0 
 
 10 7 
 5.9 to 11.3 
 4.9 to 8.8 
 
 12.2 to 14.6 
 10.3 to 14.9 
 9.6 to 11. 4 
 8.6 to 11. 7 
 
 0.7 to 1.5 
 
 1 4 to 3.1 
 
 9.0 
 
 22.3 to 32.5 
 1.0 to 5.3 
 
 24.5 to 39.9 
 0.3 to 10.9 
 0.0 to 4.9 
 
 7-3 
 
 29.1 
 
 0.8 to 1.3 
 
 5.0 
 
 0.1 to 0.7 
 0.2 to 1.3 
 
 Perci 
 
 26.8 to 33.8. 
 45.8 to 63.2 
 
 .5 to 2.1 
 .9 to 2.0 
 .3 to 1.6 
 .1 to 1 1. 3 
 
 [7.1 
 
 77.3 to 78.1* 
 57.2 to 63.5* 
 
 63-3 
 
 96.0 
 
 2 tO 2.9 
 
 68.4 to 80.6* 
 90 o* 
 
 71.9* 
 
 66.9 to 89.4 
 
 67.2 to 78.4*. 
 
 66.5* 
 
 18. 5 
 58.0 to 67.4* 
 
 78.7 
 
 75.4 to 81.9* 
 77.6 to 80.2* 
 
 IOO 
 
 69.5 to 77.0* 
 
 70.3 to 75.5 
 75.0 to 79.7* 
 
 72.1 to 74.2 
 
 IV. Fuel Value 1000-1500 Calories per Pound. 
 
 Apples (dried) 
 
 Bread (white) 
 
 Corn-bread 
 
 Dates 
 
 Figs 
 
 Fresh pork (ribs and shoulder). 
 Medium fat mutton and beef... 
 
 Mince-meat (commercial) 
 
 Mince-meat (home-made) .. ., 
 
 Pies 
 
 Prunes (dried) 
 
 Raisins , 
 
 Sandwiches 
 
 Sardines (canned) 
 
 Salt mackerel 
 
 [5.9 to 20.3 
 [4.4 to 27.8 
 
 15.0 
 
 IO. o 
 
 5-o 
 
 22.9 
 
 8. 
 
 6 to 47.4 
 
 
 35.3 
 
 28 
 
 4 10 48.0 
 
 
 1.3.8 
 
 1 1 
 
 6 to 25.0 
 
 4° 
 
 .1 to 43.6 
 
 3« 
 
 to 44.9 
 
 
 27.7 
 
 
 54-4 
 
 
 44.9 
 
 
 19.0 
 
 
 13 1 
 
 
 44-9 
 
 
 53 6 
 
 
 32.5 
 
 T 
 
 2 to 2.5 
 
 6 
 
 9.2 
 5 to io.'i 
 
 2 
 
 i-9 
 
 .6 to 5.7 
 
 1- 
 
 .710 14.5 
 .4 to 12.9 
 
 6.7 
 4.8 
 
 
 4.4 
 1.8 
 
 
 »-3 
 
 
 10.9 
 
 
 23-7 
 16.3 
 
 0.1 to 5.0 
 
 »-3 
 
 2.3 to 9.8 
 
 2.5 
 0.3 
 
 25.4 to 25.6 
 19.8 to 31.2 
 
 14 
 
 6.7 
 
 9.4 
 
 30 
 9.0 
 
 48.6 to 86.91. 
 
 53.1 
 40.31054.3 
 
 70.6 
 68.3 to 83.1 
 
 60.2 
 
 32.1 
 
 39-2 
 62.2 
 68.5 
 33-3 
 
 * One Calorie equals 1000 calories. 
 
FOOD IN RELATION TO HUMAN LIFE. 
 
 I5F 
 
 COMPOSITION OF SOME COMMON FOOD MATERIALS. — Continued. 
 V. Fuel Value 500-1000 Calories pek Pound. 
 
 Food-material. 
 
 Beef (round) 
 
 Beef (sirloin steak). 
 Chicken (fowls) . . . 
 
 Cream 
 
 Eggs 
 
 Herring (smoked) . 
 
 Meats (lean) 
 
 Olives 
 
 Salmon (fresh) . . . 
 Salmon (canned)... 
 Tapioca pudding. . 
 
 Tongue (beef) 
 
 Turkey 
 
 Veal (breast) 
 
 Refuse. 
 
 Per cent. 
 
 8.5 
 
 12.8 
 
 18.0 to 42.7 
 
 44-4 
 0.5 to 11. 3 
 
 19.0 
 23.8 to 35.:. 
 11. 7 to 16.9 
 
 9.2 to 55 3 
 17.1 to 32.4 
 15.7 to 25.4 
 
 Water. 
 
 Per cent. 
 
 62.5 
 
 54.0 
 38 3 to 53.7 
 
 74.0 
 
 65-5 
 
 19.2 
 59.9 to 69.2 
 
 52.4 
 
 45.0 to 51.2 
 54.6 to 58.2 
 52.0 to 71.6 
 
 32.4 to 69.2 
 
 41. 1 1044.7 
 
 48.5 to 55.7 
 
 Nitroge- 
 nous 
 Substances. 
 
 Per cent. 
 19.2 
 16.5 
 
 11. 5 to 16.0 
 
 2-5 
 
 11.9 
 20.5 
 
 18. 1 to 21.4 
 i-4 
 
 12.6 to 15.0 
 18.6 to 20.2 
 
 2.8 to 4.2 
 7.8 to 20.2 
 15.8 to 16.8 
 
 14.2 to 16.9 
 
 Fat. 
 
 Per cent. 
 
 9.2 
 
 16. 1 
 
 6.9 to 21.5 
 
 18.5 
 9-3 
 8.8 
 
 7.8 to 14.2 
 21.0 
 
 6.6 to 9.5 
 5.6 to 9.8 
 
 2.3 to 4.8 
 0.7 to 15.3 
 
 5.9 to 25.5 
 
 9.4 to 12.8 
 
 Carbo- 
 hydrates. 
 
 Per cent. 
 
 21.9 to 38.1 
 
 VI. Fuel Value 400-500 Calories per Pound. 
 
 Beans (canned red kidney). 
 
 Calf 's-foot jelly 
 
 Salt cod (boneless) 
 
 Succotash (canned) 
 
 Sweet potatoes 
 
 1.6 
 20.0 
 
 72.7 
 77-6 
 54-8 
 71.4 to 79.9 
 55-2 
 
 VII. Fuel Value 300-400 Calories per 
 
 Bananas .. . 
 Butter beans 
 Fish (fresh) . 
 
 Grapes 
 
 Hash 
 
 Milk 
 
 Potatoes . 
 
 3 r -o 
 50.0 
 
 25.2 to 46.0 
 25.0 
 
 48.9 
 29.4 
 46.1 to 49.1 
 58.0 
 80.3 
 87.0 
 62.6 
 
 7.0 
 
 0.2 
 
 18.5 
 
 4-3 
 
 
 17 4 
 
 27.7 
 2.9 to 4.4 
 
 o-3 
 0.7 to 1.7 
 
 
 14.9 to 22.4. 
 
 i-4 
 
 0.6 
 
 21.9 
 
 [ES PER 
 
 Pound. 
 
 
 8 
 
 °-4 
 
 14-3 
 
 4-7 
 
 o-3 
 
 14.6 
 
 1.9 to 12.0 
 
 1.8 to 5.9 
 
 
 1.0 
 
 1.2 
 
 14.4 
 
 6.0 
 
 1-9 
 
 9-4 
 
 3-3 
 
 4.0 
 
 5-o 
 
 1.8 
 
 O.I 
 
 14.7 
 
 VIII. Fuel Value 2^0-300 Calories per Pound. 
 
 Apples 
 
 Chicken (broilers) 
 
 Cranberries 
 
 Onions . 
 
 Oysters (solid) . . . 
 
 Parsnips , 
 
 Pears 
 
 25.0 
 3*-4 to 55. 
 
 20.0 
 10. o 
 
 63.3 
 44-6 to 52.4 
 87.6 to 89.5 
 
 78.9 
 
 82.2 to 92.4 
 
 66.4 
 
 76.0 
 
 9.0 to 15.7 
 0.4 to 0.5 
 
 1.4 
 
 4-5 to 7.3 
 i-3 
 o-5 
 
 to 1 
 to c 
 
 o-3 
 to 1 
 0.4 
 0.4 
 
 10.8 
 
 IX. Fuel Value 100-200 Calories per Pound. 
 
 Beets 
 
 Cabbage 
 
 Carrots 
 
 Green corn ... 
 
 Lemons 
 
 Oranges 
 
 Soups (canned) 
 
 Spinach , 
 
 Squash 
 
 Tomatoes (canned). 
 
 70.0 
 
 77 7 
 
 70.6 
 
 29.4 
 
 62.5 
 
 6^.4 
 91.0 to 92.8 
 91.6 to 92.8 
 
 44 2 
 
 92.5 to 07.9 
 
 O.7 
 
 0.6 
 
 2.9 to 5.0 
 1.8 to 2.4 
 
 o 7 
 0.3 to 1.7 
 
 0.5 
 
 to 0-8 
 to 0.5 
 
 9.3 to 10.9 
 
 8.9 
 
 1.5 to 6.2 
 
 10.8 
 
 7-7 
 
 4.8 
 
 7-4 
 
 7-7 
 
 5-9 
 
 8.5 
 0.6 to 5.7 
 3.1 to 3.4 
 
 4-5 
 1.4 to 8.1 
 
 X. Fuel Value 10-100 Calories per Pound. 
 
 Asparagus 
 
 Bouillon (canned) 
 
 Celery 
 
 Cucumbers 
 
 Watermelons 
 
 20.0 
 15.0 
 59-4 
 
 94.0 
 
 96.5 to 96.7 
 
 75-6 
 
 .7 to 2.6 
 0.9 
 0.7 
 0.2 
 
 0.2 
 0.0 to 0.2 
 
 0.2 
 
 O.I 
 
 3-3 
 
 to 0.3 
 2.6 
 2.6 
 
i5 2 
 
 AIR, WATER, AND FOOD 
 
 and of fatness or leanness in animals, of method of prepara- 
 tion or of combination in cooked foods. 
 
 Therefore examinations of materials are imperative if 
 there is to be any basis of calculation. In an institution where, 
 for instance, flour forms two-thirds of the daily ration, if it 
 contains the lowest per cent, of nitrogen it may not furnish 
 sufficient proteid for a well-balanced ration, or if the meat 
 used is very lean there may not be fat enough for the best nu- 
 trition. 
 
 The great variation in the proportion of water leads to 
 many surprises, and the amount of unedible material is to be 
 considered. The uneducated provider buys oysters under the 
 impression that he is furnishing food of high value, and does 
 not distinguish between potatoes and rice. 
 
 In the present state of our knowledge, the best use to 
 which we can put such tables and analyses is as a check 
 against gross errors of diet, which are found with alarming 
 frequency especially among children and students, those who 
 can least afford to make them. References will be found in 
 the Bibliography to works for further study along these lines. 
 
 Dietaries. — A dietary is simply a known amount of food of 
 known composition per person per day, week, or month. 
 
 What is called a standard dietary is such a combination of 
 food-materials as shall furnish the amounts held to be neces- 
 sary. The following are examples of such standard dietaries: 
 
 Approximate Amounts 
 required daily by 
 
 Nitrogenous, 
 grams. 
 
 Fats, 
 grams. 
 
 Carbohydrates, 
 grams. 
 
 Calortes. 
 
 
 62 
 
 78 
 
 IOO 
 
 IOO 
 
 125 
 
 45 
 45 
 75 
 90 
 
 125 
 
 200 
 28l 
 380 
 450 
 500 
 
 1593 
 1890 
 2665 
 3092 
 3725 
 
 
 
 Adult at moderate work 
 Adult at hard work... 
 
 (In feeding experiments from 10 to 20 per cent, more must be allowed 
 for waste and indigestibility.) 
 
FOOD IN RELATION TO HUMAN LIFE. 1 53 
 
 From the table on p. 150 may be selected such food as will 
 give the required quantities in variety enough to suit any taste. 
 That which the table cannot give is the per cent, of each which, 
 tinder any given condition, will be utilized by the person fed. 
 The strength of the digestive juices, exercise, fresh air, the 
 cooking, the mixing of the foods, the habits of mind as to 
 food, the customs of the family, all influence this utilization, 
 so that other means must be resorted to in order to gain an 
 idea of what is practicable. This is done by taking account 
 of the food of persons free to choose ; of those in different 
 countries, in different circumstances, and using a great 
 variety of materials. Since Voit made his standard dietary in 
 1870, many hundreds, at least, have been so gathered in the 
 United States alone — more than two hundred since 1886. All 
 the information thus gained goes to confirm the theoretical 
 standard, and also to show how much depends upon suitable 
 preparation and combination. These last two things help 
 each other. 
 
 As food is ordinarily prepared, about 10 per cent, must 
 be deducted for indigestibility in a customary mixed diet, and 
 about 10 per cent, more for the refuse or waste of food as 
 purchased, so that of the total pounds of meat, vegetables, 
 and groceries some 20 per cent, is of no final service in the 
 body. It is immaterial whether this amount is subtracted 
 from the final calculation or whether the higher figures be 
 taken, that is, whether 125 grams of proteid as purchased or 
 100 grams final utility is used. There will be an unknown 
 limit in either case. According to late experiments 100 
 grams of proteid is high. The waste of fats is less in propor- 
 tion as the dietary is a restricted one. 
 
 Knowledge of Food Values Necessary. — The most serious 
 aspect of the food question is that the taking of it is volun- 
 tary, not, like air, a necessity beyond control, and that the 
 
154 a: 
 
 most fantastic ideas are allowed to rule. The day-laborer is 
 in little danger, since his food demand is made strong by out- 
 of-door exercise; but the student who shuts himself up in 
 hot, close rooms, and who does not look upon food as his 
 capital, but only as a disagreeable task or an amusement, is in 
 great danger, as is he who, having heard that one can live on 
 a few cents a day, proceeds to try it without knowledge, and 
 suffers a loss of efficiency for years or for all his life. 
 
 It is not nearly so difficult to acquire a working knowl- 
 edge of food values as of whist or golf, so that on entering a 
 restaurant a suitable menu may be made up within one's al- 
 lowance. It is only necessary to correct prevailing impres- 
 sions and reinforce one's experience. 
 
 Figs, dates, raisins, and prunes are apt to be regarded as 
 luxuries instead of as rich food-substances of a most di- 
 gestible kind when freed from skin and seed. Nuts are a 
 much neglected form of wholesome food, admirably suited 
 to a winter table from their richness in fat, and also furnish- 
 ing muscular energy, as is seen in the agile squirrel, and is 
 proved by many human examples. With nuts, however, 
 must be taken fruits or other bulky foods, to balance the con- 
 centration. The somewhat compact and oily substance must 
 be finely divided and freed from its astringent skin. 
 
 In distinction from these rich foodstuffs, we find oranges, 
 apples, etc.; the usual garden vegetables, asparagus, lettuce, 
 etc., which, while they fill an important place in the dietary, 
 add little directly to the energy of the 'body and need not be 
 considered except as, by their flavor or aesthetic stimulus, 
 they add to the efficiency of the rest. 
 
 The foods which furnish the greatest nutrition for the least 
 money are such materials as corn meal, wheat flour, milk, 
 beans, cheese and sugar. The expensive cuts of meat, high- 
 priced breakfast cereals and the like, add but little to the 
 
FOOD IN RELATION TO HUMAN LIFE. 1 55 
 
 nutritive value but greatly increase the cost of living. A meal of 
 lettuce dressed with oil, eaten with bread and cheese, fulfils all the 
 requirements of nutrition, and may cost five cents. The same 
 food value from sweet breads, grape-fruit, etc., might cost a dollar. 
 Incorrect ideas in regard to food values, and prejudice inherited or 
 acquired against certain foods, have too often resulted in exclud- 
 ing wholesome and nutritious articles from the dietary and de- 
 creasing thereby the efficiency of the human machine. 
 
CHAPTER IX. 
 
 THE PROBLEM OF SAFE FOOD. ADULTERATION AND SOPHISTICATION. 
 
 Adulteration grows largely, if not almost entirely, from exces- 
 sive competition. Nearly every article of common food has been 
 found at one time or another to be adulterated, yet manufacturers 
 testify that they willingly would stop this addition of foreign 
 material if they could be sure that their competitors would stop 
 also. Other causes there are also: the demand for goods out of 
 season; for perishable products which must come many miles; 
 the failure of the supply of a given substance to meet a continu- 
 ing demand; all of these lead to adulteration, imitation and sub- 
 stitution. 
 
 To many people otherwise intelligent, the term adulterated food 
 is synonymous with poisoned food. With others, thanks to alarm- 
 ing newspaper articles, not wholly disinterested, the general im- 
 pression is far beyond the reality. It is not necessary to use poison- 
 ous or even deleterious material : it needs only to mix with the food 
 material some substance cheaper but harmless, to make some 
 change in the outward appearance of the article so that people 
 shall not recognize the familiar substance, and then to herald far 
 and wide the discovery of a new process by which the food value 
 is greatly enhanced. "Things are not what they seem" is nowhere 
 more true than in the case of foods. 
 
 Definition of Adulteration. — To adulterate is "to debase" "to 
 make impure by an admixture of baser materials." The word 
 "adulterated refers to any food to which any foreign substance, 
 not a proper portion of the food, has been added. It does not 
 
 156 
 
THE PROBLEM OF SAFE FOOD. T57 
 
 matter whether the added material is of greater value than the 
 food itself. The addition of coffee to cereal or substitute coffees, 
 is properly held to be an adulteration. Deterioration should not 
 be mistaken for adulteration. People who are not wholly familiar 
 with the appearance of a food or the chemical and physical changes 
 which it may undergo, think that if it does not taste just right or 
 look just right that it must be adulterated. Appearance has slight 
 relation to the purity of the article in these days of paint, polish 
 and powder. 
 
 Some forms of adulteration are more properly described under 
 the head of misbranding, that is, referring to foods incorrectly de- 
 scribed by the label. While the significance is not exactly the 
 same as that of the word adulterated, yet the two may sometimes 
 be applied to the same product. For instance, the addition of 
 starch to sausage to conceal the use of excessive amounts of water 
 and of fat constitutes an adulteration, which would not be the case 
 if the article were properly branded to show the presence of the 
 added "filler." 
 
 To adulterate the coin of the realm or the liquor of the bar with 
 a baser metal or an imitation whisky is a heinous offence. So is 
 the mixture of milk with the baser article, water, which thereby 
 lowers its food value. But the " wretched sophistry" which ob- 
 scures the nature of things on a package of prepared food mis- 
 leads more persons and inflicts more injury upon the community 
 than the other, yet goes unrebuked. The most barefaced asser- 
 tions are printed in magazines, and "pure-food shows" only whet 
 the appetite for something new. 
 
 Legal Definition of Adulteration and Misbranding. — In the 
 Federal Pure Food Law, commonly known as the Food and Drugs 
 Act of June 30, 1906, adulteration and misbranding are thus 
 defined : 
 
 Sec. 7. That for the purposes of this Act an article shall be 
 deemed to be adulterated : 
 
158 AIR, WATER, AND FOOD. 
 
 In the case of food : 
 
 First. If any substance has been mixed and pacjked with it so 
 ■as to reduce or lower or injuriously affect its quality or strength. 
 
 Second. If any substance has been substituted wholly or in 
 part for the article. 
 
 Third. If any valuable constituent of the article has been 
 wholly or in part abstracted. 
 
 Fourth. If it be mixed, colored, powdered, coated, or stained 
 in a manner whereby damage or inferiority is concealed. 
 
 Fifth. If it contains any added poisonous or other added dele- 
 terious ingredient which may render such article injurious to 
 health: Provided, That when in the preparation of food products 
 for shipment they are preserved by any external application applied 
 in such manner that the preservative is necessarily removed me- 
 chanically, or by maceration in water, or otherwise, and directions 
 for the removal of said preservative shall be printed on the covering 
 or the package, the provisions of this Act shall be construed as 
 applying only when said products are ready for consumption. 
 
 Sixth. If it consists in whole or in part of a filthy, decomposed, 
 or putrid animal or vegetable substance, or any portion of an animal 
 unfit for food, whether manufactured or not, or if it is the product 
 of a deceased animal, or one that has died otherwise than by 
 slaughter. 
 
 Sec. 8. That the term " misbranded," as used herein, shall 
 apply to all drugs, or articles of food, or articles which enter into 
 the composition of food, the package or label of which shall bear 
 any statement, design, or device regarding such article, or the 
 ingredients or substances contained therein which shall be false or 
 misleading in any particular, and to any food or drug product 
 which is falsely branded as to the State, Territory, or country in 
 which it is manufactured or produced. 
 
 That for the purposes of this Act an article shall also be deemed 
 to be misbranded : 
 
THE PROBLEM OF SAFE FOOD. 1 59 
 
 In the case of food : 
 
 First. If it be an imitation of or offered for sale under the dis- 
 tinctive name of another article. 
 
 Second. If it be labeled or branded so as to deceive or mislead 
 the purchaser, or purport to be a foreign product when not so, 
 or if the contents of the package as originally put up shall have 
 been removed, in whole or in part, and other contents shall have 
 been placed in such package, or if it fail to bear a statement on 
 the label of the quantity or proportion of any morphine, opium, 
 cocaine, heroin, alpha or beta eucaine, chloroform, cannabis indica, 
 chloral hydrate, or acetanilide, or any derivative or preparation of 
 any of such substances contained therein. 
 
 Third. If in package form, and the contents are stated in terms 
 of weight or measure, they are not plainly and correctly stated on 
 the outside of the package. 
 
 Fourth. If the package containing it or its label shall bear any 
 statement, design, or device regarding the ingredients or the sub- 
 stances contained therein, which statement, design, or device shall 
 be false or misleading in any particular: Provided, That an article 
 of food which does not contain any added poisonous or deleterious 
 ingredients shall not be deemed to be adulterated or misbranded 
 in the following cases: 
 
 First. In the case of mixtures or compounds which may be 
 now or from time to time hereafter known as articles of food, 
 under their own distinctive names, and not an imitation of or 
 offered for sale under the distinctive name of another article, if 
 the name be accompanied on the same label or brand with a state- 
 ment of the place where said article has been manufactured or 
 produced. 
 
 Second. In the case of articles labeled, branded, or tagged 
 so as to plainly indicate that they are compounds, imitations, or 
 blends, and the word "compound," "imitation," or "blend," as 
 the case may be, is plainly stated on the package in which it is 
 
l6o AIR, WATER, AND FOOD. 
 
 offered for sale: Provided, That the term blend as used herein 
 shall be construed to mean a mixture of like substances, not ex- 
 cluding harmless coloring or flavoring ingredients used for the 
 purpose of coloring and flavoring only: And provided further , That 
 nothing in this act shall be construed as requiring or compelling 
 proprietors or manufacturers of proprietary foods which contain 
 no unwholesome added ingredient to disclose their trade formulas, 
 except in so far as the provisions of this act may require to secure 
 freedom from adulteration or misbranding. 
 
 Extent of Adulteration. — In any discussion of the extent to 
 which adulterated foods are sold it must be borne in mind that 
 the adulterated articles make up only a relatively small proportion 
 of the food that actually passes over the counter. Flour, for ex- 
 ample, is seldom adulterated ; pepper, mustard and vanilla extract 
 often are. For one pound of these substances sold, iooo pounds 
 or more of flour go out from the store. Figures given in official 
 reports of food inspection do not represent the case exactly, be- 
 cause the inspectors are trained men, and purchase samples of 
 those lines of goods which experience has shown them to be most 
 likely to be adulterated. Brands of foods which they have reason 
 to believe are pure they do not sample. Estimated on the total 
 quantity sold, it is doubtful if more than 5 to 10 per cent, of the 
 food sold is adulterated in any way, and these figures would un- 
 doubtedly be much too high for those states in which there is a 
 well-enforced system of food inspection. 
 
 Character of Adulteration. — Much of the present propaganda 
 in the interests of pure food and the movement for the protection 
 of the consumer can be summed up in three words: "An Honest 
 Label." In many cases an accurate and true statement of the 
 contents of the can or package is the only protection needed by 
 the consumer, and is fully as efficient as well as much cheaper 
 than prosecutions or restrictive measures. Many of the terms 
 used on food packages deceive only the ignorant purchaser. 
 
THE PROBLEM OF SAFE FOOD. l6l 
 
 "Strictly pure" is a well-understood trade term, with a meaning 
 known to the initiated; the words " Home-Made" may cover 
 some of the most highly developed products of synthetic organic 
 chemistry. 
 
 The cases in which the adulteration is of a character dele- 
 terious to health are fortunately few. The use of canned goods 
 brings certain dangers in the dissolved metals from the cans or 
 from the solder, also from a careless habit of allowing food to 
 stand in the opened tins. The liking for bright green pickles and 
 peas leads to coloration by copper salts. 
 
 So rapidly do new substances come upon the market that it is 
 of little use to put into a general text-book definite statements of 
 the quality of many foods. A baking-powder or a spice which is 
 honestly made to-day may next week pass into the hands of un- 
 scrupulous dealers who please the public and thereby salve their 
 consciences. 
 
 To furnish what the people think they want has been the rule 
 from the days of an earlier generation of grocers, who divided a 
 barrel of cooking-soda in halves and set one-half on one side of 
 the store for "saleratus" and the other on the opposite side for 
 soda, so that there should be no suspicion in the mind of the cus- 
 tomer that the packages came from the same barrel, and yet each 
 might satisfy his individual preference. 
 
 Names that have passed down from a former generation as 
 being above reproach are now found to cover adulterated goods. 
 The trademark has passed into other and less scrupulous hands, 
 and the new owners do not hesitate to trade upon the reputation 
 earned by their predecessors. There are, however, several phases 
 of the subject that should be briefly mentioned. 
 
 Breakfast Foods, — The craving for something new to stimulate 
 a jaded appetite already spoiled by endless variety and bad com- 
 binations has led to the manufacture of a cereal preparation for 
 nearly every day in the year, regarding some of which the state- 
 
1 62 AIR, WATER, AND FOOD. 
 
 ment is made that they are "predigested." No better comment- 
 ary on the laziness or wilful ignorance of American providers could 
 be made than this. Little do the people know about wheat or 
 cooking if they suppose that grain can be changed by manipula- 
 tion in any kind of machine so as to give greater food value than 
 was contained in the grain. While it is true that some of these 
 preparations are far better than the half-cooked grains found on 
 so many tables, the fact remains that it is the cook and not the 
 substance which is poor. The false statements on food packages 
 of all kinds are so absurd that they would defeat their own pur- 
 pose were they viewed in the light of common sense. It is not 
 always best to have food which is too easily digested. 
 
 A predigested food is quickly absorbed into the circulation, 
 and hence a small quantity causes a sensation of fulness and satis- 
 faction, which, however, soon passes away and a faintness results. 
 This is especially true of the sugars and dextrins. Frequent meals 
 should go with easily absorbed foods. The rapid digestion is the 
 cause of much pernicious eating of sweets between meals, which 
 satisfies the appetite for the time being and prevents substantial 
 quantities of other foods being taken at the time they are offered. 
 
 From a study of analyses of a large number of foods the fol- 
 lowing conclusions are drawn by F. W. Robison : * 
 
 i. The breakfast foods are legitimate and valuable foods. 
 
 2. Predigestion has been carried on in the majority of them 
 to a limited degree only. 
 
 3. The price for which they are sold is as a rule excessive and 
 not in keeping with their nutritive values. 
 
 4. They contain as a rule, considerable fibre which, while prob- 
 ably rendering them less digestible, at the same time, may render 
 them more wholesome to the average person. 
 
 5. The claims made for many of them are not warranted by 
 the facts. 
 
 * Mich. Agr. Expt. Sta., Bull. 211 (1904). 
 
THE PROBLEM OF SAFE FOOD. 1 63 
 
 6. The claim that they are far more nutritious than the wheat 
 and grains from which they are made is not substantiated. 
 
 7. They are palatable as a rule and pleasing to the eye. 
 
 8. The digestibility of these products as compared with highly 
 milled goods, while probably favorable to the latter, does not give 
 due credit to the former, because of the healthful influence of the 
 fibre and mineral matter in the breakfast foods. 
 
 9. Rolled oats or oatmeal as a source of protein and of fuel is 
 ahead of the wheat preparations, excepting of course the special 
 gluten foods, which are manifestly in a different class. 
 
 In general, the cost of these foods is low if they are considered 
 merely as confections to please the taste, but they are expensive 
 foods regarded as substitutes for the ordinary cereal products. 
 
 This is well shown in the following table in which the fuel 
 value of breakfast foods and other common food products is 
 graphically compared. 
 
 Colors and Preservatives in Food. — For many years such sub- 
 stances as alcohol, vinegar, sugar, salt, and the like, have been 
 used to preserve food. Such materials are commonly held to be 
 harmless to persons of sound digestion if used in moderate amounts. 
 Within recent years, however, there has been a constantly increas- 
 ing tendency toward the use in food products of such powerful 
 antiseptics as formaldehyde, salicylic and benzoic acids and their 
 salts, and boric acid. An important distinction to be borne in 
 mind between this class of preservatives and those first named is 
 that the former when used in food in quantity sufficient to pre- 
 serve it make their presence known to the consumer by either 
 their taste or odor. With the chemical preservatives, however, 
 an intimation of their presence is conveyed to the consumer only 
 by a statement on the label. It is the general feeling among those 
 engaged in the enforcement of the food laws that the common 
 use of these preservatives should be forbidden, or that they should 
 be allowed only under certain definite restrictions. The question 
 
164 
 
 AIR, WATER, AND FOOD. 
 
 
 
 
 
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THE PROBLEM OF SAFE FOOD. 165 
 
 is not one of their possible harmful effect only, although it cannot 
 be successfully denied that their unrestricted use would lead to 
 grave danger to health, especially in the case of invalids and chil- 
 dren, or those with various degrees of digestive efficiency. It 
 seems reasonable to infer that the processes of digestion being 
 largely the result of bacterial and enzymic action, will be retarded 
 or interfered with to a greater or less extent by substances which 
 inhibit bacterial action in food. 
 
 There is, however, another reason for objecting to the use of 
 chemical preservatives. By their use much food that is unwhole- 
 some and unfit for consumption can be, and is placed upon the 
 market with no warning to the consumer. "The man who adds 
 formaldehyde to his milk takes down the danger signal, but does 
 not remove the danger." 
 
 Similarly, objections can be made to the use of coal-tar colors 
 in foods. There are hundreds of food packages which would 
 never leave the grocers' shelves were it not for the fact that by 
 the use of artificial color their true composition and the actual 
 nature of the materials from which they are made is hidden. 
 Apart from any question as to the harmfulness of these dyes, 
 there is ample reason for their use being strictly regulated by 
 official action, in that their use except under such supervision 
 allows the manufacturer to sell inferior articles under the appear- 
 ance of standard foods; it permits the customer to be misled as 
 to the strength and purity of the product that he buys; the age and 
 past history of the product may be made a sealed book; finally, 
 by the use of coloring, an unwholesome and improper food may 
 be put upon the market. 
 
 Summary. — The chief dangers in food are from wrong pro- 
 portions of proteid, fat, and carbohydrates, from fermentable and 
 irritating decompositions, from bad methods of cooking and un- 
 suitable combinations, from transmission of micro-organisms either 
 by exposure to dust or by contact with filthy hands or vessels, to a 
 
1 66 AIR, WATER, AND FOOD. 
 
 favorable medium for the growth of pathogenic germs, from un- 
 suitable food scientifically disguised. 
 
 From this hasty survey it will be seen how little danger to 
 health is incurred if only reasonable care is taken and if the always 
 doubtful articles are avoided. 
 
 Take, for instance, that most commonly adulterated class, 
 spices. Who will say that it may not be better to eat corn and 
 buckwheat and ground peas than pure pepper? Rice is certainly 
 a more wholesome food than ginger, and starch than soda. Glu- 
 cose is even more easily absorbed than cane-sugar. These are 
 cases of frauds on the pockets, but possibly blessings in disguise 
 for the stomachs. When any community is so ignorant as to per- 
 mit of such glaring cases of adulteration as coal-tar dyes in food, 
 and gypsum in cream of tartar, they deserve to suffer. It is 
 knowledge on the part of each intelligent citizen, which will mend 
 matters, even it it is only that kind of empirical knowledge that 
 one is forced to learn in relation to electricity and steam in order 
 to live in a modern house. 
 
 This knowledge is now easily obtained through the city, state 
 and governmental laboratories, and their publications are acces- 
 sible to all who can read and write. There is therefore no excuse 
 for general ignorance and credulity as to trade preparations of 
 foods, any more than for the degrading habit of purchasing patent 
 medicines to remedy the ills caused by the misuse of food. Both 
 together form the saddest commentary on human weakness and 
 lack of rational thought. 
 
CHAPTER X. 
 
 ANALYTICAL METHODS. 
 
 In the discussion of the methods employed for the ex- 
 amination of food-materials, only a few typical substances 
 have been considered, and the processes given are such as to 
 bring into prominence the scientific aspect rather than the 
 technical detail of the subject; at the same time it is hoped 
 that a sufficient variety of methods is given to enable 
 the student to gain considerable experience in the necessarily 
 short time which can be allotted to the subject. 
 
 Both on account of its importance as a food-material and 
 on account of its availability for the various tests, milk has 
 been chosen as a type of animal food; moreover, it may be 
 made to serve as an excellent example of the changes to 
 which food-materials are liable through the growth of the 
 micro-organisms. The analysis of milk includes determina- 
 tions of specific gravity, water, or total solids, ash, fat, nitro- 
 gen, and sugar, the separation of casein and albumin, and the 
 detection of preservatives and coloring matters. 
 
 The breakfast cereals are taken as typical of vegetable 
 foods. The examination which may be made of this class 
 includes the determination of moisture, ash, fat, nitrogen and 
 proteids, starch, cellulose, and the products of peptonization 
 and saccharification. 
 
 The nature and composition of the various fats and oils 
 
 is briefly illustrated by the examination of butter and the 
 
 determination of the principal constants of the butter-fat. 
 
 167 
 
1.6S AIR, WATER, AND FOOD. 
 
 The results of fermentation are illustrated by the deter- 
 mination of alcohol in beer, wine, meat extracts, patent medi- 
 cines and " temperance drinks," flavoring essences and the 
 like. The determination of the relative proportion of volatile 
 and fixed acids, of the saccharine products of malting, and 
 of volatile oils or flavoring principles, is also instructive. 
 
 A more elaborate discussion of the methods used in food 
 analysis and of the interpretation of results will be found in 
 the larger works upon the subject. As reference books for the 
 use of the student in the laboratory, the following in the 
 author's experience, have been found especially helpful: Leach: 
 Food Inspection and Analysis; Gill: Handbook of Oil Analysis; 
 Sherman: Organic Analysis; Rolfe: The Polariscope in the 
 Laboratory. 
 
 MILK. 
 
 General Statements. — Milk is an emulsion of fat-globules 
 with casein and other nitrogenous bodies, mineral salts 
 (probably in combination), sugar and water. The average 
 percentage composition of the more important varieties of 
 milk, as found by recent observers, is summarized in the fol- 
 lowing table: 
 
 Water. Sugar. Proteids. Fat. Ash. 
 
 Cow 86.90 4.80 3.60 4.00 O.70 
 
 Human 88.75 6.00 1.50 3.45 0.30 
 
 Goat 85.70 4.45 4.30 '4-75 0.80 
 
 Ass 89.50 6.25 2.00 1.75 0.50 
 
 Mare 90.75 5-70 2.00 1.20 0.35 
 
 Sheep 80.80 4.90 6.55 6.85 0.90 
 
 In connection with this table should be noticed the high 
 proportion of sugar and low proportion of casein and ash in 
 human milk as compared with cow's milk. The former is not 
 readily curdled, the casein never separating in a compact clot 
 which settles to the bottom, a difference which is attributed 
 to the lower proportion of fat to casein.* 
 
 The average composition of 14,967 samples of cow's milk 
 
 * Lehmann and Hempel: Arch. Physiol., 56 (1894), 558. 
 
food: analytical methods: milk. 169 
 
 for the year 1907, analyzed directly on arrival of the milk from 
 the farm, is given by Richmond * as follows: 
 
 Average, 1907. 
 
 Specific gravity 1 .0322 
 
 Total solids 1 2 . 69 
 
 Solids not fat 8 . 94 
 
 F ^ 3-75 
 
 The U. S. standard for whole milk requires that it shall 
 contain not less than 8.5 per cent of solids not fat, and not 
 less than 3.25 per cent of milk fat.j 
 
 From the average values there are constant variations, due 
 to the time of milking, the season of the year and the breed and 
 feed of the cow. The proportion of milk sugar and ash is most 
 nearly constant, while the fat is the most variable constituent. 
 
 An examination of milk as regards its health fulness usually 
 consists in determining what changes, if any, have taken place 
 in its constituents due to the growth of micro-organisms. 
 Milk is a natural culture medium for the growth of micro- 
 organisms and they increase in it with almost incredible 
 rapidity. These changes which take place are called " fer- 
 mentations." The two most common are the acid and the 
 alkaline. 
 
 Acid Fermentation. — Milk-sugar is converted wholly or in 
 part into lactic acid under the influence of a class of organisms 
 of which bacillus acidi lactici is the best known and is generally 
 regarded as predominating. The extent to which this change 
 has taken place is shown by the test for acidity. 
 
 Alkaline Fermentation. — In the alkaline fermentation the 
 albumin and casein are decomposed with the formation of 
 ammonia and other intermediate nitrogenous products, some 
 of them of a poisonous character, as is shown by the preval- 
 ence of cholera infantum when such decomposed milk is used, 
 
 * Analyst, 1908. 
 
 | Circular No. 19, Office of the Secretary, U. S. Dept. Agriculture. 
 
170 AIR, WATER, AND FOOD. 
 
 and by cases of poisoning by ice-cream, etc. This fermenta- 
 tion generally occurs simultaneously with the acid fermen- 
 tation, but at first is much less active; at a subsequent stage, 
 however, the alkaline fermentation becomes more pro- 
 nounced, and in certain cases may completely dominate the 
 other fermentations. 
 
 Other Fermentations. — Butyric acid fermentation may be 
 a result of the action of one or several groups of bacteria upon 
 the glyceride of butyric acid. This action sets free the butyric 
 acid in part and the fat becomes in time " rancid," but this 
 change takes place, as a rule, more slowly and is not so com- 
 mon as the others. 
 
 The production of koumiss is an instance of an artificially 
 incited change. Various other fermentations occasionally 
 occur which cause a slimy appearance or a bitter taste. 
 Various colors may be imparted to the milk by the presence 
 of chromogenic or color-producing micro-organisms. The 
 student is referred to the various journals and to text-books 
 on dairy bacteriology for accounts of these less important 
 changes. 
 
 Sampling. — In all manipulations with milk the importance 
 of thorough and frequent mixing, not shaking, cannot be too 
 strongly emphasized; this is best accomplished by pouring it 
 from one vessel to another. This will be found necessary 
 even when the milk has been standing for only a few minutes, 
 on account of the rapid rise of the cream. The apparatus 
 used to contain or to measure milk should be thoroughly 
 washed out as soon as possible. 
 
 PHYSICAL TESTS. 
 
 Specific Gravity. — Take the specific gravity in the usual 
 manner by means of a hydrometer at i5°.6 C. If the temper- 
 ature of the milk varies only a few degrees from this, the read- 
 ing may be corrected by means of Table IX, Appendix A. 
 
food: analytical methods: milk. 171 
 
 Hydrometers for special use with milk are known as lac- 
 tometers and are usually so graduated as to read in degrees 
 corresponding to the gravity. Thus in the Quevenne lactometer, 
 the graduation from 15 ° to 40 corresponds to a specific gravity 
 1. 015 to 1.040. 
 
 The New York Board of Health lactometer has an arbitrary 
 scale, reading zero in pure water and 100 in " pure milk," which 
 is taken as corresponding to a specific gravity of 1.029. From 
 the scale-reading the specific gravity may readily be calculated. 
 
 Notes. — The specific gravity of milk is, in the main, a func- 
 tion of two factors, namely, the percentage of solids not fat 
 and of the fat. The former raises it; the latter lowers it. The 
 determination of the specific gravity alone is not to be relied 
 upon as an absolute index of the purity of the milk. The 
 specific gravity varies in general from 1.029 to 1.034, and in 
 most cases of normal and well-mixed milk from several cows 
 the specific gravity will lie between 1.030 and 1.032. 
 
 Opacity. — The white color and opacity of milk are 
 largely due to the presence of the suspended fat-globules and 
 of the casein in colloidal form. The influence of the latter is 
 shown by the fact that the color of milk is not greatly 
 changed after it has passed through a centrifugal separator 
 which removes practically all of the fat. The degree of 
 opacity and the percentage of fat may be determined by 
 means of Feser's lactoscope, the modus operandi of which is 
 given with that instrument. Another instrument of like prin- 
 ciple is Heeren's pioscope,* which consists of an ebonite disk 
 with a raised rim; a drop or two of milk is placed upon it, the 
 painted glass cover placed over it, and the color of the milk 
 matched with one of those on the cover. 
 
 Cream. — Fill the creamometer, an elongated test-tube 
 with graduations near the top, to the zero mark with the 
 
 *Repit.f. Anal. Chem., 1881, 247, 
 
I7 2 AIR, WATER, AND FOOD. 
 
 milk, add three drops of a solution of methyl violet, mix and 
 put away in a cold place. After twenty-four hours read off 
 the percentage of cream. 
 
 Notes. — The rapidity with which the cream rises indicates 
 whether sodium carbonate has been added, its action being 
 to retard the rise of cream so that the milk is never blue. 
 Should the cream separate very quickly and the milk be blue, 
 the indication is that water has been added or that the milk 
 is of poor quality. The method is only approximate and does 
 not give the amount of fat. The methyl violet is added to 
 render the reading sharper, as it does not dissolve appreciably 
 in the cream. Cream contains most of the fat of milk with a 
 small proportion of the other constituents, ioio samples of 
 cream gave an average of 48.3 per cent. fat. 
 
 CHEMICAL TESTS. 
 
 Reaction. — Normal milk gives the amphoteric reaction, 
 that is, it turns delicate litmus both red and blue. This is due 
 to the presence of neutral and acid phosphates of the alkalies. 
 The reaction of the milk soon becomes acid, however. 
 
 Acidity. — Measure 5 c.c. of milk into a small beaker, 
 
 N 
 dilute with so c.c. of water, and titrate the acid with — 
 J 10 
 
 sodium hydroxide, using phenolphthalein as an indicator. 
 Express the acidity in degrees, considering each tenth of a 
 cubic centimeter of sodium hydroxide one degree. 
 
 Notes. — The acidity of milk is due to the fermentation of 
 milk-sugar and the production of lactic acid. Under favor- 
 able circumstances this change may take place with consid- 
 erable rapidity. For example, six hours after milking the 
 acidity may be fourteen to twenty-five degrees; forty-eight 
 hours after milking it may reach one hundred degrees. When 
 the acidity reaches twenty-three degrees milk coagulates on 
 
food: analytical methods: milk. 173 
 
 boiling.* An example of the rate of change is given in the 
 following table :f 
 
 n Acidity, Sugar, 
 
 uay - c.c. Degrees of Rotation. 
 
 1 2.2 25.2 
 
 2 5.5 23.I 
 
 3 II. O 21.6 
 
 6 13.2 I4.2 
 
 7 i5-o 9-4 
 
 8 16.3 7.8 
 
 9 17.2 1.2 
 
 Total Solids. — The determination of total solids is best 
 carried out in a platinum dish having a flat bottom about 2\ 
 inches in diameter. Small dishes of aluminum or lead foil, or 
 blacking-box covers answer very well, but of course cannot be 
 ignited to obtain the ash. 
 
 Directions. — Weigh the platinum dish and add about 5.1 
 grams to the weights on the balance-pan. With the burette 
 pipette deliver 5 c.c. of the well-mixed milk into the dish and 
 weigh the whole as rapidly as possible to the nearest milli- 
 gram. Evaporate the milk to dryness on the water-bath and 
 then dry it in the oven at ioo° to constant weight. 
 
 Notes. — It is important that the milk should be in the form 
 of a thin layer, so that the evaporation of the water shall take 
 place as quickly as possible. Under these conditions the resi- 
 due obtained is nearly white; but if the process be prolonged, 
 it may have a brownish color from the caramelization of the 
 sugar. 
 
 Various analysts have proposed modifications of the pro- 
 cedure as described above, such as drying on sand or asbestos , 
 coagulation of the milk by absolute alcohol before evaporation, 
 and so forth, but simple evaporation in an open dish is generally 
 regarded as the most advantageous. 
 
 Ash. — Directions. — Ignite the platinum dish containing 
 the residue from the preceding determination at a low red 
 
 * Thorner: Analyst, 16 {1891), 200. 
 
 t " Thesis," Ethel B. Blackwell, M.I.T., 1891. 
 
174 AIR j WATER, AND FOOD. 
 
 heat until the ash is white or nearly so. This may be done 
 over a burner carefully regulated so that the dish is nowhere 
 heated above a dull redness, or in a muffle furnace. After 
 weighing the ash, test it for carbonates by adding two drops 
 of dilute hydrochloric acid. Effervescence in the ash is quite 
 perceptible when carbonates are present in as small amount 
 as 0.05 per cent. If desired, the hydrochloric acid solution of 
 the ash can be used to test for boric acid as described on page 
 188. 
 
 Notes. — If the temperature is raised too much during ignition, 
 the results will be low on account of the partial volatilization 
 of the chlorides of the milk; hence the process should be 
 carried out at as low a temperature as will admit of the oxida- 
 tion of the carbonaceous matter. 
 
 The percentage composition of the ash of milk is given 
 by Fleischmann and Schrodt * as follows: 
 
 Per cent. 
 
 Potassium oxide, K 2 25.42 
 
 Sodium " Na 2 10.94 
 
 Calcium " CaO 21.45 
 
 Magnesium " MgO 2.54 
 
 Ferric " Fe 2 3 0.11 
 
 Sulphuric acid, S0 3 4.11 
 
 Phosphoric " P 2 5 24.11 
 
 Chlorine, CI 14.60 
 
 103.28 
 Less oxygen corresponding to chlorine f 3.28 
 
 100.00 
 
 The ash of genuine cow's milk is free from carbonates and 
 borates, and the ash soluble in water is about 30 per cent, of 
 the total. The ash determined in this way does not represent 
 exactly the mineral salts present in the milk, since these are 
 altered by the oxidation to some extent. 
 
 *Baumeister: "Milch und Molkerei-Producte." S. 16. 
 
 f This correction is necessary because the metals are all calculated as 
 oxides, when, as a matter of fact, a certain proportion are present as 
 chlorides. 
 
food: analytical methods: milk. 
 
 /:> 
 
 Fat. — Since the fat is so important a constituent of milk, 
 an endless variety of methods and modifications for its deter- 
 mination have been devised. The processes which are in 
 most general use may be divided into three classes: 
 
 i. Estimation of the fat by simple extraction of the milk, 
 best dried on some absorbent material. 
 
 2. Volumetric estimation of the fat liberated by chemical 
 treatment from the milk and collected by centrifugal force. 
 
 3. Estimation of the fat by extraction from the milk itself 
 after solution of the casein by acid. 
 
 A typical method from each class will be described in de- 
 tail. 
 
 (t) Adams' Method. — Directions. — Roll a strip of fat- 
 free blotting-paper, 22 inches long and 2-J inches wide, into 
 a rather loose coil and fasten it by a bit of copper wire. Hold 
 the coil in one hand and carefully run on to the upper end of 
 it 5 c.c. of milk from a burette pipette. Place the coil, diy 
 end downward, in the water-oven and dry it for an hour. 
 When dry remove the wire and place the coil in the Soxhlet 
 extractor. If preferred, the strip of paper may be held hori- 
 zontally in a frame and the milk run on to it. When dry the 
 paper is rolled into a coil and extracted. Weigh the extraction- 
 flask, place in it 75 to 100 c.c. of petroleum ether and connect 
 the extractor with the condenser. After the coil has been 
 extracted for at least two hours remove the extractor and 
 evaporate the petroleum ether at low temperature, taking care 
 to avoid the vicinity of free flames. Dry the flask with the 
 extracted fat in the water oven to constant weight. Avoid pro- 
 tracted heating, which would cause partial oxidation of the fat. 
 
 Notes. — Absorbent paper exercises a selective action on 
 the constituents of milk so that the fat is left on the surface of 
 the paper, mixed with only about one-third of the non-fatty 
 solids, and hence it is more easily extracted; further, owing 
 to the greatly increased surface exposed, the extraction of the 
 fat is practically complete. 
 
176 
 
 AIR, WATER, AND FOOD. 
 
 Ethyl ether may be used instead of petroleum ether, but care 
 should be taken that the ether is perfectly dry, otherwise other 
 substances than fat, principally milk-sugar, will be extracted. 
 On the other hand, substituted glycerides may not be dissolved 
 out by ether. For these reasons the petroleum ether is to be 
 preferred as a solvent, although its action is considerably 
 slower than that of the other. 
 
 Owing to the inflammable nature of the solvents employed, 
 
 Fig. 12. — Apparatus for Fat Extraction. 
 
 it is best not to use a flame as the source of heat, but to heat 
 the flask by means of a steam- or water-bath. In this labora- 
 tory small electric heaters about 4 inches in diameter are used 
 and have been found safe and convenient. The complete 
 apparatus is shown in Fig. 12. In using these it should be 
 borne in mind that considerable quantities of ether or petroleum 
 ether in contact with the heatea surface may ignite, and caution 
 should be taken not to evaporate any quantity of these solvents 
 from an open vessel. 
 
 (2) Babcock Method. — Directions. — Measure 17.6 ex. of 
 the milk from a pipette into the long-necked, graduated whirling- 
 
food: analytical methods. 177 
 
 bottle. Measure out 17.5 c.c. of sulphuric acid 1^0, gr. 1.83 ) r 
 and add it gradually to the milk, mixing the t\*-« thoroughly 
 after each addition. Take care that none of the liquid spurts 
 into the neck of the bottle. After mixing the milk and acid, 
 and while the bottles are still hot, place them in opposite 
 pockets in the centrifugal machine, in even numbers, and 
 whirl them for five minutes, at full speed. Then remove the 
 bottles and add hot water up to the necks, after which whirl 
 them again for one minute. Again add hot water until the 
 fat rises to the 8 mark on the stem. Place the bottles in the 
 machine and whirl them at the same rate as before for one 
 minute. Then measure the length of the column of fat by a 
 pair of dividers, the points being placed at the extreme limits 
 of the column, the fat being kept warm, if necessary, by standing 
 the bottle in hot water. If now one point of the dividers is 
 placed at the zero mark of the scale on the bottle used, the other 
 will indicate the per cent, of fat in the milk. 
 
 Notes. — When the acid and milk are mixed the mixture 
 becomes hot from the action of the acid on the water in the 
 milk and turns dark-colored on account of the charring of 
 the milk-sugar. The casein is first precipitated and then 
 dissolved. The fat is thus separated in a pure state from the 
 other constituents of the milk. 
 
 The fat obtained should be of a clear, golden-yellow color, 
 and distinctly separated from the acid solution beneath it. 
 If the fat is light-colored or whitish, it generally indicates that 
 the acid is too weak, and a dark-colored fat with a stratum 
 of black particles below it indicates that the acid is too strong. 
 The best results will be obtained by the use of acid of the 
 strength noted above. 
 
 A violet color is sometimes produced when the first por- 
 tions of the acid and milk are mixed. This frequently indi- 
 cates the presence of formaldehyde. (See p. 187.) 
 
1 7 8 
 
 AIR, WATER, AND FOOD. 
 
 (3) Gottlieb Method. — Directions. — Measure 5 c.c. of milk 
 into a glass-stoppered 50-c.c. cylinder and add the following 
 reagents, being careful to add them in the order given and to 
 shake the stoppered cylinder thoroughly after the addition of 
 each reagent: 1 c.c. of ammonia, sp. gr. 0.96, 5 c.c. of alcohol, 
 12.5 c.c. of ethyl ether and 12.5 c.c. of petroleum ether. Let 
 the cylinder stand until the lower layer is free from bubbles, 
 over night if necessary. 
 
 With ordinary milk the separation takes place rapidly, but 
 with sweetened condensed milk the longer time may be necessary. 
 Transfer the upper layer to a tared flask by means of the 
 apparatus shown in Fig. 13. This consists of a cork carrying 
 an ordinary glass T tube. Through the straight 
 limb of the T tube slides a bent glass tube, 
 which is turned up at the lower end. The tube 
 is adjusted by sliding it through the rubber 
 collar (C) so that the lower end rests just above 
 the junction of the two layers. On then blow- 
 ing gently in the side arm (5), the upper layer 
 is forced out into the flask. Repeat the extrac- 
 tion once, using 10 c.c. each of ether and pe- 
 troleum ether and blowing it off into the flask. 
 Distil off the solvent and dry the residual fat 
 to constant weight in the water oven. 
 
 Notes. — It is almost useless to try to extract 
 the fat from milk by shaking it directly with 
 .a solvent. An emulsion is formed with the other constituents 
 of the milk, and it is impossible to get a good separation of 
 the solvent even with the centrifugal machine. This is prob- 
 ably due to the action of the colloidal casein, because it is 
 found that when a complete or partial solution of the casein 
 is effected it is comparatively easy to extract and separate 
 the fat by a solvent immiscible with water. 
 
food: analytical methods: milk. 179 
 
 The method is applicable to whole milk but is especially 
 valuable in determining fat in such products as skim milk or 
 butter milk, which are low in fat. It is also of value in the 
 analysis of sweetened condensed milk. 
 
 Relation between Specific Gravity, Fat, and Solids 
 in Milk. — As has been stated already, the specific gravity 
 of milk is, in the main, a function of two factors, namely, 
 the percentage of solids not fat and that of the fat. The former 
 raises it, the latter lowers it. Taken by itself it affords very 
 little indication of the composition, but if any other item be 
 known, it should be possible to find, by calculation, the other 
 quantities, provided the assumption is true. The solids not 
 fat are made up of several fluctuating constituents, but " nor- 
 mal milk " seems to contain them in such a constant ratio 
 that a calculation serves at least to detect an abnormal sam- 
 ple. For example, given the specific gravity and solids to 
 calculate the fat: 
 
 Specific gravity = Gr. The amount which each per cent, 
 of solids not fat raises the specific gravity = s. The amount 
 which each per cent, of fat lowers the specific gravity = f. 
 Total solids = T. Solids not fat = 5\ Fat = F. Gr = Ss 
 — Ff; or, substituting for 5 its value T — F; Gr = (T — F) 
 s — Ff. The uncertainty of the calculation lies in the val- 
 ues of s and f, which have not been quite satisfactorily deter- 
 mined. 
 
 At different times various formulae have been proposed 
 for this calculation, varying, as a matter of course, with 
 tha method of fat extraction employed. The one most 
 extensively used is that of Hehner and Richmond,* which 
 is based on extensive observation and perfected process 
 
 * Analyst, 13 {1888), 26; 17 (1892), 170. 
 
i8o 
 
 of fat extraction. This formula is generally stated as fol- 
 lows: 
 
 F = 0.8597 — 0.2186G, 
 
 where F represents the fat, 7"the total solids, and G 1000 X 
 (specific gravity — 1.000). 
 
 The simple formula —F = T — — answers within the 
 F 5 4 
 
 limits of experimental error for normal milk, but not for 
 skimmed or watered milk. 
 
 Example. — Data: Gr = 1.0323; G = (Gr — 1) X 1000 = 
 32.3; T= 12.90. 
 
 6 32. ^ 
 
 —F= 12.90 — . F — 4.02 calculated, 3.99 found. 
 
 A similar relation has been worked out for the poteids 
 and sugar, so that from three determinations the whole com- 
 position may be calculated. Example as above: 
 
 Ash = .70 = A. 
 
 Q 
 
 Formula: P= 2.ST + 2.$A — 3.33F — .68—-, 
 
 Gr. 
 
 or P=z 36.12 + 1.75 — 13.32 — 21.28 = 3.27. 
 
 Sugar = T-{A + P+F) 
 
 = I2.90 - (.70 + 3.27 + 4.02) z= 4.9I. 
 
 Where a number of calculations are to be ma^e, Rich- 
 mond's milk-scale will be found convenient. This is an in- 
 strument based on the principle of the slide-rule, having three 
 scales, two of which, for the fat and the tota 1 solids, are 
 marked on the body of the rule, while that for the spe ific 
 gravity is marked on the sliding part. Extended tables are 
 also used for the same purpose. 
 
 Analyst, 13 {1888), 26; 17 {i8g2), 170. 
 
food: analytical methods: milk. 181 
 
 Milk-sugar. — The methods for the determination of the 
 sugar in milk may be divided into two general classes: (i) 
 those depending on the reducing power of the sugar upon an 
 alkaline copper solution; (2) those which are based upon 
 observations of the degree of rotation of the plane of polarized 
 light. 
 
 (1) Determination by Fehling's Solution according to 
 Munson and Walker.* 
 
 Directions. — The milk must first be clarified to remove 
 substances other than sugar which would exert a reducing 
 action on the Fehling's solution. 
 
 Measure 25 c.c. of milk into a 500-c.c. calibrated flask. Add 
 
 about 400 c.c. of water, 10 c.c. of Fehling's copper sulphate 
 
 N 
 solution, then 35 c.c. of — NaOH, and make up to 500 c.c. 
 
 Mix thoroughly and filter through a dry filter. 
 
 Determination. — In a No. 3 beaker mix 25 c.c. of the Fehling's 
 copper sulphate solution and 25 c.c. of the alkaline tartrate 
 solution. Add 50 c.c. of the milk sugar solution, prepared as 
 above, cover the beaker with a watch glass, and heat it upon 
 wire gauze. Regulate the flame so that boiling shall begin in 
 four minutes, and continue the boiling for exactly two minutes. 
 
 Filter the cuprous oxide without delay through asbestos in 
 a weighed Gooch crucible, wash it with hot water until free 
 from alkali, pour out the hot nitrate, then wash with 10 c.c. 
 of alcohol and finally with 10 c.c. of ether. Dry the crucible 
 for 30 minutes at the temperature of boiling water and weigh. 
 Find the milligrams of lactose monohydrate corresponding to 
 the weight of cuprous oxide from Table XII on page 248 and 
 •calculate the percentage present in the milk. 
 
 * J. Am. Chem. Soc. (1906), 663; (1907), 541. 
 
l82 AIR, WATER, AND FOOD. 
 
 Notes. — The general principle upon which all these methods 
 depend is based on the fact that certain sugars, among which 
 is lactose, have the power of reducing an alkaline solution of 
 copper to a lower state of oxidation in which copper is separated 
 as cuprous oxide. The copper salt which is found to give the 
 most delicate and reliable reaction is the tartrate. The two 
 solutions which make up the Fehling's solution are best preserved 
 separately, and rrixed only when wanted for use, as otherwise 
 the reducing power of the solution is liable to change. 
 
 The amount of reduction of the copper salt to the cuprous 
 oxide is affected by the rate at which the sugar solution is 
 added, the time and degree of heating, and the strength of 
 the sugar solution; hence the necessity for adopting a definite 
 procedure and for taking the results from a table determined 
 by exactly the same procedure for varying amounts of the 
 sugar. 
 
 The asbestos which is used should be previously boiled in 
 nitric acid and then in dilute sodium hydroxide and thoroughly 
 washed. A layer about a centimeter thick should be used in 
 the crucible, and a " blank " determination made with the 
 Fehling's solution should not show a change in weight greater 
 than one-half milligram. After the precipitated cuprous oxid: 
 has been weighed it may be dissolved in hot dilute nitric acid, 
 the asbestos in the crucible washed and dried as described, 
 when it is again ready for use. Do not remove the asbestos 
 from the crucible. 
 
 (2) Determination by the Saccharimeter. — For the 
 optical determination of milk-sugar the method of double di- 
 lution, as described by Wiley and Ewell,* will be found satis- 
 factory. 
 
 Directions. — Into each of two flasks, marked at 100 and 
 200 c.c, respectively, put 65.52 grams of milk, add 10 c.c. of 
 acid mercuric nitrate, fill to the mark, and mix by shaking. 
 
 * Analyst, 21 (ySg6), 182. 
 
food: analytical methods: milk. 183, 
 
 Filter through dry filters and polarize in a 400-millimeter 
 tube, using the Schmidt and Haensch saccharimeter. Cal- 
 culate the results as in the following example: 
 
 Weight of milk used = 65.52 grams; 
 
 Reading from 100-c.c. flask = 2o°.84; 
 " " 200-c.c. flask = io°. 15. 
 
 Then 10. 15 X 2 = 20.30; 
 
 20.84 — 20.30 = 0.54; 
 0.54 X 2 = 1.08; 
 
 20.84 — 1.08 = 19.76; 
 19.76 —■ 4 = 4.94, which is the per cent- 
 
 of milk-sugar. 
 
 Notes. — The object in using the method of double dilu- 
 tion is to avoid the necessity of making corrections for the 
 volume of the precipitate of casein and fat. The method is 
 based on the fact that, within certain limits, the polarizations 
 of two solutions of the same substance are inversely propor- 
 tional to their volumes. 
 
 The flasks should be filled at nearly the same temperature 
 as that at which the polarizations are made, and the tem- 
 perature of the room should be kept as nearly as possible 
 at 20 to avoid errors arising from marked changes in tem- 
 perature. 
 
 PROTEIDS OF MILK. 
 
 Determination of Total Proteids. — Weigh 5 grams of 
 milk into a digestion flask and determine the nitrogen by the 
 Kjeldahl process, as directed on page 206. Multiply the per 
 cent, of nitrogen by the factor 6.38 to obtain the per cent, of 
 proteids. The frothing of the alkaline solution during the 
 distillation may be prevented by the addition of a piece of 
 paraffin about the size of a bean. 
 
184 AIR, WATER, AND FOOD. 
 
 Determination of Casein and Albumin.* — Directions. — 
 To 10 grams of milk add 90 c.c. of water at 40-42 C. and 
 then 1.5 c.c. of 10 per cent, acetic acid. Agitate and warm 
 at the above temperature until a flocculent precipitate sepa- 
 rates, leaving a clear supernatant liquid. Filter, wash, and 
 determine the nitrogen in the washed precipitate and filter by 
 the Kjeldahl process. Multiply by 6.38 for the casein. 
 
 To determine the albumin neutralize the filtrate with 
 caustic alkali and phenolphthalein and heat it at ioo° C. until 
 the precipitate settles clear. Filter, wash, and determine the 
 nitrogen as before. Nitrogen multiplied by 6.38 equals albumin. 
 
 Notes. — The principal proteid bodies present in milk are 
 casein and albumin. Others are present in much smaller 
 quantity, such as fibrin or globulin. 
 
 Different observers at various times have claimed the 
 presence of other nitrogenous bodies, but these have not been 
 entirely substantiated. 
 
 It is now generally held that the colloidal state in which the 
 casein is held in milk is due to the combination with it of certain 
 mineral compounds, chiefly those of calcium. The action of 
 precipitants is on these mineral matters, breaking up the com- 
 bination and releasing the insoluble casein. 
 
 Interpretation of Results. — The most common forms of 
 adulteration of milk are the addition of water and the removal 
 of cream. Occasionally some foreign material may be added. 
 A good idea of the form of adulteration may usually be gained 
 from the relation between the fat and the solids not fat. In 
 watered milk both of these are low, but the ratio between them 
 is about the same as in normal milk. In skimmed milk the 
 solids not fat may be nearly normal while the fat is very low. 
 If the total solids and the solids not fat are both below standard, 
 
 * Van Slyke and Hart: Am. Chem. J., 29 (1903), 170. 
 
food: analytical methods: milk. 185 
 
 while the proportion of fat to solids not fat is very small, it is 
 a fair assumption that the milk is both skimmed and watered. 
 
 Leach * states that it is nearly always safe to condemn a 
 milk as watered, if the total solids are below 10.75 per cent., 
 with a corresponding amount of fat. 
 
 Direct Determination of Added Water. — This may be done 
 by determining the specific gravity of the milk-serum after 
 coagulation and removal of the casein. f The casein is coag- 
 ulated by dilute acetic acid, filtered off on a dry filter, and 
 the specific gravity of the nitrate taken at 15 C. by the West- 
 phal balance. The specific gravity of the serum from normal 
 milk is never below 1.027, an( ^ oruv rarely below 1.029. The 
 addition of each ten per cent, of water lowers tne specific 
 gravity by 0.0010 to 0.0035. 
 
 A more convenient method of determination is Dy the Zeiss 
 immersion refract ometer if this instrument is available. (See 
 Bur. of Chem., Bui. 107 (Revised), p. 120; also 1-eacn, Food 
 Inspection and Analysis, p. 766.) The Abbe reiractometer, 
 page 202, can also be used. 
 
 The determination is often of importance since it enables 
 the analyst to distinguish readily between milk which is directly 
 adulterated on the one hand, and that which is only below 
 standard on the other. In legal prosecutions the amount of 
 penalty imposed is sometimes dependant on whether the analyst 
 can show evidence of the actual addition of water. 
 
 Cane-sugar. — To detect the presence of cane-sugar boil 
 about 10 c.c. of the milk with 0.1 gram of resorcin and 1 c.c. 
 of rrydrochloric acid for five minutes. The liquid will be 
 colored rose-red if cane-sugar be present. The quantitative 
 determination may be made by means of the polariscope. 
 
 * "Food Inspection and Analysis." 
 
 f Woodman: J. Am. Chem. Soc, 21 (1899), 503; Leach: "Food Inspection 
 and Analysis," p. 765. 
 
l86 AIR, WATER, AND FOOD. 
 
 Cane sugar is occasionally found in the milk through the use 
 of diluted condensed milk to eke out the supply. 
 
 Starch. — Heat 10 c.c. of the milk to boiling in a test-tube, 
 and when cold add a few drops of the solution of iodine in 
 potassium iodide. The presence of even 0.2 per cent, of starch 
 will be shown by the characteristic blue coloration. 
 
 Coloring-matters. — The principal coloring-matters added 
 to milk are annatto, caramel, and coal-tar dyes. In general, 
 coloring-matters are added only to watered milk, but 
 general, coloring-matters are added only to watered milk, but 
 occasionally samples which were of standard quality have 
 been found to be colored. 
 
 Directions .—Put about 100 c.c. of the milk into a small 
 beaker, add 2 c.c. of 25 per cent, acetic acid and allow the 
 beaker to stand quietly for about ten or fifteen minutes in 
 a water-bath kept at 70 C, the casein being thus separated 
 as a compact cake. Decant off the whey, squeezing the 
 curd as free from it as possible by means of a spatula. Trans- 
 fer the curd to a flask and let it remain covered with ether 
 for an hour or more. 
 
 Evaporate the ether extract, which contains the annatto 
 if present, add 5 c.c. of water, and dilute sodium hydroxide 
 until the mixture, after thorough beating and stirring with 
 a glass rod is faintly alkaline to litmus paper, and filter 
 through a wet filter. If annatto is present, it will permeate 
 the filter and give it an orange color when the fat is washed 
 off under the tap. Treat the filter with stannous chloride. 
 If annatto is present, a pink color will be produced. 
 
 After pouring off the ether examine the milk-curd for 
 caramel or aniline orange. If the curd is left white, neither 
 of these colors is present. If caramel has been used, the 
 curd will be of a pinkish-brown color; if the color is due to 
 the aniline dye, the curd will have a yellow or orange tint 
 In doubtful cases the curd should be compared with one from a 
 
food: analytical methods: milk. 187 
 
 milk known to be uncolored. To distinguish between the two 
 colors shake a small portion of the curd in a test-tube with 
 strong hydrochloric acid. The caramel-colored curd will act 
 similarly to an uncolored curd, that is, it will gradually produce 
 a deep blue color in the solution. On the other hand, the 
 coal-tar color will immediately produce with the hydrochloric 
 acid a pink color. 
 
 Note. — It is to be regretted that there is no positive test 
 for caramel sufficiently delicate to serve here. The test as 
 described is a negative one, the only indication of caramel being 
 the occurrence of a colored curd in which the color is not given 
 by the coal-tar dye. 
 
 Preservatives. — The preservatives usually added to milk 
 are formaldehyde and borax or boric acid. Carbonate of soda 
 is added in some cases to disguise the acidity of sour milk. 
 
 Formaldehyde. — This is generally used as a 40 per cent, 
 aqueous solution, sold under the name of formalin. Several 
 simple tests commonly used for the detection of formaldehyde 
 will be described. 
 
 (1) When the sulphuric acid is added to the milk in making 
 the Babcock test for fat, a bluish- violet ring will be noticed 
 at the junction of the two liquids when formaldehyde is present. 
 One part of formaldehyde in 200,000 parts of milk can be 
 detected by this test, but it fails when the formaldehyde amounts 
 to 0.5 per cent. The test is more delicate if the sulphuric acid 
 contains a trace of ferric chloride. 
 
 (2) To 10 ex. of milk in a small porcelain dish add an equal 
 volume of hydrochloric acid (1.20 sp. gr.). Add one drop 
 of ferric chloride solution and heat the dish with a small flame, 
 stirring vigorously, until the contents are nearly boiling. 
 Remove the flame and continue the stirring for two or three 
 minutes, then add about 50 c.c. of water. The presence of 
 formaldehyde will be shown by a violet color which appears in 
 
i88 
 
 the particles of the precipitated casein, the depth of color 
 depending on the amount of formaldehyde present. The color 
 should be observed carefully at the moment of dilution. This 
 test readily shows the presence of one part of formaldehyde in 
 250,000 parts of milk, if fresh. 
 
 Boric Acid or Borax. — Make 25 c.c. of the milk distinctly 
 alkaline with lime water and evaporate to dryness on the 
 water bath. Char the residue over a flame but do not neces- 
 sarily heat it until white. Digest the residue with 15-20 c.c. 
 of water and add hydrochloric acid (1.12) until the mixture 
 is faintly acid to litmus paper. Filter, and add 1 c.c. of acid 
 fn excess. Place a strip of turmeric paper in the solution and 
 evaporate to dryness on the water bath. If boric acid or borates 
 are present, the paper takes on a peculiar red color, which is 
 changed by ammonia to a dark blue-green, but is restored by 
 acid. Excess of hydrochloric acid should be avoided, as it 
 turns the paper a dirty green when evaporated. This test 
 can also be applied to the hydrochloric acid solution of the ash. 
 
 Sodium Carbonate. — Detected in the milk-ash, as on page 
 174. If effervescence occurs, test the original milk with rosolic 
 acid as follows: Mix 10 c.c. of milk with an equal volume of 
 alcohol, and add a few drops of a one per cent, solution of 
 rosolic acid. The presence of sodium carbonate is indicated 
 by a more or less distinct pink coloration. A comparative 
 test should be made at the same time with milk known to be 
 pure. 
 
 CONDENSED MILK. 
 
 . It may in some cases afford an interesting variation to 
 carry out the tests on condensed milk, this having within recent 
 years become an important article of food. With the unsweet- 
 ened condensed milk, commonly sold as " evaporated milk," 
 the methods as used with whole milk can be applied directly to 
 
food: analytical methods: milk. 
 
 189 
 
 the diluted sample. In the case of sweetened condensed milk, 
 which is usually meant by the term condensed milk in this 
 country, the methods must in some cases be modified, on 
 account of the large proportion of cane sugar present. 
 
 The following are analyses of a few typical samples of 
 sweetened condensed milk: 
 
 COMPOSITION OF SWEETENED CONDENSED MILK. 
 
 
 
 
 
 
 
 
 
 
 Degree 
 
 of 
 Con- 
 densa- 
 tion. 
 
 Fat in 
 
 
 Total 
 Solids. 
 
 Water. 
 
 Milk 
 Solids. 
 
 Cane- 
 sugar. 
 
 Lac- 
 tose. 
 
 Pro- 
 tein. 
 
 Fat. 
 
 Ash. 
 
 Origi- 
 nal 
 MUk. 
 
 I 1 
 
 72.95 
 
 27.05 
 
 30.01 
 
 42.94 
 
 11.28 
 
 7-85 
 
 9-3 
 
 1.58 
 
 2.26 
 
 4. II 
 
 2 2 
 
 71 .03 
 
 28.97 
 
 27.49 
 
 43-45 
 
 11.78 
 
 7-51 
 
 6.6 
 
 1.60 
 
 2.29 
 
 2.88 
 
 3 J 
 
 7i-5« 
 
 28.42 
 
 24.24 
 
 47-34 
 
 13.08 
 
 9.04 
 
 0.15 
 
 1.97 
 
 2.8 
 
 0.05 
 
 Normal. 
 
 2 Not made from standard milk. 
 
 3 Condensed from skimmed milk. 
 
 Preparation of the Sample. — Transfer the entire contents of 
 the can to a large evaporating dish, scraping it out clean, and 
 work it thoroughly with a pestle until homogeneous. Weigh 
 out 40 grams of the mixed sample and dilute to 100 c.c. in a 
 calibrated flask. 
 
 Total Solids. — Dilute 10 c.c. of the 40 per cent, solution with 
 an equal volume of water and evaporate 5 c.c. of the diluted 
 mixture, corresponding to 1 gram of the sample, to dryness in 
 a weighed platinum dish, as directed on page 173. It is of 
 importance to have the sample very dilute in order to get an 
 accurate determination of the solids and this can best be 
 accomplished in the manner described. 
 
 Ash. — Ignite the residue from the determination of total 
 solids, as in the case of ordinary milk. 
 
 Fat. — The fat is the determination of most importance since 
 judgment of the quality of the sample is based more largely on 
 this factor than on any other. Its determination, however, is 
 
190 AIR, WATER, AND FOOD. 
 
 attended with some difficulty on account of the large amount of 
 cane sugar present. The Babcock method, for instance, does 
 not give satisfaction since the charring of the sugar by the 
 sulphuric acid prevents a clean separation of the fat. The 
 Adams method, moreover, is unreliable because the cane sugar 
 dries on the paper coil, enclosing the fat so that it is not readily 
 extracted by the solvent. Several modifications of these 
 methods have been proposed, however, by which fairly good 
 results may be obtained. 
 
 Babcock Method as modified by Leach. — Leach has modified 
 the Babcock test so as to make it available for sweetened con- 
 densed milk by precipitating the proteids and fat with copper 
 sulphate and then removing the interfering sugar by several 
 extractions with water. Directions for carrying out the test 
 will be found in Leach: Food Inspection and Analysis, p. 149, 
 or in Bur. of Chem., Bui. 107, p. 123. 
 
 Adams Method. — This can be applied in the following 
 manner: Dry 5 c.c. of the 40 per cent, solution on the paper 
 coil, as described on page 175. Extract with petroleum ether 
 in the usual manner; dry, soak the coil in 500 c.c. of water for 
 several hours; dry, extract again for five hours and weigh the 
 fat as usual. 
 
 Gottlieb Method. — Use 10 c.c. of the 40 per cent, solution 
 and carry out the determination exactly as described on page 
 178. In many ways this method will be found to give the best 
 results on condensed milk. 
 
 Proteids. — Determine nitrogen in 5 c.c. of the 40 per cent, 
 solution and multiply by 6.38. 
 
 Lactose. — Use the method described on page 181 on 25 c.c. 
 of the 40 per cent, solution. 
 
 Cane Sugar.— This may be determined with sufficient 
 accuracy for most purposes by difference, subtracting the milk 
 solids (the sum of the lactose, fat, protein and ash), from the 
 
food: analytical methods: milk. 191 
 
 total solids. The direct estimation of the cane sugar in the 
 presence of lactose may be carried out with the polariscope 
 by the choice of a suitable inverting agent. The writer has 
 obtained good results by inversion with acid mercuric nitrate, 
 as described by Harrison.* 
 
 BUTTER. 
 
 General Statements .—Butter consists of the fat of milk, 
 together with a small percentage of water, salt, and curd. 
 The curd is made up principally of the casein of the milk. 
 These various ingredients are present in about the following 
 proportions : 
 
 Fat 78.00-90.0 per cent. ; average, 82 per cent. 
 
 Water 5.00-20.0 " " " 12 " " 
 
 Salt 0.40-15.0 " " " 5 " " 
 
 Curd 0.11- 5.3 " " " 1 " 
 
 The fat consists of a mixture of the glycerides of the 
 fatty acids. The characteristic feature of butter-fat is the 
 extraordinarily high proportion of the glycerides of the solu- 
 ble and volatile fatty acids when contrasted with other fats. 
 
 Tl e following may be taken as the probable composition 
 of normal butter-fat: 
 
 Acid. Per cent. Acid. Per cent. Triglycerides. 
 
 Dioxystearic 1 .00 1 .04 
 
 Oleic 32.50 33.95 
 
 Stearic 1.83 1.91 
 
 Palmitic 38.61 40.5 1 
 
 Myristic 9.89 10.44 
 
 Laurie 2.57 2.73 
 
 Capric 0.32 0.34 
 
 Caprylic 0.49 0.53 
 
 Caproic 2.09 2.32 
 
 Butyric 5.45 6.23 
 
 Total 94-75 100.00 
 
 Accordiug to this, the proportion of volatile acids in butter 
 (butyric, caproic, caprylic, and capric acids) amounts to 8.35%. 
 The amount of volatile acid in lard, for example, is about 0.1%. 
 
 "■Analyst, 29, 248. f Browne, /. Am. Chem. Soc, 21 (1899), 807. 
 
192 AIR, WATER, AND FOOD. 
 
 The usual examination of butter consists in the examina- 
 tion of the butter-fat, in order to detect the presence of 
 foreign fats. The determination of the amount of curd may 
 be of value also in some cases, more especially from a 
 sanitary standpoint. The chief danger to health probably 
 lies in the possible decomposition of the nitrogenous portion, 
 for it is quite generally recognized that the substitution of 
 oleomargarine is not injurious to health. It is a not infre- 
 quent practice, however, as remarked in the previous chap- 
 ter, to incorporate a large amount (sometimes as high as 
 33 per cent.) of curd and other nitrogenous matters in fresh 
 butter. If this is kept for any length of time, a decomposi- 
 tion is liable to occur which may have serious effects. Other 
 determinations that are usually made are the water and salt. 
 
 The term " oleomargarine " is usually applied to a mixture 
 of refined lard, " oleo oil," which is mainly the olein of beef fat, 
 and cottonseed oil. Ordinarily a small proportion of butter 
 is added and the product is generally churned with milk. 
 
 A comparatively recent form of butter substitute which 
 finds extensive use in some sections of the country is 
 "process," or "renovated," butter. The raw material, or 
 " stock," used for the manufacture of this consists of butter 
 which cannot be sold as butter either because of deteriora- 
 tion through rancidity or moulding or because, through care- 
 lessness on the part of the makers, it possesses an unattractive 
 appearance or flavor. The chief recruiting-ground for this 
 material is the country grocery store. The fat, separated 
 from the curd by melting and settling, is aerated to remove 
 disagreeable odors and leave it nearly neutral. This is then 
 emulsified with fresh milk which has been inoculated with 
 a bacterial culture, and the whole is chilled, granulated, 
 and churned. The butter is then worked and packed for 
 market in the usual manner. The character of the prod- 
 
food: analytical methods: butter. 193 
 
 uct has much improved since the early days of the 
 industry, the best grades now approximating- the lower 
 grades of creamery butter. 
 
 The " aroma " of butter seems to be connected with the 
 decomposition produced by the action of bacteria on the 
 casein and the small amount of milk-sugar that is present, 
 and not with any change in the fats; there is no evidence, 
 however, that any unwholesome effect is produced by the 
 aroma-giving organisms. 
 
 The rancidity of butter-fat is generally considered to be 
 due to decomposition and oxidation of the fatty acids, espe- 
 cially the unsaturated ones, the amount of change depending" 
 on conditions of light, heat, and exposure to air. 
 
 Examination of the Fat. — The fat is first separated 
 from the other constituents of the butter so that it may be 
 weighed out for the various tests. 
 
 Directions. — Melt a piece of butter, about two cubic 
 inches, in a small beaker placed on top of the water-bath so 
 that the temperature shall not rise above 50°-6o°. After 
 about fifteen minutes the water, salt, and curd will have set- 
 tled to the bottom. (A better separation may be secured 
 by dividing the melted sample equally between two test-tubes 
 and whirling them for 3-4 minutes in a centrifugal machine.) 
 Place a bit of absorbent cotton in a funnel, previously waimed, 
 and decant off the clear fat through the cotton into a second 
 beaker, taking care that none of the water or curd is brought 
 upon the filter. When the filtered fat has cooled to about 40 
 place a small pipette in the beaker and weigh the whole. 
 
 By means of the pipette the desired amount of fat is taken 
 out, the pipette replaced in the beaker, and the whole again 
 weighed. The difference in weight gives the exact amount 
 of fat taken. It is a saving of time, however, if several por- 
 tions are to be weighed out, to make the weights one after 
 
194 AIR, WATER, AND FOOD. 
 
 another, so that one weight will suffice for a determination. 
 Weigh out thus : Two portions of 5 grams each into 250-c.c. 
 round-bottomed flasks for the Reichert-Meissl method, one 
 portion of 2,5 to 3 grams into a 500-c.c. beaker for Hehner's 
 process, two portions of about .35 to .5 gram each into 300-c.c. 
 .glass-stoppered bottles for determination of the iodine value. 
 In the case of the larger portions, weigh only to the nearest 
 milligram. 
 
 (1) Reichert-Meissl Number for Volatile Fatty Acids. 
 — Directions. — To the fat in the 250-c.c. flasks add 2 c.c. of 
 strong caustic potash (1:1) and 10 c.c. of 95 per cent, 
 alcohol. Connect the flask with a return-flow condenser 
 and heat on a water-bath so that the alcohol boils vigorously 
 for 25 minutes. At the end of this time disconnect the flask 
 and evaporate off the alcohol on a boiling-water bath. After 
 the complete removal of the alcohol add 140 c.c. of re- 
 cently boiled distilled water which has been cooled to about 
 50 . The water should be added slowly, a few cubic centi- 
 meters at a time. Warm the flask on the water-bath until 
 a clear solution of the soap is obtained. Cool the solution to 
 about 6o° and add 8 c.c. of sulphuric acid (1:4) to set free 
 the fatty acids. Drop two bits of pumice, about the size of 
 a pea, into the flask, close it by a well-fitting cork, which is 
 tied in with twine, and immerse it in boiling water until the 
 fatty acids have melted to an oily layer floating on the top 
 of the liquid. Cool the flask to about 6o°, remove the cork, 
 and immediately attach the flask to the condenser. 
 
 Distil no c.c. into a graduated flask in as nearly thirty 
 
 minutes as possible. Thoroughly mix the distillate, pour the 
 
 whole of it through a dry filter, and titrate 100 c.c. of the 
 
 N . 
 
 mixed filtrate with — ■ sodium hydroxide, using phenol- 
 
 phthalein as an indicator. Multiply the number of cubic centi- 
 
food: analytical methods: butter. 195 
 
 meters of alkali used by eleven-tenths, and correct the reading 
 
 also for any weight of fat greater or less than 5 grams. 
 
 For example, if 5.3 grams of butter-fat are used, and 100 
 
 N 
 c.c. of the distillate require 27.4 ex. of — NaOH, no c.c. 
 
 would require 2.7.4X^=30.14 c.c. Then 5.3 : 30.14 = 
 5 : x . #=28.4. x is the Reichert-Meissl number. 
 
 Notes. — The Reichert-Meissl number for genuine butter 
 varies from 24 to 34; the average usually taken is 28.8. 
 
 Cocoanut oil gives a value of 6-8; other edible fats and oils 
 have a value usually less than 1 . 
 
 The presence of cocoanut oil is readily shown by the Reichert- 
 Meissl number taken in connection with the saponification 
 value, that is, the number of milligrams of potassium hydroxide 
 required to saponify one gram of the fat. (For a description 
 of the method of determining this see Lewkowitsch: Oils, Fat, 
 and Waxes, or Gill: A Short Handbook of Oil Analysis). The 
 Reichert-Meissl number is higher in butter fat than in cocoanut 
 oil, while the saponification value is lower. In pure butter 
 fat the value of the expression (Saponification value — Reichert- 
 Meissl number — 200) varies from 3.4 to 4.1; in pure cocoanut 
 oil it runs from 47 to 50.7.* 
 
 When the fat is treated with potash it is decomposed, the 
 glycerine being set free, and the potassium salts of the fatty 
 acids, that is to say, the potassium soaps are formed. Hence 
 the process is called saponification. For butyric acid the 
 reaction may be expressed 
 
 C 3 H 5 (C 3 H T COO) 3 + 3KOH = 3 C 3 H 7 COOK + C 3 H 5 (OH) 3 . 
 
 The alcohol is used to dissolve the fat. But at the 
 moment the butyric acid is set free it tends to combine with 
 the alcohoi to form a volatile ether: 
 
 C 3 H 7 COOH + C 2 H 5 OH = QHCOOC 2 H 5 + H 2 0. 
 
 Juckenack and Pasternack: Ztschr. Nahr. Genussm., 7 (1904), 193. 
 
I96 AIR, WATER, AND FOOD. 
 
 The object of the return-flow condenser is to prevent the 
 escape of this volatile ether and to allow of its complete 
 saponification. 
 
 If the water used to dissolve the soap is added too rap- 
 idly, the soap may be decomposed with the liberation o c the 
 fatty acids: C 3 H 7 COOK + H 2 = C 3 H 7 COOH + KOH. 
 
 The fatty acids are set free at the proper time by means 
 of sulphuric acid, and the volatile acids distilled off and 
 ntrated. The pumice is added to prevent explosive boiling. 
 
 The whole of the volatile acids do not pass over into the 
 distillate, but only a part, the amount depending upon the 
 rate of distillation and the volume of the distillate Hence, m 
 order to get uniform results, it is necessary to follow the pre- 
 scribed procedure with great care. 
 
 (2) Hehner's Method for Direct Determination of 
 the Fixed Fsttv Acids. — Directions. — To the portion of 
 2.5 grams weighed out into the 500-c.c. beaker add 1 c.e. of 
 caustic potash and 20 c.c. of 95 per cent, alcohol. Cover 
 the beaker with a watch-glass and heat it on the water-bath 
 until the liquid is clear and homogeneous. As it is not essen- 
 tial to prevent the escape of the volatile acids, the use of a 
 return-flow condenser is not necessary. Evaporate off the 
 alcohol on the water-bath and dissolve the soap in about 
 400 c.c. of warm distilled water. When the soap is com- 
 pletely dissolved add 10 c.c. of hydrochloric acid (sp. gr. 
 1.1 2), and heat the beaker in the water-bath almost to boil- 
 ing until the clear oil floats. Meanwhile dry and weigh a 
 thick filter in a small covered beaker. Allow the solution 
 to cool until the fat forms a solid cake on top ; filter the clear 
 liquid and finally bring the solid fats upon the weighed 
 filter. Wash the beaker and fat thoroughly with cold water, 
 then wash out the fat adhering to the beaker with boiling 
 water, which is poured through the filter, taking care that 
 
food: analytical methods: butter. 197 
 
 the filter is never more than two-thirds full. If the filter paper 
 is of good texture and thoroughly wet beforehand it will retain 
 the fatty acids completely. If, however, oily particles are 
 noticed in the filtrate, cool it by adding pieces of ice, remove 
 the solidified particles with a glass rod and transfer them to 
 the filter. Cool the funnel by plunging it into cold water, 
 remove the filter, place it in the weighing-beaker and dry it at 
 ioo° to constant weight. The fat should be heated about an 
 hour at first, then for periods of about thirty minutes, until the 
 weight is constant within 2 mgs. 
 
 Notes. — 87.5 per cent, is usually taken as the proportion 
 of fixed fatty acids in butter-fat ; 88 and 89 per cent, have 
 been frequently found. All other fats yield from 95 to 96 
 per cent, of insoluble fatty acids. 
 
 (3) Determination of Iodine Value. — This method is 
 based on the fact that certain of the fatty acids, notably 
 the "unsaturated acids," as oleic acid, C 17 H 33 COOH, take 
 up the halogens with the formation of addition products. 
 
 Directions. — Dissolve the fat in the 300-c.c. bottles in 
 
 10 c.c. of chloroform. Add 30 c.c. of the iodine solution 
 
 from a pipette or glass-stoppered burette, and allow the 
 
 bottles to stand with occasional shaking for fifteen minutes. 
 
 Add 10 c.c. of 20 per cent, potassium iodide solution, then 
 
 100 c.c. of distilled water, and titrate the excess of iodine 
 
 N 
 with — sodium thiosulphate until the solution is faintly 
 
 yellow. Add 2-3 c.c. of starch solution and titrate to 
 the disappearance of the blue color. Calculate the result 
 in grams of iodine absorbed by 100 grams of fat. This is 
 called the Iodine Number, or Iodine Value. 
 
 At the time of making the determination carry out two 
 * ' blanks ' ' in exactly the same way except that no fat is used 
 and only 20 c.c. of the iodine solution is added. 
 
 Standardization of the Thiosulphate Solution. — As this is 
 
198 AIR, WATER, AND FOOD. 
 
 not permanent, its strength should be determined by means 
 of the standard potassium bichromate solution, 1 c.c. of 
 which is equivalent to 0.0 1 gram of iodine. 
 
 Measure 20 c.c. of the potassium bichromate from a 
 pipette into an Erlenmeyer flask. Add 5 c.c. of potassium 
 iodide, 100 c.c. of water, and 5 c.c. of strong hydrochloric 
 acid. Titrate the liberated iodine with the thiosulphate solution 
 until the color has almost disappeared, then add starch solution 
 and continue the titration until the blue color changes to a 
 sea-green, due to the formation of chromium chloride. The 
 iodine is liberated in accordance with the following equation: 
 
 K 2 Cr 2 7 + 14HCI + 6KI = 8KC1 + 2 CrCl 3 + 7 H 2 + 61. 
 
 Calculation of Results. — Example. — From the standardi- 
 zation, 
 
 16.07 c.c. thiosulphate = 20 c.c. bichromate =0.200 gram I; 
 1 c.c. thiosulphate =0.0125 gram I. 
 Also, from blank, 
 
 20 c.c. iodine solution =42.40 c.c. thiosulphate; 
 1 c.c. iodine solution = 2.12 c.c. thiosulphate. 
 If 30 c.c. iodine solution have been added to 0.6542 
 grams of fat, then 30X2.12=63.60 c.c. is the equivalent 
 amount of thiosulphate solution; and if 44.85 c.c. thio- 
 sulphate were used to titrate excess of free iodine, 63.60 — 
 44.85 = 18.75 c.c. is the amount of thiosulphate equivalent 
 to the iodine combined with the fat. Then, since 1 c.c. 
 thiosulphate is equivalent to 0.0125 gram free iodine, 
 
 — —^-7 — '■ X 100 =35.83 grams of iodine combined with 
 
 0.0542 
 
 100 grams fat. 
 
 Notes. — It is assumed that 100 grams of pure butter-fat 
 
 absorb 30-40 grams iodine; oleomargarine, 63-75 grams; 
 
 olive-oil, 83 grams; and cottonseed-oil, 106 grams. 
 
food: analytical methods: butter. 199 
 
 The products formed by the action of iodine on the fats 
 are mainly addition products with a slight proportion of 
 substituted bodies. Thus the unsaturated olein, 
 
 (C 17 H 33 COO) 3 C 3 H 5 , 
 
 takes up six atoms of iodine, forming an addition product^ 
 di-iodo-stearin, (C 17 H 33 I 2 COO) 3 C 3 H 5 . 
 
 The method in general use for determining the iodine 
 value of fats and oils has been that of Baron Hubl,* an 
 alcoholic solution of iodine and mercuric chloride being 
 used as the reagent. The method here described, due to 
 Hanust, has the advantage that the solutions keep better, 
 remaining practically unchanged for several months, and 
 that the action is about sixteen times as rapid. For the 
 fats and for oils with low iodine values the results are very 
 close to the figures obtained by the Hubl process. If it is 
 desired to carry out the determination by the older method, 
 directions can be found in any standard work on the analysis 
 of oils. 
 
 Great care should be taken that there is no change in 
 temperature between the time of measuring the solution of 
 iodine for the blanks and for the determinations, since the 
 high coefficient of expansion of acetic acid may cause a material 
 error. 
 
 The Spoon Test or " Foam " Test. — Melt a piece of the 
 sample as large as a small chestnut in an ordinary tablespoon 
 or a small tin dish. A test-tube can be used if desired. Use 
 a small flame and stir the melting fat with a splinter of wood 
 (such as a match). Then increase the heat so that the fat 
 
 * Ding. Poly. J., 253, 281; /. Soc. Chem. Ind., 3 {1884), 641. 
 •j" Ztschr. Unters. Nahr. u. Genussm., 4 (ipoi), 913. 
 
200 AIR, WATER, AND FOOD. 
 
 shall boil briskly, and stir thoroughly, not neglecting the outer 
 edges, several times during the boiling. 
 
 Oleomargarine and renovated butter boil noisily, usually 
 sputtering like a mixture of grease and water when boiled, 
 and produce little or no foam. Genuine butter usually boils 
 with much less noise and produces an abundance of foam. 
 The difference in regard to the foam is very marked. 
 
 Note also the appearance of the particles of curd after the 
 boiling. With genuine butter these will be very small and finely 
 divided, hardly noticeable in fact, while with oleomargarine 
 and renovated butter the curd gathers in much larger masses 
 or lumps. 
 
 Notes. — This simple method is of value for giving a quick 
 decision regarding a sample, and is especially useful for the 
 detection of renovated butter. The differences in the composi- 
 tion of butter-fat brought about by renovation are so slight 
 that chemical methods are here of no avail. 
 
 The spoon test, however, will distinguish in the great 
 majority of cases between genuine butter on the one hand and 
 oleomargarine and renovated butter on the other; the index 
 of refraction or the chemical methods just described readily 
 distinguish between the two latter. 
 
 Physical Methods. — Microscopic Examination. — Pure, fresh 
 butter is not ordinarily crystalline in structure. Butter which 
 has been melted, however, and fats which have been liquefied 
 and allowed to cool slowly show a distinct crystalline structure, 
 especially by polarized light. If only fresh butter were sold, 
 and all adulterants had been previously melted and slowly 
 cooled, this method would be all that would be necessary for 
 the detection of adulteration. As it is, however, it is most 
 useful in making comparative examinations of samples which 
 have been subjected to the same conditions. From an examina- 
 tion of the accompanying plate,* which shows the appearance 
 
 * From photomicrographs by A. G. Woodman and A. I. Kendall, 1900. 
 
food: analytical methods: butter. 201 
 
 by polarized light of four samples of known origin which were 
 melted and cooled slowly under exactly similar conditions, it 
 will be seen that, while the differences are noticeable, they are 
 not sufficient in all cases to form a basis for absolute identi- 
 fication. 
 
 About the most that can be said is that if a small bit, about 
 the size of a pin-head, of the fresh, unmelted sample, is taken 
 from the center of the mass and pressed out on a slide by gentle 
 pressure on the cover glass, it ought to show a fairly uniform 
 field if examined with a one-sixth objective, using polarized 
 light and a selenite plate. Other fats melted and cooled, and 
 mixed with butter, generally show a crystalline structure and 
 a variegated color with the selenite plate. 
 
 For a further discussion of this point the student is referred 
 to Bulletin 13, U. S. Dept. Agric, Part I, pp. 29-40; Part 
 IV, pp. 449-455- 
 
 Specific Gravity. — This is most conveniently determined 
 at ioo° C. by means of the Westphal balance (see Allen, The 
 Analyst, n, 223; also Bull. 13, Part IV, pp. 430-431). The 
 pyknometer method is, however, the one adopted by the Asso- 
 ciation of Official Agricultural Chemists as the official method. 
 See Bulletin 107, p. 130. 
 
 Melting Point. — This may be determined by the capillary- 
 tube method as generally employed for organic substances and 
 described in text books on organic analysis. (See for instance, 
 Mulliken: Identification of Pure Organic Compounds, Vol. I, 
 p. 218.) Wiley's method, however, which is the official method 
 of the A. O. A. C, has the advantage that it avoids the incorrect 
 results which are sometimes obtained with other methods due 
 to the adherence of the melting fat to solid surfaces. A descrip- 
 tion of the method will be found in Bull. 107, p. 133. 
 
 Refractive Ina]ex. — The determination of the refractive index 
 is especially valuable in food analysis on account of the ease 
 
202 
 
 AIR, WATER, AND FOOD 
 
 and rapidity with which the determination can be made and 
 the fact that so little of the substance is necessary for the 
 determination. Various forms of refractometers are used for 
 the purpose, a fairly complete description of which will be found 
 
 1 [l 'H fl 
 
 Fig. 14. 
 
 in some of the larger works, such as Leach: Food Inspection 
 and Analysis, or Vaubel:' Quantitative Bestimmung organischer 
 Verbindungen. The instrument having the widest range is 
 the Abbe refractometer, in which the index of refraction is 
 determined by measuring the total reflection produced by a 
 very thin layer of the melted fat, placed between two prisms 
 
food: analytical methods: butter. 203 
 
 of flint glass. This instrument, fitted with water- jacketed 
 prisms is shown in Fig. 14. 
 
 Directions. — Revolve the whole instrument on the axis b until 
 it reaches the stop provided, then open the prism casing AB by 
 giving the pin v a half-turn (to the right). Be sure the prism 
 surfaces are clean. It not, clean them carefully with a soft 
 cloth and a little alcohol. Place a few drops of the melted 
 sample directly on the surface of the prism and clamp the two 
 together again by turning the pin v in the opposite direction. 
 Now turn the instrument back (toward the observer) as far as 
 possible and bring the " critical line " into the field of vision 
 of the telescope. This is done by holding the sector 5 firmly 
 with the hand and revolving the double prism by means of the 
 alidade / until the field is divided into a light and a dark 
 portion. If the line is not sharp focus the ocular 01 the tele- 
 scope. If it is colored it is due to dispersion of trie light by 
 the liquid and should be corrected by revolving tne compen- 
 sator T by the milled screw M. The correction is made by a 
 system of two revolving Amici prisms in the lower part of the 
 telescope. Adjust the critical line so that it falls on the inter- 
 section of the cross hairs of the telescope. Observe the temper- 
 ature by the thermometer inserted in the prism casing. In the 
 case of solid fats a sufficiently high temperature should be 
 maintained by a current of warm water to keep the sample 
 well above its melting point. A temperature of 30-40 C. is 
 usually sufficient. Do not let the temperature rise above 70 
 or the prisms may be injured. Read the index of refraction 
 directly through the small lens L, estimating the fourth decimal. 
 Calculate the value for the refractive index at 25 ° C. 
 
 Notes. — The index of refraction decreases with rising tem- 
 perature. With the common oils and lats the change for each 
 degree is very nearly a constant, amounting to 0.000365. 
 Leach and Lythgoe* have devised a sliding scale by means of 
 
 * J. Am. Chem. Soc. (1904), 1193. 
 
204 AIR, WATER, AND FOOD. 
 
 which the temperature correction may be readily made without 
 reference to tables. 
 
 The values of wff for genuine butter lie between 14590 
 and 1.4620; for oleomargarine the values range from 1.4650 to 
 1.4700. 
 
 The correctness of the adjustment of the instrument may 
 be tested by the " test-plate " which comes with it, using 
 monobromnaphthalene, or by means of distilled water. The 
 theoretical value for the refractive index of water at 18 C. is 
 
 1.3330. 
 
 Determination of Water. — Directions. — Weigh 2 grams 
 of butter into a shallow metal dish having a flat bottom two 
 inches in diameter and containing a slender stirring-rod two 
 and a half inches long. Heat the butter in the oven at ioo° 
 C. for thirty minutes, cool in a desiccator, and weigh. Heat 
 again for periods of fifteen minutes, until the weight remains 
 constant within 2 or 3 milligrams. During the process of heat- 
 ing stir the butter frequently to hasten evaporation of the water. 
 
 Determination of Salt.- -Directions. — Weigh 10 grams 
 
 of butter in a small beaker, add 30 c.c. of hot water, and 
 
 when the fat is completely melted transfer the whole to a 
 
 separately funnel. Shake the mixture thoroughly, allow 
 
 the fat to rise to the top, and draw off the water, taking care 
 
 that none of the fat-globules pass the stopcock. Repeat the 
 
 operation four times, using 30 c.c. of water each time. Make 
 
 the washings up to 250 c.c, mix thoroughly, and titrate 25 
 
 N 
 c.c. in a six-inch porcelain dish, using — silver nitrate with 
 
 potassium chromate as an indicator. 
 
 Complete Analysis of Butter in One Sample. — Direc- 
 tions. — Weigh about 2 grams of butter into a platinum 
 Gooch crucible, half-filled with ignited fibrous asbestos, and 
 dry it at ioo° C. to constant weight. The loss in weight is 
 the amount of water. Then treat the crucible repeatedly 
 
A. Butter X 30. 
 
 C. Oleomargarine X 30. 
 
 B. Beef-fat X 30, 
 D. Lard X 30. 
 
food: analytical methods: butter. 205 
 
 with small portions of petroleum ether, using- gentle suction, 
 and again dry it to constant weight. The difference between 
 this and the preceding weight will be the amount of fat. 
 Now carefully heat the crucible over a sma 1 l flame or in a 
 muffle until a light grayish ash is obtained. The loss in 
 weight is the amount of curd, and the residual increase in 
 weight over that of the crucible and asbestos is the ash. If de- 
 sired, the salt may be washed out of the ash and determined 
 by titration with silver nitrate after neutralizing the solution 
 with calcium carbonate. 
 
 FLOUR, PREPARED CEREALS, ETC. 
 
 This class of foodstuffs is usually in a dry form and not 
 liable to rapid change by micro-organisms, and the examina- 
 tion consists in the determination of their " food value." This 
 may require a simple analytical process, as in the case of the 
 quantity of nitrogen in a sample of " gluten " sold for diabetic 
 patients, or in the case of a brand of flour to be used in a 
 hospital or State institution. It may also require an estimation 
 of the available food-material, as in the case of two kinds of 
 beans or corn. The results of chemical analysis will often put 
 the statements made on packages of breakfast cereals in a 
 different light. 
 
 Owing to the extensive use at present of various cereal 
 breakfast foods, many of which are modified from their original 
 composition by cooking or treatment with malt, the extent to 
 which the starch has by this treatment been converted to 
 soluble forms is also an important question for consideration. 
 The actual determination of digestibility belongs to physio- 
 logical chemistry and need not be taken into consideration here. 
 
 Moisture. — Directions. — Spread about 2 grams of the finely 
 ground material in a thin layer on a watch-glass and dry it 
 in the oven at ioo° C. for five hours. On account of the ready 
 
206 AIR, WATER, AND FOOD. 
 
 absorption of moisture by the dried sample, the use of clipped. 
 watch-glasses will be found advantageous. 
 
 Note. — With some substances drying in a current of hydrogen 
 or some inert gas may be necessary, but for most cereals the 
 method given will be found satisfactory. 
 
 Ash. — Directions. — Weigh about 2 grams into a platinum 
 dish, such as is used for the determination of solids in milk, 
 and char it carefully. Ignite at a very low red heat until the 
 ash is white, preferably in a muffle. 
 
 Notes. — If a white ash cannot be obtained in this manner, 
 exhaust the charred mass with water, collect the insoluble 
 residue on a filter, burn it, add this ash to the residue from 
 the evaporation of the aqueous extract and heat the whole at 
 a low red heat until the ash is white. 
 
 Some cereals, such as whole wheat and bailey, will act 
 destructively on platinum dishes, on account of the phosphates 
 present but can be ignited safely in platinum in the muffle. 
 
 Ether Extracts: Fats and Oils. — Directions. — Place the 
 residue from the determination of moisture, as described above, 
 in an extraction-cone and extract it with pure anhydrous 
 ether for sixteen hours. Evaporate off the ether and dry the 
 residual fat at the temperature of boiling water to constant 
 weight. 
 
 The ether extract of cereals is not pure fat but may contain 
 more or less coloring matter or resins. Petroleum ether can be 
 used for the extraction, giving results not essentially different 
 from those obtained with anhydrous ethyl ether. 
 
 Total Proteids: Determination of Nitrogen by the 
 Kjeldahl Process. *— --Principle. — Oxidation of carbon and 
 hydrogen, and conversion of organic nitrogen to ammonium 
 sulphate by means of boiling sulphuric acid in presence of 
 
 * Ztschr. anal. Chem., 22 {1883), 366. 
 
food: analytical methods: butter. 207 
 
 mercury, the latter acting as a carrier of oxygen, and being 
 converted to mercuric sulphate. Precipitation of mercury by 
 potassium sulphide to prevent the formation of mercur-ammo- 
 nium compounds when the solution is made alkaline. Setting 
 free of ammonia by neutralization of the acid by potassium 
 
 hydroxide. Distillation of ammonia into a measured quantity 
 
 N 
 of — acid. Titration of excess of acid. 
 10 
 
 Directions. — Transfer about 0.5 gram of the finely divided 
 substance from a weighing-tube to a pear-shaped digestion 
 flask, add 10 c.c. of concentrated sulphuric acid free from 
 nitrogen, and 0.2 gram (three small drops) of metallic mercury. 
 Place a small funnel in the neck of the flask, which should be 
 supported in an inclined position on wire gauze and heated 
 with a small flame until frothing has ceased and the liquid boils 
 quietly. Then increase the heat and boil the solution for at 
 least half an hour after it becomes colorless. Allow the flask 
 to cool for a minute or two, and add a few crystals of potassium 
 permanganate until the liquid has acquired a slight green or 
 
 purple color. 
 
 N 
 Measure 25 c.c. of — acid from a burette into a 300-c.c. 
 
 Erlenmeyer flask and place the condenser-tip beneath the 
 surface of the liquid, adding a little water, if necessary, to 
 seal it. 
 
 Transfer the digestate with several small portions of distilled 
 water to the distilling flask of the apparatus, add 20 c.c. of 
 potassium sulphide solution, and connect the flask with the 
 condenser. Add 50 c.c. of caustic potash through the separa- 
 tory funnel, and distil off the ammonia by steam. When 200 
 c.c. have distilled over, remove the collecting-flask, after rinsing 
 off the condenser-tip with distilled water, and titrate the excess 
 
 N 
 of acid with — sodium hydroxide, using methyl orange or 
 
2o8 
 
 cochineal as indicator. If using new reagents, a blank deter- 
 mination should be made with 0.5 gram of cane-sugar in order 
 to reduce any nitrates present which might otherwise escape 
 detection. 
 
 Notes. — The temperature during the digestion must be 
 maintained at or near the boiling-point of the acid, since at a 
 lower temperature the formation of ammonia is incomplete. 
 
 The process is considered by Dafert * to take place in four 
 steps: (1) the sulphuric acid takes the elements of water from 
 the organic matter; (2) the sulphur dioxide produced by the 
 action of the residual carbon on the sulphuric acid exercises 
 a reducing action on the nitrogenous bodies; (3) the nitro- 
 genous substances formed in this way are converted to am- 
 monia by a process of oxidation; (4) the ammonia formed is 
 fixed by the acid as ammonium sulphate. 
 
 In some cases the potassium permanganate is necessary 
 to insure the complete conversion of the nitrogenous bodies 
 into ammonia, although it is probable that its use is unneces- 
 sary in the majority of analyses. 
 
 The Kjeldahl process in the form outlined above is not 
 applicable to the determination of nitrogen in the form of 
 nitrates. In order to render it of more general application 
 various modifications of the method have been proposed, the 
 one generally used in this country being that suggested by 
 Scovell.t In this method salicylic acid is used with the sul- 
 phuric acid, being converted by the nitrate into nitro-phenol. 
 By the use of sodium thiosu'phate or zinc-dust this is reduced 
 to amido-phenol. The amido-phenol is transformed into am- 
 monium sulphate by the heating with sulphuric acid, the use 
 of mercury being absolutely necessary in this case to secure 
 
 * Ztschr. anal. Chem., 24 (1885), 455- 
 t U. S. Dept. Agr., Bull. 16 (1887), 51 
 
food: analytical methods: cereals. 209 
 
 the complete transformation. It is true also that certain other 
 nitrogenous bodies, notably the alkaloids and certain organic 
 bases, do not yield all their nitrogen to the Kjeldahl process 
 without modifications which complicate the method. For a 
 discussion of the efficiency of these various modifications the 
 student is referred to a paper by Sherman and Falk.* 
 
 The per cent, of proteids may be found by multiplying the 
 per cent, of nitrogen by an appropriate factor, the one in general 
 use being 6.25. Recent work has shown, however, that most 
 of the proteids of cereals contain more than 16 per cent, of 
 nitrogen, so that the factor 6.25 gives results that are too high. 
 Because all the older work was calculated on this factor, it is 
 still generally used, nevertheless. 
 
 Kjeldahl-Gunning Method. — The Gunning method can be 
 used in all cases where the Kjeldahl-Wilfarth modification, just 
 described, is employed, and in some ways it is simpler. 
 
 The digestion and distillation are carried out as described 
 on page 207, using the same amount of sample, together with 
 20 c.c. of concentrated sulphuric acid and 10 grams of powdered 
 potassium sulphate. No mercury and consequently no potas- 
 sium sulphide is used. 100 c.c. of the potash should be added 
 instead of 50. 
 
 Note. — The potassium sulphate is added to raise the boiling 
 point of the sulphuric acid and thus shorten the time required 
 for the digestion. 
 
 Carbohydrates. — The total carbohydrates, often stated in 
 analyses as " nitrogen-free extract," may be readily obtained 
 by subtracting from 100 the sum of the percentages 
 of the other constituents, viz., moisture, ash, ether extract, 
 and nitrogenous bodies. In many cases, however, espe- 
 cially with the cooked or treated cereals and with such 
 
 * J. Am. Chem. Soc. {1904), 26, 1469. 
 
2IO AIR, WATER, AND FOOD. 
 
 classes of cereal preparations as infant or invalid foods, a 
 further study of the carbohydrates is desirable. These are 
 made up of two general classes: (a) soluble carbohydrates, 
 including sugars, as sucrose, dextrose and maltose, dextrin 
 and soluble starch, by the latter term being meant starch 
 which is soluble in water but still gives the characteristic 
 blue color with iodine, in distinction from some of the more 
 completely broken-down forms like dextrin, which no 
 longer give blue or purple colors with iodine; (b) insoluble 
 carbohydrates, including starch, pentosans, lignin bodies, and 
 cellulose. The three latter occur chiefly in the husk or 
 envelope of the grain or in the woody fibre of the plant. 
 The pentosans or gums are distinguished from one another 
 by the formation of specific sugars upon hydrolysis with 
 acids. For ordinary analytical purposes it is sufficient to 
 determine the lignin and cellulose together as " crude fibre." 
 Since the exact procedure to be followed in the determina- 
 tion of the carbohydrates varies largely with each specific 
 case, only a general outline can be presented here. 
 
 Sugars. — The finely ground material, previously dried 
 and extracted with ether for the removal of crude fat, is 
 extracted with 85 per cent, alcohol. In the extract the 
 reducing sugars may be determined by means of Fehling's 
 solution as described on page 181, and the sucrose deter- 
 mined in the same way after inversion with hydrochloric 
 acid. 
 
 Dextrin and Soluble Starch. — The residue from the ex- 
 traction of the sugars is treated for eighteen to twenty-four 
 hours with water at laboratory temperature with frequent 
 agitation, made up to definite volume, and filtered. This 
 may be tested with iodine, and if no blue color is produced, 
 evaporated to small volume, and the dextrin converted to 
 dextrose by dilute hydrochloric acid and determined by 
 
food: analytical methods: cereals. 211 
 
 Fehling's solution. In some few cases, however, a blue 
 color with iodine may indicate the presence of soluble starch, 
 in which case an aliquot part of the filtrate may be treated 
 with an excess of barium hydroxide to precipitate the starch. 
 In the filtrate from this precipitate the dextrin is deter- 
 mined by inversion and copper reduction as before. The 
 difference between the dextrin thus found and the first 
 determination gives the soluble starch. 
 
 Starch. — The methods for the determination of starch 
 vary with the condition in which the starch is found. In the 
 case of nearly pure starch it may be converted into dextrose 
 by boiling with dilute acid, the dextrose being then deter- 
 mined by Fehling's solution in the usual way. Hot acids, 
 however, cannot be used to convert starch in the natural 
 state, as it is found in cereals, because other carbohydrate 
 bodies, especially the pentosans, become soluble under these 
 conditions and the results are too high. In such cases the 
 starch is brought into solution by treatment with diastase or 
 by heating with water under pressure. The results obtained 
 by direct acid hydrolysis, however, in cases where the highest 
 accuracy is not required, may be sufficient and the method is 
 much quicker and easier of execution than the digestion with 
 diastase. 
 
 Direct Acid Hydrolysis. — Directions. — Weigh out from 2 
 to 5 grams of the sample, depending upon the amount of starch 
 present, and wash on a filter with five successive portions of 
 10 c.c. each of ether. Allow the ether to evaporate from the 
 residue and then wash it with 10 per cent, alcohol until free 
 from soluble carbohydrates. 150 c.c. of the dilute alcohol is 
 generally sufficient, but if much reducing sugar or dextrin is 
 present, as may be the case with malted cereals, more will be 
 necessary. Wash the residue from the filter with 200 c.c. of 
 water into a 500 c.c. graduated flask, add 20 c.c. of hydrochloric 
 acid, sp. gr. 1.125, place a funnel in the neck of the flask to 
 
212 AIR, WATER, AND FOOD. 
 
 retard evaporation, and heat in a boiling water bath for two and 
 one-half hours. Cool, nearly neutralize with sodium hydroxide 
 and make up to 500 c.c. Filter, and determine dextrose in an 
 aliquot portion, 25 or 50 c.c., of the filtrate, using the method 
 described on page 181. Convert dextrose to starch by the 
 factor 0.9. 
 
 Note. — The washing to remove soluble carbohydrates is 
 performed with dilute alcohol rather than with water because 
 the former is less likely to carry starch granules through the 
 paper. The sugar solution when added to the Fehling's solution 
 should be clear and only faintly acid. It should in general 
 contain not more than 0.5 per cent, of reducing sugar. 
 
 Determination with Diastase. — Directions. — Treat 2 to 5 
 grams of the sample with ether and dilute alcohol, as in the 
 previous method, and wash the residue into a 250-c.c. flask 
 with 50 c.c. of water. Heat slowly to boiling, or immerse the 
 flask in boiling water, until the starch gelatinizes, stirring 
 constantly to prevent the formation of lumps. Cool to 55 ° C, 
 add 20-40 c.c. of malt extract, and keep the solution within 
 two degrees of the stated temperature for an hour or until the 
 solution no longer gives the starch reaction with iodine under 
 the microscope. In either case heat the solution again to 
 boiling to gelatinize any remaining starch granules, test again 
 and if starch is found, cool to 55 C, and treat as before, using 
 a fresh portion of malt extract. Continue this treatment until, 
 when carefully examined under the microscope, a drop of the 
 solution fails to give the iodine reaction for starch. Cool, 
 make up to 250 c.c. and filter through a dry filter. Transfer 
 200 c.c. of the filtrate to a 500-c.c. graduated flask, add 20 c.c. 
 of hydrochloric acid, sp. gr. 1.125, and carry out the determina- 
 tion as described in the preceding method. 
 
 A blank determination must be carried through, using 50 
 c.c. of water and exactly the same amount of malt extract as 
 
food: analytical methods: cereals. 213 
 
 vised in the regular procedure, in order to correct for the cupric 
 reducing power of the malt extract. 
 
 Malt Extract. — Treat 40 grams of fresh coarsely ground malt 
 several hours with 200 c.c. of water, shaking occasionally. 
 Filter and add a few drops of chloroform to prevent the growth 
 of molds. 
 
 Notes. — The action of the diastase on the gelatinized starch 
 is to convert it into maltose and dextrin, that is, into soluble 
 bodies that can be separated by filtration from the pentosans 
 and other carbohydrates that give the high results in the direct 
 acid method. By the action of acid (hydrolysis) the maltose 
 and dextrin are converted to dextrose. 
 
 The determination should, if possible, be carried through 
 without interruption. In case this cannot be done salicylic 
 acid may be used to prevent fermentation, not adding it, how- 
 ever, until after the digestion with diastase. 
 
 If the malt itself is not readily procurable, certain forms 
 of prepared diastase are on the market and may be found more 
 convenient either for analytical use or for purposes of illustra- 
 tion. When possible, however, it is preferable to use the freshly 
 prepared malt extract, as the prepared diastase, made at 
 different times and from separate portions of malt, may show 
 great differences in hydrolytic power. 
 
 It is sometimes convenient to use freshly collected saliva, 
 this being free from carbohydrate. In this case the digestion 
 should be carried out at 38 C. instead of 55 C. 
 
 Pentosans. — These are determined usually directly upon 
 the original material. The methods in general use depend 
 upon the conversion of the pentose substance into furfural 
 by distillation with strong acid and the subsequent precipi- 
 tation and estimation of the furfural. The latter may be done 
 by treatment with phenylhydrazine acetate and formation of 
 the furfural hydrazone, or by the formation of an insoluble 
 
214 AIR, WATER, AND FOOD. 
 
 condensation product with phloroglucin according to the method 
 of Councler. 
 
 For the details of these methods reference may be made 
 to Wiley, " Principles and Practice of Agricultural Analysis," 
 Vol. Ill, p. 178 et seq., also an article by Sherman.* The 
 phloroglucin method is given as a provisional method in BulL 
 107 of the Bureau of Chemistry. 
 
 Crude Fibre. — The Weende method, the method adopted 
 by the Association of Official Agricultural Chemists, is based 
 on the assumption that the starch and other digestible carbo- 
 hydrates and proteid will be removed from the cereal by succes- 
 sive digestion at a boiling temperature with acid and alkali of 
 a definite strength. The complex body thus obtained is not a 
 definite chemical compound, but may be considered as being 
 composed largely of cellulose. 
 
 Use 2 grams of .the finely ground sample and wash on a 
 niter with 5 portions of 10 ex. each of ether. (The residue 
 from the determination of " ether extract " can be used if 
 desired.) 
 
 Transfer the washed material to a 500-c.c. Erlenmeyer flask, 
 add 200 c.c. of boiling 1.25 per cent, sulphuric acid, place a 
 funnel in the neck of the flask and boil gently for 30 minutes. 
 Filter on a ribbed filter and wash with several portions of boiling 
 water. Transfer the precipitate by means of 200 c.c. of boiling 
 1.25 per cent, sodium hydroxide in a small wash-bottle to the 
 same 500-c.c. Erlenmeyer flask, and boil again gently for 30 
 minutes. 
 
 Filter on ignited asbestos in a Gooch crucible, wash with 
 boiling water until free from alkali, then with 10 c.c. of alcohol, 
 and finally with 10 c.c. of ether. Dry at the temperature of 
 boiling water to constant weight. Ignite carefully at first, 
 
 * /. Am. Chem. Soc, 19 {1897), 291. 
 
food: analytical methods: cereals. 215 
 
 then at a low red heac until the organic matter is destroyed. 
 Calculate the loss on ignition as " crude fibre." 
 
 Note. — The filtration will be found to proceed fairly rapidly 
 if the solution is filtered hot and care is taken to keep the 
 residue from the filter as long as possible. 
 
 The sulphuric acid and sodium hydroxide should be carefully 
 prepared and the strength determined by titration. 
 
 EXAMINATION OF FERMENTED LIQUORS. 
 WINE. 
 
 General Statements. — The object of a wine analysis is 
 ordinarily to determine whether or not a wine is pure and 
 unadulterated, or whether it has been properlv made. 
 Special works furnish sufficient information concerning pro- 
 cesses of manufacture, and it is essential to know here onlv 
 the general composition of the grape-juice or "must" and 
 how, by the natural process of fermentation, this may be 
 altered in the finished product. 
 
 The "must " contains sugars (mainly dextrose) ; dextrin; 
 organic acids and salts, mainly tartaric and malic acids; 
 salts of inorganic acids, chiefly phosphates, sulphates, and 
 chlorides. Various extractive matters, which largely affect 
 the color and flavor of the wine, together with a little tannin 
 and albuminous substances, are also present. The wine will 
 contain then, besides water, the following : Alcohol, glycerine, 
 frequently some sugar that has escaped fermentation, ethers, 
 which determine largely the "bouquet" of the wine, and 
 more or less of the acids, salts, coloring and extractive mat- 
 ters of the must, together with varying amounts of carbonic, 
 acetic, and succinic acids. 
 
 According to differences in their composition wines may 
 be divided into various classes, such as " dry " w T ines, which 
 
2l6 AIR, WATER, AND FOOD. 
 
 contain very little sugar, as distinguished from the sweet 
 wines, in which a notable quantity of sugar has escaped 
 fermentation, or to which an addition of sugar has been 
 made subsequent to the main fermentation. Or they may 
 be divided according to the content of alcohol into natural 
 wines and those fortified by addition of alcohol, as port, 
 sherry, and madeira. 
 
 The composition of the wine may be changed, moreover, 
 by the various methods which are used for its "improve- 
 ment," such as fortification already mentioned, plastering, 
 petiotization, etc. Information regarding these methods 
 will be found in some of the larger works mentioned in the 
 bibliography. 
 
 The determinations of most value in judging the purity 
 of wine are alcohol, glycerine, extract, ash, total and volatile 
 acids. The actual percentages of these substances are not of 
 so great value as certain relations between them, such as 
 the ratio of ash to extract, extract to alcohol, alcohol to 
 glycerine, alcohol to acids, and volatile to total acids. 
 Examination for preservatives and foreign coloring matters 
 should also be made. It should be remembered, however, 
 in judging the quality of American wines that the standards 
 of European practice are not entirely applicable and that 
 further study will be necessary before even tentative stand- 
 ards can be fixed. 
 
 Specific Gravity. — This is to be taken by means of the 
 Westphal balance or Sprengel tube at i5°.5 C. 
 
 Notes. — Where the specific gravity of the sample is known, 
 the various portions taken for analysis can be more conven- 
 iently measured than weighed. The results can be calculated 
 to per cent, by weight by dividing the results expressed as 
 grams per ioo ex. by the specific gravity. 
 
 Effervescing wines should, before analysis, be vigorously 
 
food: analytical methods: fermented liquors. 217 
 
 shaken in a large flask to hasten the escape of carbon dioxide. 
 The liquid may then be poured from under the foam into 
 another vessel. 
 
 Alcohol. — Principle. — The alcohol is obtained freed from 
 everything but water, and its amount determined by ascertain- 
 ing the specific gravity of the mixture, and taking the per cent, 
 from the tables. 
 
 Directions. — Measure (or weigh) 100 ex. of the wine into 
 a 500-c.c. round-bottomed flask. Add 50 c.c. of water, neutralize 
 
 N 
 free acid with — sodium hydroxide, and add 0.5 gram of tannic 
 
 acid, if necessary, to prevent foaming. Distil off about 95 to 
 98 c.c. into a ioo-c.c. graduated flask. Fill up to the mark 
 with distilled water, mix thoroughly, and take the specific 
 gravity of the distillate at 15 °. 5 C. with a pyknometer. The 
 percentage of absolute alcohol by volume corresponding to 
 the observed density will be found in Table X, page 244. 
 
 To find the alcohol by weight in the sample, multiply the 
 per cent, of alcohol in the distillate as taken from the table, by 
 the weight of the distillate and divide the result by the weight 
 of the sample used. 
 
 Notes. — The object of neutralizing the wine with sodium 
 hydroxide is to prevent the distillation of volatile acids, prin- 
 cipally acetic. A certain amount of volatile ethers may also 
 pass over into the distillate, but in most cases it is so slight 
 that its influence may be neglected. 
 
 Normal wines ordinarily contain between 4.5 and 12 per 
 cent, of alcohol except in the case of " fortified " wines, where 
 the amount may be even 20 per cent. Fermentation does 
 not yield more than about 14 per cent, of alcohol. 
 
 Extract. — The method to be employed depends on the 
 proportion of extract. A preliminary calculation should be 
 made by the aid of the formula 
 
 x = i+d— &'\ 
 
2.1 8 AIR, WATER, AND FOOD. 
 
 where x is the specific gravity of the dealcoholized wine, d 
 the specific gravity of the wine, and d' the specific gravity 
 of the distillate obtained in the determination of alcohol. The 
 value for x is found from Table XI, page 247. 
 
 Dry Wines. — (Having an extract content of less than 
 3 per cent.) Evaporate 50 c.c. on the water-bath to a 
 sirupy consistency in a flat-bottomed platinum dish. Heat 
 the residue in the oven at ioo° C. for two hours and a half, 
 cool in a desiccator and weigh. 
 
 Sweet Wines. — When the extract content is between 3 
 and 6 per cent, treat 25 c.c. of the sample as described under 
 dry wines. When the amount of extract exceeds 6 per cent, 
 it is best to accept the result found from the table and not 
 to determine it gravimetrically. 
 
 Notes. — The gravimetric determination will be inac- 
 curate with wines high in extract on account of the serious 
 error caused by drying levulose at high temperatures. The 
 figures in the table are based on determinations made at 
 75 C. in vacuo. 
 
 Wine made from the juice of ripe grapes rarely contains 
 less than 1.5 per cent, of extract in the case of white wines 
 and about 2.0 per cent, in the case of red wines. The 
 amount of extract decreases of course with age. 
 
 Alcohol-extract Ratio. — The municipal laboratory of 
 Paris considers a wine "fortified" if the alcohol exceeds 4.5 
 times the extract for red wines and 6. 5 for white wines. The 
 amount of added alcohol is calculated by the municipal 
 laboratory by subtracting the "natural" alcohol (extract 
 X4.5 or 6.5) from the total alcohol. 
 
 Ash. — Ignite the residue from the extract determination 
 as described on page 206. 
 
 Note. — The amount of ash in a natural wine averages 
 about 10 per cent, of the extract, varying ordinarily be- 
 tween 0.14 per cent, and 0.35 per cent. 
 
food: analytical methods: fermented liquors. 219 
 
 Glycerine. — Evaporate 100 c.c. of wine in a porcelain 
 dish on the water-bath to a volume of about 10 c.c, and 
 treat the residue with about 5 grams of fine sand and with 
 from 1.5 to 2 c.c. of milk of lime (containing 40 grams 
 Ca(OH) 2 per 100 c.c.) for each gram of extract present, and 
 evaporate almost to dryness. [With wines whose extract 
 exceeds 5 grams per 100 c.c, heat the portion to be used in 
 the determination of glycerine to boiling in a flask, and 
 treat with successive small portions of milk of lime until 
 it becomes, first, darker, and then light in color. When 
 cool, add 200 c.c. of 96 per cent, alcohol (sp. gr. 0.81 18), 
 allow the precipitate to subside, filter, and wash with 96 
 per cent, alcohol (sp. gr. 0.81 18). Evaporate the filtrate 
 to about 10 c.c, add about 5 grams of sand and from 1.5 
 to 2 c.c of milk of lime, and proceed as before.] Treat 
 the moist residue with 5 c.c of alcohol (96 per cent, by vol- 
 ume), remove the substance adhering to the sides of the 
 dish with a spatula, and rub the whole mass to a paste, with 
 the addition of a little more alcohol. Heat the mixture on 
 the water-bath, with constant stirring, to incipient boiling, 
 and decant the liquid into a flask graduated at 100 and no 
 c.c. Wash the residue repeatedly by decantation with 
 10 c.c. portions of hot 96 per cent, alcohol. Cool the con- 
 tents of the flask to 15 , dilute to the no-c.c mark with 
 96 per cent, alcohol, and filter through a folded filter. 
 Evaporate 100 c.c. of the filtrate to a sirupy consistency 
 in a porcelain dish, on a hot, but not boiling, water-bath,, 
 transfer the residue to a small glass-stoppered graduated 
 cylinder with 20 c.c of absolute alcohol, and add three 
 portions of 20 c.c each of absolute ether, with thorough 
 shaking after each addition. Let stand until clear, then 
 pour off through a filter, and wash the cylinder three times 
 or more with a mixture of one part absolute alcohol to one 
 
220 AIR, WATER. AND FOOD. 
 
 and one-half parts of absolute ether, pouring the wash- 
 liquor also through the filter. Evaporate the filtrate to a 
 sirupy consistency, dry for one hour at the temperature of 
 boiling water, weigh, ignite, and weigh again. The loss in 
 ignition increased by one-tenth gives the glycerine. 
 
 Notes. — The ratio of glycerine to alcohol is of great 
 importance in judging the purity of a wine. According to 
 European standards in pure wines the glycerine-alcohol 
 ratio varies from between 6 and 14 parts by weight of the 
 former to 100 of the latter. The little work done on 
 American wines indicates a lower ratio. 
 
 Free Acids : Total Acidity Calculated as Tartaric 
 
 N 
 Acid. — Titrate 10 c.c. of the wine with — sodium hydroxide. 
 
 The end-point is reached when a drop of the liquid placed 
 
 upon faintly-red litmus paper produces a blue spot in the 
 
 middle of the portion moistened. Calculate the results as 
 
 N 
 tartaric acid. One c.c. — sodium hydroxide =0.0075 gram 
 
 of tartaric acid. 
 
 Volatile Acids Calculated as Acetic Acid. — Measure 
 50 c.c. of wine into a 3 00 -c.c. flask provided with a cork 
 having two perforations. One is fitted with a tube 6 mm. in 
 diameter and blown out to a bulb 40 mm. in diameter a short 
 distance above the cork; this tube is connected with a con- 
 denser. The other perforation carries a tube reaching nearly 
 to the bottom of the flask and drawn out to a small aperture 
 at its lower end; this is connected with a 500-c.c. flask con- 
 taining water. Heat both flasks to boiling ; then lower the 
 flame under that containing the wine, adjusting the flame so 
 that the volume of liquid remains constant, and continue the 
 distillation by means of steam until 200 c.c. have gone over. 
 
food: analytical methods: fermented liquors. 221 
 
 N 
 Titrate the distillate with — sodium hydroxide, using phe- 
 
 nolphthalein as an indicator. Calculate the results as 
 
 N 
 acetic acid. One c.c. — sodium hydroxide =0.0060 eram 
 
 10 
 
 of acetic acid. 
 
 Fixed Acids Calculated as Tartaric Acid. — These 
 may be found by calculating the volatile acids as tartaric and 
 subtracting the result from the total tartaric acid found by 
 direct titration. 
 
 Note. — The total acids in a wine vary usually between 
 0.45 per cent, and 1.5 per cent. The acid content is fre- 
 quently diminished by aging or by the separation of cream of 
 tartar. The volatile acid should, in general, not be over 
 0.12 to 0.16 per cent., depending upon the age of the wine. 
 A wine properly made should not have the volatile acid, 
 estimated as acetic, exceed one-fourth of the total free acid, 
 calculated as tartaric. 
 
 Coloring Matters: Detection of Coal-tar Dyes. — Double 
 Dyeing Method of Sostegni and Carpentieri* — Fifty c.c. of the 
 sample are diluted to 100 c.c. with water, filtered if necessary, 
 acidified with from 2 to 4 c.c. of 10 per cent, solution of hydro- 
 chloric acid, and a piece of woolen cloth which has been washed 
 in a very dilute solution of boiling potassium hydroxide, and 
 then washed in water, immersed in it and boiled for five to ten 
 minutes. The cloth is removed, thoroughly washed in water, 
 and boiled with very dilute hydrochloric acid solution. Then 
 after washing out the acid the color is dissolved in a solution 
 of ammonium hydroxide (1 to 50). With some of the dyes 
 solution takes place quite readily, while with others it is neces- 
 sary to boil some time. The wool is taken out, a slight excess 
 of hydrochloric acid is added to the solution, another piece 
 
 * Ztschr. anal. Chem., 35 (1896), 397. 
 
22 2 AIR, WATER, AND FOOD. 
 
 of wool is immersed and again boiled. With vegetable coloring 
 matter this second dyeing gives practically no color, and there 
 is no danger of mistaking a fruit color for one of coal-tar origin. 
 
 Notes. — It is absolutely necessary that the second dyeing 
 should be made, as some of the coal-tar dyes will dye a dirty 
 orange in the first acid bath which might be easily passed 
 for vegetable color but on treatment in alkaline bath and 
 second acid bath becomes a bright pink. 
 
 Another advantage in the second dyeing is that if a large 
 piece of woolen cloth is used in the first dyeing, and a small 
 piece in the second dyeing, small amounts of coloring matter 
 can be brought out much more decidedly in the second 
 dyeing, where practically all of the vegetable coloring matter 
 has been excluded. 
 
 Several colors which are not coal-tar dyes, notably archil, 
 archil derivatives, and sulphonated indigo, give reactions by 
 this method and are liable to be confused with coal-tar colors. 
 For hints as to the method for detecting these reference may 
 be made to Bulletin 107, Bureau of Chemistry, page 190. 
 
 Methods for the further separation and identification of 
 the artificial colors cannot be taken up here for lack of space. 
 The student is referred to Leach: "Food Inspection and 
 Analysis," p. 628 et seq.\ Mulliken: " The Identification of 
 Commercial Dyestuffs;" and a paper by Green, Yeoman, 
 and Jones on " The Identification of Dyestuffs on A nimal Fibres."* 
 
 Preservatives. — The preservatives most commonly em- 
 ployed in wines are salicylic and benzoic acids. Sulphurous 
 acid and sulphites are also used. For methods of detecting 
 other substances less commonly employed, such as abrastol, 
 beta-naphthol, etc., reference may be made to Bulletin 107 of 
 the Bureau of Chemistry. Boric acid is occasionally used, 
 
 * /. Soc. Dyers and Colourists, 1905, 236-243. 
 
food: analytical methods: fermented liquors. 223 
 
 but since a small amount of it is normally present in wines, 
 tests, to be of value, should be quantitative. 
 
 Salicylic Acid. — Acidify about 50 c.c. of the wine with 
 5 c.c. of dilute (1:3) sulphuric acid and extract in a separatory 
 funnel with 25 c.c. of ether. Draw off the lower layer, wash 
 the ether twice with water, using 10 c.c. each time and finally 
 evaporate the ether in a porcelain dish at room temperature. 
 To the residue in the dish add 2 to 3 drops of ferric alum solu- 
 tion (p. 261). or very dilute ferric chloride. A deep purple 
 or violet color indicates salicylic acid. 
 
 Notes. — Not more than 50 c.c. should be used for the test, 
 since a trace of salicylic acid seems normally present in some 
 wines. 
 
 The washing with water is to free the ether from traces of 
 sulphuric acid which interferes w r ith the development of the 
 violet color. 
 
 Benzoic Acid* — Acidify about 100 c.c. of wine with sul- 
 phuric acid, extract with ether, and evaporate the ethereal 
 solution as in the detection of salicylic acid. Treat the resi- 
 due with 2 or 3 c.c. of strong sulphuric acid. Heat till 
 white fumes appear; organic matter is charred and benzoic 
 acid is converted into sulpho-benzoic acid. A few crystals 
 of ammonium nitrate are then added. This causes the for- 
 mation of metadinitrobenzoic acid. When cool the acid is 
 diluted with water and ammonia added in excess, followed 
 by a drop or two of ammonium sulphide. The nitro-compound 
 becomes converted into ammonium metadiamidobenzoic acid, 
 which possesses a red color. This reaction takes place imme- 
 diately, and is seen at the surface of the liquid without stirring. 
 
 Sulphurous Acid and Sulphites.- — See directions under Beer, 
 page 225. 
 
 * Mohler: Bull. Soc. Chim. [3], 3, {1896) 414. 
 
224 AIR J WATER, AND FOOD. 
 
 BEER AND OTHER MALT LIQUORS. 
 
 Before analysis the sample must be thoroughly shaken in 
 a large flask, in order to remove carbon dioxide. 
 
 Specific Gravity. — Taken with a pyknometer or Sprengel 
 tube at I5°.5 C. 
 
 Alcohol. — Determined as in the analysis of wine. It will 
 not be necessary to neutralize the free acid before distilling. 
 
 Extract. — Determine the extract content corresponding 
 to the specific gravity of the dealcoholized beer according to 
 Table For this purpose employ the formula 
 
 in which Sp is the specific gravity of the dealcoholized beer, 
 g the specific gravity of the beer, and g f the specific gravity 
 of the distillate obtained in the determination of alcohol. 
 Instead of using this formula the residue from the distillation of 
 alcohol is sometimes diluted to the original volume, and its 
 specific gravity taken. This is often impracticable owing to 
 the necessity of employing tannic acid to prevent foaming 
 in the distilling flask, and owing to the coagulation of 
 proteids during the distillation. 
 
 Note. — The extract of beer cannot be accurately deter- 
 mined by evaporation and drying at the boiling-point of 
 water because of the dehydration of the maltose. 
 
 Ash. — Evaporate 25 c.c. to diyness and determine as in 
 the analysis of wine. 
 
 Free Acids. — Heat 20 c.c. to incipient boiling to expel 
 
 carbon dioxide and titrate as in the analysis of wine. Fixed 
 
 acids, consisting principally of lactic and succinic, are calcu- 
 
 N 
 lated as lactic acid. One c.c. of — sodium hydroxide =0.0090 
 
 gram of lactic acid. 
 
food: analytical methods: fermented liquors. 225, 
 
 Reducing Sugar. — Dilute 25 c.c. of the beer, freed from 
 carbon dioxide, to 100 c.c. Determine the reducing sugar in 
 25 c.c. of this solution as directed on page 181, enough water 
 being added to make the total volume of the Fehling's solution- 
 sugar mixture 100 c.c. Express the results in terms of maltose, 
 as given in Table XII. 
 
 Preservatives. — The preservatives most commonly em- 
 ployed in beer are benzoic and salicylic acids and their sodium 
 salts, sulphites and fluorides. 
 
 Benzoic and Salicylic Acids. — Detected as described under 
 Wine. 
 
 Sulphites. — Qualitative Test. — Use an apparatus similar to 
 that described for the determination of volatile acids in wine. To 
 50 c.c. of the sample add about a gram of sodium bicarbonate, 
 20 c.c. of 20 per cent, phosphoric acid, and immediately con- 
 nect the flask with the condenser. Pass steam through the 
 flask until about 20 c.c. have collected in the distillate. To 
 the distillate add bromine water in slight excess and boil. 
 Expel the excess of bromine and test for sulphuric acid with 
 hydrochloric acid and barium chloride in the usual manner. 
 
 Notes. — The method described does not distinguish between 
 free sulphurous acid and that present in the form of sulphites. 
 The former can be distilled without the addition of phosphoric 
 acid. 
 
 The presence of sulphites in a sample should not be con- 
 sidered evidence of added preservatives unless an excessive 
 amount is found since the use of sulphured malt or hops may 
 introduce a small amount. To obtain conclusive data a quan- 
 titative determination of the amount present should be made. 
 This can be done by a method very similar to that used for 
 the detection, taking greater precautions against oxidation 
 and absorbing the sulphurous acid in standard iodine solution. 
 Care should be taken also to avoid the distillation of iodine- 
 
2 26 AIR, WATER, AND FOOD. 
 
 reducing substances other than sulphurous acid. For a detailed 
 discussion of the determination reference may be made to 
 the following papers: Bureau of Chemistry, Bull. 107, p. 187; 
 Gudeman: /. Ind. Eng. Chem., 1909, p. 81; Woodman and 
 Gadsby: /. Ind. Eng. Chem., 1909. 
 
 Fluorides. — The well-known qualitative test for fluorides by 
 etching a glass plate may be modified by the use of a suitable 
 condenser and made sufficiently delicate to be used here. It 
 is possible also by suitable regulation of the temperature to 
 make the test approximately quantitative.* 
 
 FLAVORING EXTRACTS. 
 
 The work on alcoholic liquids can be pleasantly varied by 
 substituting for it in some cases the determination of alcohol 
 and other important components of the usual flavoring essences, 
 the most important of which are vanilla and lemon. Several 
 important types of food methods, such as the determination 
 of essential oils and quantitative extraction with volatile 
 solvents, are also brought to the attention of the student. 
 
 VANILLA. 
 
 Vanilla extract is a dilute alcoholic tincture of the vanilla 
 bean, the fruit of a climbing plant of the orchid family. The 
 best grades are made by allowing the cut and bruised beans to 
 macerate in the alcohol for several months, the liquid thus 
 obtained being deep brown in color, with a delightful perfume 
 and flavor. Sugar is added to assist in the extraction and to 
 sweeten the product. 
 
 The cost of a quart of the pure extract, according to Winton,f 
 
 * Woodman and Talbot: J. Am. Chem. Soc, 1906, 1437; 1907, 1362. 
 t Conn. Agr. Exp. Sta. Report, 1901, 150. 
 
food: analytical methods: flavoring extracts. 227 
 
 is from about 60 cents to S2.50, depending chiefly upon the 
 grade of beans used. 
 
 The composition of five pure vanilla extracts, made from 
 beans of different grades, is given in the following table, * the 
 results being expressed in per cent, by weight: 
 
 Grade of Bean. 
 
 Specific 
 Gravity. 
 
 Vanillin. , Alcohol. 
 
 Total 
 Residue. 
 
 Cane- 
 sugar. 
 
 Mexican (whole) 
 
 Mexican (cut) 
 
 South American (whole) 
 
 Bourbon (whole) 
 
 Tahiti (whole) 
 
 1. 0159 
 1. 0146 
 1 .0109 
 1 .0166 
 1. 0104 
 
 0.125 
 0.065 
 0.215 
 0.138 
 0.108 
 
 37-96 
 39-92 
 38-58 
 38.32 
 38-84 
 
 22.60 
 23.10 
 22.00 
 23-13 
 
 75 
 
 21 
 
 19.90 
 19.20 
 19.00 
 20.40 
 20.00 
 
 The adulteration of vanilla extract consists principally in 
 the use of extract of Tonka bean, a cheap substitute somewhat 
 resembling vanilla in its flavor, in the use of artificial prepara- 
 tions of the active principles of vanilla and tonka, vanillin and 
 coumarin, and in the addition of artificial color, usually cara- 
 mel. A cheap extract may be entirely an artificial mixture, 
 made of artificial vanillin or coumarin, or both, in weak alcohol, 
 colored with caramel. An occasional adulteration is the use 
 of alkali, such as potassium bicarbonate, to hold the resin in 
 solution and permit the use of a more dilute alcohol. 
 
 Analytical Methods. — Alcohol. — Measure 25 c.c. of the 
 sample, add 100 c.c. of water, and determine the alcohol by 
 volume, as directed on page 217, omitting the use of sodium 
 hydroxide or tannic acid. 
 
 Vanillin and Coumarin. — (Method of Hess and Prescott, 
 modified by Winton and Bailey. f) Weigh 25 grams into a 
 200-C.C beaker with marks showing volumes of 25 and 50 c.c. 
 Dilute to the 50-c.c. mark and evaporate in a water-bath to 
 
 * Conn. Agr. Exp. Sta. Report, 1901, 150. 
 
 f J. Am. Chem. Soc, 1905, 719; Bur. o/Chem., Bull. 107, 156. 
 
2 28 AIR, WATER, AND FOOD. 
 
 25 c.c. at a temperature in the bath of not more than yo° C. 
 Dilute a second time to 50 c.c. and evaporate to 25 c.c. Add 
 neutral lead acetate solution drop by drop until no more pre- 
 cipitate forms. Stir with a glass rod to facilitate flocculation 
 of the precipitate, filter through a moistened filter, and wash 
 three times with hot water, taking care that the total filtrate 
 does not measure more than 50 c.c. Cool the filtrate and shake 
 with 20 c.c. of ether in a separatory funnel. Remove the ether 
 to another separatory funnel and repeat the shaking of the 
 aqueous liquid with ether three times, using 15 c.c. each time. 
 Shake the combined ether solutions four or five times with 2 
 per cent, ammonium hydroxide, using 10 c.c. for the first 
 shaking and 5 c.c. for each subsequent shaking. Set aside the 
 combined ammoniacal solutions for the determination of 
 vanillin. 
 
 Wash the ether solution into a weighed dish and allow the 
 ether to evaporate at the room temperature. Dry in a desic- 
 cator, and weigh. Stir the residue for fifteen minutes with 
 15 c.c. of petroleum ether (boiling-point 30 to 40 C.) and 
 decant the clear liquid into a beaker. Repeat the extraction 
 with petroleum ether two or three times. Allow the residue 
 to stand in the air until apparently dry, completing the drying 
 in a desiccator. Weigh, and deduct the weight from the weight 
 of the residue obtained after the ether evaporation, thus obtain- 
 ing the weight of the coumarin. 
 
 Allow the petroleum ether extract to evaporate at room 
 
 temperature. If it is coumarin it may be recognized by the 
 
 characteristic odor, resembling that of "sweet grass," and by 
 
 Leach's test * as follows: Dissolve the residue in a few drops of 
 
 N 
 hot water, and add one or two drops of — iodine in potassium 
 
 * Leach: "Food Inspection and Analysis," 738. 
 
food: analytical methods: flavoring extracts. 229 
 
 iodide. On stirring with a rod, a brown precipitate will form, 
 which will gather into dark green flocks. The reaction is 
 especially marked if carried out in a white porcelain crucible 
 or dish. 
 
 Slightly acidulate the ammoniacal solution reserved for 
 vanillin with 10 per cent, hydrochloric acid. Cool, and shake 
 out in a separatory funnel with four portions of ether, as 
 described for the first ether extraction. Evaporate the ether 
 at room temperature in a weighed dish, dry over sulphuric 
 acid, and weigh the vanillin. 
 
 If the residue is white it may be safely assumed in the 
 majority of cases that it is pure vanillin. If dark colored, 
 however, it should be purified as in the case of conmarin, and 
 the percentage calculated from the loss in weight. 
 
 Notes. — The separation of vanillin and coumarin is based 
 on the differences in their chemical constitution. Vanillin is 
 hydroxymethoxy benzoic aldehyde, while coumarin is the anhy- 
 dride of orthohydroxycinnamic acid. On account of the 
 aldehydic nature of the vanillin the separation by dilute ammo- 
 nia is possible, the aldehyde ammonia compound of vanillin 
 being readily soluble in water, while the coumarin remains 
 wholly in the ether. 
 
 Acetanilid has been reported in vanillin extracts, being 
 present as an adulterant of the artificial vanillin employed, 
 but its use is rare. If present, it will be found in the residue 
 from the petroleum ether extraction and can be recognized by 
 its melting-point, 11 2° C, and appropriate tests. 
 
 Resins. — Evaporate 25 or 50 c.c. of the extract to one-third 
 its volume on the water-bath in order to remove the alcohol. 
 Make up to the original volume with hot water. If no alkali 
 has been used in the manufacture of the extract, the resin 
 should appear at this point as a flocculent brown residue. Add 
 acetic acid in slight excess, allow the evaporating-dish to stand 
 
230 AIR, WATER, AND FOOD. 
 
 in a warm place for a time to separate the resin completely, 
 and filter. Wash the residue on the filter, and save both the 
 filtrate and residue. Test the resin by placing pieces of the 
 filter, with the resin attached, in a few cubic centimeters of dilute 
 caustic potash. The resin is dissolved with a deep red color, 
 and on acidifying is again precipitated. Test the filtrate by 
 adding to it a few drops of basic lead acetate. A bulky pre- 
 cipitate is formed, on account of the organic acid, gums, etc., 
 present. 
 
 Confirm the resin test by shaking 5 c.c. portions of the 
 extract in separate test-tubes with 10 c.c. of amyl alcohol and 
 10 c.c. of ether. With pure extracts the upper layers will be 
 colored, varying from light yellow to deep brown; with artificial 
 extracts, free from resin, the amyl alcohol and ether layers will 
 be uncolored. 
 
 Note. — While the artificial vanillin, as sold on the market 
 and used in the manufacture of low-grade extracts, is identical 
 with the vanillin of the vanilla bean, it is true that pure extracts 
 owe their value and flavor to other ingredients as well as to the 
 vanillin present. Among these " extractive matters" the resins 
 are important from an analytical standpoint, serving by their 
 presence or absence to determine whether true vanilla is present 
 or the extract entirely artificial. As a quick and ready test, 
 serving to distinguish artificial extracts from genuine prepara- 
 tions of the vanilla bean, the amyl alcohol and ether tests will 
 be found especially useful. 
 
 Color: Caramel. — Caramel is the color commonly used in 
 vanilla extracts, although coal-tar dyes have been found. The 
 presence of dyes is sometimes indicated by the color of the 
 amyl alcohol in testing for the resin, they being in many cases 
 soluble in amyl alcohol, but insoluble in ether. The two tests 
 for caramel which in the author's experience have proven most 
 satisfactory are the lead acetate test and the paraldehyde test. 
 
food: analytical methods: flavoring extracts. 231 
 
 Lead Acetate Test. — The coloring matter present in vanilla 
 extracts is almost completely removed when the dealcoholized 
 extract is treated with a few cubic centimeters of basic lead 
 acetate solution. When caramel is present, the filtrate and 
 precipitate, if any, have the characteristic red-brown color of 
 caramel. 
 
 Paraldehyde Test. — To 15 c.c. of the extract add 2 c.c. of 
 zinc chloride (5 per cent, solution), and 2 c.c. of caustic potash 
 (2 per cent, solution). Filter, wash the precipitate with hot 
 water, and dissolve it in 15 c.c. of acetic acid (10 per cent, 
 solution). Concentrate on the water-bath to one-half or one- 
 third its volume, neutralize the excess of acid, and transfer the 
 clear solution to a rather large test-tube. Add three volumes 
 of paraldehyde and just enough alcohol to make the mixture 
 homogeneous. If caramel is present a brown flocculent pre- 
 cipitate will form on standing over night. 
 
 Note. — The treatment with zinc hydroxide is to separate 
 the caramel from sugar, which is present in many extracts, 
 and interferes with the paraldehyde test.* The precipitate 
 obtained with paraldehyde is probably caramel and not the 
 product of a chemical reaction. 
 
 LEMON. 
 
 Lemon extract is usually made by dissolving oil of lemon, 
 obtained by expression or distillation from the rind of the 
 lemon, in strong alcohol. The product is sometimes colored 
 with the color of lemon peel. The Federal standards f require 
 a content of lemon oil of at least 5 per cent, by volume. The 
 expensive ingredient of the extract is the alcohol, since alcohol 
 of at least 80 per cent, strength by volume must be used to 
 dissolve 5 per cent, of lemon oil; hence in making cheap extracts 
 
 * Woodman and Newhall: Tech. Quart., 21, 280. 
 
 \ U. S. Dept. Agric, Office of the Secretary, Circ. iq. 
 
232 AIR, WATER, AND FOOD. 
 
 the manufacturer endeavors to use a dilute alcohol, even under 
 the necessity of omitting a portion or all of the oil of lemon. 
 
 The common forms of adulteration of lemon extract are the 
 use of weak alcohol and consequent deficiency of lemon oil, 
 as already noted; the substitution for the lemon oil of small 
 amounts of stronger oils, as oil of citronella, oil of lemon-grass, 
 and the like; the use of citral, the odorous principle of lemon 
 oil, used for making the so-called "terpeneless lemon extracts;" 
 and the coloring of the extracts by coal-tar colors or turmeric. 
 
 Preliminary Test. — To a little of the extract in a test-tube 
 add seven or eight times its volume of water. A high-grade 
 extract will show a heavy cloud, due to the precipitation of the 
 lemon oil. If no cloudiness or turbidity appears it may be 
 safely inferred that no oil is present. 
 
 Alcohol. — The determination of alcohol is somewhat com- 
 plicated in this case by the presence of the volatile oil of lemon 
 which must be removed before distilling. 
 
 Dilute 20 c.c. of the extract to 100 ex. with water, and 
 pour the mixture into a dry Erlenmeyer flask containing 5 grams 
 of light magnesium carbonate. Shake thoroughly and filter 
 through a dry filter. Measure 50 c.c. of the clear filtrate, add 
 about 15 c.c. of water, and distil 50 c.c, as directed on page 217. 
 From the specific gravity of the distillate determine the per cent, 
 of alcohol by volume, and this, multiplied by 5, will give the 
 percentage in the original extract. 
 
 Note. — The magnesia serves to absorb the precipitated 
 oil and prevent it from passing through the filter. 
 
 Lemon Oil. — Pipette 20 c.c. of the extract into a Babcock 
 milk bottle; add 1 c.c. dilute hydrochloric acid (1:1); then 
 add from 25 to 28 c.c. of water previously warmed to 6o° C; 
 mix and let stand in water at 6o° for five minutes; whirl in 
 centrifuge for five minutes; fill with warm water to bring the 
 oil into the graduated neck of the flask; repeat whirling for 
 
food: analytical methods: flavoring extracts. 233 
 
 two minutes; stand the flask in water at 6o° C. for a few minutes 
 and read the per cent, of oil by volume. If the determination 
 is not made in duplicate the flask should be balanced by another 
 containing an equal weight of water. In case oil of lemon is 
 present in amounts over 2 per cent, add to the percentage of 
 oil found 0.4 per cent, to correct for the oil retained in solution. 
 If less than 2 per cent, and more than 1 per cent, is present, 
 add 0.3 per cent, for correction. 
 
 Refractive Index of the Oil. — With a narrow glass tube 
 remove a few drops of the oil obtained in the neck of the Babcock 
 flask in the previous determination and determine its index 
 of refraction at 25 °, using the Abbe refractometer. The read- 
 ing for pure lemon oil at 25 is 1 .4715-1 .4740. Most of the 
 adulterants give a higher refractive index; oil of turpentine 
 is distinctly lower. 
 
 Color. — Test for coal-tar colors by evaporating a portion of 
 the extract to dryness on the water-bath. Dissolve the residue 
 in water and carry out the double dyeing method, as described 
 on page 221. 
 
 To test for turmeric add to a portion of the sample three 
 drops of saturated boric acid solution, one small drop of dilute 
 (1:10) hydrochloric acid, and a piece of filter-paper so arranged 
 that it is only half immersed in the liquid. Evaporate to 
 dryness on the water-bath. In the presence of turmeric the 
 paper will be colored pink and the test may be confirmed as 
 described on page 188, Excess of hydrochloric acid should be 
 avoided, as in testing for boric acid. 
 
 Citral. — See /. Am. Chem. Soc. y 1906, 1472. 
 
APPENDICES. 
 
APPENDIX A. 
 
 Table I. 
 
 TENSION OF AQUEOUS VAPOR IN MILLIMETERS OF MERCURY FROM 
 0° TO 30°. 9 C, REDUCED TO 0° AND SEA-LEVEL. 
 
 
 o°.o. 
 
 o°.i. 
 
 O .2. 
 
 o°3- 
 
 o°. 4 . 
 
 o°. 5 . 
 
 o°.6. 
 
 o°. 7 . 
 
 o°.8. 
 
 o°. 9 . 
 
 o° 
 
 4-57 
 
 4.60 
 
 4.64 
 
 4.67 
 
 4- 70 
 
 4-74 
 
 4-77 
 
 4.80 
 
 4.84 
 
 4.87 
 
 I 
 
 4.91 
 
 4.94 
 
 4.98 
 
 5.02 
 
 5.05 
 
 5 -09 
 
 5-12 
 
 5.16 
 
 5-20 
 
 5.23 
 
 2 
 
 5.27 
 
 5.31 
 
 5-35 
 
 5-39 
 
 5-42 
 
 5-46 
 
 5.5o 
 
 5-54 
 
 5-58 
 
 5.62 
 
 3 
 
 5-66 
 
 5.70 
 
 5-74 
 
 5-78 
 
 5-82 
 
 5-86 
 
 5-90 
 
 5-94 
 
 5-99 
 
 6.03 
 
 4 
 
 6.07 
 
 6. 11 
 
 6.15 
 
 6.20 
 
 6.24 
 
 6.28 
 
 6-33 
 
 6-37 
 
 6.42 
 
 6.46 
 
 5 
 
 6.51 
 
 6-55 
 
 6.60 
 
 6.64 
 
 6.69 
 
 6-74 
 
 6.78 
 
 6.83 
 
 6.88 
 
 6.92 
 
 6 
 
 6.97 
 
 7.02 
 
 7.07 
 
 7.12 
 
 7.17 
 
 7.22 
 
 7.26 
 
 7-31 
 
 7.36 
 
 7.42 
 
 7 
 
 7-47 
 
 7-52 
 
 7-57 
 
 7.62 
 
 7-67 
 
 7-72 
 
 7.78 
 
 7.83 
 
 7.88 
 
 7-94 
 
 8 
 
 7-99 
 
 8.05 
 
 8.10 
 
 8.15 
 
 8.21 
 
 8.27 
 
 8.32 
 
 8.38 
 
 8-43 
 
 8-49 
 
 9 
 
 8.55 
 
 8.61 
 
 8.66 
 
 8.72 
 
 8.78 
 
 8.84 
 
 8.90 
 
 8.96 
 
 9.02 
 
 9.08 
 
 10 
 
 9.14 
 
 9.20 
 
 9.26 
 
 9-32 
 
 9-39 
 
 9-45 
 
 9-5i 
 
 9.58 
 
 9.64 
 
 9.70 
 
 11 
 
 9-77 
 
 9-33 
 
 9.90 
 
 9.96 
 
 10.03 
 
 10.09 
 
 10.16 
 
 10.23 
 
 10.30 
 
 10.36 
 
 12 
 
 10.43 
 
 10.50 
 
 io.57 
 
 10.64 
 
 10.71 
 
 10.78 
 
 10.85 
 
 10.92 
 
 10.99 
 
 11.06 
 
 13 
 
 11. 14 
 
 11. 21 
 
 11.28 
 
 11.36 
 
 H-43 
 
 11 .50 
 
 11.58 
 
 11.66 
 
 H-73 
 
 11. 81 
 
 14 
 
 11.88 
 
 11.96 
 
 12.04 
 
 12. 12 
 
 12.19 
 
 12.27 
 
 12-35 
 
 12.43 
 
 12.51 
 
 12.59 
 
 15 
 
 12.67 
 
 12.76 
 
 12.84 
 
 12.92 
 
 13.00 
 
 13.09 
 
 13.17 
 
 !3-25 
 
 13-34 
 
 13.42 
 
 16 
 
 I35I 
 
 13-60 
 
 13.68 
 
 13-77 
 
 13.86 
 
 13-95 
 
 14.04 
 
 14.12 
 
 14.21 
 
 14.30 
 
 17 
 
 14.40 
 
 14.49 
 
 14.58 
 
 14.67 
 
 14.76 
 
 14.86 
 
 14-95 
 
 15.04 
 
 15.14 
 
 1523 
 
 18 
 
 15-33 
 
 15-43 
 
 15-52 
 
 15-62 
 
 15.72 
 
 15.82 
 
 15-92 
 
 16.02 
 
 16.12 
 
 16.22 
 
 19 
 
 16.32 
 
 16.42 
 
 16.52 
 
 16.63 
 
 16.73 
 
 16.83 
 
 16.94 
 
 17.04 
 
 17.15 
 
 17.26 
 
 20 
 
 I7-36 
 
 17-47 
 
 17-58 
 
 17.69 
 
 17.80 
 
 17.91 
 
 18.02 
 
 18.13 
 
 18.24 
 
 18.35 
 
 21 
 
 18.47 
 
 18.58 
 
 18.69 
 
 18.81 
 
 18.92 
 
 19.04 
 
 19.16 
 
 19.27 
 
 19-39 
 
 19-51 
 
 22 
 
 19.63 
 
 19-75 
 
 19.87 
 
 19.99 
 
 20.11 
 
 20.24 
 
 20.36 
 
 20.48 
 
 20.61 
 
 20.73 
 
 23 
 
 20.86 
 
 20.98 
 
 21. 11 
 
 21 .24 
 
 21-37 
 
 21. 50 
 
 21.63 
 
 21.76 
 
 21.89 
 
 22.02 
 
 24 
 
 22.15 
 
 22.29 
 
 22.42 
 
 22.55 
 
 22.69 
 
 22.83 
 
 22.96 
 
 23. 10 
 
 23-24 
 
 23.38 
 
 25 
 
 23.52 
 
 23.66 
 
 23.80 
 
 23-94 
 
 24.08 
 
 24.23 
 
 24-37 
 
 24.52 
 
 24.66 
 
 24.81 
 
 26 
 
 24.96 
 
 25-10 
 
 25.25 
 
 25.40 
 
 25-55 
 
 25.70 
 
 25.86 
 
 26.01 
 
 26.16 
 
 26.32 
 
 27 
 
 26.47 
 
 26.63 
 
 26.78 
 
 26.94 
 
 27. 10 
 
 27.26 
 
 27.42 
 
 27.58 
 
 27-74 
 
 27.90 
 
 28 
 
 28.07 
 
 28.23 
 
 28.39 
 
 28.56 
 
 28.73 
 
 28.89 
 
 29.06 
 
 29.23 
 
 29.40 
 
 29- 57 
 
 29 
 
 29.74 
 
 29.92 
 
 30.09 
 
 30.26 
 
 30.44 
 
 30.62 
 
 30.79 
 
 30.97 
 
 31-15 
 
 31.33 
 
 30 
 
 3I-5I 
 
 31.69 
 
 31.87 
 
 32.06 
 
 32.24 
 
 32-43 
 
 32.61 
 
 32.80 
 
 32.99 
 
 33.18 
 
 236 
 
APPENDIX A. 
 
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240 
 
 APPENDIX A. 
 
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APPENDIX A. 
 
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242 
 
 APPENDIX A. 
 Table VII. 
 
 TABLE OF HARDNESS, SHOWING THE PARTS OF CALCIUM CAR- 
 BONATE (CaC0 3 ) IN 1,000,000 FOR EACH TENTH OF A CUBIC 
 CENTIMETER OF SOAP SOLUTION USED. 
 
 
 0.0 
 
 O.I 
 
 0.2 
 
 0.3 
 
 0.4 
 
 0.5 
 
 0.6 
 
 0.7 
 
 0.8 
 
 0.9 
 
 
 cu. cm. 
 
 cu. cm. 
 
 cu. cm. 
 
 cu. cm. 
 
 cu. cm. 
 
 cu. cm. 
 
 cu. cm. 
 
 cu. cm. 
 
 cu. cm. 
 
 cu. cm. 
 
 0.0 
 
 
 
 
 
 
 
 
 O.O 
 
 1.6 
 
 3-2 
 
 1 .0 
 
 4.8 
 
 6.3 
 
 7-9 
 
 9-5 
 
 II. I 
 
 12.7 
 
 14-3 
 
 15-6 
 
 16.9 
 
 18.2 
 
 2.0 
 
 19-5 
 
 20.8 
 
 22.1 
 
 23.4 
 
 24.7 
 
 26.O 
 
 27-3 
 
 28.6 
 
 29.9 
 
 31-2 
 
 30 
 
 32.5 
 
 33-8 
 
 35-1 
 
 36.4 
 
 37-7 
 
 39 
 
 40- 3 
 
 41.6 
 
 42.9 
 
 44-3 
 
 4.0 
 
 45 -7 
 
 47.1 
 
 48.6 
 
 50.0 
 
 51.4 
 
 52.9 
 
 54.3 
 
 55-7 
 
 57-1 
 
 58.6 
 
 5-o 
 
 60.0 
 
 61.4 
 
 62.9 
 
 64-3 
 
 65.7 
 
 67.1 
 
 68.6 
 
 70.0 
 
 71.4 
 
 72.9 
 
 6.0 
 
 74-3 
 
 75-7 
 
 77-1 
 
 78.6 
 
 80.O 
 
 81.4 
 
 82.9 
 
 84-3 
 
 85-7 
 
 87.1 
 
 7.0 
 
 88.6 
 
 90.0 
 
 91.4 
 
 92.9 
 
 94-3 
 
 95-7 
 
 97.1 
 
 98.6 
 
 100. 
 
 101.5 
 
 8.0 
 
 103.0 
 
 104.5 
 
 106.0 
 
 1075 
 
 IOg.O 
 
 no. 5 
 
 112. 
 
 II3-5 
 
 1150 
 
 116. 5 
 
 9.0 
 
 118.0 
 
 "9-5 
 
 Z2I.I 
 
 122.6 
 
 124. 1 
 
 125.6 
 
 127. 1 
 
 128.6 
 
 130. 1 
 
 131-6 
 
 10. 
 
 133-1 
 
 134.6 
 
 I36. I 
 
 137-6 
 
 I39-I 
 
 140.6 
 
 142. 1 
 
 143-7 
 
 145-2 
 
 146.8 
 
 11 .0 
 
 148 4 
 
 150 
 
 151. 6 
 
 153-2 
 
 154-8 
 
 156.3 
 
 157-9 
 
 159-5 
 
 161. 1 
 
 162.7 
 
 12.0 
 
 164.3 
 
 165.9 
 
 I67-5 
 
 169.0 
 
 170.6 
 
 172.2 
 
 173-8 
 
 175.4 
 
 177-0 
 
 178.6 
 
 13.0 
 
 180.2 
 
 181. 7 
 
 183.3 
 
 184.9 
 
 186.5 
 
 188. 1 
 
 189.7 
 
 I9I-3 
 
 192.9 
 
 194.4 
 
 14.0 
 
 196.0 
 
 197.6 
 
 199.2 
 
 200.8 
 
 202.4 
 
 204.0 
 
 205.6 
 
 207.1 
 
 208.7 
 
 210.3 
 
 15-0 
 
 211. 9 
 
 213-5 
 
 215. 1 
 
 216.8 
 
 218.5 
 
 220.2 
 
 221.8 
 
 223.5 
 
 225.2 
 
 226.9 
 
 Table VIII. 
 
 SHOWING THE NUMBER OF CUBIC CENTIMETERS OF OXYGEN DIS- 
 SOLVED IN IOOO CUBIC CENTIMETERS OF WATER WHEN 
 SATURATED AT DIFFERENT TEMPERATURES, AS CAL- 
 CULATED BY WINKLER.' 
 
 * 
 
 Deg. Cent. 
 
 Cu. Cm. 
 
 Deg. Cent. 
 
 Cu. Cm. 
 
 Deg. Cent. 
 
 Cu. Cm. 
 
 O 
 
 IO.187 
 
 II 
 
 7.692 
 
 21 
 
 6.233 
 
 I 
 
 9.910 
 
 12 
 
 7.518 
 
 22 
 
 6. 114 
 
 2 
 
 9-643 
 
 13 
 
 7-352 
 
 23 
 
 5.999 
 
 3 
 
 9-387 
 
 14 
 
 7.192 
 
 24 
 
 5.886 
 
 4 
 
 9.142 
 
 15 
 
 7.038 
 
 25 
 
 5 • 776 
 
 5 
 
 8.907 
 
 16 
 
 6.891 
 
 26 
 
 5-669 
 
 6 
 
 8.682 
 
 17 
 
 6.750 
 
 27 
 
 5 • 564 
 
 7 
 
 8.467 
 
 18 
 
 6.614 
 
 28 
 
 5.460 
 
 8 
 
 8.260 
 
 19 
 
 6.482 
 
 29 
 
 5.357 
 
 9 
 
 8.063 
 
 20 
 
 6.356 
 
 30 
 
 5.255 
 
 10 
 
 7.873 
 
 
 
 
 
 * Berichte, 22 (1889), 1772. 
 
APPENDIX A. 
 
 243 
 
 Table IX. 
 
 FOR CORRECTING THE SPECIFIC GRAVITY OF MILK ACCORDING TO 
 TEMPERATURE. ADAPTED FROM THE TABLE OF VIETH. 
 
 (Temperature in Degrees Centigrade.) 
 
 Specific 
 Gravity. 
 
 I.025 
 26 
 
 27 
 28 
 29 
 30 
 31 
 32 
 33 
 34 
 35 
 
 24.1 
 25- 1 
 
 26.1 
 27.0 
 2S.0 
 29.0 
 29.9 
 
 30.9 
 31.8 
 
 32.7 
 33-6 
 
 24-3 
 25.2 
 26.2 
 27.2 
 
 28.2 
 29. 1 
 30. 1 
 
 3i-i 
 32.0 
 33-o 
 33-9 
 
 24 
 25 
 
 20 
 
 27 
 
 28 
 
 29 
 
 30 
 
 31-3 
 
 32.3 
 
 33-2 
 
 34-i 
 
 J-.O 
 
 - 
 
 24.6 
 
 24.7 
 
 25-5 
 
 25-7 
 
 26.5 
 
 26.7 
 
 27.5 
 
 27.7 
 
 28.5 
 
 28.7 
 
 29-5 
 
 29 -7j 
 
 30.4 
 
 30.6 
 
 31-4 
 
 3 1 - ! 
 
 32.4 
 
 32.6 
 
 33-4 
 
 33-6 
 
 34-4 
 
 34-6 
 
 24.9 
 
 25.9, 
 26.9: 
 
 27. 9I 
 2S.9 
 29.9 
 
 30.9 
 
 3i-9 
 32-9 
 33-9 
 34-9 
 
 25.1 
 26. 1 
 
 27.1 
 
 28.1 
 
 29 
 
 30 
 
 3i 
 
 32 
 
 33 
 
 34 
 
 35-2 
 
 37 
 
 18 
 
 25-3 
 
 25-4 
 
 26.3 
 
 26.5 
 
 27.4 
 
 27-5 
 
 28.4 
 
 28.5 
 
 29.4 
 
 29-5 
 
 30.4 
 
 30.5 
 
 3i-4 
 
 31.5 
 
 32.4 
 
 32.6 
 
 33-4 
 
 33-6 
 
 34-4 
 
 34-6 
 
 35-4 
 
 35-o 
 
 25.6 
 26.7 
 
 27-7 
 28.7; 
 29.8 
 30.8 
 3i-8| 
 32-9 
 33-9 
 
 34-9: 
 
 35-9 
 
 25 
 27 
 28 
 
 29 
 
 30 
 
 3i 
 
 32.2 
 
 33-2 
 
 34-2 
 
 35-2 
 
 36.2 
 
 Directions. — Find the observed gravity in the left-hand column. Then 
 in the same line, and under the observed temperature, will be found the 
 corrected reading. 
 
244 
 
 APPENDIX A. 
 
 Table X. 
 
 PERCENTAGE OF ALCOHOL 
 
 i5°.5 c 
 
 FROM THE SPECIFIC 
 (HEHNER.) 
 
 GRAVITY AT 
 
 
 Percent 
 
 Per cent 
 
 
 Per cent 
 
 Per cent 
 
 
 Per cent 
 
 Per cent 
 
 Sp. Gr. 
 
 Alcohol 
 
 Alcohol 
 
 Sp. Gr. 
 
 Alcohol 
 
 Alcohol 
 
 Sp. Gr. 
 
 Alcohol 
 
 Alcohol 
 
 i5°-5C. 
 
 by 
 
 by 
 
 is°.sc. 
 
 by 
 
 by 
 
 iS°.5 C. 
 
 bv 
 
 by 
 
 
 Weight. 
 
 Volume. 
 
 
 Weight. 
 
 Volume. 
 
 
 Weight. 
 
 Volume. 
 
 I.OOOO 
 
 0.00 
 
 O.OO 
 
 
 
 
 
 
 
 0.9999 
 
 0.05 
 
 O.07 
 
 0.9959 
 
 2-33 
 
 2-93 
 
 O.9919 
 
 4.69 
 
 5-86 
 
 8 
 
 O.II 
 
 0.13 
 
 8 
 
 2-39 
 
 3.00 
 
 8 
 
 4-75 
 
 5-94 
 
 7 
 
 0.16 
 
 0. 20 
 
 7 
 
 2.44 
 
 3-°7 
 
 7 
 
 4.81 
 
 6.02 
 
 6 
 
 O. 21 
 
 0.26 
 
 6 
 
 2.50 
 
 3-i4 
 
 6 
 
 4-87 
 
 6.10 
 
 5 
 
 O. 26 
 
 °-33 
 
 5 
 
 2.56 
 
 3.21 
 
 5 
 
 4-94 
 
 6.17 
 
 4 
 
 O.32 
 
 0.40 
 
 4 
 
 2.61 
 
 3.28 
 
 4 
 
 5.00 
 
 6.24 
 
 3 
 
 0-37 
 
 0.46 
 
 3 
 
 2.67 
 
 3-35 
 
 3 
 
 5.06 
 
 6.32 
 
 2 
 
 O.42 
 
 o-53 
 
 2 
 
 2.72 
 
 3-42 
 
 2 
 
 5-12 
 
 6.40 
 
 I 
 
 O.47 
 
 0.60 
 
 1 
 
 2.78 
 
 3-49 
 
 1 
 
 5-i9 
 
 6.48 
 
 O 
 
 0-53 
 
 0.66 
 
 
 
 2.83 
 
 3-55 
 
 
 
 5-25 
 
 6-55 
 
 O.9989 
 
 0.58 
 
 0-73 
 
 0.9949 
 
 2.89 
 
 3-62 
 
 0.9909 
 
 5-3i 
 
 6.63 
 
 8 
 
 O.63 
 
 0.79 
 
 8 
 
 2.94 
 
 3- 6 9 
 
 8 
 
 5-37 
 
 6.71 
 
 7 
 
 O.68 
 
 0.86 
 
 7 
 
 3.00 
 
 3-76 
 
 7 
 
 5-44 
 
 6.78 
 
 6 
 
 O.74 
 
 °-93 
 
 6 
 
 3.06 
 
 3-83 
 
 6 
 
 5-5o 
 
 6.86 
 
 5 
 
 O.79 
 
 0.99 
 
 5 
 
 3.12 
 
 3-9° 
 
 5 
 
 5-56 
 
 6-94 
 
 4 
 
 O.84 
 
 1.06 
 
 4 
 
 3-i8 
 
 3-98 
 
 4 
 
 5.62 
 
 7.01 
 
 3 
 
 O.89 
 
 1-13 
 
 3 
 
 3-24 
 
 4-o5 
 
 3 
 
 5-69 
 
 7.09 
 
 2 
 
 0-95 
 
 1. 19 
 
 2 
 
 3-29 
 
 4.12 
 
 2 
 
 5-75 
 
 7.17 
 
 1 
 
 I. OO 
 
 1. 26 
 
 1 
 
 3-35 
 
 4.20 
 
 1 
 
 5-8i 
 
 7-25 
 
 
 
 I.06 
 
 i-34 
 
 
 
 3-4i 
 
 4.27 
 
 
 
 5-87 
 
 7-32 
 
 0.9979 
 
 I. 12 
 
 1.42 
 
 0-9939 
 
 3-47 
 
 4-34 
 
 0.9899 
 
 5-94 
 
 7.40 
 
 8 
 
 1. 19 
 
 i-49 
 
 8 
 
 3-53 
 
 4-42 
 
 8 
 
 6.00 
 
 7-48 
 
 7 
 
 1-25 
 
 i-57 
 
 7 
 
 3-59 
 
 4-49 
 
 7 
 
 6.07 
 
 7-57 
 
 6 
 
 I. 31 
 
 1-65 
 
 6 
 
 3-65 
 
 4-5° 
 
 6 
 
 6.14 
 
 7.66 
 
 5 
 
 i-37 
 
 i-73 
 
 5 
 
 3-7i 
 
 4-63 
 
 5 
 
 6.21 
 
 7-74 
 
 4 
 
 1-44 
 
 1. 81 
 
 4 
 
 3-76 
 
 4.71 
 
 4 
 
 6.28 
 
 7-83 
 
 3 
 
 1.50 
 
 1.88 
 
 3 
 
 3.82 
 
 4-78 
 
 3 
 
 6.36 
 
 7.92 
 
 2 
 
 1-56 
 
 1.96 
 
 2 
 
 3-88 
 
 4-85 
 
 2 
 
 6-43 
 
 8.01 
 
 1 
 
 1.62 
 
 2.04 
 
 1 
 
 3-94 
 
 4-93 
 
 1 
 
 6.50 
 
 8.10 
 
 
 
 1-69 
 
 2.12 
 
 
 
 4.00 
 
 5.00 
 
 
 
 6-57 
 
 8.18 
 
 0.9969 
 
 1-75 
 
 2.20 
 
 0.9929 
 
 4.06 
 
 5-o8 
 
 0.9889 
 
 6.64 
 
 8.27 
 
 8 
 
 1. 81 
 
 2.27 
 
 8 
 
 4.12 
 
 5-i6 
 
 8 
 
 6.71 
 
 8.36 
 
 7 
 
 1.87 
 
 2-35 
 
 7 
 
 4.19 
 
 5-24 
 
 7 
 
 6.78 
 
 8-45 
 
 6 
 
 i-94 
 
 2-43 
 
 6 
 
 4-25 
 
 5-32 
 
 6 
 
 6.86 
 
 8-54 
 
 5 
 
 2.00 
 
 2-51 
 
 5 
 
 4-3 1 
 
 5-39 
 
 5 
 
 6 -93 
 
 8.63 
 
 4 
 
 2.06 
 
 2.58 
 
 4 
 
 4-37 
 
 5-47 
 
 4 
 
 7.00 
 
 8.72 
 
 3 
 
 2. 11 
 
 2.62 
 
 3 
 
 4-44 
 
 5-55 
 
 3 
 
 7.07 
 
 8.80 
 
 2 
 
 2.17 
 
 2.72 
 
 2 
 
 4-5° 
 
 5-63 
 
 2 
 
 7-i3 
 
 8.88 
 
 1 
 
 2. 22 
 
 2-79 
 
 1 
 
 4-56 
 
 5-7i 
 
 1 
 
 7.20 
 
 8.96 
 
 
 
 2.28 
 
 2.86 
 
 
 
 4.62 
 
 5-78 
 
 
 
 7.27 
 
 9.04 
 
APPENDIX A. 
 
 245 
 
 Table X. — Continued. 
 
 PERCENTAGE OF ALCOHOL. 
 
 
 Per cent 
 
 Per cent 
 
 
 Per cent 
 
 Per cent 
 
 
 ! Per cent 
 
 Per cent 
 
 Sp. Gr. 
 
 Alcohol 
 
 Alcohol 
 
 Sp. Gr. 
 
 Alcohol 
 
 Alcohol 
 
 Sp. Gr. 
 
 ! Alcohol 
 
 Alcohol 
 
 i5°.S C. 
 
 by 
 
 by 
 
 I5°.SC. 
 
 by 
 
 by 
 
 I5°-SC. 
 
 ! by 
 
 by 
 
 
 Weight. 
 
 Volume. 
 
 
 1 Weight. 
 
 Volume. 
 
 
 i Weight. 
 
 Volume. 
 
 O.9879 
 
 7-33 
 
 9-13 
 
 4 
 
 10.54 
 
 i3-°5 
 
 O.9789 
 
 14.OO 
 
 17.26 
 
 8 
 
 7.40 
 
 9. 21 
 
 3 
 
 10.62 
 
 13-15 
 
 8 
 
 14.09 
 
 17.37 
 
 7 
 
 7-47 
 
 9.29 
 
 2 
 
 10.69 
 
 l3- 2 4 
 
 7 
 
 14.18 
 
 17.48 
 
 6 
 
 7-53 
 
 9-37 
 
 1 
 
 10.77 
 
 13-34 
 
 6 
 
 14.27 
 
 17-59 
 
 5 
 
 7.60 
 
 9-45 
 
 
 
 10.85 
 
 J3-43 
 
 5 
 
 I4-3 6 
 
 17.70 
 
 4 
 
 7.67 
 
 9-54 
 
 
 
 
 4 
 
 14-45 
 
 17.81 
 
 3 
 
 7-73 
 
 9.62 
 
 0.9829 
 
 IO.92 
 
 13-52 
 
 3 
 
 14-55 
 
 17.92 
 
 2 
 
 7.80 
 
 9.70 
 
 8 
 
 11 .00 
 
 13.62 
 
 2 
 
 14.64 
 
 18.03 
 
 1 
 
 7-87 
 
 9-78 
 
 7 
 
 11.08 
 
 13-72 
 
 1 
 
 J 4-73 
 
 18.14 
 
 
 
 7-93 
 
 9.86 
 
 6 
 
 5 
 
 11. 15 
 11.23 
 
 13.81 
 !3-9° 
 
 
 
 14.82 
 
 18.25 
 
 0.9869 
 
 8.00 
 
 9-95 
 
 4 
 
 11. 31 
 
 *3-99 
 
 0.9779 
 
 14.90 
 
 18.36 
 
 8 
 
 8.07 
 
 10.03 
 
 3 
 
 11.38 
 
 14.09 
 
 8 
 
 15.00 
 
 18.48 
 
 7 
 
 8.14 
 
 10.12 
 
 2 
 
 11.46 
 
 14.18 
 
 7 
 
 15.08 
 
 18-58 
 
 6 
 
 8.21 
 
 10.21 
 
 1 
 
 n-54 
 
 14.27 
 
 6 
 
 I5-I7 
 
 18.68 
 
 5 
 
 8.29 
 
 10.30 
 
 
 
 11.62 
 
 J 4-37 
 
 5 
 
 15-25 
 
 18.78 
 
 4 
 
 8.36 
 
 10.38 
 
 
 
 
 4 
 
 15-33 
 
 18.88 
 
 3 
 
 8-43 
 
 10.47 
 
 0.9819 
 
 II.69 
 
 14.46 
 
 3 
 
 15-42 
 
 18.98 
 
 2 
 
 8.50 
 
 10.56 
 
 8 
 
 11.77 
 
 14.56 
 
 2 
 
 i5-5o 
 
 19.08 
 
 1 
 
 8-57 
 
 10.65 
 
 7 
 
 11.85 
 
 14-65 
 
 1 
 
 15-58 
 
 19.18 
 
 
 
 8.64 
 
 IO -73 
 
 6 
 
 5 
 
 11.92 
 12.00 
 
 14.74 
 14.84 
 
 
 
 15-67 
 
 19.28 
 | 
 
 0.9859 
 
 8-71 
 
 10.82 
 
 4 
 
 12.08 
 
 14-93 
 
 0.9769 
 
 15-75 
 
 19.39 
 
 8 
 
 8-79 
 
 10.91 
 
 3 
 
 12.15 
 
 15.02 
 
 8 
 
 15.83 
 
 19.49 
 
 7 
 
 8.86 
 
 11.00 
 
 2 
 
 12.23 
 
 15.12 
 
 7 
 
 15-92 
 
 19-59 
 
 6 
 
 8-93 
 
 11.08 
 
 1 
 
 12.31 
 
 15.21 
 
 6 
 
 16.00 
 
 19.68 
 
 5 
 
 9.00 
 
 11. 17 
 
 
 
 12.38 
 
 15-30 
 
 5 
 
 16.08 
 
 19.78 
 
 4 
 
 9.07 
 
 11.26 
 
 
 
 
 4 
 
 16.15 
 
 19.87 
 
 3 
 
 9.14 
 
 ii-35 
 
 0.9809 
 
 12.46 
 
 I5-40 
 
 3 
 
 16.23 
 
 19.96 
 
 2 
 
 9. 21 
 
 11.44 
 
 8 
 
 12.54 
 
 15-49 
 
 2 
 
 16.31 
 
 20.06 
 
 1 
 
 9.29 
 
 11.52 
 
 7 
 
 12.62 
 
 15.58 
 
 1 
 
 16.38 
 
 20.15 
 
 
 
 9-36 
 
 11. 61 
 
 6 
 
 5 
 
 12.69 
 12.77 
 
 15.68 
 15-77 
 
 
 
 16.46 
 
 20.24 
 
 0.9849 
 
 943 
 
 11.70 
 
 4 
 
 12.85 
 
 15-86 
 
 0-9759 
 
 16.54 
 
 20.33 
 
 8 
 
 9-5o 
 
 11.79 
 
 3 
 
 12.92 
 
 15.96 
 
 8 
 
 16.62 
 
 20.43 
 
 7 
 
 9-57 
 
 11.87 
 
 2 
 
 13.00 
 
 16.05 
 
 7 
 
 16.69 
 
 20.52 
 
 6 
 
 9.64 
 
 11.96 
 
 1 
 
 13.08 
 
 16.15 
 
 6 
 
 16.77 
 
 20.61 
 
 5 
 
 9.71 
 
 12.05 
 
 
 
 13-15 
 
 16.24 
 
 5 
 
 16.85 
 
 20.71 
 
 4 
 
 9-79 
 
 12.13 
 
 
 
 
 4 
 
 16.92 
 
 20.80 
 
 3 
 
 9.86 
 
 12.22 
 
 0.9799 
 
 13-23 
 
 16.33 
 
 3 
 
 17.00 
 
 20.89 
 
 2 
 
 9-93 
 
 12.31 
 
 8 
 
 13-31 
 
 16.43 
 
 2 
 
 17.08 
 
 20.99 
 
 1 
 
 10.00 
 
 12.40 
 
 7 
 
 13-38 
 
 16.52 
 
 1 
 
 17.17 
 
 21.09 
 
 
 
 10.08 
 
 12.49 
 
 6 
 
 5 
 
 13.46 
 13-54 
 
 16.61 
 16.70 
 
 
 
 17.25 
 
 21.19 
 
 0. 0839 
 
 10.15 
 
 12.58 
 
 4 
 
 13.62 
 
 16.80 
 
 0.9749 
 
 17-33 
 
 21.29 
 
 8 
 
 10.23 
 
 12.68 
 
 3 
 
 13.69 
 
 16.89 
 
 8 
 
 17.42 
 
 20.39 
 
 7 
 
 10.31 
 
 12.77 
 
 2 
 
 13-77 
 
 16.98 
 
 7 
 
 i7-5o 
 
 21.49 
 
 6 
 
 10.38 
 
 12.87 
 
 1 
 
 13.85 
 
 17.08 
 
 6 
 
 17.58 
 
 21-59 
 
 5 
 
 10.46 
 
 12.96 
 
 
 
 13.92 
 
 17.17 
 
 5 
 
 17.67 
 
 21.69 
 
246 
 
 APPENDIX A. 
 
 Table X. — Continued. 
 
 PERCENTAGE OF ALCOHOL. 
 
 
 Per cent 
 
 Per cent 
 
 1 
 
 Per cent 
 
 Per cent 
 
 
 Per cent 
 
 Per cent 
 
 Sp. Gr. 
 
 Alcohol 
 
 Alcohol 
 
 Sp. Gr. 
 
 Alcohol 
 
 Alcohol 
 
 Sp. Gr. 
 
 Alcohol 
 
 Alcohol 
 
 I5°.5C. 
 
 by 
 
 by 
 
 is°-sc. 
 
 by 
 
 by 
 
 I5°.SC. 
 
 by 
 
 by 
 
 
 Weight. 
 
 Volume. 
 
 
 Weight. 
 
 "Volume. 
 
 
 Weight. 
 
 Volume. 
 
 4 
 
 17-75 
 
 21.79 
 
 4 
 
 20.17 
 
 24.68 
 
 4 
 
 22.54 
 
 27.49 
 
 3 
 
 17-83 
 
 21.89 
 
 3 
 
 20.25 
 
 24.78 
 
 3 
 
 22.62 
 
 27-59 
 
 2 
 
 17.92 
 
 21.99 
 
 2 
 
 20.33 
 
 24.88 
 
 2 
 
 22.69 
 
 27.68 
 
 I 
 
 18.00 
 
 22.09 
 
 1 
 
 20.42 
 
 24.98 
 
 1 
 
 22.77 
 
 27.77 
 
 O 
 
 18.08 
 
 22.18 
 
 
 
 20.50 
 
 25.07 
 
 
 
 22.85 
 
 27.86 
 
 0.9739 
 
 18.15 
 
 22. 27 
 
 0.9709 
 
 20.58 
 
 25.17 
 
 0.9679 
 
 22.92 , 
 
 27-95 
 
 8 
 
 18.23 
 
 22.36 
 
 8 
 
 20.67 
 
 25.27 
 
 8 
 
 23.00 
 
 28.04 
 
 7 
 
 18.31 
 
 22.46 
 
 7 
 
 20-75 
 
 25.37 
 
 7 
 
 23.08 
 
 28.13 
 
 6 
 
 18.38 
 
 22-55 
 
 6 
 
 20.83 
 
 25-47 
 
 6 
 
 23-15 
 
 28.22 
 
 5 
 
 18.46 
 
 22.64 
 
 5 
 
 20 92 
 
 25-57 
 
 5 
 
 23.23 
 
 28.31 
 
 4 
 
 18.54 
 
 22,73 
 
 4 
 
 2I.OO 
 
 25-67 
 
 4 
 
 23-31 
 
 28.41 
 
 3 
 
 18.62 
 
 22.82 
 
 3 
 
 21.08 
 
 25 76 
 
 3 
 
 23.38 
 
 28.50 
 
 2 
 
 18.69 
 
 22.92 
 
 2 
 
 21.15 
 
 25.86 
 
 2 
 
 23.46 
 
 28-59 
 
 1 
 
 18.77 
 
 23 OI 
 
 1 
 
 21.23 
 
 25.95 
 
 1 
 
 23-54 
 
 28.68 
 
 
 
 18.85 
 
 23.IO 
 
 
 
 21.31 
 
 26.04 
 
 
 
 23.62 
 
 28.77 
 
 O.9729 
 
 18 92 
 
 23.19 
 
 0.9699 
 
 21.38 
 
 26.13 
 
 0.9669 
 
 23.69 
 
 28.86 
 
 8 
 
 19 00 
 
 23-28 
 
 8 
 
 21.46 
 
 26 22 
 
 8 
 
 2 3-77 
 
 28.95 
 
 7 
 
 19.08 
 
 23-38 
 
 7 
 
 21-54 
 
 26.3I 
 
 7 
 
 23.85 
 
 29.04 
 
 6 
 
 19 17 
 
 23-48 
 
 6 
 
 21.62 
 
 26.4O 
 
 6 
 
 23.92 
 
 29-13 
 
 5 
 
 l9- 2 5 
 
 23 58 
 
 5 
 
 21.69 
 
 26.49 
 
 5 
 
 24.00 
 
 29.22 
 
 4 
 
 19-33 
 
 23.68 
 
 4 
 
 21.77 
 
 26.58 
 
 4 
 
 24.08 
 
 29.31 
 
 3 
 
 19.42 
 
 23-78 
 
 3 
 
 21.85 
 
 26.67 
 
 3 
 
 24-15 
 
 29.40 
 
 2 
 
 I9-50 
 
 23-88 
 
 2 
 
 21.92 
 
 26.77 
 
 2 
 
 24-23 
 
 29-49 
 
 1 
 
 19.58 
 
 23.98 
 
 1 
 
 22.00 
 
 26.86 
 
 1 
 
 24. 3 1 
 
 29.58 
 
 
 
 19.67 
 
 24.08 
 
 
 
 22.08 
 
 26.95 
 
 
 
 24.38 
 
 29.67 
 
 0.9719 
 
 19-75 
 
 24. l8 
 
 0.9689 
 
 22.15 
 
 27.04 
 
 0.9659 
 
 24.46 
 
 29.76 
 
 8 
 
 19.83 
 
 24.28 
 
 8 
 
 22.23 
 
 27- J 3 
 
 8 
 
 24-54 
 
 29.86 
 
 7 
 
 19.92 
 
 24-38 
 
 7 
 
 22.31 
 
 27.22 
 
 7 
 
 24.62 
 
 29-95 
 
 6 
 
 20.00 
 
 24.48 
 
 6 
 
 22.38 
 
 27-31 
 
 6 
 
 24.69 
 
 30.04 
 
 5 
 
 20 08 
 
 24.58 
 
 5 
 
 22.46 
 
 27.40 
 
 5 
 4 
 
 3 
 2 
 
 24-77 
 24-85 
 24.92 
 25.00 
 
 30.22 
 30.40 
 
APPENDIX A. 
 
 247 
 
 Table XL 
 
 EXTRACT IN WINE. 
 
 Per Cent by Weight. 
 [According to Windisch.] 
 
 Sp. Gr. 
 
 Ex- 
 
 Sp. Gr. 
 
 Ex- 
 
 Sp. Gr. 
 
 Ex- 
 
 1 
 
 'Sp. Gr. 
 
 Ex- 
 
 Sp. Gr. 
 
 Ex- 
 
 Sp. Gr 
 
 Ex- 
 
 
 tract. 
 
 
 tract. 
 
 
 tract. 
 
 
 tract. 
 
 
 tract. 
 
 
 tract. 
 
 1 . 0000 
 
 0.00 
 
 1 .0200 
 
 5-17 
 
 1 .0400 
 
 10.35 
 
 1 .0600 
 
 15.55 
 
 1 .0800 
 
 20.78 
 
 1 . 1 00a 
 
 26 .04 
 
 1 .0005 
 
 0.13 
 
 1.0205 
 
 5.30 
 
 1 .0405 
 
 10.48 
 
 1 .0605 
 
 15.68 
 
 1 .0805 
 
 20.91 
 
 1 . 1005 
 
 26. 17 
 
 1 .0010 
 
 0.26 
 
 1 .0210 
 
 5-43 
 
 1 .0410 
 
 10.61 
 
 1 .0610 
 
 15.81 
 
 1. 0810 
 
 21 .04 
 
 1 . IOIO 
 
 26.30 
 
 1 .0015 
 
 0.39 
 
 1 .0215 
 
 5.56 
 
 1-0415 
 
 10.74 
 
 1 .0615 
 
 15-94 
 
 1. 0815 
 
 21.17 
 
 1. 1015 
 
 26.43 
 
 r .0020 
 
 0.52 
 
 1 .0220 
 
 5.69 
 
 1 .0420 
 
 10.87 
 
 1 .0620 
 
 16.07 
 
 1 .0820 
 
 21.31 
 
 1 . 1020 
 
 26.56 
 
 1 .0025 
 
 0.64 
 
 1 .0225 
 
 5-82 
 
 1 .0425 
 
 1 1 . 00 
 
 1 .0625 
 
 16.21 
 
 1 .0825 
 
 21.44 
 
 1 .1025 
 
 26.70 
 
 1 .0030 
 
 0.77 
 
 1.0230 
 
 5-94 
 
 1.0430 
 
 11 . 13 
 
 1.0630 
 
 16.33 
 
 1 .0830 
 
 21.57 
 
 1 . 1030 
 
 26.83 
 
 1 -0035 
 
 0.90 
 
 10235 
 
 6.07 
 
 1 -0435 
 
 11.26 
 
 1-0635 
 
 16.47 
 
 1.0835 
 
 21 . 70 
 
 1 -1035 
 
 26 . 96 
 
 1 .0040 
 
 1 °3 
 
 1 .0240 
 
 6. 20 
 
 1 .0440 
 
 n.39 
 
 1 .0640 
 
 16.60 
 
 1 .0840 
 
 21.83 
 
 1 . 1040 
 
 27.09 
 
 1. 0045 
 
 1. 16 
 
 1.0245 
 
 6.33 
 
 1.0445 
 
 11 .52 
 
 1 0645 
 
 16.73 
 
 1.0845 
 
 21 .96 
 
 1. 1045 
 
 27.22 
 
 1 .0050 
 
 1.29 
 
 1 .0250 
 
 6.46 
 
 1.0450 
 
 11 .65 
 
 1 .0650 
 
 16.86 
 
 1 .0850 
 
 22 .09 
 
 1. 1050 
 
 27.35 
 
 1.0055 
 
 1.42 
 
 1-0255 
 
 6.59 
 
 1.0455 
 
 11.78 
 
 1-0655 
 
 16.99 
 
 1-0855 
 
 22 . 22 
 
 i- 1055 
 
 27.49 
 
 1 .0060 
 
 1. 55 
 
 1 .0260 
 
 6.72 
 
 1 .0460 
 
 11. 91 
 
 1 .0660 
 
 17.12 
 
 1 .0860 
 
 22 .36 
 
 1 . 1060 
 
 27.62 
 
 1 .0065 
 
 1.68 
 
 1.0265 
 
 6.8s 
 
 1 .0465 
 
 13 .04 
 
 1 .0665 
 
 17.25 
 
 1.0865 
 
 22.49 
 
 1 . 1065 
 
 27.75 
 
 1 .0070 
 
 1. 81 
 
 1 .0270 
 
 6.98 
 
 1.0470 
 
 12.17 
 
 1 .0670 
 
 17.38 
 
 1 .0870 
 
 22 . 62 
 
 1 . 1070 
 
 27.88 
 
 1.0075 
 
 1.94 
 
 1.0275 
 
 7. 11 
 
 1 -0475 
 
 12 .30 
 
 1.0675 
 
 17-51 
 
 1.0875 
 
 22.75 
 
 1. 1075 
 
 28.01 
 
 1 .0080 
 
 2.07 
 
 1 .0280 
 
 7.24 
 
 1 .0480 
 
 12.43 
 
 1.0680 
 
 17.64 
 
 1.0880 
 
 22.88 
 
 1 . 1080 
 
 28.15 
 
 1 .0085 
 
 2.19 
 
 1.0285 
 
 7-37 
 
 1 .0485 
 
 12.56 
 
 1.0685 
 
 17.77 
 
 1.0885 
 
 23.OI 
 
 1. 1085 
 
 28.28 
 
 1 .0090 
 
 2.32 
 
 1 .0290 
 
 7- SO 
 
 1 .0490 
 
 12 .69 
 
 1 .0690 
 
 17 .90 
 
 1 .0890 
 
 23.I4 
 
 1 . 1090 
 
 28.41 
 
 1.0095 
 
 2-45 
 
 1 .0295 
 
 7.63 
 
 I.Q495 
 
 12.82 
 
 1 .0695 
 
 18.03 
 
 1.0895 
 
 23.28 
 
 1. 1095 
 
 28.54 
 
 1 .0100 
 
 2.58 
 
 1 .0300 
 
 7.76 
 
 1 .0500 
 
 12.95 
 
 1 .0700 
 
 18.16 
 
 1 .0900 
 
 23 .41 
 
 1 . 1 100 
 
 26 .67 
 
 1 .0105 
 
 2.71 
 
 1.0305 
 
 7.89 
 
 1 -0505 
 
 I3.08 
 
 1.0705 
 
 18.30 
 
 1 .0905 
 
 23.54 
 
 1 . 1105 
 
 28.81 
 
 1 .0110 
 
 2.84 
 
 1 .0310 
 
 8.02 
 
 1 .0510 
 
 13-21 
 
 1 .0710 
 
 18.43 
 
 1 .0910 
 
 23.67 
 
 I . IIIO 
 
 28.94 
 
 1.0115 
 
 2.97 
 
 1-0315 
 
 8.14 
 
 1-0515 
 
 13-34 
 
 1 -0715 
 
 18.56 
 
 1. 0915 
 
 23.80 
 
 I . 1115 
 
 29.07 
 
 1 .0120 
 
 3- 10 
 
 1 .0320 
 
 8.27 
 
 1.0520 
 
 13-47 
 
 1 .0720 
 
 18.69 
 
 1 .0920 
 
 23.93 
 
 I . II20 
 
 29.20 
 
 1. 0125 
 
 3-23 
 
 1-0325 
 
 8.40 
 
 1-0525 
 
 I3.6o 
 
 1 .0725 
 
 18.82 
 
 1 .0925 
 
 24.07 
 
 I . 1125 
 
 29-33 
 
 1. 0130 
 
 3.36 
 
 1.0330 
 
 8-53 
 
 1.0530 
 
 13-73 
 
 1 .0730 
 
 18.95 
 
 1.0930 
 
 24.20 
 
 I.II30 
 
 29.47 
 
 1.0135 
 
 3-49 
 
 I-0335 
 
 8.66 
 
 1. 053S 
 
 13-86 
 
 I-0735 
 
 19.08 
 
 1 -0935 
 
 24.33 
 
 r."35 
 
 29. 60 
 
 1 .0140 
 
 3-02 
 
 1 .0340 
 
 8.79 
 
 1 . 0540 
 
 13 -99 
 
 1 .0740 
 
 19.21 
 
 1 .0940 
 
 24.46 
 
 1 . 1 1 40 
 
 2973 
 
 1. 0145 
 
 3-75 
 
 I-0345 
 
 8.92 
 
 I-054S 
 
 14. 12 
 
 1.0745 
 
 19.34 
 
 I.Q945 
 
 24.59 
 
 1. "45 
 
 29.86 
 
 1. 0150 
 
 3.87 
 
 1.0350 
 
 9.05 
 
 1.0550 
 
 14-25 
 
 1.0750 
 
 19-47 
 
 1 .0950 
 
 24.72 
 
 1.1150 
 
 29.99. 
 
 1.015s 
 
 4.00 
 
 I-0355 
 
 9.18 
 
 I-0555 
 
 14.38 
 
 I-0755 
 
 19.60 
 
 1 -0955 
 
 24.85 
 
 1. "55 
 
 30.13 
 
 1 .0160 
 
 4.13 
 
 1.0360 
 
 9.3i 
 
 1 .0560 
 
 14.51 
 
 1 .0760 
 
 19-73 
 
 1 .0960 
 
 24.99 
 
 
 
 1.016s 
 
 4. 26 
 
 1-0365 
 
 9-44 
 
 1.0565 
 
 14.64 
 
 1.0765 
 
 19.86 
 
 1 .0965 
 
 25.12 
 
 
 
 1. 0170 
 
 4-39 
 
 1.0370 
 
 9-57 
 
 1.0570 
 
 M-77 
 
 1.0770 
 
 20.00 
 
 1 .0970 
 
 25-25 
 
 
 
 1. 017s 
 
 4.52 
 
 I-0375 
 
 970 
 
 I.0575 
 
 14.90 
 
 1 -0775 
 
 20. 12 
 
 1 -0975 
 
 25.38 
 
 
 
 1 .0180 
 
 4.65 
 
 1 .0380 
 
 9.83 
 
 1 .0580 
 
 15-03 
 
 1 .0780 
 
 20. 26 
 
 1 .0980 
 
 25-51 
 
 
 
 1. 0185 
 
 4.78 
 
 1-0385 
 
 9.96 
 
 1.0585 
 
 15.16 
 
 1.0785 
 
 20.39 
 
 1 .0985 
 
 25.64 
 
 
 
 1 .0190 
 
 4.91 
 
 1 .0390 
 
 10.09 
 
 1 .0590 
 
 15-29 
 
 1 .0790 
 
 20. 52 
 
 1 .0990 
 
 25.78 
 
 
 
 1. 0195 
 
 5-04 
 
 1 -0395 
 
 10. 22 
 
 1 .0595 
 
 15.42 
 
 1.0795 
 
 20.65 
 
 I-Q995 
 
 25.91 
 
 
 . 
 
248 
 
 APPENDIX A. 
 
 Table XII. 
 
 TABLE FOR REDUCING SUGAR CONDENSED 
 MUNSON AND WALKER. 
 (Expressed in milligrams.) 
 
 FROM THAT OF 
 
 
 
 
 O 
 
 
 
 
 
 O 
 
 
 
 
 u 
 
 X 
 
 
 CD 
 
 
 u 
 
 X 
 
 
 p 3 
 
 6 
 
 «5 
 
 
 u 
 
 <D 
 
 Q 
 
 M 
 M 
 u 
 
 > 
 
 C 
 
 + 
 
 A 
 
 BX 
 
 s 
 
 < 
 
 O 
 aT S3 
 
 O - 
 
 2 ^ 
 u 
 
 6 
 
 en 
 
 2 
 Q 
 
 a 
 bo 
 
 to 
 
 u 
 
 CD 
 > 
 
 C 
 
 + 
 
 A 
 
 2X 
 jc5 
 
 O 
 
 1)8 
 
 ISO 
 
 9 
 
 10 
 
 4.0 
 
 4-5 
 
 4.0 
 
 5-9 
 
 260 
 
 117 .6 
 
 121. 4 
 
 176.3 
 
 203.9 
 
 is 
 
 6.2 
 
 6-7 
 
 7-5 
 
 9-9 
 
 265 
 
 120.0 
 
 123.9 
 
 179-7 
 
 207.9 
 
 20 
 
 8.3 
 
 8-9 
 
 10.9 
 
 13-8 
 
 270 
 
 122.5 
 
 126. 4 
 
 183.2 
 
 211. 8 
 
 25 
 
 10.5 
 
 11 . 2 
 
 14.4 
 
 17.8 
 
 275 
 
 124.9 
 
 I28.9 
 
 186.6 
 
 215.8 
 
 30 
 
 12.6 
 
 13-4 
 
 17.8 
 
 21.8 
 
 280 
 
 127.3 
 
 I3I-4 
 
 190. I 
 
 219.7 
 
 35 
 
 14.8 
 
 15.6 
 
 21.3 
 
 25-7 
 
 285 
 
 129.8 
 
 133-9 
 
 193-5 
 
 223.7 
 
 40 
 
 16.9 
 
 17.8 
 
 24.7 
 
 29.7 
 
 290 
 
 132.3 
 
 I36.4 
 
 196.9 
 
 227.6 
 
 45 
 
 19. 1 
 
 20. 1 
 
 28.2 
 
 33-7 
 
 295 
 
 134-7 
 
 138.9 
 
 200. 4 
 
 231.6 
 
 SO 
 
 21.3 
 
 22.3 
 
 31-6 
 
 37-6 
 
 300 
 
 137.2 
 
 141. 5 
 
 203.8 
 
 235-5 
 
 55 
 
 23-5 
 
 24.6 
 
 35-0 
 
 41.6 
 
 305 
 
 139-7 
 
 144.0 
 
 207 . 2 
 
 239.5 
 
 60 
 
 25.6 
 
 26.8 
 
 38.4 
 
 45-6 
 
 310 
 
 142 .2 
 
 146.6 
 
 210. 7 
 
 243-3 
 
 65 
 
 27.8 
 
 29.1 
 
 41 .9 
 
 49-5 
 
 315 
 
 144-7 
 
 149- 1 
 
 214. 1 
 
 247.4 
 
 70 
 
 30.0 
 
 31-3 
 
 45-4 
 
 53-5 
 
 320 
 
 147.2 
 
 I5I-7 
 
 217.6 
 
 251-3 
 
 75 
 
 32 .2 
 
 33-6 
 
 48.8 
 
 57-5 
 
 325 
 
 149-7 
 
 154-3 
 
 221.0 
 
 255-3 
 
 80 
 
 34-4 
 
 35-9 
 
 52.3 
 
 61 .4 
 
 330 
 
 152.2 
 
 156.8 
 
 224.4 
 
 2S9-3 
 
 85 
 
 36.7 
 
 38.2 
 
 55-7 
 
 65.4 
 
 335 
 
 154.7 
 
 159-4 
 
 227.9 
 
 263.3 
 
 90 
 
 38.9 
 
 40.4 
 
 59-2 
 
 69 -3 
 
 340 
 
 157.3 
 
 162 .0 
 
 231-3 
 
 267. 1 
 
 95 
 
 41. I 
 
 42. 7 
 
 62.6 
 
 73-3 
 
 345 
 
 159-8 
 
 164.6 
 
 234-7 
 
 271 . 1 
 
 100 
 
 433 
 
 45-0 
 
 66.1 
 
 77-3 
 
 350 
 
 162 . 4 
 
 167. 2 
 
 238.2 
 
 275.0 
 
 105 
 
 45-5 
 
 47-3 
 
 69.5 
 
 81.2 
 
 355 
 
 164.9 
 
 169.8 
 
 241 .6 
 
 279.0 
 
 no 
 
 47-8 
 
 49-6 
 
 73-0 
 
 85.2 
 
 360 
 
 l675 
 
 172.5 
 
 245-1 
 
 282.9 
 
 n5 
 
 50.0 
 
 51-9 
 
 76.4 
 
 89.2 
 
 365 
 
 170. I 
 
 I75-I 
 
 248.5 
 
 286.9 
 
 120 
 
 52.3 
 
 543 
 
 79-8 
 
 93-1 
 
 370 
 
 172.7 
 
 177.7 
 
 252 .0 
 
 290.8 
 
 125 
 
 54-5 
 
 56.6 
 
 833 
 
 97.1 
 
 375 
 
 175-3 
 
 180.4 
 
 255-4 
 
 294.8 
 
 130 
 
 56.8 
 
 58.9 
 
 86.7 
 
 101 .0 
 
 380 
 
 177.9 
 
 183.0 
 
 258.8 
 
 298.7 
 
 135 
 
 59-o 
 
 61.2 
 
 90. 2 
 
 105.0 
 
 38s 
 
 180.5 
 
 185.7 
 
 262.3 
 
 302.7 
 
 140 
 
 61.3 
 
 63.6 
 
 93-6 
 
 109 .0 
 
 390 
 
 183. 1 
 
 188.4 
 
 265.7 
 
 306.6 
 
 145 
 
 63.6 
 
 65-9 
 
 97-1 
 
 112 .9 
 
 395 
 
 185.7 
 
 191 .0 
 
 269. 1 
 
 310.6 
 
 150 
 
 659 
 
 68.3 
 
 100.5 
 
 116. 9 
 
 400 
 
 188.4 
 
 193-7 
 
 272 .6 
 
 3M.5 
 
 155 
 
 68.2 
 
 70.6 
 
 104.0 
 
 120.8 
 
 405 
 
 191 .0 
 
 196.4 
 
 276.0 
 
 3IK.5 
 
 160 
 
 70.4 
 
 73-0 
 
 107.4 
 
 124.8 
 
 410 
 
 193-7 
 
 199- 1 
 
 279-5 
 
 322.4 
 
 165 
 
 72.8 
 
 75-3 
 
 no. 9 
 
 128.8 
 
 415 
 
 196.3 
 
 201.8 
 
 282 .9 
 
 326.3 
 
 170 
 
 75-i 
 
 77-7 
 
 114. 3 
 
 132.7 
 
 420 
 
 199.0 
 
 204.6 
 
 286.3 
 
 330.3 
 
 175 
 
 77-4 
 
 80.1 
 
 117. 7 
 
 136.7 
 
 425 
 
 201 . 7 
 
 207.3 
 
 289.8 
 
 334-2 
 
 180 
 
 79-7 
 
 82.5 
 
 121 . 2 
 
 140.6 
 
 430 
 
 204.4 
 
 210.0 
 
 293-2 
 
 338.3 
 
 185 
 
 82.0 
 
 84.9 
 
 124.6 
 
 144-6 
 
 435 
 
 207. 1 
 
 212.8 
 
 296.6 
 
 342.1 
 
 190 
 
 84.3 
 
 87.2 
 
 128. 1 
 
 148.6 
 
 440 
 
 209 . 8 
 
 215-5 
 
 300. 1 
 
 346.1 
 
 195 
 
 86.7 
 
 89.6 
 
 I3I-5 
 
 152.5 
 
 445 
 
 212.5 
 
 218.3 
 
 3035 
 
 350.0 
 
 200 
 
 89.0 
 
 92 .0 
 
 I35-0 
 
 156. s 
 
 450 
 
 215.2 
 
 221 . 1 
 
 306.9 
 
 353-9 
 
 205 
 
 91.4 
 
 94-5 
 
 138.4 
 
 160. 4 
 
 455 
 
 218.0 
 
 223.9 
 
 310.4 
 
 3579 
 
 210 
 
 93-7 
 
 96.9 
 
 141. 9 
 
 164.4 
 
 460 
 
 220. 7 
 
 226.7 
 
 313.8 
 
 361.8 
 
 215 
 
 96. 1 
 
 99-3 
 
 145-3 
 
 168.3 
 
 465 
 
 223.5 
 
 229.5 
 
 317.3 
 
 365.8 
 
 220 
 
 98.4 
 
 101 .7 
 
 148.7 
 
 172.3 
 
 470 
 
 226. 2 
 
 232.3 
 
 320.7 
 
 369.7 
 
 225 
 
 100. 8 
 
 104. 2 
 
 152 .2 
 
 176.2 
 
 475 
 
 229.0 
 
 235-1 
 
 324.1 
 
 373-7 
 
 230 
 
 103.2 
 
 106.6 
 
 155-6 
 
 180.2 
 
 480 
 
 231.8 
 
 237-9 
 
 327.6 
 
 377-6 
 
 235 
 
 105 .6 
 
 109. 1 
 
 159. 1 
 
 184.2 
 
 485 
 
 234.6 
 
 240.8 
 
 33io 
 
 381. 5 
 
 240 
 
 108.0 
 
 in. 5 
 
 162.5 
 
 188. 1 
 
 490 
 
 237.4 
 
 243-6 
 
 334-4 
 
 385-5 
 
 245 
 
 no. 4 
 
 114. 
 
 166.0 
 
 192 . 1 
 
 
 
 
 
 
 250 
 
 112. 8 
 
 116. 4 
 
 169.4 
 
 196.0 
 
 
 
 
 
 
 355 
 
 115. 2 
 
 118. 9 
 
 172.8 
 
 200.0 
 
 
 
 
 
 
APPENDIX A. 
 
 Table XIII. 
 
 EXTRACT IN BEER- WORT. 
 
 (According to Schultzand Ostermann.) 
 
 249 
 
 Specific 
 
 Extract. 
 
 Specific 
 
 Extract. 
 
 Specific 
 
 Extract. 
 
 Specific 
 
 Extract. 
 
 Gravity at 
 
 Per cent 
 
 Gravity at 
 
 Per cent. 
 
 Gravity at 
 
 Per cent. 
 
 Gravity at 
 
 Per cent. 
 
 i 5 ° C. 
 
 by Weight. 
 
 >5°C. 
 
 by Weight. 
 
 15° C. 
 
 by Weight. 
 
 .5°C. 
 
 by Weight, 
 
 1 .OOOO 
 
 O.OO 
 
 I 0235 
 
 6.07 
 
 I . 0470 
 
 II.89 
 
 I.0705 
 
 17-59 
 
 1 .0005 
 
 O.13 
 
 I . 0240 
 
 6.I9 
 
 1-0475 
 
 I2.0I 
 
 I .0710 
 
 17.70 
 
 1 .0010 
 
 O.26 
 
 I.O245 
 
 6.31 
 
 I . 0480 
 
 12 . 14 
 
 1-0715 
 
 17.81 
 
 1. 0015 
 
 0-39 
 
 I.0250 
 
 6.44 
 
 I.0485 
 
 12 . 26 
 
 I .0720 
 
 17.93 
 
 1 .0020 
 
 O.52 
 
 ^0255 
 
 6.58 
 
 I . 0490 
 
 I2.38 
 
 I.0725 
 
 18.04 
 
 1 .0025 
 
 O.66 
 
 1 .0260 
 
 6.71 
 
 1-0495 
 
 I2.50 
 
 I.0730 
 
 18.15 
 
 I . 0030 
 
 O.79 
 
 1.0265 
 
 6.85 
 
 I .0500 
 
 I2.63 
 
 I 0735 
 
 18.26 
 
 1-0035 
 
 O.92 
 
 1 .0270 
 
 6.99 
 
 1-0505 
 
 12-75 
 
 I .0740 
 
 18.38 
 
 1 . 0040 
 
 I.05 
 
 1.0275 
 
 7.12 
 
 I. 0510 
 
 12.87 
 
 I 0745 
 
 18.49 
 
 1 . 0045 
 
 I. 18 
 
 1 .0280 
 
 7. 26 
 
 1-0515 
 
 12.99 
 
 I.075O 
 
 18.59 
 
 1 .0050 
 
 i-3i 
 
 1.0285 
 
 7-37 
 
 I .0520 
 
 13.12 
 
 I 0755 
 
 18.70 
 
 1-0055 
 
 1.44 
 
 1 .0290 
 
 7.48 
 
 I.0525 
 
 I3.24 
 
 I .0760 
 
 18.81 
 
 1 .0060 
 
 1.56 
 
 1-0395 
 
 7.60 
 
 I 0530 
 
 I3-36 
 
 I.0765 
 
 18.91 
 
 1 . 0065 
 
 1 .69 
 
 1.0300 
 
 7-7i 
 
 1-0535 
 
 I3-48 
 
 I.0770 
 
 19.02 
 
 1 . 0070 
 
 1.82 
 
 I -030 5 
 
 7.82 
 
 I . 0540 
 
 I3.6I 
 
 I0775 
 
 19. 12 
 
 1.0075 
 
 i-95 
 
 1. 0310 
 
 7-93 
 
 I 0545 
 
 13-73 
 
 T .O78O 
 
 I9.23 
 
 1 .0080 
 
 2.07 
 
 1-0315 
 
 8.04 
 
 I-0550 
 
 13-86 
 
 I.O785 
 
 19.33 
 
 1 .0085 
 
 2. 20 
 
 1.0320 
 
 8.16 
 
 IO555 
 
 I3-98 
 
 I .O79O 
 
 19.44 
 
 1 .0090 
 
 2-33 
 
 !032 5 
 
 8.27 
 
 I . 0560 
 
 14. 11 
 
 I-0795 
 
 19-56 
 
 1.0095 
 
 2.46 
 
 1.0330 
 
 8.40 
 
 1-0565 
 
 14.23 
 
 I O8OO 
 
 19.67 
 
 I .0100 
 
 2.58 
 
 I 0335 
 
 8-53 
 
 I.0570 
 
 I4-36 
 
 I.O8O5 ' 
 
 19.79 
 
 1. 0105 
 
 2.71 
 
 1.0340 
 
 8.67 
 
 LO575 
 
 74.49 
 
 I. 08lO 
 
 19.91 
 
 1 .01 10 
 
 2.84 
 
 J0345 
 
 8.80 
 
 I .0580 
 
 14.62 
 
 I. O8I5 
 
 20.03 
 
 1.0115 
 
 2.97 
 
 1-0350 
 
 8-94 
 
 I.0585 
 
 14-75 
 
 I .0820 
 
 20. 14 
 
 1 .0120 
 
 3.10 
 
 1-0355 
 
 9.07 
 
 I . 0590 
 
 14.89 
 
 I.0825 
 
 20.26 
 
 1-0125 
 
 3-23 
 
 1 . 0360 
 
 9. 21 
 
 1-0595 
 
 15.02 
 
 I .O83O 
 
 20.37 
 
 1. 0130 
 
 3-35 
 
 1-0365 
 
 9-34 
 
 I . 0600 
 
 15-14 
 
 LO835 
 
 20.48 
 
 i- OI 35 
 
 3-48 
 
 1.0370 
 
 9-45 
 
 I . 0605 
 
 1525 
 
 I . O84O 
 
 20.59 
 
 1 .0140 
 
 3-6i 
 
 1 0375 
 
 9-57 
 
 I .0610 
 
 1536 
 
 I.O845 
 
 20. 70 
 
 1. 0145 
 
 3-74 
 
 1.0380 
 
 9.69 
 
 I. 0615 
 
 15.47 
 
 I .O85O 
 
 20.8I 
 
 1. 0150 
 
 3-87 
 
 1-0385 
 
 9.81 
 
 I .0620 
 
 I5-58 
 
 I.0855 
 
 20.93 
 
 1-0155 
 
 4.00 
 
 1.0390 
 
 9.92 
 
 I.0625 
 
 1569 
 
 I . O86O 
 
 21 .06 
 
 1 .0160 
 
 4-13 
 
 !0395 
 
 10.04 
 
 I . 0630 
 
 15.80 
 
 I.0865 
 
 21 . 19 
 
 1. 0165 
 
 4.26 
 
 1 . 0400 
 
 10. 16 
 
 IO635 
 
 1592 
 
 I .O87O 
 
 21-33 
 
 1 .0170 
 
 4-39 
 
 1.0405 
 
 10.27 
 
 I . 0640 
 
 16.03 
 
 I.O875 
 
 21-43 
 
 1. 0175 
 
 4-53 
 
 1 .0410 
 
 10.40 
 
 I . 0645 
 
 16. 14 
 
 I.O88O 
 
 21-54 
 
 1 .0180 
 
 4.66 
 
 1-0415 
 
 10.52 
 
 I . 0650 
 
 16.25 
 
 I.O885 
 
 21 .64 
 
 1. 0185 
 
 4-79 
 
 1 . 0420 
 
 10.65 
 
 I 0655 
 
 16.37 
 
 I . O89O 
 
 21-75 
 
 1 .0190 
 
 4-93 
 
 1.0425 
 
 10.77 
 
 I . 0660 
 
 16.50 
 
 IO895 
 
 21.86 
 
 - 1. 0195 
 
 5.06 
 
 1.0430 
 
 10.90 
 
 I . 0665 
 
 16.62 
 
 I . 0900 
 
 21.98 
 
 1 . 0200 
 
 5.20 
 
 J0435 
 
 11.03 
 
 I .0670 
 
 16.74 
 
 I . 0905 
 
 22.08 
 
 1 .0205 
 
 5-33 
 
 1 . 0440 
 
 11. 15 
 
 I.0675 
 
 16.86 
 
 I .O9IO 
 
 22. 19 
 
 1 .0210 
 
 5-45 
 
 1.0445 
 
 11.28 
 
 I . 0680 
 
 16.99 
 
 I-09I5 
 
 22.30 
 
 1. 0215 
 
 5-57 
 
 1 . 0450 
 
 11 .40 
 
 I.0685 
 
 17. 11 
 
 I .0920 
 
 22.41 
 
 1 .0220 
 
 5 70 
 
 1 0455 
 
 1 1 ■ 53 
 
 I . 0690 
 
 17.23 
 
 I . 0925 
 
 22.52 
 
 1 .0225 
 
 5-82 
 
 1 . 0460 
 
 11.65 
 
 1.0695 
 
 17-35 
 
 I . O93O 
 
 22.63 
 
 1 .0230 
 
 5-94 
 
 1.0465 
 
 11.77 
 
 I .0700 
 
 17.48 
 
 I 0935 
 
 22.73 
 
250 
 
 APPENDIX A. 
 
 Table XIII. — Continued. 
 
 EXTRACT IN BEER-WORT. 
 (According to Schultz and Ostermann.) 
 
 Specific 
 
 Extract. 
 
 Specific 
 
 Extract. 
 
 Specific 
 
 Extract. 
 
 Specific 
 
 Extract. 
 
 Gravity at 
 
 Per cent. 
 
 Gravity at 
 
 Per cent 
 
 Gravity at 
 
 Per cent. 
 
 Gravity at 
 
 Per cent. 
 
 . ..5°C. 
 
 by Weight. 
 
 15° C. 
 
 by Weight. 
 
 15° L- 
 
 by Weight 
 
 15° C. 
 
 by Weight. 
 
 I . 0940 
 
 22.84 
 
 I . I020 
 
 24-53 
 
 I . I IOO 
 
 26. 27 
 
 1. 1 180 
 
 27.88 
 
 1-0945 
 
 22.94 
 
 I. 1025 
 
 24.64 
 
 I.IIO5 
 
 26.37 
 
 1.1185 
 
 27.98 
 
 1.0950 
 
 23-05 
 
 I . IO3O 
 
 24-74 
 
 I . II IO 
 
 26.48 
 
 I . 1 1 90 
 
 28.09 
 
 1-0955 
 
 23.16 
 
 I • IO35 
 
 24.85 
 
 I.III5 
 
 26.58 
 
 1. "95 
 
 28.19 
 
 I . 0960 
 
 23.27 
 
 I . IO40 
 
 24.96 
 
 I . 1 1 20 
 
 26.68 
 
 1 . 1 200 
 
 28.28 
 
 I.0965 
 
 23-37 
 
 I . IO45 
 
 25.07 
 
 I.II25 
 
 26.79 
 
 1-1205 
 
 28.38 
 
 I .0970 
 
 23.48 
 
 I . 1050 
 
 25.18 
 
 I. 1 130 
 
 26.89 
 
 1 . 1210 
 
 28.48 
 
 I.0975 
 
 23-59 
 
 I IO55 
 
 25.29 
 
 I.II35 
 
 26.99 
 
 1.1215 
 
 28.58 
 
 I . 0980 
 
 23.69 
 
 I . IO60 
 
 25.40 
 
 I . I I40 
 
 27.09 
 
 1 . 1220 
 
 28.68 
 
 I . 0985 
 
 23.80 
 
 I. IO65 
 
 25-50 
 
 I- 1 145 
 
 27.19 
 
 1. 1225 
 
 28.78 
 
 I . 0990 
 
 23.90 
 
 I . IO70 
 
 25.61 
 
 I.II50 
 
 27.29 
 
 1 . 1230 
 
 28.88 
 
 I.0995 
 
 24.01 
 
 I. IO75 
 
 25-71 
 
 III55 
 
 27.38 
 
 1 1235 
 
 28.98 
 
 I . IOOO 
 
 24. 1 1 
 
 I . IO80 
 
 25.82 
 
 I . I l6o 
 
 27.48 
 
 1 . 1 240 
 
 29.08 
 
 I. 1005 
 
 24.21 
 
 I . IO85 
 
 25-93 
 
 I.H65 
 
 27.58 
 
 1. 1245 
 
 29.18 
 
 I . IOIO 
 
 24.32 
 
 I . IO90 
 
 26.05 
 
 I . 1 1 70 
 
 27.68 
 
 1. 1250 
 
 29. 28 
 
 1.1015 
 
 24-43 
 
 I . IO95 
 
 26. 16 
 
 III75 
 
 27.78 
 
 L1255 
 
 29.38 
 
APPENDIX A. 
 LOGARITHMS OF NUMBERS. 
 
 251 
 
 It « 
 
 
 
 
 
 
 
 
 
 
 
 Proportional Parts. 
 
 £j3 
 
 
 
 1 
 
 2 
 
 3 ' 
 
 4 
 
 5 
 
 
 
 7 
 
 8 
 
 9 
 
 
 
 2 £ 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 i 7 
 
 8 
 
 9 
 
 IO 
 
 0000 
 
 0043 
 
 0086 
 
 0128 
 
 0170 
 
 1 I 
 0212 0253 0294 
 
 0334 
 
 0374 
 
 4 
 
 S 
 
 1 2 
 
 17 
 
 21 
 
 25!2g 
 
 33 
 
 37 
 
 II 
 
 0414 
 
 0453 
 
 0492 
 
 0531 
 
 0569 
 
 0607 
 
 0645 0682 
 
 0719 
 
 0755 
 
 4 
 
 8 
 
 1 1 
 
 15 
 
 19 
 
 23 
 
 26 
 
 30 
 
 34 
 
 12 
 
 0792 
 
 0828 
 
 0864 
 
 0899 
 
 0934 
 
 0969 
 
 1004 1038 
 
 1072 
 
 1 106 
 
 J 
 
 7 
 
 10 
 
 14 
 
 1 
 
 21 
 
 24 
 
 28 
 
 3i 
 
 13 
 
 "39 
 
 ii73 
 
 1206 
 
 1239 
 
 1271 
 
 1303 
 
 1335 1367 
 
 1399 
 
 1430 
 
 3 
 
 6 
 
 10 
 
 13 
 
 IC 
 
 19 
 
 23 
 
 26 
 
 29 
 
 14 
 
 1461 
 
 1492 
 
 1523 
 
 1553 
 
 1584 
 
 1614 
 
 1644 
 
 ( X6 73 
 
 1703 
 
 1732 
 
 3 
 
 6 
 
 9 
 
 1 2 
 
 is 
 
 18 
 
 21 
 
 24 
 
 27 
 
 15 
 
 1761 
 
 1790 
 
 1818 
 
 1847 
 
 1875 
 
 1903 
 
 1931 
 
 1 
 ,1959 
 
 1987 
 
 2014 
 
 3 
 
 6 
 
 8 
 
 1 1 
 
 14 
 
 17 
 
 20 
 
 22 
 
 25 
 
 16 
 
 2041 
 
 2068 
 
 2095 
 
 2122 
 
 2148 
 
 2175 
 
 2201 
 
 ^227 
 
 2253 
 
 2279 
 
 3 
 
 5 
 
 8 
 
 11 
 
 13 
 
 16 
 
 18 
 
 21 
 
 24 
 
 17 
 
 2304 
 
 2330 
 
 2355 
 
 2380 
 
 2405 
 
 2430 
 
 2455 
 
 2480 
 
 2504 
 
 2529 
 
 2 
 
 5 
 
 7 
 
 10 
 
 1 2 
 
 |- IS 
 
 17 
 
 20 
 
 22 
 
 18 
 
 2553 
 
 2577 
 
 2601 
 
 2625 
 
 2648 
 
 2672 
 
 2695 
 
 2718 
 
 2742 
 
 2765 
 
 2 
 
 5 
 
 7 
 
 9 
 
 1 2 
 
 14 
 
 16 
 
 19 
 
 21 
 
 19 
 
 2788 
 
 2810 
 
 2833 
 
 2856 
 
 2878 
 
 2900 
 
 2923 
 
 2945 
 
 2967 
 
 2989 
 
 2 
 
 4 
 
 7 
 
 9 
 
 1 1 
 
 13 
 
 16 
 
 18 
 
 20 
 
 20 
 
 3010 
 
 3032 
 
 3054 
 
 3075 
 
 3096 
 
 3n8 
 
 3i39 
 
 3l60 
 
 3181 
 
 3201 
 
 2 
 
 4 
 
 6 
 
 8 
 
 1 
 
 13 
 
 15 
 
 17 
 
 19 
 
 21 
 
 3222 
 
 3243 
 
 3263 
 
 3284 
 
 3304 
 
 3324 
 
 3345 
 
 33 6 5 
 
 3385 
 
 3404 
 
 2 
 
 4 
 
 6 
 
 8 
 
 10 
 
 12 
 
 14 
 
 16 
 
 18 
 
 22 
 
 3424 
 
 3444 
 
 34 6 4 
 
 3483 
 
 3502 
 
 3522 
 
 354i 
 
 356o 
 
 3579 
 
 3598 
 
 2 
 
 4 
 
 6 
 
 8 
 
 10 
 
 1 2 
 
 14 
 
 15 
 
 17 
 
 23 
 
 3617 
 
 3636 
 
 3655 
 
 3674 
 
 3692 
 
 37" 
 
 3729 
 
 3747 
 
 3766 
 
 3784 
 
 2 
 
 4 
 
 6 
 
 7 
 
 9 
 
 1 1 
 
 13 
 
 IS 
 
 17 
 
 24 ' 
 
 3802 
 
 3820 
 
 3838 
 
 3856 
 
 3874 
 
 3892 
 
 3909 
 
 3927 
 
 3945 
 
 3962 
 
 2 
 
 4 
 
 5 
 
 7 
 
 9 
 
 1 1 
 
 1 2 
 
 14 
 
 16 
 
 25 
 
 3979 
 
 3997 
 
 4014 
 
 4031 '4048 
 
 4065 
 
 4082 
 
 4099 
 
 4116 
 
 4133 
 
 2 
 
 3 
 
 5 
 
 7 
 
 9 
 
 10 
 
 12 
 
 14 
 
 1 5 
 
 26 
 
 4150 
 
 4166 
 
 4183 
 
 4200 4216 
 
 4232 l 4 249 , 4265 
 
 4281 
 
 4298 
 
 2 
 
 3 
 
 5 
 
 7 
 
 8 
 
 10 
 
 11 
 
 13 
 
 15 
 
 27 
 
 4314 
 
 4330 
 
 4346 
 
 4362 4378 
 
 4393 
 
 4409 4425 4440 
 
 4456 
 
 2 
 
 3 
 
 5 
 
 
 
 8 
 
 9 
 
 1 1 
 
 13 
 
 14 
 
 28 
 
 4472 
 
 4487 
 
 4502 
 
 4518 4533 
 
 4548 
 
 4564 4579 4594 
 
 4609 
 
 2 
 
 3 
 
 5 
 
 6 
 
 8 
 
 9 
 
 1 1 
 
 12 
 
 14 
 
 29 
 
 4624 
 
 4639 
 
 4654 
 
 4669 4683 
 
 4698 
 
 47134728 
 
 4742 
 
 4757 
 
 I 
 
 3 
 
 4 
 
 
 
 7 
 
 9 
 
 10 
 
 12 
 
 13 
 
 30 
 
 477i 
 
 4786 
 
 4800 
 
 4814 
 
 4829 
 
 4843 
 
 4857 
 
 4871 
 
 4886 
 
 4900 
 
 
 3 
 
 4 
 
 6 
 
 7 
 
 9 
 
 10 
 
 1 1 
 
 13 
 
 31 
 
 +914 
 
 49284942 
 
 4955 4969 
 
 4983 
 
 4997 501 1 
 
 5024 
 
 5038 
 
 
 3 
 
 4 
 
 
 
 7 
 
 8 io 
 
 11 
 
 12 
 
 32 
 
 5051 
 
 50655079 
 
 5092 5105 
 
 5ii9 
 
 51325145 
 
 5i59 
 
 5172 
 
 
 3 
 
 4 
 
 5 
 
 7 
 
 8 
 
 9 
 
 11 
 
 12 
 
 33 
 
 5i85 
 
 5198 5211 
 
 52245237 
 
 5250 
 
 52635276 
 
 5289 
 
 5302 
 
 
 3 
 
 4 
 
 5 
 
 6 
 
 8 
 
 9 
 
 10 
 
 12 
 
 34 
 
 5315 
 
 5328.5340 
 
 5353 5366 
 
 5378 
 
 539i 
 
 5403 
 
 54i6 
 
 5428 
 
 
 3 
 
 4 
 
 5 
 
 6 
 
 8 
 
 9 
 
 10 
 
 11 
 
 35 
 
 544i 
 
 5453^465 
 
 5478 5490 
 
 5502 
 
 55H 
 
 5527 
 
 5539 
 
 555i 
 
 
 2 
 
 4 
 
 5 
 
 6 
 
 7 
 
 , 
 
 10 
 
 11 
 
 36 
 
 5563 
 
 55755587 
 
 5599 561 1 
 
 5623 
 
 5635 
 
 5647 
 
 5658 
 
 5670 
 
 
 2 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 1 
 
 11 
 
 37 
 
 5682 
 
 5694 57°5 
 
 5717 
 
 5729 
 
 5740 
 
 5752 
 
 5763 
 
 5775 
 
 5786 
 
 
 2 
 
 3 
 
 5 
 
 6 
 
 » 
 
 8 
 
 9 
 
 10 
 
 38 
 
 5798 
 
 58095821 
 
 5832 
 
 5843 
 
 5855 
 
 5866 
 
 5877 5888 
 
 5899 
 
 
 2 
 
 3 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 39 
 
 59i 1 
 
 5922 
 
 5933 
 
 5944 
 
 5955 
 
 5966 
 
 5977 
 
 5988 5999 
 
 6010 
 
 
 2 
 
 3 
 
 4 
 
 5 
 
 7 
 
 8 
 
 9 
 
 10 
 
 40 
 
 6021 
 
 6031 
 
 6042 
 
 6053 
 
 6064 
 
 6075 
 
 6085 
 
 6096 
 
 6107 
 
 6117 
 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 8 
 
 9 
 
 IO- 
 
 4i 
 
 6128 
 
 6138 6149 
 
 61606170 
 
 6180 
 
 6191 
 
 6201 
 
 6212 
 
 6222 
 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 42 
 
 6232 
 
 6243^253 
 
 6263 
 
 6274 
 
 6284 
 
 6294 
 
 6304 
 
 63H 
 
 6325 
 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 43 
 
 6335 
 
 6345 
 
 6355 
 
 6365 
 
 6375 
 
 6385 
 
 6395 
 
 6405 
 
 6415 
 
 6425 
 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 44 
 
 6435 
 
 6444 
 
 6454 
 
 6464 
 
 6474 
 
 6484 
 
 6493 
 
 6503 
 
 65X3 
 
 6522 
 
 
 2 
 
 3 
 
 4 
 
 ' 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 45 
 
 6532 
 
 6542 
 
 6551 
 
 6561 
 
 6571 
 
 6580 
 
 6590 
 
 6599 
 
 6609 
 
 6618 
 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 46 
 
 6628 
 
 6637 
 
 6646 
 
 6656 
 
 6665 
 
 6675 
 
 6684 
 
 6693 6702 
 
 6712 
 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 7 
 
 8 
 
 47 
 
 S721 
 
 6730 
 
 6739 
 
 6749 
 
 6758 
 
 6767 
 
 67761678516794 
 
 6803 
 
 
 2 
 
 3 
 
 4 
 
 5 
 
 5 
 
 6] 
 
 7 
 
 8 
 
 48 
 
 6812 
 
 6821 
 
 6830 
 
 6839 
 
 6848 
 
 6857 
 
 68666875 6884 
 
 6893 
 
 
 2 
 
 3 
 
 4 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 49 
 
 6902 
 
 691 1 
 
 6920 
 
 6928 
 
 6937 
 
 6946 
 
 6955 
 
 6964 
 
 6972 
 
 6981 
 
 
 2 
 
 3 
 
 - 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 50 
 
 6990 
 
 6998 
 
 7007 
 
 7016 
 
 7024 
 
 7033 
 
 7042 
 
 7050 
 
 7059 
 
 7067 
 
 
 2 
 
 3 
 
 3 
 
 4 
 
 s 
 
 6 
 
 7 
 
 8 
 
 5i 
 
 7076 
 
 7084 
 
 7093 
 
 7101 
 
 7110 
 
 7118 
 
 7126 
 
 7135 
 
 7143 
 
 7152 
 
 
 2 
 
 3 
 
 3 
 
 4 
 
 5 
 
 6 1 7 
 
 8 
 
 52 
 
 7160 
 
 7168 
 
 7177 
 
 7185 
 
 7i93 
 
 7202 
 
 7210 
 
 7218 
 
 7226 
 
 7235 
 
 
 2 
 
 2 
 
 3 
 
 4 
 
 .5 
 
 61 7 
 
 7 
 
 53 
 
 7243 
 
 7251 
 
 7259 
 
 7267 
 
 7275 
 
 7284 
 
 7292 
 
 7300 
 
 73o8 
 
 73I 6 
 
 
 2 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 6 
 
 7 
 
 54 
 
 7324 
 
 7332 
 
 7340 
 
 7348 7356 
 
 7364 
 
 7372 
 
 738o l 7388f73 9 6 
 
 I 2 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 1 
 
 6 
 
 7 
 
*D* 
 
 
 
 
 APPENDIX A. 
 LOGARITHMS OF NUMBERS. 
 
 
 <a 
 
 *<3 u 
 
 
 
 
 
 
 
 
 
 
 Proportional Parts. 
 
 Ca 
 
 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 
 2 E 
 
 
 
 
 
 
 
 
 
 
 12 3 4 
 
 5 6 7 8 9 
 
 55 
 
 7404 
 
 7412 
 
 74i9 
 
 7427 
 
 7435 
 
 7442 
 
 745i 
 
 7455 
 
 7466 
 
 » 7474 1223 
 
 4SS67 
 
 56 
 
 7482 
 
 749c 
 
 7497 
 
 7505 
 
 7513 
 
 752C 
 
 7528 
 
 753^ 
 
 7542 
 
 755i 1223 
 
 4 5 5 6 7 
 
 57 
 
 7559 
 
 7566 
 
 7574 
 
 7582 
 
 7589 
 
 7597 
 
 7604 
 
 7612 
 
 7615 
 
 7627 I 2 3 
 
 4 5 67 
 
 58 
 
 7634 
 
 7642 
 
 7649 
 
 7657 
 
 7664 
 
 7672 
 
 7679 
 
 7686 
 
 7694 
 
 77°i 1 1 2 3 
 
 4 4 5 7 
 
 59 
 
 7709 
 
 7716 
 
 7723 
 
 773i 
 
 7738 
 
 7745 
 
 7752 
 
 7760 
 
 7767 
 
 7774 1 1 2 3 
 
 4 4 5 6 7 
 
 60 
 
 7782 
 
 7789 
 
 77967803 
 
 7810 
 
 7818 
 
 7825 
 
 7832 
 
 7839 
 
 7846 1 2 3 
 
 4 4 5 6 6 
 
 61 
 
 7853 
 
 7860 
 
 78687875 
 
 7882 
 
 7889 
 
 7896 
 
 7903 
 
 7910 
 
 7917 112 
 
 4 4 5 6 6 
 
 62 
 
 7924 
 
 793i 
 
 7938i7945 
 
 7952 
 
 7959 
 
 7966 
 
 7973 
 
 7980 
 
 7987 1 1 2 3 
 
 3 4 5 6 6 
 
 63 
 
 7993 
 
 8000 
 
 8007 8014 
 
 8021 
 
 8028 
 
 8035 
 
 8041 
 
 8048 
 
 8055 1 1 2 3 
 
 3 4 5 5 6 
 
 64 
 
 8062 
 
 8069 
 
 80758082 
 
 8089 
 
 8096 
 
 8102 
 
 8109 
 
 8116 
 
 8122 1 1 2 3 
 
 3 4 5 5 6 
 
 65 
 
 8129 
 
 8136 
 
 8i42'8i49 
 
 8156 
 
 8162 
 
 8169 
 
 8176 
 
 8182 
 
 8189 1 1 2 3 
 
 3 4 5 5 6 
 
 66 
 
 8i95 
 
 8202 
 
 8209:8215 
 
 8222 
 
 8228 
 
 8235I8241 
 
 8248 
 
 8254 1 1 2 3 
 
 3 4 5 5 6 
 
 67 
 
 8261 
 
 8267 
 
 8274I8280 
 
 8287 
 
 8293 
 
 8299 
 
 8306 
 
 8312 
 
 8319 1 1 2 3 
 
 3 4 5 5 6 
 
 68 
 
 8325 
 
 8331 
 
 8338|8 3 44 
 
 835i 
 
 83578363 
 
 8370 
 
 8376 
 
 8382 1 1 2 3 
 
 3 4 4 5 6 
 
 69 
 
 8388 
 
 8395 
 
 8401 8407 
 
 8414 
 
 8420 8426 
 
 8432 
 
 8439 
 
 8445 1 1 2 2 
 
 3 4 4 5 6 
 
 70 
 
 8451 
 
 8457 
 
 846318470 
 
 8476 
 
 8482 8488 
 
 8494 
 
 8500 
 
 8506 1 1 2 2 
 
 3 4 4 5 6 
 
 7i 
 
 8513 
 
 8519 
 
 85258531 
 
 8537 
 
 8543'8549 
 
 8555 
 
 8561 
 
 8567 1 1 2 2 
 
 3 4 4 5 5 
 
 72 
 
 8573 
 
 8579 
 
 85858591 
 
 8597 
 
 8603 
 
 8609 
 
 8615 
 
 8621 
 
 8627 1 1 2 2 
 
 3 4 4 5 5 
 
 73 
 
 8633 
 
 8639 
 
 864 5 |86 5 i 
 
 8657 
 
 8663 ! 8669 
 
 8675 
 
 8681 
 
 8686 1 1 2 2 
 
 3 4 4 5 5 
 
 74 
 
 8692 
 
 8698 
 
 8704 
 
 8710 
 
 8716 
 
 87228727 
 
 8733 
 
 8739 
 
 8745 x x 2 2 
 
 3 4 4 5 5 
 
 75 
 
 875i 
 
 8756 
 
 8762 
 
 8768 
 
 8774 
 
 8779 
 
 8785 
 
 8791 
 
 8797 
 
 8802 1 1 2 2 
 
 3 3 4 5 5 
 
 76 
 
 8808 
 
 881488208825 
 
 8831 
 
 8837 
 
 8842 
 
 8848 
 
 8854 
 
 8859 1 1 2 2 
 
 3 3 4 5 5 
 
 77 
 
 8865 
 
 8871 
 
 88768882 
 
 8887 
 
 8893 
 
 8899 
 
 8904 
 
 8910 
 
 8915 1 1 2 2 
 
 3 3 4 4 5 
 
 78 
 
 8921 
 
 8927 
 
 89328938 
 
 8943 
 
 8949 
 
 8954 
 
 8960 
 
 8965 
 
 8971 i 1 2 2 
 
 3 3 4 4 5 
 
 79 
 
 8976 
 
 8982 
 
 89878993 
 
 8998 
 
 9004 
 
 9009 
 
 9015 
 
 9020 
 
 9026 1 1 2 2 
 
 3 3 4 4 5 
 
 80 
 
 9031 
 
 9036 
 
 9042 9047 
 
 9053 
 
 9058 
 
 9063 
 
 9069 
 
 9074 
 
 9079 1 1 2 2 
 
 3 3 4 4 5 
 
 81 
 
 9085 
 
 9090 
 
 9096 9 10 1 
 
 9106 
 
 9112 
 
 9117 
 
 9122 
 
 9128 
 
 9133 x x 2 2 
 
 3 3 4 4 5 
 
 82 
 
 9138 
 
 9143 
 
 9H99I54 
 
 9159 
 
 9165 
 
 9170 
 
 9*75 
 
 9180 
 
 9186 1 1 2 2 
 
 3 3 4 4 5 
 
 83 
 
 9191 
 
 9196 
 
 9201 9206 
 
 9212 
 
 9217 
 
 9222 
 
 9227 
 
 9232 
 
 9238 1 1 2 2 
 
 3 3 4 4 5 
 
 84 
 
 9243 
 
 9248 
 
 9253 
 
 9258 
 
 9263 
 
 9269 
 
 9274 
 
 9279 
 
 9284 
 
 9289 1 1 2 2 
 
 3 3 4 4 5 
 
 85 
 
 9294 
 
 9299 
 
 9304 
 
 93°9 
 
 93 J 5 
 
 9320 
 
 9325 
 
 9330 
 
 9335 
 
 9340 1 1 2 2 
 
 3 3 4 4 5 
 
 86 
 
 9345 
 
 9350 
 
 9355 
 
 9360 
 
 93 6 5 
 
 9370 
 
 9375 
 
 9380 
 
 9385 
 
 9390 1 1 2 2 
 
 3 3 4 4 5 
 
 87 
 
 9395 
 
 9400 
 
 9405 
 
 9410 
 
 9415 
 
 9420 
 
 9425 
 
 9430 
 
 9435 
 
 9440 1 1 2 
 
 2 3 3 4 4 
 
 88 
 
 9445 
 
 9450 
 
 9455 
 
 9460 
 
 9465 
 
 9469 
 
 9474 
 
 9479 
 
 9484 
 
 9489 1 1 2 
 
 2 3 3 4 4 
 
 89 
 
 9494 
 
 9499 
 
 95°4 
 
 9509 
 
 9513 
 
 95i8 
 
 9523 
 
 9528 
 
 9533 
 
 9538 1 1 2 
 
 2 3 3 4 4 
 
 90 
 
 9542 
 
 9547 
 
 9552 
 
 9557 
 
 9562 
 
 9566 
 
 957i 
 
 9576 
 
 958i 
 
 9586 1 1 2 
 
 2 3 3 4 4 
 
 9i 
 
 9590 
 
 9595 
 
 9600 
 
 9605 
 
 9609 
 
 9614 
 
 9619 
 
 9624 
 
 9628 
 
 9633 1 1 2 
 
 2 3 | 3 4 4 
 
 92 
 
 9638 
 
 9643 
 
 9647 
 
 9652 
 
 9657 
 
 9661 
 
 9666 
 
 9671 
 
 9675 
 
 9680 1 1 2 
 
 2 3 3 4 4 
 
 93 
 
 9685 
 
 9689 
 
 9694 
 
 9699 
 
 9703 
 
 9708 
 
 9713 
 
 9717 
 
 9722 
 
 9727 1 1 2 
 
 2 3 3 4 4 
 
 94 
 
 973i 
 
 9736 
 
 974i 
 
 9745 
 
 9750 
 
 9754 
 
 9759 
 
 9763 
 
 9768 
 
 9773 1 1 2 
 
 2 3 3 4 4 
 
 95 
 
 9777 
 
 9782 
 
 9786 
 
 9791 
 
 9795 
 
 9800 
 
 9805 
 
 9809 
 
 9814 
 
 9818 1 1 2 
 
 2 3 3 4 4 
 
 96 
 
 9823 
 
 9827 
 
 9832 
 
 9836 
 
 9841 
 
 9845 
 
 9850 
 
 9 8 54 
 
 9859 
 
 9863 1 1 2 
 
 2 3 3 4 4 
 
 97 
 
 9868 
 
 9872 
 
 9877 
 
 9881 
 
 9886 
 
 9890 
 
 9894 
 
 9899 
 
 9903 
 
 9908 1 1 2 
 
 2 3 3 4 4 
 
 98 
 
 9912 
 
 9917 
 
 9921 
 
 9926 
 
 9930 
 
 9934 
 
 9939 
 
 9943 
 
 9948 
 
 9952 1 1 2 
 
 2 3 3 4 4 
 
 99 
 
 9956 
 
 9961 
 
 9965 9969 
 
 9974 
 
 9978 
 
 998^ 
 
 9987 
 
 999i 
 
 9996 1 1 2 
 
 2 3 3 3 4 
 

 
 
 
 
 
 APPENDIX A. 
 
 
 253 
 
 ANTILOGARITHMS. 
 
 
 
 
 
 
 
 
 
 
 
 Proportional Paits. 
 
 ki 
 
 
 
 1 
 
 2 
 
 2 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 
 O >- 
 
 t-1 
 
 12 3 4 
 
 5 6 7 8 9 
 
 .OO 
 
 1000 
 
 1002 
 
 1005 
 
 1007 
 
 1009 
 
 1012 
 
 IOli 
 
 1016 
 
 IOIC 
 
 1021 1 1 
 
 x 1 2 2 2 
 
 .01 
 
 1023 
 
 1026 
 
 1028 
 
 1030 
 
 1033 
 
 1035 
 
 io 3 £ 
 
 1040 
 
 1042 
 
 1045 1 1 
 
 1122a 
 
 .02 
 
 1047 
 
 1050 
 
 1052 
 
 io 54 
 
 1057 
 
 1059 
 
 1062 
 
 1064 
 
 1067 
 
 1069 001 1 
 
 1 1 2 2 a 
 
 .03 
 
 1072 
 
 1074 
 
 1076 
 
 1079 
 
 1081 
 
 1084 
 
 1086 
 
 1089 
 
 1091 
 
 1094 1 i 
 
 1 1 2 2 3 
 
 .04 
 
 1096 
 
 1099 
 
 1 102 
 
 1 104 
 
 1 107 
 
 1 109 
 
 III2 
 
 1 1 14 
 
 1117 
 
 1 1 19 1 1 1 
 
 12222 
 
 .05 
 
 1122 
 
 1125 
 
 1127 
 
 1 1 30 
 
 1132 
 
 1135 
 
 1138 
 
 1 140 
 
 1143 II 46 I I I 
 
 12 2 2 2 
 
 .06 
 
 114811151 
 
 1153 
 
 1 1 56 
 
 1159 
 
 1161 
 
 I 164 
 
 1167 
 
 1169 1172 I I I 
 
 12 2 2 2 
 
 .07 
 
 1175J1178 
 
 1 180 
 
 "83 
 
 1186 
 
 1189 
 
 II9I 
 
 1194 
 
 1197 11991 I I I 
 
 12 2 2 2 
 
 .08 
 
 1202 1205 
 
 1208 
 
 1211 
 
 1213 
 
 1216 
 
 1219 
 
 1222 
 
 1225 
 
 1227I0 1 1 1 
 
 12 3 2 3 
 
 .09 
 
 1230 1233 
 
 1236 
 
 1239 
 
 1242 
 
 1245 
 
 1247 
 
 1250 
 
 1253 
 
 1 256J 1 1 1 
 
 12 2 2 3 
 
 .IO 
 
 1259 
 
 1262 
 
 1265 
 
 1268 
 
 1271 
 
 1274 
 
 1276 
 
 1279 
 
 1282 
 
 1285 1 1 1 
 
 12 2 2 3 
 
 .11 
 
 1288 
 
 1291 
 
 1294 
 
 1297 
 
 1300 
 
 i3°3 
 
 I306 
 
 1309 
 
 1312 
 
 1315 1 1 1 
 
 2 2 2 2 3 
 
 .12 
 
 1318 
 
 1321 
 
 1324 
 
 1327 
 
 1330 
 
 1334 
 
 1337 
 
 1340 
 
 1343 
 
 1346 1 1 1 
 
 2 2 2 2 3 
 
 .13 
 
 1349 
 
 1352 
 
 1355 
 
 1358 
 
 1361 
 
 1365 
 
 I368 
 
 1371 
 
 1374 
 
 1377 1 1 1 
 
 2 2 2 3 3 
 
 .14 
 
 1380 
 
 1384 
 
 1387 
 
 1390 
 
 1393 
 
 1396 
 
 I4OO 
 
 i4°3 
 
 1406 
 
 1409 1 1 1 
 
 2 2 2 3 3 
 
 .15 
 
 H J 3 
 
 1416 
 
 1419 
 
 1422 
 
 1426 
 
 1429 
 
 1432 
 
 H35 
 
 1439 
 
 1442 1 1 1 
 
 2 2 2 3 3 
 
 .16 
 
 1445 
 
 1449 
 
 1452 
 
 1455 
 
 1459 
 
 1462 
 
 I466 
 
 1469 
 
 1472 
 
 1476 1 1 1 
 
 22233 
 
 .17 
 
 1479 
 
 1483 
 
 i486 
 
 1489 
 
 1493 
 
 1496 
 
 I5OO 
 
 1503 
 
 1507 
 
 1510 1 1 1 
 
 2 2 2 3 3 
 
 .18 
 
 1514 
 
 1517 
 
 1521 
 
 1524 
 
 1528 
 
 1531 
 
 1535 
 
 1538 
 
 1542 
 
 1545 1 1 1 
 
 2 2 2 3 3 
 
 .19 
 
 1549 
 
 1552 
 
 1556 
 
 1560 
 
 1563 
 
 1567 
 
 I570 
 
 1574 
 
 1578 
 
 1581 o- I I I 
 
 22333 
 
 .20 
 
 1585 
 
 1589 
 
 1592 
 
 1596 
 
 1600 
 
 1603 
 
 1607 
 
 1611 
 
 1614 
 
 1618 1 1 1 
 
 22333 
 
 .21 
 
 1622 
 
 1626 
 
 1629 
 
 1633 
 
 1637 
 
 1641 
 
 1644 
 
 1648 
 
 1652 
 
 1656 1 1 2 
 
 2 2 3 3 3 
 
 .22 
 
 1660 
 
 1663 
 
 1667 
 
 1671 
 
 1675 
 
 1679 
 
 1683 
 
 1687 
 
 1690 
 
 1694 1 1 2 . 
 
 2 2 3 3 3 
 
 .23 
 
 1698 
 
 1702 
 
 1706 
 
 1710 
 
 1714 
 
 1718 
 
 1722 
 
 1726 
 
 173° 
 
 1734 1 1 2 . 
 
 '2334 
 
 •24 
 
 1738 
 
 1742 
 
 1746 
 
 I750 
 
 1754 
 
 1758 
 
 1762 
 
 1766 
 
 1770 
 
 1774 1 1 2 5 
 
 •2334 
 
 .25 
 
 1778 
 
 1782 
 
 1786 
 
 1791 
 
 1795 
 
 1799 
 
 1803 
 
 1807 
 
 1811 
 
 1816 1 1 2 : 
 
 '2334 
 
 .26 
 
 1820 
 
 1824 
 
 1828 
 
 1832 
 
 1837 
 
 1841 
 
 1845 
 
 1849 
 
 1854 
 
 T858 1 1 2 2 
 
 3 3 3 4 
 
 -27 
 
 1862 
 
 1866 
 
 1871 
 
 1875 
 
 1879 
 
 1884 
 
 1888 
 
 1892 
 
 1897 
 
 19OI 1 1 2 2 
 
 3 3 3 4 
 
 .28 
 
 i9°5 
 
 1910 
 
 1914 
 
 1919 
 
 1923 
 
 1928 
 
 1932 
 
 1936 
 
 1 941 
 
 1945 x 1. a s 
 
 3 3 4 4 
 
 .29 
 
 1950 
 
 1954 
 
 1959 
 
 1963 
 
 1968 
 
 1972 
 
 1977 
 
 1982 
 
 1986 
 
 1 99 I 1 1 2 5 
 
 3 3 4 4 
 
 .30 
 
 1995 
 
 2000 
 
 2004 
 
 7009 
 
 2014 
 
 2018 
 
 2023 
 
 2028 
 
 2032 
 
 2037 1 1 2 2 
 
 3 3 4 4 
 
 .31 
 
 2042 
 
 2046 
 
 2051 
 
 2056 
 
 2061 
 
 2065 
 
 2070 
 
 2075 
 
 2080 
 
 2084 1 1 2 1 
 
 3 3 4 4 
 
 -32 
 
 2089 
 
 2094 
 
 2099 
 
 2104 
 
 2109 
 
 2113 
 
 2Il8 
 
 2123 
 
 2128 
 
 2133 1 1 22 
 
 3 3 4 4 
 
 •33 
 
 2138 
 
 2143 
 
 2148 
 
 2153 
 
 2158 
 
 2163 
 
 2l68 
 
 2173 
 
 2178 
 
 2183 1 1 2 2 
 
 3 3 4 4 
 
 • 34 
 
 2188 
 
 2193 
 
 219^ 
 
 2203 
 
 2208 
 
 2213 
 
 2218 
 
 2223 
 
 2228 
 
 2234 1 1 2 2 3 
 
 3 4 1 4 5 
 
 • 35 
 
 2239 
 
 2244 
 
 2249 
 
 2254 
 
 2259 
 
 2265 
 
 2270 
 
 2275 
 
 2280 
 
 2286 1 1 2 2 3 
 
 3 4 4 5 
 
 .36 
 
 2291 
 
 2296 
 
 2301 
 
 2307 
 
 2312 
 
 2317 
 
 2323 
 
 2328 
 
 2333 
 
 2339 1 1 2 2 3 
 
 3 4 4 5 
 
 • 37 
 
 2344 
 
 2350 
 
 2355 
 
 2360 
 
 2366 
 
 2371 
 
 2377 
 
 2382 
 
 2388 
 
 2393 1 1 2 2 ; 
 
 3 4 4 5 
 
 .38 
 
 2399 
 
 2404 
 
 24 1 c 
 
 Hi5 
 
 2421 
 
 2427 
 
 2432 
 
 2438 
 
 2443 
 
 2449 1 1 2 2 ; 
 
 3 4 4 5 
 
 • 39 
 
 2455 
 
 2460 
 
 246C 
 
 2472 
 
 2477 
 
 2483 
 
 2489 
 
 2495 
 
 2500 
 
 2506 1 1 2 2 ; 
 
 3 4 5 5 
 
 .40 
 
 2512 
 
 2518 
 
 2522 
 
 2529 
 
 2535 
 
 2541 
 
 2547 
 
 2553 
 
 2559 
 
 -564 1 1 2 2 ; 
 
 4 4 5 5 
 
 .41 
 
 2570 
 
 2576 
 
 2582 
 
 2588 
 
 2594 
 
 2600 
 
 2606 
 
 2612 
 
 2618 
 
 2624 j ! 2 2 
 
 5 4 4 5 5 
 
 .42 
 
 2630 
 
 2636 
 
 2642 
 
 2649 
 
 2655 
 
 2661 
 
 2667 
 
 2673 
 
 2679 
 
 2685 1 1 2 2 . 
 
 5 4 4 5 <•> 
 
 •43 
 
 2692 
 
 2698 
 
 2704 
 
 2710 
 
 2716 
 
 2723 
 
 2729 
 
 2735 
 
 2742 
 
 2748 1 t 2 3 : 
 
 * ' 4 4 5 *> 
 
 •44 
 
 2754 
 
 2761 
 
 2767 
 
 2773 
 
 2780 
 
 2786 
 
 2793 
 
 2799 
 
 2805 
 
 28l2 J 1 2 3 
 
 5 4 4 5 6 
 
 •45 
 
 2818 
 
 2825 
 
 2831 
 
 2838 
 
 2844 
 
 2851 
 
 2858 
 
 2864 
 
 2871 
 
 2877 a 1 2 3 
 
 3 4 5 5 6 
 
 .46 
 
 2884 
 
 2891 
 
 2897 
 
 2904 
 
 291 1 
 
 2917 
 
 2924 
 
 293 1 
 
 2938 
 
 2944 1 1 2 3 
 
 ^4556 
 
 •47 
 
 2951 
 
 2958 
 
 2965 
 
 2972 
 
 2979 
 
 2985 
 
 2992 
 
 2999 
 
 3006 
 
 30I3 1 1 2 3 
 
 3 4 5 5 6 
 
 .48 
 
 3020 
 
 3027 
 
 3034 
 
 3041 
 
 3048 
 
 3055 
 
 3062 
 
 3069 
 
 3076 
 
 3083 1 1 2 3 
 
 4 4 5 6 6 
 
 •49 
 
 3090 
 
 3097 
 
 3105 
 
 3112 
 
 1119 
 
 3126 
 
 3133 
 
 3141 
 
 3148131.^ 1 1 2UI 
 
 4 4 5 6 6 
 
254 
 
 
 
 
 
 
 APPENDIX A. 
 
 
 I 
 
 ANTILOGARITHMS. 
 
 s 
 
 
 
 
 
 
 
 
 
 
 Proportional Parts. 
 
 rt-5 
 
 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 
 o u 
 
 12 3 4 
 
 5 6 7 8 9 
 
 •50 
 
 3162 
 
 3!7o 
 
 3i77 
 
 3184 
 
 3192 
 
 3199 
 
 3206 
 
 3214 
 
 3221 
 
 3228 1 1 2 3 
 
 44567 
 
 .51 
 
 3236 
 
 3243 
 
 3251 
 
 3258 
 
 3266 
 
 3273 
 
 3281 
 
 3289 
 
 3296 
 
 3304 1223 
 
 45567 
 
 •52 
 
 33" 
 
 3319 
 
 3327 
 
 33.34 
 
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 335° 
 
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 45567 
 
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 95 
 
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 9311 2468 
 
 11 13 15 17 19 
 
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 9528 2479 
 
 11 13 15 17 20 
 
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 96^8 
 
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 9683 
 
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 9727 
 
 9750 2' 47 O 
 
 11 13 16 18 20 
 
 •99 19772 
 
 9795 
 
 9817 
 
 9840 986^ 
 
 98869908 9931 
 
 99549977 Ws 1 
 
 11 14 16 18 20 
 
APPENDIX B. 
 
 REAGENTS. 
 
 AIR ANALYSIS. 
 
 Barium Hydroxide. — A solution containing about 4 grams 
 of BaO and 0.2 gram of BaCl 2 to the liter. (1 c.c. = 1 mg. 
 C0 2 , approximately.) 
 
 Sulphuric Acid. — Dilute 45.45 c.c. of normal sulphuric 
 acid to one liter. ( 1 c.c. = 1 mg. C0 2 .) To standardize the 
 solution measure 25 c.c. into a weighed platinum dish, add 
 dilute ammonia- water in slight excess,, eyanorate to dryness 
 on the water-bath, and dry at 120 C. to constant weight. 
 
 Standard Lime-water. — (For Popular Tests.)— Shake one 
 part of freshly slaked lime with 20 parts of distilled water for 
 twenty minutes and let the solution stand overnight or until 
 perfectly clear. This solution should be very nearly equiva- 
 lent to the above standard sulphuric acid. To a liter of dis- 
 tilled water add 5 c.c. of a solution of 0.7 gram of phenol- 
 phthalein in 100 c.c. of 50 per cent, alcohol and add lime- 
 water drop by drop until a slight permanent pink color is 
 produced. Add 12.6 c.c. of the above calcium hydroxide 
 solution. The resulting solution is the standard lime-water 
 used for the tests. 
 
 WATER ANALYSIS. 
 
 For Ammonia. — Water Free from Ammonia. — The am- 
 monia-free water used in this laboratory is made by redis- 
 tilling distilled water from a solution of alkaline permangan- 
 
 255 
 
256 
 
 APPENDIX B. 
 
 ate in a steam-heated copper still. The apparatus used is 
 shown in Fig. 15. Only the middle portion of the distillate 
 is collected. Oftentimes the distillate from a good spring- 
 water may be used. 
 
 Nesslers Reagent. — Dissolve 61.750 grams KI in 250 c.c. 
 distilled water and add a cold solution of HgCl 2 which has 
 been saturated by boiling an excess of the salt and allowing 
 it to crystallize out. Add the HgCl 2 cautiously until a slight 
 permanent red precipitate (Hgl 2 ) appears. Dissolve this 
 
 Fig. 15. — Still for Ammonia-free Water. 
 
 slight precipitate by adding 0.750 gram powdered KI. Then 
 add 150 grams of KOH dissolved in 250 c.c. of water. Make 
 up to the liter and allow it to stand overnight to settle. This 
 solution should give the required color with ammonia within 
 five minutes, and should not precipitate within two hours. 
 
 Alkaline Permanganate. — Dissolve 233 grams of the best 
 stick potash in 350 c.c. of distilled water. Filter this strong 
 
APPENDIX B. 257 
 
 solution, if necessary, through a layer of glass wool on a por- 
 celain filter-plate. Dilute with 700 to 750 c.c. of distilled 
 water to a sp. gr. of 1.125, add 8 grams of potassium per- 
 manganate crystals, and boil down to one liter to free the 
 solution from nitrogen. Each new lot of reagent must be 
 tested before being used, but when the chemicals used are all 
 good there should be no correction needed for ammonia in 
 the solution. 
 
 Standard Ammonia Solution. — Dissolve 3.8215 grams . 
 chemically pure NH 4 C1 in a liter of water free from ammo- 
 nia. This is the strong solution from which the s.andard 
 solution is made by diluting 10 c.c. to a liter wkh wa'.er free 
 from ammonia. One c.c. of the standard solution = o.orcoi 
 gram nitrogen. This solution, like the nitrite standard and 
 other dilute solutions, must be preserved in sterilized bottles 
 protected from dust and organic matter. 
 
 For Nitrites. — Standard Nitrite Solution. — The pure sil- 
 ver nitrite used in making this solution is prepared by the 
 double decomposition of silver nitrate and potassium nitrite, 
 and repeated crystallizations from water of the rather diffi- 
 cultly soluble silver nitrite. 1.1 grams of this silver nitrite 
 are dissolved in nitrite-free water, the silver completely pre- 
 cipitated by the addition of the standard salt solution used in 
 the determination of chlorine, and the solution made up to 
 1 liter. 100 c.c. of this strong solution are diluted to 1 liter, 
 and 10 c.c. of this last solution again diluted to 1 liter. The- 
 rmal solution is the one used in preparing standards. 1 c.c 
 = 0.000000 1 gram nitrogen. 
 
 Sulpkanilic Acid. — Dissolve 3.3 grams sulphanilic acid 
 in 750 c.c. of water by the aid of heat, and add 250 c.c. 
 glacial acetic acid. 
 
 Naphtylamine Acetate. — Boil 0.5 gram of a-naphtylamine 
 in 100 c.c. of w ater in a small Erlenmeyer flask for about five. 
 
258 APPENDIX B, 
 
 minutes, filter through a plug of washed absorbent cotton, 
 add 250 c.c. glacial acetic acid, and dilute to a liter. 
 
 For Nitrates. — Standard Nitrate Solution. — Dissolve 
 0.720 gram of pure recrystallized KN0 3 in 1 liter of water. 
 Evaporate 10 c.c. of this strong solution cautiously on the 
 water-bath, moisten quickly and thoroughly with 2 c.c. of 
 phenol-disulphonic acid, and dilute to 1 liter for the stand- 
 ard solution. 1 c.c. =0.000001 gram nitrogen. 
 
 Phenol-disulphonic Acid. — Heat together- 3 grams syn- 
 thetic phenol with 37 grams pure, concentrated H 2 S0 4 in a 
 boiling -water bath for six hours. 
 
 For Kjeldahl Process. — Sulphuric Acid. — Sp. gr. 1,84.. 
 This should be free from nitrogen. May be obtained from 
 Baker and Adamson, Easton, Pa. 
 
 Potassium Hydroxide. — Dissolve 350 grams of the best 
 stick potash in ..25 liters of water and boil down to some : 
 thing less thai a liter with 3 grams of permanganate crys- 
 tals. When cold, dilute to a liter with water free from am-, 
 monia. 
 
 For Phosphates. — Ammonium Molybdate. — Dissolve 50 
 grams of the pure neutral salt in a liter of distilled water. 
 
 Nitric Acid (sp. gr. 1.07).— One part of acid (sp. gr. 1.42) 
 to five parts of water. 
 
 Standard Phosphate Solution. — Dissolve 0.5324 gram of 
 pure crystallized sodium phosphate (Na 2 HP0 4 .i2H 2 0) in 
 freshly distilled water, add 100 c.c. of nitric acid (1.07), and 
 dilute to 1 liter. 1 c.c. =0.0001 gram P 2 5 . The solution 
 keeps without change for several months if preserved in 
 well-stoppered bottles of hard glass ; after a longer time it 
 becomes slightly stronger, owing to the silica dissolved from 
 the glass. 
 
 For Chlorine. — Salt Solution. — Dissolve 16.48 grams of 
 fused NaCl in a liter of distilled water. For the standard 
 
APPENDIX B. 259 
 
 solution dilute 100 c.c. of this strong solution to 1 liter. 
 1 c.c. =0.001 gram chlorine. 
 
 Silver Nitrate. — Dissolve about 2.42 grams of AgNO s (dry 
 crystals) in 1 liter of chlorine-free water. 1 c.c. = .0005 gram 
 CI, approximately. Standardize against the NaCl solution. 
 
 Potassium Chromate. — Dissolve 50 grams neutral K 2 CrO i 
 in a little distilled water. Add enough AgN0 3 to produce a 
 slight red precipitate. Filter and make the filtrate up to a 
 liter with water free from chlorine. 
 
 Milk of Alumina for P)e color ization. — Dissolve 125 grams 
 of potash or ammonia alum in a liter of distilled water. Pre- 
 cipitate the Al(OH) 3 by the cautious addition of NH 4 OH. 
 Wash the precipitate in a large jar by decantation until free 
 from chlorine, nitrites, and ammonia. 
 
 For Hardness. — Standard Calcium Chloride Solution. — 
 Dissolve 0.200 gram of pure Iceland spar in dilute HC1, tak- 
 ing care to avoid loss by spattering, and evaporate to dryness 
 several times, to remove the excess of acid. Dissolve the 
 calcium chloride thus formed in 1 liter of water. 
 
 Standard Soap Solution. — Dissolve 100 grams of the best 
 white, dry castile soap In a liter of 80 per cent, alcohol. Of 
 this strong solution dissolve 75-100 c.c. in a liter of 70 per 
 cent, alcohol. This solution must have 70 per cent, alcohol 
 added to it until 14.25 c.c. of it give the required lather with 
 50 c.c. of the above CaCl 2 solution. 
 
 Erythrosine Indicator. — Dissolve 0.1 gram of erythrosine 
 in 1 liter of water. 
 
 For Iron. — Standard Iron Solution. — Dissolve 0.86 gram 
 of ferric ammonium alum, (NH 4 ) 2 S0 4 .Fe 2 (S0 4 ) 3 .24H 2 0, or 
 a corresponding amount of the potassium salt in 500 c.c. of 
 water, add 5 c.c. HNO s (1.20), and dilute to 1 liter. 1 c:c. = 
 0.000 1 gram Fe. 
 
 Potassium Sulphocyanide. — 5 grams per liter. 
 
26o APPENDIX B. 
 
 Hydrochloric Acid. — i part HC1 (sp. gr. 1.20) to 1 part of 
 water. 
 
 Potassium Permanganate. — 5 grams KMn0 4 in 1 liter of 
 water. 
 
 For Dissolved Oxygen. — (a) 48 grams of MnS0 4 .4H 2 in 
 100 ex. of water; (b) 360 gra^s of NaOH and 100 grams of 
 KI in 1 liter of water; (c) HC1, sp. gr. 1.20 
 
 Sodium Thios^lphate Solution. — Dissolve 2$ grams of pure 
 recrystallized sodium thiosulphate in 1 liter of water. Dilute 
 200 c.c. to 1 liter and standardize against a known K 2 Cr 2 7 
 solution. 
 
 For Lead. — Standard Lead Solution. — To a strong solu- 
 tion of lead acetate add a slight excess of H 2 S0 4 , filter off 
 and wash the precipitate. Dissolve it in ammonium acetate 
 solution, made by neutralizing glacial acetic acid with strong: 
 ammonia. Make up to a known volume and determine the lead 
 in an aliquot part by precipitating with K 2 Cr 2 7 and weigh- 
 ing the lead chromate. Dilute an aliquot part to make a con- 
 venient standard, say about 1 c.c. = 0.001 gram of Pb. 
 
 FOOD ANALYSIS. 
 
 Acid Mercuric Nitrate. — Dissolve mercury in double its 
 weight of nitric acid (sp. gr. 1.42) and dilute the solution 
 with five times its volume of water. 
 
 Pumice. — Bits of ignited pumice, about the size of a pea, 
 dropped while hot into water and bottled for use. 
 
 Alcohol (for Reichert-Meissl method). — 95 per cent, alcohol 
 redistilled from potassium hydroxide. 
 
 Potassium Hydroxide (for Reichert-Meissl method). — One 
 part good quality caustic potash dissolved in one part of 
 water. 
 
 Iodine Solution (for Hanus' method). — This is conven- 
 iently made up according to the directions of Hunt.* Dis- 
 
 * /. Soc. Chem. Ind., 21 (1902), 454. 
 
APPENDIX B. 26 1 
 
 solve 13.2 grams iodine in 1 liter of glacial acetic acid (99 per 
 cent., showing no reduction with bichromate and sulphuric 
 acid). This will best be done by adding the acetic acid in 
 portions and heating on the water-bath with frequent shaking. 
 To the cold solution add enough bromine to double the halogen 
 content, as shown by titration. Three c.c. of bromine is suffi- 
 cient. A slight excess of iodine is not detrimental. 
 
 Potassium Iodide. — Dissolve 200 grams of potassium iodide 
 in 1 liter of water. 
 
 Anhydrous Ether. — Wash ordinary ether several times with 
 distilled water and add solid caustic potash until most of the 
 water has been removed. Then add small pieces of clean 
 metallic sodium until there is no further evolution of hydrogen 
 gas. The ether thus prepared should be kept over metallic 
 sodium and a tube of calcium chloride should be inserted in 
 the stopper, in order to allow of the escape of any accumulated gas. 
 
 Potassium Sulphide. — Dissolve 40 grams of the crystallized 
 salt in 1 liter of water and filter through glass wool. 
 
 Potassium Hydroxide (for Kjeldahl process). — Dissolve 700 
 grams of the best quality of stick potash in water and dilute 
 to 1 liter. 
 
 Basic Lead Acetate. — Boil for half an hour 440 grams of 
 lead acetate and 264 grams of litharge in 1500 c.c. of water. 
 Cool and dilute to 2 liters. Allow to settle and siphon off 
 the clear liquid. (Sp. gr. about 1.27, containing about 35 
 per cent, of the basic salt.) 
 
 Ferric Alum. — Dissolve 2 grams of ferric alum in 100 c.c. 
 of water, boil the solution until a precipitate appears, and filter. 
 
 Fehling's Solution. — (a) Dissolve 69.28 grams of C.P. crys- 
 tallized copper sulphate, carefully dried between blotting-paper, 
 in water and make up to 1 liter, including 1 c.c. of strong sul- 
 phuric acid; (b) Dissolve 346 grams of sodium potassium tar- 
 trate and 100 grams of sodium hydroxide in water and make 
 up to a liter. 
 
BIBLIOGRAPHY. 
 
 The following list comprises some of the more important 
 works bearing on the subjects treated in the preceding 
 pages. A bibliography of the chemistry of foods com- 
 plete to 1882 may be found in the Second Annual Report 
 of the New York State Board of Health, and more or less 
 complete bibliographies are to be found in Sadtler's ''In- 
 dustrial Organic Chemistry," Blyth's " Composition and 
 Analysis of Foods," and Leach's " Food Inspection and 
 Analysis." 
 
 AIR. 
 
 Air and Rain. R. Angus Smith. Longmans, Green & Co. London. 1872. 
 
 Air and its Relations to Life. Walter N. Hartley. D. Appleton & Co. 
 New York. 1875. 
 
 Report on the Air of Glasgow. E. M. Dixon. Robert Anderson. Glas- 
 gow. 1877. 
 
 Recherches sur l'Air Confine. A. Braud. Bailliere et Fils. Paris. 1880. 
 
 Air Analysis. J. A. Wanklyn and W. J. Cooper. Kegan Paul, Trench,. 
 Trubner & Co. London. 1890. 
 
 Les Poisons de l'Air. N. Grehaut. Bailliere et Fils. Paris. 1890. 
 
 Treatise on Hygiene and Public Health. Vol. I. Thomas Stevenson and 
 S. F. Murphy. Blakiston, Son & Co. Phila. 1892. 
 
 Air and Water. Vivian B. Lewes. Methuen & Co. London. 1892. 
 
 Methods for the Determination of Organic Matter in Air. D. H. Bergey. 
 Smithsonian Institution. Washington, D. C. 1896. 
 
 The Detection and Measurement of Inflammable Gas and Vapor in the 
 Air. Frank Clowes. Crosby, Lockwood & Son. London. 1896. 
 
 Sanitation in Daily Life. Ellen H. Richards. Whitcomb & Barrows. 
 
 Air Currents and the Laws of Ventilation. W. W. Shaw. Cambridge, at 
 the University Press. 
 
 VENTILATION, 
 
 Heating and Ventilation of the New Building, Mass. Inst. Tech. S. H. 
 Woodbridge. Tech. Quart., 2, 76. 1888. 
 
 263 
 
264 BIBLIOGRAPHY. 
 
 Heating and Ventilation. J. S. Billings. Sanitary Engineer. New York. 
 
 1893. 
 Heating and Ventilating Buildings. Rolla C. Carpenter. John Wiley & 
 
 Sons. New York. 1895. 
 
 WATER. 
 
 Report of the Royal Commission on Water Supply. Great Britain Par- 
 liamentary Documents. London. 1869-70. 
 
 Sixth Report of Rivers Pollution Commission, Great Britain. London. 
 1876. 
 
 Water Softening and Scientific Filtration. Walter George Atkins. E. & 
 F. N. Spon. London. 1880. 
 
 National Board of Health Report for 1882. 
 
 Water Supply (Considered mainly from a Chemical and Sanitary Standpoint). 
 W. R. Nichols. John Wiley & Sons. New York. 1883. 
 
 Water Analysis for Sanitary Purposes. E. Frankland. John Van Voorst. 
 London. 1890. 
 
 "The Organic Analysis of Potable Waters. J. A. Blair. 1890. 
 
 Drinking Water and Ice Supplies. T. Mitchell Prudden. G. P. Putnam 
 & Sons. New York. 1891. 
 
 Potable Water. Floyd Davis. Silver, Burdett & Co. New York. 1891. 
 
 The Action of Water on Lead. John Henry Garrett. H. K. Lewis. 
 London. 1891. 
 
 Treatise on Hygiene and Public Health. Vol. I. Thomas Stevenson and 
 S. F. Murphy. Blakiston, Son & Co. Phila. 1892. 
 
 Sewage Disposal in the United States. Geo. W. Rafter and M. N. Baker. 
 D. Van Nostrand Co. New York. 1894. 
 
 Xes Eaux-d' Alimentation, Epuration, Filtration, Sterilization. Edm. 
 Guinochet. Bailliere et Fils. Paris. 1894. 
 
 Micro-Organisms in Water. Percy F. Frankland and Mrs. Percy F. Frank- 
 land. London. 1894. 
 
 The Filtration of Public Water Supplies. Allen Hazen. John Wiley & 
 Sons. New York. 1895. 
 
 Examination of Water for Sanitary and Technical Purposes. Henry Leff- 
 man. Blakiston, Son & Co. Phila. 1895. 
 
 Sewage Disposal on the Farm and Protection of Drinking Water. Theo- 
 bald Smith. U. S. Dept. Agr., Farmers' Bull. 43. 1896. 
 
 Water Supply (Considered Principally from a Sanitary Standpoint). W 
 P. Mason. John Wiley & Sons. New York. 1903. 
 
 Water Analysis. J. A. Wanklyn and E. T. Chapman. Tenth Ed. Kegan 
 Paul, Trench, Triibner & Co. London. 1896. 
 
 Examination of Water and Water Supplies. John C. Thresh. H. A. 
 Churchill & Co. London. 1896. 
 
 Mikroskopische Wasseranalyse. Carl Mez. J. Springer. Berlin. 1898. 
 
 A Simple Method of Water Analysis. John C. Thresh. J. & A. Churchill. 
 London. 1898. 
 
BIBLIOGRAPHY. 265 
 
 Water Purification at Louisville, Ky. Geo. W. Fuller. D. Van Nostrand 
 
 Co. New York. 1898. 
 Report on Water Purification at Cincinnati, O. Geo. W. Fuller. Board 
 
 of Trustees, Cincinnati. 1899. 
 Report of Filtration Commission, Pittsburgh, Pa. 1899. 
 Examination of Water (Chemical and Bacteriological). William P. Mason. 
 
 John Wiley & Sons. New York. 1899. 
 The Microscopy of Drinking Water. Geo. C. Whipple. John Wiley & 
 
 Sons. New York. 1 899. 
 Geological Survey. State of Washington. 1901. 
 Report of Streams Examination, Sanitary District of Chicago. 1902. 
 Chemical Survey of the Waters of Illinois. 1 897-1902. 
 Water and its Purification. S. Rideal. Crosby, Lockwood & Son. London. 
 
 1902. 
 Report on Water Purification Investigations. New Orleans Sewerage and 
 
 Water Board. 1903. 
 Elements of Water Bacteriology. S. C. Prescott and C.-E. A. Winslow. 
 
 John Wiley & Sons. New York. 1904. 
 State Board of Health Reports for Massachusetts, Michigan, Illinois, Ohio. 
 
 The Mass. Reports for 1872-75 and 1890-1900, especially, contain 
 
 many valuable papers, the following being some of the most important 
 
 of them : 
 Chemical Examination of Water and Interpretation of Analyses. Thomas 
 
 M. Drown. Rep. Mass State Board of Health, 1892, 319. 
 Discussion of Special Topics Relating to the Quality of Public Water Sup- 
 plies. F. P. Stearns and T. M. Drown. Rep. Mass. State Board of 
 
 Health, 1890, 717. 
 On the Amount of Dissolved Oxygen contained in Waters of Ponds and 
 
 Reservoirs at Different Depths. Thomas M. Drown. Rep. Mass. 
 
 State Board of Health, 1891, 373. 
 On the Amount of Dissolved Oxygen contained in Waters of Ponds and 
 
 Reservoirs at Different Depths in Winter under the Ice. Thomas M. 
 
 Drown. Rep. Mass. State Board of Health, 1892, 333. 
 On the Mineral Contents of Some Natural Waters in Mass. Thomas M. 
 
 Drown. Rep. Mass. State Board of Health, 1892, 345. 
 The Effect of the Aeration of Natural Waters. Thomas M. Drown. Rep. 
 
 Mass. State Board of Health, 1891, 385. 
 
 In addition to the above the following papers contain 
 much information of value on special topics relating to 
 water supply and water analysis: 
 
 Chemical Examination of Drinking Water. Thomas M. Drown. Proc. 
 Soc. Arts., M. I. T., 1887-8, 87. 
 
266 BIBLIOGRAPHY*. 
 
 THe^ Analysis of Water — Chemical, Microscopical, and -Bacteriological 
 
 Thomas M. Drown. J. N. E. Water Works Assoc, 4 (1889) ,79. 
 Uti the Boss on Ignition in Water Analysis. Thomas M. Drown. Tech. 
 
 Quart., 2 (1888), 132. 
 The Odor and Color of :] Surface Waters. Thomas M. Drown. Tech. 
 
 Quart., 1 (1888), 256;^ -■ 
 Reduction of Nitrates by Bacteria. Ellen H. Richards and George W. 
 : V Rolfe! Tech. Quart:; 9 (1 896) , 40. 
 The Purification of Water by Freezing. Thomas M. Drown. J. N. E. 
 
 Water Works Assoc, 8 (1893), 46. 
 The Filtration of Natural Waters. Thomas M. Drown. J. of the Assoc. 
 
 of Eng. Soc, 9 (1890), 356. - 
 
 A Study of Self-Purification in the Sudbury River. A. G. Woodman, 
 
 C.-E. A. Winslow, and P. Hansen. Tech. Quart., 15, 1902. 
 Normal Distribution of Chlorine in Connecticut. H. E. Smith and F. 'SI 
 
 Hollis. Rept. Conn. State B'd Health, 1902. ' 
 Water Supplies of S. E. Alaska and the Black Hills of S. Dak; E. H. 
 
 Richards. Tech. Quart., 16,-1903. 
 Notes on the Potable Waters of Mexico. E. H. Richards". Trans. Ami 
 J Inst. Min. Eng., 1901. ; ; ' ' 
 
 -Rainfall on the Pacific Coast and the Factors of Water Stlpply in California. 
 
 J. Assoc. Eng. Soc, 1903. 
 
 , j WATER. 
 
 Department of Interior. U. S. Geological Survey. Underground Water f Water 
 
 1 Supply and Irrigation Paper. No. 160. Myron L.' Fuller. ' 
 
 Field Assay of Water. No. 151. Marshall O. Leigntoh. 
 
 Value of Pure Water. George C. Whipple. Published by John Wiley- & Sons. 
 
 ■ l: New York. ' ' ■ '" ' " ; ' " iv »- : :; " : ''-■ M" «0 
 
 Report of the Commission on Additional Water Supply for the City of New York. 
 Appendix VI. ! 
 
 Report of the Committee on Standard Methods of Water Analysis td the Labora- 
 tory Section of the American Public ' Health Association. (Reprinted from 
 the journal of Infectious Diseases, Supplement No. i.- May, 1965:) 
 
 Disposal of Dairy and Farm Sewage and Water Supply. Oscar Erf. 'Kansas 
 State Agricultural College Experiment Station Bulletin. 
 
 
BIBLIOGRAPHY. 267 
 
 •'-^ -■■ '-."- ; ■- ;; -m -- FOOD.- •; l'. ; .-!m.-,;m,-! •,;; K-;-: ;-. •.-; 
 
 The list given here is limited to, , books published since 
 1890. •/•-* 
 
 Traite General d' Analyse des Beurres. A. J. Zune. H. Lamartin. 
 
 r; : ? ; Paris. 1892. «.* 
 
 Die Menschlichen Nahrungs- u. Genussmittel. J. Konig. Julius Springer. 
 
 j Berlin.- 1893. 
 
 Foods and Dietaries. R. W. Burnet, M.D. . P. Blakiston, Son & Co. 
 .,];,, lEhila; £893,, , . . -., , l: ri ■ . f ... : . : . p . : ...-' : 
 
 Analyse des Matieres Alimentaires et Recherche de Leur- Falsifications. 
 V/ . ;;/ jCh. r Girar4 et A r ,Dupre. Vve. Ch. Dunod &;P... Vicq. ; : Paris. , .... 1 894. . 
 Animal and Vegetable Oils, Fats, Butters and Waxes. C. R. Alder Wright. 
 
 ; Jf •Griffin-& Co;- \ London. 1894. . rv ■ •...;: '.,.:... 
 
 Chemistry of Wheat, Flour, and Bread. Wm. Jago. Simpkin Marshall. 
 ,/j . I.ondon. ; . ^895, ■ ( - <j ., . ■• ■■■ j. .. : . ... .j^j^.a -jfotfj \ . 
 The Food Products of the World. Dr. Mary E. Green. Th^ Hotel. World? 
 
 Chicago. 1895. 
 The Story of Germ Life. H. W. Conn. Appleton & Co. New York 
 
 -,.. I ?97 T . j, ^ f if ;.,: fV: , ,. V • ; .: ; . t .= . ,? .„....,. ;, , . 
 
 The Relation of Food to Health. George H. Townshe'nd. Witt Publish- 
 
 20 l jngCo. :; St. Louis. 11897;' ' ■•'■ < : : : ' v .•••-;•;•■.■::;,, A =. .;;•■ - : 
 
 The Analysis of Food and Drugs., Part I: ; Mjlk and. Milk, .Products. ., T. 
 
 H. Pearmain and C. G. Moor. Bailliere Tindall & Cox. London.' 
 
 l8 97- ,^ -,v. , u , ... ■,..,......, ,, ,, ; ; ,.,.,-,^ 
 
 Principles and Practice of Agricultural Analysis. Harvey W. Wiley. Chem. 
 
 Pub. Co. Easton, Pa. 1897. ■ if, ' ';< : ■■.:)■■ ■■■. ■•-. ■■.-■. ■ ; , ; ,f 
 
 Testing Milk and its Predicts. E. H. Farririgton and F= W. Woll. Men- 
 
 dota Book Co. Madison, Wis. ■ 1898;- -.L mD - ■'.•: :'■ i .= *j v ■iihniriVj . , 
 Chemical Analysis of Oils, Fats, and rWaxes. . Ji . ^ewkowitsch. .--Mac*. 
 > ! - ; millMi &<Co. nLdndor/, kgc^uL-iKoqt. •:.-.) !■:•:<■:: .;.?>;{ .;,:.. 
 Commercial Organic Analysis. A. H. Allen. Third Ed. Rev.-- by H. Leff- 
 
 man. Blakiston, Son" >&i Co. Phila. ^1^98;: '*■■ ■■■'■- ■■.:■/;:•■-■ 
 Die Untersuchung ' ■ landwirtschaftlich und ge'werbiich wichtiger Stoffe. 
 
 J. Konig. Paul Parey; Berlin.- i.i 1898U-: I ■ ■-''■ 
 Food Materials ahd^their Adulterations. 1 Ellfeni H,' Richards: Borne 
 
 Science Pub. Co; Boston. (i908; : •-. = >ttv-? ^■■^ -.- 
 
 Plain Words about Food; -The .Rumford Kitchen .Leaflets. Ellen H 
 
 Richards,: Ed. Home Science Pub. Co. Boston. 1899. 
 Muscle, Brain, and Diet: A Plea for Simpler Foods. E. 1 H. Miles. Sonnen- 
 
 schien. London.' ^1900. :■ '' V - ■■^vzcqf-r/. ri 
 
 AV- Handbook of Industrial Organic Chemistry. ; .'. SJ-> • Pi-vSadtler. J. B. 
 
 Lippincott Co. Phila. 1900. 
 Flesh Foods with Methods for their Chemical, Microscopical, and Bacte- 
 riological Examination. C. A. Mitchell. Griffin & Co. London. 
 
 1900. 
 
268 BIBLIOGRAPHY. 
 
 Food and the Principles of Dietetics. R. Hutchinson. Wood. New York. 
 
 iooi. 
 The Cost of Food: A Study in Dietaries. E. H. Richards. J. Wiley & 
 
 Sons. New York. iooi. 
 Select Methods in Food Analysis. H. Leffman and W. Beam. P. Blakis- 
 
 ton's Son & Co. Phila. 1905. 
 Suggested Standards for Food and Drugs. C. G. Moor. Bailliere, Tindall 
 
 & Cox. London. 1902. 
 Enzymes ?,nd their Applications. J. Effront. Trans. S. C. Prescott. J. 
 
 Wiley & Sons. New York. 1902. 
 Foods: their Composition and Analysis. A. W. Blyth and M. W. Blyth, 
 
 Griffin & Co. London. 1903. 
 Food Inspection and Analysis. Albert E. Leach. Wiley & Sons. New 
 
 York. 1904. 
 Organic Analysis. Henry C. Sherman. Macmillan Co. New York. 
 
 1905. 
 Foods and their Adulteration. H. W. Wiley. P. Blackiston's Son & Co. 
 
 Phila. 1907. 
 
 The following bulletins of the United States Depart- 
 ment of Agriculture will also be found useful for study or 
 reference on the general question of food: 
 
 Office of Experiment Stations, Bulletins. 
 
 Ko. 9. Fermentations of Milk. 1892. 
 
 11. Analyses of American Feeding Stuffs. 1892. 
 
 ai. Chemistry and Economy of Food. 1895. 
 
 No. 25. Dairy Bacteriology. 1895. 
 
 28. (Rev. Ed.) Chemical Composition of American Food Materials 
 
 1895. 
 
 29. Dietary Studies at the University of Tennessee. 1896. 
 
 31. " " " " " " Missouri. 1896. 
 
 32. " " " Purdue University. 1896. 
 
 34. Carbohydrates of Wheat, Maize, Flour, and Bread. 1896. 
 
 35. Food and Nutrition Investigations in New Jersey. 1896. 
 
 37. Dietary Studies at the Maine State College. 1897. 
 
 38. " " — Food of the Negro in Alabama. 1897. 
 40. " " in New Mexico. 1897. 
 
 43, Composition and Digestibility of Potatoes and Eggs. 1897. 
 
 44. Metabolism of Nitrogen and Carbon in the Human Organism. 1897. 
 
BIBLIOGRAPHY. 26 9 
 
 45> A Digest of Metabolism Experiments. 1897. 
 46. Dietary Studies in New York City. 1898. 
 
 52. Nutrition Investigations in Pittsburgh, Pa. 189&. 
 
 53. " " at the University of Tennessee. 1898. 
 
 54. " " in New Mexico, 1898. 
 
 55. Dietary Studies in Chicago. 1898. 
 
 63. Experiments on the Conservation of Energy in the Human Body. 
 1899. 
 
 66. Creatin and Creatinin. 1899. 
 
 67. Bread and Bread Making. 1899. 
 
 69. Experiments on the Metabolism of Matter and Energy in the Human 
 Body. 1899. 
 
 71. Dietary Studies of Negroes. 1899. 
 
 75. " " " University Boat Crews. 1900. 
 
 84. Nutrition Investigations at the California Agr. Expt. Station. 1900. 
 
 85. Investigations on the Digestibility and Nutritive Value of Bread. 
 
 1900. 
 89. Effect of Muscular Work on Digestion of Food and Metabolism of 
 
 Nitrogen. 1901. 
 91. Nutrition Investigations at the University of Illinois, etc. 1901. 
 98. Effect of Severe and Prolonged Muscular Work on Food Consump- 
 tion, Digestibility, and Metabolism. 1901. 
 
 101. Studies on Bread and Bread Making. 1901. 
 
 102. Losses in Cooking Meat. 1901. 
 
 107. Nutrition Investigations among Fruitarians and Chinese. 1901. 
 109. Metabolism of Matter and Energy in the Human Body. 1902. 
 
 116. Dietary Studies in New York City. 1902. 
 
 117. Effect of Muscular Work upon Digestibility of Food and Metab- 
 
 olism of Nitrogen. 1902. 
 121. Metabolism of Nitrogen, Sulphur, and Phosphorus in the Human 
 
 Organism. 1902. 
 126. Digestibility and Nutritive Value of Bread. 1903. 
 129. Dietary Studies: Boston and other Places. 1903. 
 132. Further Investigations among Fruitarians. 1903. 
 
 Division of Chemistry, Bulletins. 
 
 No. 13. Foods and Food Adulteration — (Ten Parts). 1887-1902. 
 
 45. Analyses of Cereals. 1895. 
 
 46. Official Methods of Analysis. 1895. 
 50. Composition of Maize. 1898. 
 
 59. Composition of American Wines. 1900. 
 
 61. Pure Food Laws of Foreign Countries. 1901. 
 
 65. Provisional Methods for Analysis of Foods. 1902. 
 
 66. Fruits and Fruit Products. 1902. 
 69. Foods and Food Control. 1902. 
 
 72. American Wines at Paris Exposition of 1900. 1903, 
 
%70 bibliography; 
 
 . Farmers' Bulletins. ... 
 
 . -..'i.\ . .-.'...•■=: . :■•>.;•?•! •::•.;.-: r ';-b. 
 
 No. 23. Foods : Nutritive Value and Cost, i 894, : : 
 
 29; -Souring of Milk. ! • tSg 5 . * • ■ ■■ ! 
 
 34. Meats: Composition and Cooking. 1896. .;•:*' 
 
 74. Milk as Food. 1898. .,,>. .!:i-: . ■•,-•. 
 
 •Yi 85. FiSh: a ! S Food.' 1898.;- : ; "J : • ■:^:'i '. .; ,.:;:, .. :■;.: i ... > 
 03. Sugar as Food. 1899, <k< 
 1 1 2. Bread and the Principles of Bread Making; 1 stftjddji '•- : ') 
 
 121. Beans, Peas, and other Legumes as Food. (190108 hi v » 
 ; 128. Eggs and their 1 Uses as Food. 1901. 
 
 131. Household Tests for Detection of Oleomargarine and Renovated 
 
 Butter. 1901. . i ; 
 
 142. The Nutritive and Economic Value of Food 1961. • v 
 
 i / ■■■•(: Bureau of Chemistry Bulletins.' : . ; 
 
 No. 77. Olive Oil and Its Substitutes. 
 
 84. I flue nee of Food Preservatives and Artificial Colors on Digestion and 
 
 Health. 
 100. Some Forms of Food Adulteration and Simple Methods for their Detection. 
 107. Official arid' Provisional Methods of Analysis, 
 j 10. Chemical Analysis and Composition of American Honeys. 
 114. Meat Extracts and Similar Preparations. 
 
 Much valuable information will also be found in the monthly bulletins and 
 (reports of several of the State experiment stations and boards of health, notably 
 those of Connecticut, North Dakota, Maine, Kansas, New Hampshire, Vermont, 
 and Massachusetts. 
 
INDEX. 
 
 PAGE 
 
 Acceptable water 80 
 
 Acid hydrolysis, of starch 211 
 
 mercuric nitrate, preparation of 260 
 
 , sulphanilic, reagent for nitrite test 257 
 
 , sulphuric, reagent for air analysis 255 
 
 , " , free from nitrogen 258 
 
 Acids, determination in wine 220 
 
 , volatile, in wine 220 
 
 Adams' method for fat determination 175 
 
 Adulteration, cause of . 156 
 
 defined 156 
 
 , extent of 160 
 
 Air, amount required per capita 20 
 
 currents, location of 25 
 
 , composition of expired ip 
 
 , ' ' inspired 10 
 
 , dust in 18 
 
 , effect of humidity in 14 
 
 essential to life 3 
 
 , occasional impurities in 16, 17 
 
 of cities 17 
 
 , variations in composition of 12 
 
 , water vapor in . 14 
 
 Albumin, determination in milk . 184 
 
 Albuminoid ammonia, in relation to organic nitrogen 108 
 
 in water, determination of 100 
 
 Alcohol, determination in lemon extract 232 
 
 , " "wine 217 
 
 , table for determining 244 
 
 -extract ratio 218 
 
 Alkalinity in water 119 
 
 Alkaline permanganate, reagent for water analysis 256 
 
 Aluminum hydroxide . . 259 
 
 .271 
 
272 INDEX. 
 
 PAGET 
 
 Alum in water, determination of x 3* 
 
 Alumina, milk of, reagent 259 
 
 Ammonia, standard solution, preparation of 257 
 
 , presence in water *-g 
 
 , in water, determination of ICK > 
 
 Analyses, interpretation of g 2 
 
 Aqueous vapor, tension of 236 
 
 Ash, determination in cereals 206 
 
 , in wine 218 
 
 , of milk 1 73 
 
 Babcock method for fat determination 1 76- 
 
 Barium hydroxide, reagent for air analysis 255 
 
 Beer, analysis of , 224 
 
 Benzoic acid, detection of 223 
 
 Bibliography 263 
 
 Biological examination of water 135 
 
 Boric acid, detection in milk 188 
 
 Breakfast foods 161 
 
 Brook water 86 
 
 Butter, analysis of 193 
 
 , complete analysis of 204. 
 
 , composition of 191 
 
 Calcium chloride, standard solution of 259 
 
 Calorie, definition of 148 
 
 Cane-sugar, detection in milk 185 
 
 Caramel, detection in vanilla 230 
 
 Carbohydrates, function of 146 
 
 , separation in cereals 209 
 
 Carbon dioxide, amount expired 15 
 
 , determination of, in air 27 
 
 , "popular tests" for 40 
 
 as a disturbing factor 12 
 
 , properties of 21 
 
 table of weight of cubic centimeter of 237 
 
 in water, determination of 1 29 
 
 , a test of ventilation 23 
 
 Carbonaceous matter in water, determination of 112 
 
 Carbonic acid in water, determination of free 129 
 
 Carbon monoxide, detection of, in air 49 
 
 , estimation of, in air 50 
 
 , effect on blood 16 
 
 Change on ignition 117 
 
INDEX. 
 
 27^ 
 
 PAGE 
 
 Chlorine in ground water go- 
 water, determination 113 
 
 ' ' , source of 71 
 
 Casein, determination of j#4 
 
 Citral, determination of 233 
 
 Clark's method for hardness 117 
 
 Classification of waters &$ 
 
 Cocoanut oil, detection in butter 195 
 
 Cohen method for carbon dioxide 48. 
 
 Collection of water samples 94 
 
 Color of water, determination of 130 
 
 standards for water 1 3°~ 1 3$- 
 
 Colors, detection of 221 
 
 , " in milk 186- 
 
 in food 163 
 
 Condensed milk, analysis of 189 
 
 , composition of 189. 
 
 Cooking, changes caused by 148 
 
 Coumarin, determination of ,.. 227 
 
 , Leach's test for 228. 
 
 Cream, determination of 171 
 
 " Crowd poison " 18-24 
 
 Crude fibre, determination of 214 
 
 Cycle of nitrogen 65 
 
 Dextrin, estimation in cereals 21a 
 
 Diastase, estimation of starch by 212 
 
 Dietaries 152 
 
 Dissolved oxygen, reagents for, preparation of 260 
 
 in water, determination of 1 23 
 
 Distilled water 73. 
 
 Dust and soot 54, 55, 56 
 
 , estimation of, in air 54 
 
 Ether, anhydrous, preparation of 261 
 
 extract of cereals 206 
 
 Extract in beer-wort, table for 249 
 
 ... , determination in beer 224 
 
 , "wine 217 
 
 in wine, table of 247 
 
 Fat, determination of, in milk 175 
 
 Fats, value of 145 
 
 Fatty acids, determination of, in butter 196 
 
274 /INDEX. 
 
 PAGE 
 
 Fehling's solution, preparation of . , * 261 
 
 Filters r , r 87 
 
 Fitz and Wolpert 43 
 
 method for. carbon dioxide 45 
 
 shaker 45~47 
 
 Fluorides, detection of ,. -. 226 
 
 Food, composition of . . . .143 
 
 , definition and uses 143 
 
 , principles — ........... 143 
 
 , materials, table of composition of . . . . . 150 
 
 , predigested .. .... 162 
 
 .Formaldehyde, detection in milk 187 
 
 Glass pipe . 94 
 
 Glycerine, determination in wine 219 
 
 Gottlieb method for fat estimation 178 
 
 Ground water, history of 62 
 
 Gunning method for nitrogen 209 
 
 Hanus' iodine solution, preparation of 260 
 
 Hardness in water, determination of 117 
 
 , table of 242 
 
 Heat of combustion, values for 148 
 
 Humidity in air, effect of 14 
 
 Ice, rules for use of 72 
 
 Interpretation of water analysis 82 
 
 Iodine value, determination of 197 
 
 Iron in water, determination of — 127 
 
 , standard solution of 259 
 
 Kjeldahl method for nitrogen 206 
 
 Lactose, estimation of 181 
 
 Lake water -. . ■ 84 
 
 Lead acetate, basic, preparation of 261 
 
 in water, determination of 139 
 
 , standard solution of 260 
 
 Lemon extract 23 1 
 
 oil, determination of 23 2 
 
 Lime water, reagent for air analysis 255 
 
 .Loss on ignition in water, determination of 115 
 
INDEX. 275 
 
 ;. >T PAGE 
 
 Malt extract, preparation of ... ..... ,..„. 213 
 
 Melting point of butter 2or 
 
 Meteoric water . . 59 
 
 Micro-organisms, estimation of in air 51 
 
 , role of, in water 65 
 
 Milk, acidity of . . 172 
 
 , adulterations of 184 
 
 , composition of ■, .■ 168 
 
 , fermentations of 169 
 
 , reaction of 172 
 
 , relation of constituents . 179 
 
 , United States standard 169 
 
 sugar, estimation of 181 
 
 Mineral salts, value in food 147 
 
 substances in water 91 
 
 Misbranding, defined 157 
 
 Mountain " sickness " 13 
 
 Nutritive ratio 149 
 
 Nitrates in ground water ^. 91 
 
 in water, determination of no 
 
 Nitrate standard solution, preparation of 258 
 
 Nitrogen, cycle of 65 
 
 , determination of, by Kjeldahl method 106 
 
 essential to living matter 75 
 
 , total organic, determination of, in water 106 
 
 Nitrogenous substances, function of 144 
 
 Nitrites in water, determination of 108 
 
 estimation of , in air 51 
 
 Nitrite standard solution, preparation of 257 
 
 Naphthylamine acetate reagent for nitrite test 257 
 
 Nessler's reagent, preparation of 256 
 
 Odor of water, detection of 133 
 
 , analytical value of 88 
 
 Oleomargarine 192 
 
 Opacity of milk 171 
 
 Organic matter in the air 52 
 
 nitrogen in water, determination of . 106 
 
 *' Oxygen consumed," determination of 112 
 
 Oxygen dissolved in water, determination of 123-129 
 
 table for 242 
 
 Pentosans, determination of 213 
 
 Pettenkofer method for carbon dioxide 28 
 
276 INDEX. 
 
 PAGK 
 
 Petterson and Palmquist apparatus 40 
 
 Phosphates in water, determination of 1 20 
 
 Purified vs. clarified water 69 
 
 " Popular tests " for carbon dioxide 70 
 
 Potassium chromate, reagent, preparation of 259 
 
 ferrocyanide 61 
 
 hydroxide 258 
 
 iodide reagent, 261 
 
 sulphide reagent 262 
 
 sulphocyanide reagent 259 
 
 Pressure, influence on respiratory exchange 13 
 
 Preservatives in food 163 
 
 Proteids of milk, determination of 183 
 
 , Kjeldahl method for 206 
 
 Residue on evaporation, determination of 115 
 
 Reducing sugar, determination in beer 225 
 
 Reducing sugar, Munson and Walker's table for 248 
 
 Refractive index of butter 201 
 
 Refractometer, Abbe 202 
 
 Reichert-Meissl number 194 
 
 Renovated butter 192 
 
 , detection of 200 
 
 Resins, detection in vanilla 229 
 
 Respiratory exchange 15 
 
 quotient 14 
 
 River water 85 
 
 " Safe " water 75-79 
 
 Salicylic acid, detection of 223 
 
 Salt, determination in butter 204 
 
 Samples, collection of water 96 
 
 Sanitary chemistry, scope of 1 
 
 science, importance of 2 
 
 Sediment of water, estimation of 136 
 
 " Sewer-air " 1 7-24 
 
 Shallow wells 90 
 
 Silver nitrate, chlorine reagent 259 
 
 Soap, standard solution of 259 
 
 Sodium carbonate, detection in milk 188 
 
 chloride, standard solution 258 
 
 Solids of milk 173 
 
 Soot, estimation of, in air 54 
 
 Specific gravity of butter 201 
 
 milk 170 
 
INDEX. 
 
 277 
 
 PAGB 
 
 Specific gravity of milk, table for 243 
 
 wine 216 
 
 Spoon test 199 
 
 Springs 88 
 
 Starch, detection in milk 186 
 
 , determination of 211 
 
 Steam vacuum 50, 51 
 
 Storage of water 71, 87 
 
 Sugars, determination in cereals 210 
 
 Sulphites, detection of 225 
 
 Surface water 85, 89 
 
 , character of 72 
 
 Turbidity of water, estimation of 136 
 
 Turmeric, detection of 233 
 
 Vanilla extract 226 
 
 Vanillin, determination of 227 
 
 Ventilation, apparatus to illustrate r 24 
 
 , natural vs. artificial 23 
 
 a necessity 19 
 
 , principle of 22 
 
 , requirements of 26 
 
 , to test efficiency of 24 
 
 Vital capacity 10 
 
 Walker method for carbon dioxide 34 
 
 Water, acceptable 82 
 
 Water analysis, blank form for 141 
 
 , points to determine in 80 
 
 , statement of results 140 
 
 , value of 94 
 
 Water, classification of 85 
 
 , circulation of 61 
 
 , determination in butter 204 
 
 , illustration of contamination of 62 
 
 , its relation to health 66 
 
 , legal restrictions upon use of 57 
 
 , need of 6 
 
 , passage through the ground 64 
 
 , preliminary inspection of source of 80 
 
 , presence of organisms in 66 
 
 , solvent power of 65 
 
 , storage of 71 
 
 j the ideal drinking-water 59 
 
78 INDEX. 
 
 PAGE- 
 
 Water-rvapor in air ...... .. . . . ■ 16 
 
 Water siphon — 48, 49 
 
 <. j daily quantity needed ....... 6 
 
 Water-pipes ... 94 
 
 Waters, table of average composition of .... 238 
 
 normal . 239 
 
 ,. polluted, table of . . 240, 241 
 
 Water free from ammonia, preparation of 255: 
 
 , determination in cereals • 2p|i 
 
 "- ."milk. ' :c/,.j&f 
 
 Well-water . — .-,=....:.■ , &w. arw&bcjd 
 
 Wine, analysis of ................. .. . r 216 
 
 , composition of 215 
 
 Wolpert shaker ....... .----. • - - - uftrv? 47' 
 
 Wooden pipe n?sf*~ 94-' 
 
HOV 5 19 09 
 
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