COLUMBIA LIBRARIES OFFSITE HEALTH SCIENCES STANDARD HX00060623 Class Book Columbia College Library- Madison Av. and 49th St. New York. 1?A43o Columbia (Hnttier^ftp College of ^fjpsiictang anb ^urgeong w^ i^ / . SANITAEY EXAMINATIONS OF WATEE, AIE, AND FOOD 'Cyi ( f w SANITAEY EXAMINATIONS OF WATEE, AIB, AND FOOD Jl 3ia;nbb00k iox the itt^bkd ®Mux at Wjz^lth WITH ILLUSTRATIONS By COENELIUS B. FOX, M.D., M.E.C.P., Lond, MEDICAL OFFICER OF HEALTH OF EAST, CENTRAL, AND SOUTH ESSEX ; FELLOW OP THE CHEMICAL SOCIETY ; FELLOW OF THE BRITISH METEOEOLOGICAL SOCIETT ; MEMBER OF THE SCOTTISH METEOROLOGICAL SOCIETY ; MEMBER OF THE FRENCH SOCIETY OF HYGIENE, ETC. ; AUTHOR OF " OZONE AND ANTOZONE : — WHERE, WHEN, WHY, AND HOW IS OZONE OBSERVED IN THE ATMOSPHERE?" "THE DISPOSAL OF THE SLOP WATER OF VILLAGES," ETC. LONDON J. & A. CHUECHILL, NEW BUELINGTON STEEET 1878 [Al/ rights reservedJi r4 TO JOHN" SIMON, C.B. D.C.L., F.R.S. WHOSE LABOURS IN THE DEVELOPMENT OP ^^ THE SCIENCE OP PREVENTIVE OR STATE MEDICINE MERIT THE S " GRATITUDE OP ALL MEN OP ALL NATIONS THIS VOLUME IS WITH HIS PERMISSION DEDICATED. c o o n PEEFACE. The demand for a third edition of my 'brochure on " Water Analysis," affords me an opportunity of offering to the public the results of an increased and more extended experience. The additions are so great as to compel me to re-write nearly all that I have previously published on the subject. The many kind appreciative comments that have been made on it by the scientific world, and especially by that section of it that is engaged in the public health service of the country, coupled with the sug- gestions of friends, have led me to incorporate with my essay on " Water Analysis " sections on " Examinations of Air and Food." I trust that none of my readers will imagine that I have the presumption to place myself forward as a teacher of the medical officers of health of the country. I wish rather to offer suggestions and hints, that, I am sure, will be helpful to those who have not plodded as I have, along long, tedious, and tortuous paths for many years, at the sacrifice of much time and labour, because I could not find a short cut. It does not follow that because there is " no royal road to learning," that the road which we have to traverse should be viii PEEFACE. beset with all kinds of unnecessary obstacles and diffi- culties. The objects which I have kept steadily in view in writing the following pages have been : — 1. To avoid a consideration of these three subjects solely after the manner of an analyst who mechanically deals with chemical operations and arithmetical cal- culations, but to treat them as a physician who studies them in connection with health and disease ; 2. To render such details respecting examinations of water, air, and food, as fall within the province of the medical officer of health, so free from technicalities and all cloudy and chaotic surroundings, as to enable any one who possesses the average chemical knowledge of a jDhysician to teach himseK by the aid of this vade mecum of the health officer. It affords me much pleasure to acknowledge with gratitude the assistance rendered to me by scientific men throughout the country, amongst whom may be mentioned Drs. Attfield, Bartlett, Brown, Cameron, F. de Chaumont, Hill, Shea, Thome, Tidy, and Messrs. Dixon, Slater, Thomas, etc., etc. Chelmsford, Mai/ 1878. CONTENTS. Preface Introductory Observations Vll 1 SECTION I.— SANITAEY EXAMINATION OF A DEINKING WATEE. CHAPTER I. The Wholesomene&s op a Water . . . CHAPTER IT. The Determination of the Amount and Nature OF THE Or&ANIC MaTTER . 13 1. The Smell and Keeping Powers 14 2. The Colour Test 17 3. The Trichloride of Gold Test 20 4. Heisch's Test . 21 5. Fleck's Test 22 6. The Zymotic or Micro2yme Test 22 7. The Permanganate of Potash Process 23 A. Qualitative 23 B, Quantitative , 29 Drs. Letheby and Tidy's Process 29 Drs. Woods' and F. de Chaumont's Process 32 X CONTENTS. PAGE 8. The Wanklyn, Chapman, and Smith Process . 36 9. The Frankland and Armstrong Process . 48 Table exhibiting different classes of Waters . 54 A Comparison between the Results furnished by the three last-named Processes . .57 Table of Comparison . . . .64 CHAPTEE III. The Detekmination of the Mineral Peoducts re- sulting FROM Changes in the Animal Organic Matter . . . . . .66 1. Ammonia . . . . .66 2. Nitrogen as Mtrates and Nitrites . . 70 A. Qualitative — the Horsley Test . . 80 B. Quantitative — Modification of Thorp's Process 83 CHAPTEE IV. The Determination of the Amount op Solid Resi- due, its Appearance Before, During, and After Ignition, and the Loss of Volatile Matters thereby occasioned . . . .94 A. The Amount of Saline Matters . - 94 B. The Appearance of Solid Residue Before, During, and After Incineration . .97 Table of lUustration . . .100 C. The Amount of Volatile Matters burnt off by Ignition ..... 102 CHAPTEE V. The Determination of the Amount of Chlorine . 104 CONTENTS. . XI CHAPTER VI. PAGE The Determination of the Haedness . .107 CHAPTER YII. The Determination of the Amount of Magnesia, Sulphates, and Phosphates . . .111 A Magnesia, Sulphate, Carbonate, and Nitrate . 112 B, Sulphates of Lime, Magnesia, and Soda, as Anhydrous Sulphuric Acid . . .114 C. Phosphates . . . . .118 CHAPTER VIII. The Determination of Poisonous Metals . .121 CHAPTER IX. Microscopic Examination of the Sediment op a Water . . . . . .124 CHAPTER X. The Collection op Samples of Water for Analysis 131 CHAPTER XI. Time occupied in performing an Analysis . .133 CHAPTER XII. Entry of Analysis in Note and Record Books . 137 XU CONTENTS. CHAPTEE XIII. PAGE Mistakes op Water Analysts and how to avoid THEM . . . . . . 139 CHAPTEE XIV. Useful Memoranda foe Medical Officers of Health when performing Water Analysis . 147 CHAPTEE XV. Formation of Opinion and Preparation op Eeport RESPECTING SAMPLES OF WaTER SUBMITTED TO Analysis ...... 150 Data on which to base an opinion . .157 A. Diagnosis and formation of an opinion . 160 Diagnosis of a Peaty Water . . .164 Diagnosis of Pollution by Urine, or by Slop and Sink Water . . .167 Diagnosis of Pollution by contents of Cesspools and Sewers . . . .168 B. Preparation of Eeport . . .170 CHAPTEE XVI. Concluding Eemarks . . . . .172 Eecipes of Standard Solutions, etc. . . .173 CONTENTS. XUl SECTION II.— SANITAET EXAMINATION" OF AIE. CHAPTEE XVII. PAGE The Pueity op Air . . . .179 PAET I. Different Kinds of Impurities . . .188 CHAPTEE XVIII. Organic Matter . , . . .189 CHAPTEE XIX. Oxides op Carbon . . . . .199 A. Carbonic Acid . . . .199 B. Carbonic Oxide . . . .209 CHAPTEE XX. Putrefactive Processes, Sewage Emanations, and EXCREMENTAL FiLTH . . . .215 CHAPTEE XXI. Poisonous Cases and Injurious Vapours . .218 CHAPTEE XXII. Suspended Animal, Vegetable, and Metallic, as WELL AS Mineral Impurities . . .219 PAGE xiv CONTENTS. CHAPTEE XXIII. Emanations from Geouotd having Damp and Filthy Subsoil — Subsoil Air, Churchyard Air, Marsh Air 225 CHAPTEE XXIV. The Deleterious Effects on Health of the Air of our Houses ..... 231 PAET XL The Detection and Estimation of the Amount of THE MOST Important Impurities found in the Air ...... 252 DIRECT METHOD. CHAPTEE XXV. Modes of Observing Solid Bodies in the Air, AND of Separating them for Examination . 253 CHAPTEE XXVI. Microscopical Examination of the Dust of the Air 264 CHAPTEE XXVII. Chemical Examination of Air . . .272 A Organic Matter .... 274 B. Carbonic Acid . . . .292 CHAPTEE XXVIII. Metallic Poisons : — Arsenic, Copper, and Lead . 305 CONTENTS. ' XV INDIRECT METHOD. CHAPTEE XXIX. PAGE OZONOMETRY . . . . • .311 PAET III. Sketch of Relation between certain Meteorolo- gical Variations in the Condition op the Air, and states of health and disease . . 320 CHAPTER XXX. 1. — The Influence of Differences of Tempera- ture, Moisture, and Barometric Pressure of the Air, Direction of the Wind, etc., on Health 322 A. The Temperature of the Air . . .322 B. The Hygrometric state of the Air . .324 0. The Pressure of the Air . , . 330 D. The Direction of the Wind . . 336 CHAPTER XXXI. 2. — The Meteorological Conditions which appear to favour or retard the development of cer- taln Diseases ..... 337 1. Surgical Fever and Shock after Operations . 337 2. Smallpox . . . . .340 3. Measles . . . . .341 4. Whooping-Cough . . . .343 5. Scarlet Fever . . , .343 6. Fever . , . . .346 XVI CONTENTS. 7. Diarrhoea, Dysentery, and Cholera , 348 8. Bronchitis, Pneumonia, and Asthma , 350 9. Phthisis Pulmonalis .... 351 10. Hsemorrhages, Apoplexy, Abortion, and Neu- ralgia ..... 352 11. Hydrophobia .... 352 12. Erysipelas and Puerperal Fever 353 13. Insanity ..... 354 14. Eheumatism .... 354 Mortality at Different Ages and of each Sex 355-357 PAET IV. Mode of Observing the Meteoeological States AJSTD Variations in the Condition of the Air 359 CHAPTEE XXXII. 1. — The Atmospheric Pressure . . . 360 CHAPTEE XXXIII. 2. — The Temperature of the Air . .365 CHAPTEE XXXIV. 3. — The Hygrometric Condition op the Air . 377 CHAPTEE XXXV. 4. — The Direction and Strength of the Wind . 384 CHAPTEE XXXVI. 5. — The Electrical State of the Air . , 388 Kegistration of Meteorological Observations , 394 CONTENTS. XVU SECTION III.— SANITAEY EXAMINATION" OF FOOD. CHAPTER XXXVII. PAGE The Purity of Food . . . 397 CHAPTER XXXVIII. Inspection and Examination of any Animal in- tended FOR THE Food of Man . . . 399 CHAPTER XXXIX. Inspection and Examination of Carcases of Ani- mals, Meat and Flesh Exposed for Sale, or Deposited for the Purpose of Sale, or of Pre- paration FOR Sale, and intended for the Food of Man ...... 402 Characters of Good and Bad Meat . . . 403 The Prevalent Diseases of Stock in relation to the Supply of Meat for Human Food . . 407 1. Contagious Fevers . . . 408 2. Anthracic and Anthracoid Diseases, etc. . 412 Arguments against the Employment of Diseased Meat 416 Arguments in favour of the Employment of Diseased Meat . . . . . .417 3. Parasitic Diseases . . .421 CHAPTER XL. Inspection and Examination of Poultry, Game, etc. 428 6 XVm CONTENTS. CHAPTEE XLL PAOE Inspection and Examination of Fish . . 429 CHAPTEE XLII. Desteuction of Condemned Flesh . . .431 CHAPTEE XLHI. Inspection and Examination of Feuit and Vege- tables ...... 434 CHAPTEE XLIV. Inspection and Examination of Coen . . 435 CHAPTEE XLV. Inspection and Examination of Floue . . 439 Chemical Examiuation .... 441 Microscopic Examination .... 445 CHAPTEE XLVI. Inspection and Examination of Beead . . 455 Microscopic Examination . . . .456 Adulterations of Bread . . . .457 Chemical Examiuation . . . .460 CHAPTEE XLVII. Inspection and Examination of Milk ^ . 468 Microscopic Appearance and Examination . . 470 CONTENTS. XIX PACE Chemical Examination . . . .473 Milk of Diseased Animals .... 483 Appendix — Distilled Water and Chemicals . . . 493 List of Apparatus requisite . . . 494 Rules for Conversion of Different Expressions of Results of Analysis . . . .496 Metrical Weights and Measures . . .496 Table for Reducing Barojnetrlc Observations to the Freezing Point (32° F.) . . . .498 Table for Reducing Barometric Observations to the Level of the Sea ; and conversely, for the Deter- mination of Heights by the Barometer . . 499 Table of the Relative Humidity given by the Differ- ence between the Dry and Wet Bulb . .501 Form — Register of Rainfall . . .502 iOHAh' INTEODUCTOEY OBSEEYATIONS. The elementary principles on which the greater part of the work of the Medical Officer of Health is based, may be truly said to be the prevention of the pollution of Water and of Air with filth and its products, and the prevention of the consumption of articles of Food deleterious to health. Pure Water, pure Air, and good, wholesome un- adulterated Food, constitute the piQars which form the tripod on which rests the " mens sana in corpore sano." My ideal of a Medical Officer of Health is that of a physician who is thoroughly conversant with every question affecting Public Health, and who is able to analyse quantitatively water, air, and food ; and is so well versed in analytical work as to be able to take his oath in a court of justice respecting any matter requiring the assistance of a scientific expert in state medicine. Such a man should be debarred from private practice, and placed over a large area with definite boundaries, such as a county or riding. His appointment should be permanent, so that he may fearlessly and conscientiously perform his duty. Every medical practitioner in his district should act towards him in the capacity of an assistant. The Medical B 2 INTRODUCTOEY OBSERVATIONS. Officer of Health should in fact be the Head Centre of all Public Health aflfairs in each county. First, as to Water. — The examination of drinking waters forms a very important portion of the duty of those who engage in a crusade against preventable disease. A Health Officer should not only be prepared to answer such a question, as, "Does a water contain a deleterious amount of organic matter ?" but should be able to reply to such interrogations, as, " Is this water wholesome and good?" "Which of several specified wells furnishes the purest water ?" etc. Some are disposed to think that it is unadvisable for a Medical Officer of Health to analyse water. The list of his duties, as laid down by the Local Govern- ment Board, certainly contains no order that he should act as a water analyst. The latest Adulteration Act (Food and Drugs Act of 1875) expressly excludes water from its provisions ; although few, I should pre- sume, would hold that water is not in some sense a food (much more so than either mustard or pickles) ; or that, having regard to the derivation of the word " adulterate," the sewage and water supplied by some wells could not strictly be considered to be " a change to another " (the exact meaning of the word), of an article of daily consumption of a very serious character. A Medical Officer of Health who can promptly give an authoritative opinion as to the quality of a water, is much more helpful to the Sanitary Authorities with which he may be connected, than one who is unable so to do. Continually cases arise, in the working of a large district, where a Sanitary Authority requires an immediate decision as to the quality of a water, in order that steps may be taken with the least possible INTEODUCTOEY OBSEEVATIONS. 3 delay in the prevention of the extension of a disease. If, as is customary in some places, samples of water are sent to professional analysts living at a distance, great loss of time is generally experienced, and the analyses of waters yield illusory results in consequence of being examined in a stale instead of in a fresh condition. I have often known a month or more to elapse before the report is received, when, frequently, the opportunity for acting on the opinion expressed has passed away. More- over, a Medical Officer of Health requires, for his owe guidance in tracing out the causes of diseases, and in taking measures to stop their spread, to ascertain ex- peditiously and with precision the state of waters. Secondly, as to Air. — ^What can be more important than the establishment of some rules of practice as to the purity of the air of our houses and public buildings ? There can be no question but that there is a distinct causative relation between consumption and re-breathed air, between the condition of the air in unventilated and crowded dwellings and the prevalence of lung affections. An enormous field is afforded to the health officer in the study of the subject of the defilement of the air by metallic, mineral, and other visible impuri- ties, with a view to the discovery of some means, whereby the condition of those classes who have to earn their daily bread by working at such unwholesome avocations as button manufacture, stone masonry, cotton, wool, and silk spinning, etc., may be ameliorated. Thirdly, as to Food. — The attention of the Medical Of&cer of Health should undoubtedly be restricted in his analytical examinations to the necessaries of life, and to those substances that are apt to be injurious in themselves, or are liable to be adulterated with 4 INTEODUCTOEY OBSEEVATIONS. substances deleterious to health. Professional analysts, distinct from Medical Of&cers of Health, there always must be. On these officials devolves the duty of analysing foods, etc., which contain fraudulent but harmless admixtures, such, for example, as the compound of mustard, and of cocoa with starch — an innocuous diluent, — the mixture of sardines and sprats with an- chovies, and of salt with gelatine to increase its weight in the scales, etc. The duties of the Medical Officer of Health, as laid down by the Legislature, all rest on the assumption that he is the judge on all subjects relating to public health. It is of course difficult to draw a hard and fast line in this matter, as in every other in this world. " 1st Duty. — He shall inform himself, as far as prac- ticable, respecting all influences affecting or threatening to affect injuriously the public health within the district. "2d Duty. — He shall inquire into, and ascertain by such means as are at his disposal, the causes, origin, and distribution of diseases within the district, and ascertain to what extent the same have depended on conditions capable of removal or mitigation. " Zd Duty. — He shall, by inspection of the district, both systematically at certain periods, and at intervals as occasion may require, keep himself informed of the conditions injurious to health existing therein. " ^th Duty. — In any case in which it may appear to him to ba necessary or advisable, or in which he shall be so directed by the Sanitary Authority, he shaU himself inspect and examine any animal, carcase, meat, poultry, game, flesh, fish, fruit, vegetables, corn, bread, or flour, exposed for sale, or deposited for the purpose of sale, or of preparation for sale, and intended for the I INTEODUCTORY OBSERVATIONS. 6 food of man, which is deemed to be diseased, or "iinsound, or unwholesome, or unfit for the food of man ; and if he finds that such animal or article is diseased, or un- sound, or unwholesome, or unfit for the food of man, he shall give such directions as may be necessary for causing the same to be seized, taken, and carried away, in order to be dealt with by a justice, according to the provisions of the statutes applicable to the case." The First Duty alone is comprehensive enough to include the consideration of each of the three subjects treated of in the following pages, and even more. As Medical Officers of Health are often at present inun- dated with analytical work by those who are simply curious as to whether their drinking water is or is not good, or as to the reason why it does not make good tea, or as to why their sugar turns their tea of a black colour, or as to whether their wall papers contain arsenic, or as to why their brandy and water assumes sometimes an inky hue, it is a great protection to the Medical Officer of Health, if he refers all applicants to the Sanitary Authority of the district for an order, with the previous understanding, arrived at with the Sanitary Authority, that it will not give him any instructions to analyse at the public expense, unless evidence is placed before it of a nature calculated to show that the sub- stance respecting which the request is made has been or is likely to be deleterious to health, and that the applicant cannot afford to pay for the analysis out of his or her own pocket. As all chemical examinations to be exact must be quantitative, and as all inaccurate examinations are of little worth, and as, moreover, the quantitative analysis of a substance is not laid down as one of the duties of a 6 INTEODUCTOEY OBSEEVATIONS. Medical Officer of Health by the Government, it follows as a matter of logical sequence, that all quantitative analytical work conducted for a Sanitary Authority and for the public should be paid for. Work performed gratuitously is rarely valued. The progress of a knowledge of Preventive Medicine is exceedingly slow. The Medical Officer of Health, who is the schoolmaster of his district as to sanitary matters, must necessarily find his work of a very up- hill character. He is continually regarded as an irreverent individual, who is wicked enough to interfere with the purposes and designs of the Almighty. Thousands are still to be found who believe that if a water is bright and clear, and not unpleasant to the taste, it must be good ; whilst it has been proved, over and over again, that such a water may be polluted with unspeakable filth, and that an excessive brilKancy of a water is a suspicious sign. There can be no question, however, but that the elements of sanitary science are slowly and surely in- fluencing the people of this and of other countries for good. Such cases as that of the servant who, coming from an obscure village near the Dartmoor, objected to the pure water of a distant town where she was in service, on the ground of its being devoid of either taste or smell, are becoming rare. SECTION I. SANITARY EXAMINATION DRINKING WATER fk CHAPTER I. THE WHOLESOMENESS OF A WATEE. Pure spring waters, devoid of all metallic impurities, are imdoubtedly the most wholesome waters for drinking purposes. Pure shallow well waters occupy a second place. The waters furnished by artesian wells, and the rain that descends in the country far away from towns and cities, occupy jointly a third position in order of merit; and lastly come the waters of streams and rivulets, the majority of which contain more or less filth, and in times of heavy rains soil and mineral debris of every description. All will readily understand the reason that spring water should be placed first, and river water last in the order of wholesomeness, but the motive for assigning to artesian well water and rain water a situation inferior to both spring and shallow well water is perhaps not so obvious. Artesian well waters gene- rally contain an excess of saline matters i^ide page 97). Rain water contains, an infinitesimal amount of saline substances, and is almost entirely devoid of lime, a body which is so important in building up the bony tissues of young animals. I am aware that some few eminent men consider that young creatures solely derive the lime which they require from their food * {vide, for example, the evidence of Dr. Lyon Playfaix in the Sixth * One pound of flour contains only 1 \ grain of lime, and that in a form -which is associated with the more insoluble part of the grain. 10 THE WHOLESOMENESS OF A WATER. Eeport of the Eivers Pollution Conunissioners, page 189. Those who entertain this view consider, I believe, that water simply acts as a diluent or solvent in nutrition. I have no room here to combat these views, but can simply give it as my opinion that the young animal supplies the wants of its system for lime from every available source. It is almost impossible to define a wholesome water ; but here are two examples of most wholesome spring waters : — Spring water. Name and Description of the Sample of Water. Grains per Gallon. Part per MiUion = Milligramme per Litre. Total Hardness Spring supplying village of Woodham Walter, Essex .... Solids. 21- Chlorine. 2-4 Free Ammonia •00 Albumi- noid Ammonia •01 Degrees. 6 Spring near Drewsteign- ton, Dartmoor, Devon 14- 1-6 •02 •01 8 N.B. — Ko metals in either water. It may be useful to give examples of the composition of good shallow well and good artesian well waters and pure rain water ; — Name and Description of the Sample of Water. Grains per Gallon. Part per Million = Milligramme per Litre. Total Hardness Free Albumi- Solids. Chlorine. noid Degrees. Shallow Good shallow well water. Ammonia well water. Depth 25 feet . 30 • 7- •01 •05 13 Artesian Good Artesian well water. well water. Depth 300 feet . Good Artesian well water. 85 ^4 27-1 •74 ■03 5 Depth 175 feet . 106-4 37-7 •01 •02 9^ Bain water. Pure rain water collected in open country . 1- •6 •45 •08 •7 THE WHOLESOMENESS OF A WATEK. 11 In forming an opinion as to the quality of a water for sanitary purposes, tlie old-fashioned plan of carefully estimating the number of grains per gallon of each saline constituent, often 8 or 10, and at times as many as 18 or 1 9 in number, is perfectly lumecessary. Of what importance is it to ascertain the exact fraction of a grain of silica or alumina which a water may contain, or whether it does or does not possess a trace of fluorine ? It is of not the sKghtest practical moment as to whether our drinking water contains 3 or 6 grains of carbonate of lime per gallon, or whether 1 or 5 grains of chloride of sodium are dissolved in the same quantity, provided it is pure. In the case of mineral waters, and of waters proposed to be used for brewing and other commercial purposes, a detailed analysis, containing the exact amount of every salt, may sometimes be required. Equally useless for all sanitary work is the estimation of the amount of cubic inches of the nitrogen, oxygen, and carbonic acid gases evolved on boiling a water, and the determination of the temperature of a water. In forming a judgment as to the character of a water, it is desirable for the Medical Officer of Health to ascertain some or all of the following particulars : — {a) The amount and nature of the organic matter. Data on which an (&.) The existence or not of the products of the opinion oxidation of organic matter, such as the based. nitrates and nitrites, and in certain cases the quantity of these salts. (c.) The amount and nature of the sahne consti- tuents. (d) The degree of hardness. 12 THE WHOLESOMENESS OF A WATEE. (e.) The existence and the amount, if present, of metals. (/.) The existence and the amount of purgative salts, such as the sulphate and carbonate of magnesia, or the sulphates of soda and potash. In the majority of cases that present themselves, information on the first two points is alone needed. CHAPTEE II. THE DETEEMINATION OF THE AMOUNT AND NATURE OF THE ORGANIC MATTER. All waters, even tlie purest, contain some organic matter. The excess is alone objected to ; and espe- cially that of animal origin, which is especially prone to pass through certain putrefactive changes. A great variety of methods have been employed at different times by EngKsh and German chemists. "With- out adverting to the history of the subject, which would be foreign to the purpose of this little work, I shall describe those which have taken the lead, and are now believed in and practised by medical officers of health and analysts in their attempts to pronounce on the quality of a water. The employment of these very dissimilar modes has led, unfortunately, to most con- tradictory results : — 1. By noting the presence or absence of any smell in Most popu- lar tests ai ' processes. the air with which the water has been violently shaken. and by observing the " keeping powers " of a water. 2. The colour test. 3. The trichloride of gold test. 4. Heisch's test. 5. Fleck's test. 6. The zymotic or microzyme test. 7. The permanganate of potash process. 8. The Wanklyn, Chapman, and Smith process. 9. The Frankland and Armstrong process. 14 the determination of the amount and 1. — The Smell and "Keeping Powers" of a Water. The smell. Tlu Smell. — The most rough-and-ready way that has been employed for ascertaining whether or not a water is polluted with organic matter is to partly fill a clean bottle with a sample of it, and having violently shaken the same, to take a hearty sniff at the air of the bottle which has been agitated with the water. If the air smells sweet and fresh, the absence of an in- jurious amount of organic matter is inferred, and vice versd. There is no doubt but that much may be learnt in this way by those who do not blunt their sense of smell by smoking, especially if they frequently practise this primitive test. It is very easy to distinguish thus between river and spring water; and a very impure water, which may exhibit no fault to the eye, may frequently disclose to the olfactory nerves the fact of its pollution. If no smell is noticed in this manner, some may be observed on gently warming the water ; and if none then, the addition of a few grains of caustic potash may render it apparent. Mr. Crookes' device is as follows : — " Take two or three ounces of the water, the smell of which is to be tested, and warm it care- fully and quickly in a flask to a temperature of about 102° or 104° Fahr., say 4° or 6° above blood heat; then take a glass tube of about -|-inch diameter and 3 feet long, put the flask containing the water on the floor, carefully suck up the water five or six times into this tube until the inside of the tube is thoroughly wetted with the water, then allow the water to escape, and closing one nostril with the finger, take two or three full inspirations through the tube with the other nostril." It should be borne in mind, however, that 'NATURE OF THE OEGANIC MATTER. 15 the existence of an unpleasant odour or taste about the water from a well sunk in clay is no proof of the pollution of that water with organic matter. Water, if allowed to remain long in contact with certain kinds of clay, in some situations, acquires such an objectionable smell as to be sometimes quite undrinkable, and yet may not, at the same time, contain an amount of organic matter that would warrant its condemnation. Com- plaints are made sometimes of this smell in the case of waters of artesian wells, sunk through the clay, where the supply of water is much greater than the demand. A well of this kind can be made to furnish excellent water by the frequent withdrawal of its contents, or, if that is not practicable, and the well be an artesian one, by the filling up of the dug portion of the well and by drawing the supply solely from the bore-pipe. In this way the water is prevented from lying long in contact with the sides of the well. The clay contains in some situations little nodules of iron pyrites — i.e., sulphide of iron, and fossils of the same composition. They possess a peculiar odour, which they give forth, espe- cially when wetted and rubbed. This odour seems to be in some cases communicated to the water, and re- minds one of sulphurous acid, and occasionally of fennel. These offensive waters often contain such an enormous excess of chlorides and other saline matters as to be not potable; they are known by the public as " brackish" "Brackisii" . TT • T water. waters. Here is an example : — Grains per Gallon. Solids. Chlorine. Well behind "Compasses," PH. WH . 380- 29-5 Other waters from the clay have a decided smell of "Rotten sulphuretted hydrogen gas, and become turbid on stand- ®^^ "^^i^^^- ing, in consequence of the separation of sulphur. Books odours. 16 THE DETERMINATION OF THE AMOUNT AND tell US that sulphuretted hydrogen is generated from the decomposition of water and iron pyrites. Before this gas is produced, I think with Mr. Slater that a partial decomposition of sulphide of iron probably occurs with a formation by oxidation of sulphuric acid. This acid acts, then, on the remaining sulphide of iron, evolving sulphuretted hydrogen gas. It has been considered probable by some that this gas arises from the decomposition of sulphates through the instrumentality of certain algse. Professor Kubel states '''' that if water is warmed to 110° F., the olfactory nerves can detect coal gas if present in a water, when chemical means fail to do so. Rsh-uke A pcculiar fish-like odour has been observed in some of the lakes and rivers of the United States. The water supplies of New York, Boston, Baltimore, and many other cities, and the water of the Tennessee river near Nashville, have been at times thus unpleasantly affected. A very interesting investigation has recently been made by Professor Lattimore, of the University of Eochester, respecting the Hemlock Lake supply of that city, who arrived at the following conclusions : — 1. The fish-like odour is due to some obscure con- dition of certain undetermined species of algae, probably to their decay and decomposition ; 2. The development of this odour seems to be generally connected with the rise of temperature in summer ; in one case it commenced with a falling tem- perature in autumn ; 3. No evidence is forthcoming to warrant a suspi- * Anleitung zur Untersuchung von Wasser. Zweite Auflage von Dr. F. Tiemann: Braunschweig, 1874. NATUEE OF THE OEGANIC MATTEK. 17 cion of such water possessing any deleterious effect on the health of those who drink it. Tlie "Keeping Poivers" of a Water. — The property "Keeping possessed by a water of "keeping" for a greater or less ^°^"^"°^^ length of time, without undergoing any change percep- tible to the unaided eye, has been employed as a gauge of the purity of a water. That a pure water can be preserved unchanged for a considerable time, and that an impure water will soon become altered in appearance, are undoubted facts. It is equally true, however, that some waters of the greatest purity will, very soon after removal from their sources, be found to display vegetable life ; for example, some artesian waters, that possess a large amount of free ammonia. The temperature of the air has, of course, much to do with the "keeping powers" of a water ; life and growth being more active in hot than. in cold weather. 2. — The Colour Test. It is helpful in forming an opinion as to the quality The colour of a water to pay a certain regard to its colour, although, apart from other indications of its condition, no reliance should be placed on this test. Speaking generally, it may be said that waters polluted by filth have various shades of a straw or brownish tint, deeper in proportion to the amount of filth which they contain. To this rule there are many exceptions. A water may possess a strong brown or yellowish tint and yet be pure— e.^., some peaty waters, and waters containing iron. Certain artesian waters of great purity have a straw tint. The Loch Katrine water, which supplies the city of Glasgow, displays a colour apparent to every one. On c 18 THE DETEEMINATION OF THE AMOUNT AND the other hand, some waters that are as devoid of colour as distilled water, and exhibit a greater brilliancy, are found to be polluted with a large amount of animal filth. "Waters from different sources are often proposed for the supply of a town or village with the object of selecting that one which is in all respects the best. If, on analysis, two or three of the collection should appear to be equally good, the one possessing the least colour should be preferred. It has been proposed to measure definitely the Mr. P.King's colour of Water in two or three ways. Mr. F. King, mode of^ Analyst, of Edinburgh, accompHshes this object by pre- ment. paruig a standard "solution of caramel or burnt sugar (such as is used for colouring soups), which, by means of a graduated burette, is dropped in certain known quantities into distilled water so as to match the tint of the water under examination.'"'' An apparatus has Dr. Bow- recently been devised by Dr. Bowditch t for testing the instrument, depth of colouT of different specimens of water. The instrument consists of two tubes, B and D, sliding, water- tight, one within the other, the lower end of each tube being closed with a disc of plate glass. Into the large tube, B, just above the plate glass disc, is inserted a piece of small tubing, which terminates in a funnel- shaped receiver, A. Water poured into this receiver will therefore pass into the space between the two glass discs, entirely filhng the outer tube when the inner tube is withdrawn, and again returning to the receiver when the inner tube is passed down, so that the glass discs come in contact with each other. * Chemical News, March 25, 1875. + Described in Eeport upou the Purity of the different rivers around Boston (City Document, No. 142). NATUEE OF THE OEGANIC MATTER, 19 Through an opening, near the upper end of the smaller tube, is inserted one end of a rhombic prism, E, in which total internal reflection takes place twice. This prism extends half-way across the inner tube, so that an eye, looking through the eyepiece, sees the field of vision nearly half filled by the surface of the prism (see Mg. 2). The eyepiece, G-, contains a single lens, which is focussed upon the upper surface of the prism. The position and angles of the prism are such that a ray of light, outside of and parallel to the tube, B, is reflected first directly into the tube, D, and then parallel to its axis, thus emerging from the prism and entering the eyepiece alongside of the rays of light which have passed through the two plate-glass discs. It wiQ thus be seen that the conditions for comparing the colour and in- tensity of these two sources of light are as favourable as possible. 20 THE DETEEMINATION OF THE AMOUNT AJSTD A piece of white card, C, fastened at the lower end of the larger tube, throws a "uniform white light through both tubes, and also along the outside of the instrument into the prism. In using the instrument a piece of brownish yellow glass is placed in front of the prism, and the water whose colour is to be determined is poured into the re- ceiver. The inner tube is then withdrawn until the column of water between the two glass discs is sufficiently long to give to the light passing through it a colour equal to that imparted by the coloured glass to the light passing through the prism. The length of this column of water, which will, of com^se, vary inversely with the depth of the colour, can be determined by means of the scale on the inner tube. By this means the relative intensity of colour of various specimens of water may be determined with considerable accuracy. The late Dr. Letheby was in the habit of employing glass cylinders 2 feet long and 2 inches in diameter for making comparative observations. It is sufficient for the health of&cer to take two Nessler glasses of the ordinary size, 6 inches long and 1-|- inch in diameter, which should be free from colour, and having filled one with the water to be examined and the other with distilled water, to stand them side by side on a white porcelain slab, and looking down through both columns of fluid judge of the degree of difference (if any) in tint. 3. — The Teichloeide of Gold Test. A neutral or feebly acid solution of the trichloride NATUEE OF THE OEGANIC MATTEE. 21 of gold has been employed by some for the estimation of the amount of oxidizable organic matter. About 100 c.c. of the sample of water, having been rendered yellow with a few drops of this valuable solution, is boiled. The organic matter reduces the gold, and yields a purplish colour more or less deep, and a precipitate of a dark violet hue. Nitrites, if present in the water, produce the same effect. This test has been almost entirely abandoned in water examinations. 4. — Heisch's Test. This test consists in the addition of 1 grains of the purest sugar to 5 ounces of the water, in a perfectly clean bottle, which should be completely filled by it. The stopper having been accurately adjusted so as to thoroughly exclude atmospheric air, the bottle of water is exposed to daylight at a temperature of about 70° F. In the course of about 24 hours certain httle bodies, if the water contains sewage, may be seen floating about, provided we look carefully through the water against a black cloth suspended behind it. These bodies are found to consist, when examined by ^ or ^ inch objec- tive, of cells with very brilliant nuclei. These cells subsequently group themselves like grapes in a bunch. Ultimately the odour of butyric acid becomes perceptible. Dr. Frankland found that growths were producible in pure water containing in solution nitrate of ammonia, phosphate of soda and sugar, and came to the conclusion that the presence of phosphates in a water is solely needful to occasion this phenomenon. Mr. Heisch con- tends that the growths considered by biin as distinctive of the existence of sewage differ altogether from those 22 THE DETEEMINATION OF THE AMOUNT AND seen by Dr. Frankland as resulting from the presence of phosphates. He holds that the bodies due to sewage are developed without the presence of air (he had indeed first observed them in a liquid saturated with carbonic acid), whilst those noticed by Dr. Frankland in waters containing phosphates would not form if air is excluded, and are then always accompanied by bacteria, and are not attended by the formation of butyric acid. 5. — Fleck's Test, which is scarcely known in this country, is employed by some Germans. The nitrate of silver and hypo- sulphite of soda are the salts that are requisite in the working of the method.'"' 6. — The Zymotic oe Microzyme Test. The water to be operated on is collected by heating the tube or flask intended for its transportation to a high temperature, and hermetically sealing it. The neck thus sealed is broken underneath the surface of the water of which a sample is to be taken. Some of Pasteur's solution! (clear and fresh) having been boiled, one or two cubic centimetres of it are dropped into a test tube that has been heated to 395° F. Four or five j drops of the water to be examined are then added, and the mouth of the tube is plugged with cotton wool. If microzymes or organic germs exist in the water, it will * Jahreslericlit der Ghem. Centralstelle f. off. Ges. Pfl. i. Dresden. Dresden, 1872. + Kecipe — Crystallised sugar, 10 grammes ; ammonium tartrate,! "5 gramme ; yeast ash (well burnt), "1 gramme ; distilled water, lOCi cub. cent. NATUEE OF THE OEGANIC MATTEK. 23 in a few days become opaque from the presence of myriads of bacteria. The amount of impurity in a water is estimated by the degree of opacity and the greater or less rapidity with which this degTee is reached. Bacteria, vibriones, etc., are found in the purest waters in an infinitesimal amount. Their presence in any quantity indicates the co-existence of certain organic substances in a state of decomposition. Unfortunately no unchangeable line or basis, on which comparative examinations of waters could rest, is discernible in this or in the last described methods. 7. — The Peemanganate of Potash Peocess. A. Qualitatim Examination. In the year 1850, Prof. GT. Forchhammer of Copenhagen proposed ^' to employ a solution of per- manganate of potash for determining the amount of organic matter in water. The test solution, which is prepared by dissolving a small quantity of pure permanganate of potash in some distilled water, forming, in fact, " Condy's Fluid," has been used qualitatively and quantitatively as a measure of the oxidizable organic matter in a drinking water, in terms of the oxygen required to oxidize. Per- manganate of potash readily yields oxygen to many substances capable of combining with this element, of which organic matter is one amongst several others, such as iron, nitrites, and sulphuretted hydrogen, that are liable to occur in drinking waters, this chemical change * Trans. Royal Danish Socy., 5tli series. Physical and Mathem. Section. Vol. ii. 24 THE DETERMINATION OF THE AMOUNT AND Qualita- tively. Not relied upon by Analysts. being accompanied by the disappearance of the cliarac- teristic violet tint of the solution. The common practice amongst coimtry surgeons and dummy medical ofl&cers of health has in the past been to add two or three drops of a solution of per- manganate of potash to the water to be examined in a test tube, and to note the extent to which the original pink "tint is replaced by a brown colour, and the rapi- dity of the change. The amount of organic matter is supposed to be indicated by the degree and rapidity of the de-oxidation. The rules that guide those who rely on the perman- ganate of potash as a qualitative test are the follow- ing : — " If decomposed organic matter be present in a degree hurtful to health, the pink colour is changed to a dull yellow ; or, if a still larger quantity exists in the water, the colour will in time entirely disappear. "\'VTiere the colour is rendered paler, but still retains a decidedly reddish tinge, then, although putrefying or- ganic matter is j)resent, it is so in such minute quanti- ties as are not likely to be immediately hurtful. The quicker and more perfect the decoloration of the water tested, the greater is the quantity of decomposing organic matter." Dr. Frankland* and Mr. Wanklyn have both shown the uselessness of this permanganate of potash test ; but it is, notwithstanding, still employed by some, and often with misleading results. In a " Eeport of the Analytical Sanitary Commission on Disinfectants " {Lomcet, August 9, 1873, p. 194), this fact is referred to. The writer, however, adds that the fallacious in- dications of this permanganate of potash test " has led * Journal of Chemical Society, vol. xxi. p. 77. NATUEE OF THE ORGANIC MATTER. 25 to the total disuse of the old method of testing water." If this result had been attained I should not now be warning my brother health officers against this pro- cess, which has become obsolete amongst professional analysts. Scientific chemists well know that this salt does not oxidize albuminous matters ; and to this fact, its failure, as a test for the organic matter in water, may doubtless in part be attributed. Without entering into chemical details, it may be said : — (1) That it some- objections. times fails to afford any indication of the presence of organic matter in water that may contain a large quan- tity of it ; and (2) that it is not sufficiently sensitive. If I prove these statements, it will, I think, be admitted that ample evidence has been afforded to warrant the assertion that the permanganate of potash test should not solely be relied on for determining the organic pol- lution of a water. I was asked some time ago to examine the water from a well, the purity of which was questioned, the result of the analysis being a matter of the greatest moment, involving important interests. It was collected by the inspector of nuisances in a perfectly clean bottle, supplied by myself. The permanganate of potash test gave no indication whatever of the presence of organic matter, although allowed to act on the water for different periods of time. On making a quantitative analysis of the water by means of the Wanklyn, Chapman, and Smith process, the following result was arrived at : — Date. WankljTi, Chapman, and Smith process. Permang. of Potash Test. Sept. 3. Dec. 15. Part per Million = Milligramme per Litre. ISTo change. No change. Free Ammonia. •02 •03 Alb. Ammonia. •36 •42 Fallacies. 26 THE DETERMINATION OF THE AMOUNT AND Here, then, is a water, exhibiting between four and five times more of organic matter than the maximum quantity contained m good drinking water which yields no change with permanganate of potash. The analysis of December shows an increase in. the degree of pollu- tion of the water. The permanganate of potash neither indicated the increase in the amount of impurity, nor, indeed, the presence of any organic matter. Dr. Par- sons refers'"' to an interesting case, which shows the unreliability (if I may coiu a word) of the permangan- ate of potash test. He writes : " I have had to examine a sample of water upon which suspicion fell, from the fact that five persons who drank it were taken ill at the same time with enteric fever. The owner of the well refused to believe that the water could be in fault, because it was clear, and had no unpleasant taste or smell, and because he had tried it with Condy's fluid which had kept its colour. ISTever- theless, on analysis, it yielded the following large amounts : — Grains per Gallon, Parts per Million = Milligramme per Litre. Chlorine. 11-5 Ammonia. 6-00 Albuminoid Ammonia. 1-08. " On examining the well it was found that the cess- pool of a privy had overflowed into it." It must be admitted by all that the permanganate of potash is not sufiiciently sensitive when it fails to make any distinction between such waters as the follow- ing : — * " Memorandum on Water Analysis." — PtMic Health, June 16, 1874, NATUEE OF THE OKGANIC MATTEE. 27 Wanklyn, Chapman, and Smith Process. Permanganate of Potash. ■WiCKFORD Village. Artesian well, 385 feet in depth. Water employed by majority of villagers, and of the neighbouring farmers. Part per Million = Milligramme per Litre. Alb. Ammonia. •04 Pink colour is paler. Slight brick-red sediment. Great Baddow. In which diphtheria or enteric fever is every now and then present. Well at back of schools is 14 yds. from a cesspool. Gravelly porous soil. •28 Pink colour remains, but is paler. Yery slight brick-red sediment. In the subjoined analyses the permanganate of potash positively leads ns into the error of supposing that the offensive and impure water is purer than the artesian water which is of the highest excellence. Samples of water. Part per Million = Milligramme per Litre. Alb. Ammonia. Permanganate of Potash Test. Well at Galleywood, close to heaps of decomposing filth. Water complained of by cottagers as some- what offensive to the smell. •24 Pink colour remains. Stagg's Artesian well, Burn- ham. •03 Has become very pale. Eather copious brick- red sediment. The medical officer of health of the Goole and Selby Sanitary Districts very properly remarks, with reference to this test : " The permanganate of potash test is, I find, as tedious as the ammonia process, while the shades of colour, from their dissimilarity in kind as 28 THE DETERMINATION OF THE AMOUNT AND well as in degree, are far more difficult to compare than those of the latter process. Should decoloration occur, it does not follow that it is due to sewage con- tamination ; nor, on the other hand, if the colour he permanent does it always prove that the water is pure." Enteric fever broke out at a little town in my dis- trict, and was confined to the market-place. Being temporarily prevented from analysing waters according to the Wanklyn, Chapman, and Smith process, I tested that of the pubhc well around which the fever was confined, with a solution of permanganate of potash, and found no indication of impurity. As the fever still spread, notwithstanding the adoption of the pre- ventive measures customary in such cases, I made a proper analysis of the water. Finding it impure, I advised the Sanitary Authority to order the well to be closed, which was accordingly done. The cottagers were directed to a pure water supply, and the fever speedily disappeared. I subsequently ascertained that a rotten drain passed within two yards of the well, and that a neighbouring cesspool had been occasionally seen to overflow into it. Such is the permanganate of potash test applied in the usual rough and ready manner. Some, such as Dr. W. A. Miller, Mr. V. Harcourt, and Dr. Woods, have applied it in a quantitative manner for the analysis of water with better success. There are such diverse ways of employing this test that it is impossible to institute any comparison between the results arrived at. Some add an acid, e.g., sulphuric acid, and others add an alkali, e.g., milk of lime, to the water, before treating with the permanganate solution. Some conduct the process at the temperature of 140° F., NATUEE OF THE OEGANIC MATTEE. 29 and others at the temperature of the air. Some allow the permanganate to act for a few minutes, and others for hours, on the water under examination. Some who employ this test prepare a solution by dissolving two grains of the pure salt in 10^ oz. of distilled water. Ten minims of this solution is said to yield x-giyo °^ ^ grain of oxygen. The quantity of the solution required for a known quantity of the water is divided by 10, the result giving the number of thousandths of a gTain of oxygen .consumed. B. Quantitative Examination. The two best quantitative processes are undoubtedly that for many years practised by the late Dr. Letheby, and now employed by Dr. Tidy, and that modification adopted by Drs. "Woods and F. de Chaumont, which in my opinion is the simpler and the better. Professor Kubel's variety of the permanganate of potash process closely resembles the latter, but is inferior to it. Drs. Letheby and Tidy's Permanganate of Potash Quantitative Process of Water Analysis. The following mode of employing the permanganate of potash test was originally devised by Dr. W. A. Miller and Mr. Y. Harcourt,"^^' but has been almost exclusively practised by Dr. Letheby and his successor. Before commencing the analysis a solution of the Quantita- sodic hyposulphite should have been prepared by dis- ^^^^^^' solving 5 "4 grains in a decigallon of distilled water. As a solution of this salt readily decomposes even in 24 hours, it is necessary to make a fresh solution very * "Observations on some Points in the Analysis of Potable Waters," in Journal of Chemical Society, May 1865, Ser. II. vol. iii. p. 117. 30 THE DETERMINATION OF THE AMOUNT AND frequently. Take a -|-decigall. flask and two stoppered 20 -ounce bottles. Pour a -|-decigall. of distilled water free from ammonia into one of the bottles, and then introduce a like amount of the sample of water to be examined into the other stoppered bottle. Add to the contents of each bottle by means of a pipette (gradu- ated in septems) 20 septems of dilute sulphuric acid (one part of acid mixed with three parts of distilled water). Add to the acidified water in each bottle by means of a pipette 20 septems of a standard solution of potassic permanganate (made by dissolving 2 grains of the salt in 1000 septems of distilled water). Allow both bottles and their contents to stand for three hours. At the expiration of this time, when the pink colour of the sample will have been exchanged for a tint of reddish brown more or less great, add to each bottle a little of a solution of potassium iodide of any strength (pot. iodide Sj in gx of distilled water is generally employed), taking care to add it in excess. The mixtures in the two bottles then become of a pale amber colour. The sodic hyposulphite solution, which has been placed in a burette (100 septems in 100 parts graduation), should be run into each bottle in sufficient quantity to create the almost complete disappearance of the colour, and the amount used should be noted. Before the colour quite disappears, add two or three drops of a solution of starch (one part of starch boiled in 100 parts of distilled water) to each bottle, which gives rise to the production of the blue iodide of starch. Then resume the addition of the solution of the sodic hyposulphite to each bottle until the blue colour has wholly disappeared. The sample of water tested will of course be found to require less sodic hyposulphite than the distilled water sample or standard. If this analysis NATURE OF THE ORGANIC MATTER. 31 is properly performed, a single drop of the permanganate of potash solution should give to the contents of each bottle a tinge of the original pink colour. Nitrites, which immediately decolourize the permanganate of potash solution, are supposed to be estimated by noting the amount of this salt decolourized in five minutes, a datum from which the quantity of oxygen consumed is easily calculated. At the end of an analysis, a deduc- tion of the oxygen thus withdrawn is made from the total amount that has been expended. In practice, how- ever, the nitrites are rarely troubled about. Dr. Tidy's assistant, who kindly showed me how to work the pro- cess, and who performs the majority of his analyses, does not estimate the nitrites in this way, and make the needful correction. Dr. Tidy's published tables of his analyses of the metropolitan waters* do not contain a separate determination of nitrites, wherewith the results arrived at by the employment of the permanganate of potash process may be improved in accuracy. The amount of oxygen required to oxidize the organic matter is calculated thus : — X = total oxygen required. y = oxygen consumed by nitrites. z = oxygen unused. X- (y+ z) = oxygen required by organic matter, which should be multiplied by 8 or 9 when metropolitan waters are under examination (the number in the case of other waters being unknown), in order to obtain the quantity of organic matter. A special examination is directed to be made for iron, and a deduction be allowed for its amount, which is in practice rarely carried out. * Vide "The Composition and Character of Water supplied to London from 1868 to 1877," being a Keport to the Soc. of Med. Officers of Health. 18-78. 32 THE DETEEMINATION OF THE AMOUNT AND Rules for guidance. Bules. — No rules have been laid down for guidance as to the amount of organic matter found by this pro- cess, which would authorize the assertion that any given sample of water was good, bad, or indifferent. Sole reliance is not placed on its indications, apart from those afforded by a determination of the salme ( = free) and organic ( = albuminoid) ammonia and the chlorides. It will be useful, perhaps, to give, as examples of fairly good waters, the following analyses of metropolitan supplies examined in part by the permanganate of potash process : "Average Composition and Quality of two of the London Waters during 1876. By Dr. Tidy. ■i .^ Hardness, es are Grains on = rains. Ammonia. ir. on Clark's ■g z S aj .2 IB 1= scale. Quantiti stated in per gall 70,000 g 33 a 32 1 o as §1 0-" m 3 o 3 a as public Spring in Trinity Lane, Springfield, Essex . 5-8 j supplies. Spring supplying Grove House, Great Baddow, Essex ..... 2-7 Manchester water .... 1-1 Sunderland water .... •93 Croydon water .... •5 The Rhine at Bonn .... 1-4 Clareen well, Camck-on-Suir 1-2 Do. river do. . . . •9 Public pump, Waterford Pump at University Club, St. Stephen's Green, 17-76 /'Closed, as it caused Dublin ..... 49-4 •<^ diarrhoea Flooded stream. Holm firth, Yorkshire Moors •87 1 and Carlisle Waterworks .... 1-5 (^dyspepsia. Water of shallow well in Rose Valley, Brent- wood ..... 4-54 Water of deep well, Stanwix, Carlisle 3-79 Fountain water from High Town, near Halt- whistle ..... •81 Water from pump in Rutherford's Court, Stanwix, Carlisle .... 10-57 Pump in yard. Prospect Place, Stanwix 4-03 The water of the river Ouse, near York, on September 1st, 1876 4-3 The water of the river Ouse, near York, on September 6th, 1876 1^58 Water from shallow well of Jeffrey's Endowed School, Great Baddow, Essex 16-36 Water from well at Brentwood HaU, Brent- wood ..... 3-13 Water from Maldon Waterworks 4-51 Water from weU at Little Burstead . 64-5 Water from well in Mountnessing 100-0 Water from well in Hutton . 182-0 Water from well at Hutton Railway Bridge . 2-7 ' Grand Junction . 1-5 Thames West Middlesex . 1-47 Water Southwark and Vauxhall 1-43 Companies. Chelsea .... 1-52 -Lambeth 1-56 Kent .... 2-82 Other Companies. , New River East London 1-05 1-59 118 DETERMINATION OF AMOUNT OF MAGNESIA, Of the Metropolitan waters, that of the Kent Com- pany is objected to by some on the ground of the excess of sulphates. As much as from 20 to 70 grains of sulphates per gallon have been found in some drinMng waters in Dublin by Dr. Cameron. A water may exhibit a large amount of magnesia and but a very small quantity of sulphates, that alkaline earth being in the form of carbonate, as for example, in the waters of the dolomite formation. I have examined well waters, pure as to organic matter, containing 4^ grams per gallon of sulphuric acid in the form of sulphate of lime, but have not felt warranted in publicly expressing disapproval of the use of such waters for drinking purposes. If samples of water were brought to me in order that I might select the best, I should certainly at the outset place a water containing this amount of sulphates out of competition. We have very httle rehable information as to the effects of these salts in drinking water on the health, but that they must have a very decided influence admits of no doubt. Can it be a matter of no moment from a public health point of view whether people are drinking water containing 100 grains per gallon, as at Mountnessing, or "5 of a grain per gallon, as at Croydon, of anhydrous sulphuric acid from sulphates ? I have never yet seen a person who habitually employs a drinking water containing a large amount of sulphates that could be regarded in any sense by a medical eye as " a picture of health." C. Phosphates. When we remember the important role played in the human organism by phosphates, and in how many SULPHATES, AND PHOSPHATES. 119 different forms they occur in tlie various parts of the body, it is a matter of great interest to study the re- lation between the use of waters emanating from phos- phatic strata, and the condition of health of those who employ them/'' The presence of an excess of phosphates when they cannot thus be accounted for is often due to sewage impregnation. Tiemann has noticed phosphates in large quantity in the water derived from marshy meadows. Mr. Wanklyn states, f that " much nonsense has been talked about phosphates in drinking water." " Carbonate of lime and phosphates are incompatible in drinking water." Dr. Dupre has recently affirmed that he never examined a water in which he could not detect phosphoric acid. In Professor Kubel's Treatise on Water Analysis, edited by Dr. Tiemann, is to be found the following description of the most approved mode of testing for phosphoric acid : " Boil the water ; the precipitate contains the phosphates ; dissolve this precipitate in hydrochloric acid ; evaporate to dryness, and heat for a short time a little over 212° Fahr. Then dissolve in a little hydrochloric acid and water, filter, and add filtrate to a slightly warm clear solution * Mons. Joly, in an interesting paper to one of the Parisian scien- tific societies, says tliat tlie importance of the phosphates in the animal economy may be measured by the fact that five different phos- phates are found in the body : in the red blood corpuscles, phosphate of iron ; in the lic[uor sanguinis, phosphate of soda ; in the nervous system, phosphate of potash ; in the muscles, phosphate of magnesia ; and in the bones, phosphate of lime. In each case the phosphoric acid fulfils very different functions, according to the bases with which it is united. t Op. cit. 120 DETERMINATION OF AMOUNT OF MAGNESIA, ETC. of ammomiiiii molybdate and nitric acid, when a yellow colour and precipitate occur." The nitric acid employed should be of the greatest purity, and free from all colour. If the phosphates are in very small propor- tion, the water should be concentrated by evaporation previous to the analysis. DETEEMINATION OF POISONOUS METALS. 121 CHAPTEE VIII. THE DETERMINATION OF POISONOUS METALS. The poisonous metals wliicli we, as water analysts, need alone consider are lead and copper. The occurrence of arsenic, barium, etc., in drinking water, is so rare, as to hardly merit the attention of the health ofl&cer. Lead and copper are usually the poisonous metals, especially the former, with which waters are liable to be contaminated. A water sometimes contains iron, which is of course undesirable in all cases, except for medicinal purposes, and hurtful in some. Place 70 c. c. of water to be examined in a porcelain dish, and stir it with a glass rod moistened with sul- phuret of ammonium. Note whether or not there be any coloration. If so, it may be owing to a sulphuret of iron or lead, or of copper. If, on adding two or three drops of hydrochloric acid, the brown colour dis- appears or diminishes, iron is present, for the hydro- chloric acid dissolves the sulphuret of iron. If, on the other hand, the colour does not vanish or diminish on this addition, lead or copper is present. It matters not which, for both are equally injurious. Wanklyn writes : " If there be coloration," on introducing the sul- phuret of ammonium, " it should only be just visible, and on adding two or three drops of hydrochloric acid. 122 DETERMINATION OF POISONOUS METALS. it ought to vanisli absolutely." Water wliicli answers to this test in a satisfactory manner is registered as sufficiently free from poisonous metals, and water ■whicli does not, is to be condenmed as contaminated with metallic impurity. If the quantity of either of these metals in a water be required, it is necessary to employ standard solutions, containing one milligramme of each metal in each cub. cent, of its solution (made by dissolving 1"66, 3'93, and 4" 9 6 grammes of crystal- lized acetate of lead, or sulphate of copper or proto- sulphate of iron in a litre of distilled water) ; and, if we desire to ascertain whether lead or copper be pre- sent, it is needful to operate on a larger quantity of water, and to work according to the directions in that distmguished chemist's exhaustive treatise on water analysis. The above simple mode of testing for poison- ous metals is sufficient for the medical officer of health, for it enables bi-m to say that a water contaias less than x^th grain of lead or copper per gallon, an amount which should condemn a drinldng water. Water is considered to be admissible for domestic purposes if containing \ grain of iron per gallon, but the presence of one grain of this metal per gallon is deemed to be sufficient to justify its rejection. Medical literature teems with instances of poison- ing by lead and copper. It is curious to note the timidity with which Cornish miners look upon waters issuing from strata known to contain metals, and how they altogether ignore the risk of drinking water con- taminated with filth of the filthiest description. Should The action of different kinds of water on lead forms in leaden ^ 'V'sry large subject, which cannot here be even briefly DETERMINATION OF POISONOUS METALS. 123 adverted to. My experience teaches me the wisdom cisterns be and expediency of recommending a strict avoidance for ^y„,,[°g drinking purposes of all water that has been stored in purposes ? leaden cisterns, or has otherwise rested for some time in contact with lead, until we possess data of a less contradictory and more definite description than at present as to the influence of various kinds of water under different circumstances on this metal. 124 MICROSCOPIC EXAMINATION OF CHAPTEE IX. MICROSCOPIC EXAMINATION OF THE SEDIMENT OF A WATER. The best and most simple mode of examining tlie de- posit from any sample of water is, first, to allow sus- pended matters to subside in the sample bottle ; and secondly, to decant the greater part of the water, and pour that at the bottom of the bottle containing the sediment into a conical glass. After subsidence a drop of the water containing the deposit may be removed by means of a pipette to the cell of a micro- scope slide and be allowed to evaporate, or the drop may be immediately covered with a thin glass, the excess being removed with blotting-paper, and examined. If a water possesses much turbidity this transfer to a conical glass is of course unnecessary. If the amount of sediment procured in this way is practically ml, the greater part of the water m the conical glass should be poured away, and that remaining in the angle of the cone should be transferred to a burette similar to, but of much larger diameter than that depicted in Fig. 3. After subsidence the solid bodies may easily be removed in single drops of fluid on to microscope slides. For work of a special kind immersion lenses and a polari- scope are desirable, but for all ordinary practical pur- THE SEDIMENT OF A WATEK. 125 poses the universally employed half-inch and quarter- inch are sufficient. The microscopic examination of the floating particles Fig. 7. Conical Glass and Pipette. sometimes seen in water, will often afford valuable in- formation concerning it, where there is any doubt as to its quality. Mineral gritty matters,''^ silt of clay, and i^°^?fi^^° sandy particles, may be the cause of persistent and unaccountable diarrhoea, which medicines will only tem- porarily relieve. New comers to a place where such water is used often suffer. Those who drink such waters long become generally unaffected by these intestiaal irritants. Chalky particles are dissipated by acids, whilst the other mineral matters apt to occur in drinking waters are unaffected thereby. * The mountain dysentery prevalent in certain districts in India has been shown to he due to the employment of drinking water con- taining ia suspension minute particles of mica. 126 MICEOSCOPIC EXAMINATION OF The existence of animal life in a water affords good evidence in itself of the presence of a very sensible amount of organic matter, alias filth, whether it be the infusorial beings seen in the fairly pure waters supplied by the majority of the London companies, with an average of about "08 milligramme of albuminoid am- monia per litre, or the various humble animal organisms of pond water, with its '3 8 milligramme of alb. ammonia per litre. These little creatures feed and flourish on what we call organic matter, and in perfectly pure water they cannot Hve. Description The kind of animal and vegetable life seen in water and"^e^e^- givGS a Certain clue to the description of water we are table life examining. Speaking generally, the infusorise, the ascertained, confcrvse, and vorticellsB, are the inhabitants of the least pure of spring waters; entomostracse or water fleas are seen in spring ponds, lochs, and impounded waters ; euplota and fungoid growths, etc. etc., abound in pond and ditch waters, and in well water polluted with filth ; whilst bacteria and paramecia and spirilla are pro- minent in sewage-polluted water. There is no evi- dence to show that the lowest forms of hfe, such as the fungoid and bacteroid, are in themselves hurtful if taken into the system, but it is highly probable that the poisons of several of the zymotic diseases find a congenial soil amongst such organisms, which act as carriers, to which they attach themselves, and amongst which they multiply. Dr. Frankland and his followers regard the presence of anything like a moving organism in a water as a danger-signal, for the reason that, if the poisons of such diseases as cholera and typhoid fever attach themselves to particles of organic matter, and can operate in in- y.iCF.i 3PIC OEJE.j: THE SEDIMENT OF A WATER. 127 conceivably minute quantities, as is generally believed, there is a possibility of the disease ferment or germ of such maladies accompanying elementary forms of life. Dr. MlQs of Glasgow, following Dr. Frankland's example as to the metropolitan waters, frequently refers iu his public reports to the presence of living organisms in the water of Loch Katrine as detracting from its purity. DESCRIPTION OF PLATE OF MICROSCOPIC OBJECTS FOUND IN DRINKING WATER.* 1. Actinophrys Sol. Order— Eadiolaria. 22. 2. Algae, with bacteria and diatoms. 3. Bacillus. \ 23. 4. Bacteria. \ P»'''^ily-Bacte'nacece. ^4. 5. Amoeba. Class — Bhizopoda. 25. 6. Vorticellae. Class — Infusoria. 26. 7. Ova of Entozoa. 27. 8. Euplotes Vannus. Class — Infusoria. 9. Paramecium. Class— Infusoria. 28^ 10. Young FUaria, or thread worms. 11. ConfervEe. 29. 12. Muscular fibre. 30. 13. Spirillum. Family — Bacteinacece. 31. 14. Hair (human). 32. 15. Linen fibre. 33. 16. Cotton fibre. 34. 17. Mineral particles. 18. Fragment of deal wood. 35. 19. Stomata of leaf. 30. 20. Epithelial scales. 37. 21. Closterium moniliformis. Family — 38. Desmidiacece. Tabellaria floecosa. Family — Diato- macece. Chsetophora Elegans. Euglenia. Class — Infusoria. Anguillula. Order — Nematode.. Rotifera. Cyclops Quadricomis. Order — Cope- poda. Sub-class — Entomostraxa. Cosmarium Margaritiferum. Family — Desmidiacece. Diatoma Vulgare. Diatom. PungL Vegetable cellular tissue Scenedesmus. Faraily—Desmidiacem. Daphnia pulex. Order — Cladocera. Sui-class — Entonwstraca. Micrococcus. Family— Baxteriacem. Infusoria. Ova of Nais. Class — Annelida. Vegetable debris. * In inserting these drawings tlie desire has been to fix on the attention the forTus and appearances of the various animal and vegetable bodies visible in waters, and of the extraneous substances with which they are most liable to be mingled, in order that a recognition of their differences may prove of diagnostic value. 128 mcKoscopic examination of The public water-supply of Llandudno was recently con- demned by Mr. Wigner, the analyst, on the ground, I presume, of its unfavourable appearance when examined by the microscope, for the results of his chemical study of it would not certainly warrant a censiu-e. Free Ammonia . '068 ) ,,.it t. .,, A • M^ > Jilillieramme per litre. Alb. Ammonia . "06 J ° ^ Nitrogen as Nitrates and Nitrites . . "24 gr. per gallon. Another class of scientific men regard insects in water as scavengers that assist, like plants, in its purification, and place the greatest reliance on those great natural purifying processes of oxidation and dilution, the exist- ence of which we are all too prone to forget. They urge that there is no reason for supposing that an ani- mal poison will attach itseK to an infusorian animal- cule, but rather to organic matter in a state of putre- factive change, and that there exist good grounds for An animal thinking that an animal poison, when enormously enormously diluted with watcr, becomes harmless, as it does when diluted with ygpy freely mingled with the other medium, air. Per- waterorair, ^ becomes in- soually I feel a greater sympathy with the latter than nocuous. ^^-^ ^-^Q former class, although there can be no doubt but that when Dr. Frankland sees by the aid of his micro- scope fragments of partially-digested muscular fibre in the water of the Thames, as furnished to a portion of the inhabitants of London, he is perfectly justified in making the fact public, and in urging the need for some amendment in the condition of the metropolitan water-supply. Sufficient attention has not hitherto been directed to the kind of moving organisms found in drinking THE SEDIMENT OF A WATEE. 129 water, and the lessons tauglit by these differences. Mr. Ivison Macadam has recently expressed the opinion "''" that the presence of the Daphnia pulex and Cyclops naphma quadricornis in a water is a proof of its purity, because ^^^^ these water-fleas are not found in bad waters, in which ) it appears they cannot live. He finds them in all our good impounded waters, such, for example, as that of Edinburgh, Eothesay, etc. A perfectly pure water contains no suspended matter, nor any animal or vegetable life. The ova of the round and the thread worms, the eggs and joints of the tape- worm, and small leeches, which may give rise to grave disorders, should not be forgotten in making micro- scopic examinations of drinking waters. The excellent illustrations in Dr. Macdonald's Guide to the Micro- scopical Exatnination of Drinking Water, will be very helpful to students of this branch of water analysis. As scientific literature is possessed of this valuable guide, I shall not dweK more on this topic than by making the following extract from the Hygienic Classi- fication of Waters contained in Parkes' Hygiene (5 th edit.) :— 1. Pwre and, Whole- 2. Usahle. some. Same as Mineral matter; vege- No. 1. table forms with endochrome ; large animal forms ; no organic debris. 3. Suspicious. Vegetable and animal forms more or less pale and colour- less ; organic deb- ris ; fibres of cloth- ing or other evi- dence of house re- fuse. 4. Impure. Bacteria of any kind ; fungi ; numerous vege- table and animal forms of lov,' types ; epithelia or other animal struc- tures ; evidences of sew- age ; ova of parasites, etc. Those who are conversant with the use of the microscope will recognize vegetable tissue, starch, epi- theKal scales, human hair, the hairs of cats and other ani- * Paper entitled "Animal Life in Fresh "Water Reservoirs."— Aberdeen Meeting of Social Science Congress, 1877. K 130 MICROSCOPIC EXAMINATION OF SEDIMENT OF WATER. mals, wool, bits of deal, fibres of silk and linen, cotton fila- ments, scales and legs of insects, and feathers, and will not be puzzled by such, apparitions in the field of the microscope. Those who are not familiar with the appearances presented by these objects when magni- fied, should make themselves as soon as possible ac- quainted with them under low and high powers. Medical officers of health who are thus well grounded, will find the microscopic contents of water an exceed- ingly interesting and instructive subject of study. COLLECTION OF SAMPLES OF WATEE FOE ANALYSIS. 131 CHAPTER X. THE COLLECTION OF SAMPLES OF WATEE FOE ANALYSIS. EvEEY water analyst should have his samples of water collected in strong stoppered glass bottles, supplied by himself ; which have been thoroughly cleansed with a strong acid before leaving his laboratory. Stoneware bottles should not be used, for that material is liable to introduce calcic sulphate, silicates, and common salt, into the water. By avoiding waste, I find that about Quantity one litre of water is, as a general rule, sufficient for ''^i""'^'^- analysis, unless it is wished to make any special exami- nation, as, for example, an estimate of the amount of magnesia in a water, when a stoppered " "Winchester Quart " is employed. Before taking a sample, the bottle should be weU. rinsed three times with the water to be collected. The stopper should be firmly tied down by twine or tape, and a printed label, with gummed back, of the accompanying description, should be filled up and Sanitary District, SAMPLE FOR ANALYSIS. Date of Collection^ Source ^ Depth of Well Pump or Draw Well_ Nature of Soil and Stibsoil Distance of nearest Filth or Drain _ Reason for Analysis L EiQual, or nearly equal, in amount. Alb. Ammonia. — j j -t. j Hardness. — Very little. Nitrogen as Nitrates and Nitrites. — Nil, or almost nil. Volatile Matters. — On burning solid residue, very little. Behaviour of Residue during Ignition. — It blackens patches or waves, whicli colour is very persistent. N.B. — Water often contains some hydrogen sulphide. Analyst. Examples of Water. Grains per Gallon. Parts per Million = Milligramme per Litre. Solids. Volatile Matters. ClUo- rine. Nitrogen as Nitrates and Nitrites. Free Amra. Alb. Amm. Dr. Shea 1. From peaty soil 10-85 -95 1-85 •25 -065 •085 Do. 2. From peat in sand 6-05 •85 1-4 None. •04 •06 Author 3. Peat spring ; hardness 2 or 2^ degrees 5-00 1-40 1-1 -02 -03 •11 Dr. Shea 4. From peat ; soil contained car- bonate of iron, and consisted of a chalky marl. Water smelt strongly of hydrogen sulphide 29-35 1-57 1-2 ■08 -06 SAMPLE OF WATER SUBMITTED TO ANALYSIS. 165 The knowledge of the source of the water will pre- vent the possibility of making a mistake between a water vitiated with vegetable organic matter, and one poisoned by sewer gases, such as is referred to on page 106. 7. If a water contains an enormous excess of free waters ammonia and an excess of albuminoid ammonia, the p°^^^*^* ^^ ' excremental strongest evidence is afforded that a cesspool or urinal matters, is delivering its contents into the well. Urine very diagnosis, rapidly decomposes, and developes carbonate of am- monia, e.g. — Water from well polluted by urinal : — Milligramme per Litre. Free ammonia, above 1*0 Alb. „ „ -35 It is necessary to remember that rain-watesr holds in solution a large amount of free ammonia, derived from the air which it washes as it descends, and from the soot with which it is generally mingled ; and that, in consequence of the uncleanliness of the surfaces that collect it, which are often stained with the excreta of birds, it is apt to exhibit an excess of albuminoid am- monia. It is desirable not to confound the water of a well polluted with urine with water commingled with sooty rain-water. The manner in which the free ammonia comes over, and the collateral evidence, almost render such an acci- dent impossible. On distilling -i litre of rain-water collected on a slate roof in the country, which presented a slightly sooty appearance, I obtained the following result : — 166 OPINION AND PREPAEATION OF REPORT AS TO Free ammonia "35 •25 •12 •09 •09 •04 •03 •97 I took off 7 distillates of 50 c. c. each, and did not come to the end of the free ammonia in this ^ litre of water. In the case of a water polluted with urine, the free ammonia passes over in a wholly different fashion, e.g., in ^ litre. Free ammonia '38 •14 . •065 •035 urme. •620 In litre above 1 ^0 part per million = milligramme per litre. Rain-water The followiug differences between rain-water and wateT^' urine-polluted water should also be borne in mind : — polluted by (a.) Particles of soot may generally be seen in rain by the naked eye, or by the aid of th^ microscope, which are absent in the latter. (h.) The latter will probably contain an excess of nitrates unless actual sewage pollutes the water, whilst the former will probably exhibit only a trivial amount, or none. (c.) The latter will possess an excess of chlorine, whilst rain will not, unless it falls near the sea. (d.) The latter will display a greater or less degree of hardness, whilst the former will be soft. SAMPLE OF WATER SUBMITTED TO ANALYSIS. 167 Diagnosis of Pollution by Urine, or by Slop and Sink Water. Free Ammonia. — Overwhelining amount, from '50 to 2 milligramme per litre. Albuminoid >4mmoma.— Excessive. Often about '3 or "4, or even '6 milligramme per litre. Chlorine. — Generally in large excess. Nitrogen as Nitrates and Nitrites. — In either minute amount, or in large excess. Diagnosis of pollution by slops, etc. 1 Milligramme Analyst. Examples. Grains per Gallon. | PER Litre = Part per Remarks. Million. Solids. Volatile Matters. Chlo- rine. Free Amm. Alb. Amm. Dr. Shea Water from well close to broken sink pipe 50 2 9 Very abund- ant •35 Author Water from artesian well into which drain conveying urine from stable leaked 8-2 •51 ■31 The com- paratively small pro- portion of free am- monia was ^due to the 'admixture of the urine with a vast quantity of water in this deep well. Author Same after diver- sion of drain Water from a Shallow WeU. Nitrogen as Nitrates and Nitrites. 7-3 •04 •08 Before "i Pollution by Y contents of 1 Drain. 75-6 None . 12-3 •01 ■07 Author After J 103 Abundant 16 •69 ■28 Persistent uncontroll- able diar- rhoea pro- duced. 1 168 OPmiON AND PEEPARATION OF REPOET AS TO Dr. Shea lias kindly sent me particulars of an inte- resting case where a new cesspool was constructed about tliirty yards from a well to receive slop water. Fourteen days after its completion the water of the well was noticed to taste unpleasantly. On analysis it proved to contain neither free nor albuminoid am- monia in excess, for the intervening earth acted as a filter. No less than 17'5 grains per gallon of chlorine were found in it, whilst neighbouring unpolluted wells possessed only 1"5 to 2*3 grains of chlorine per gallon. Diagnosis of pollution ■by sewage. Diagnosis of Pollution by Contents of Cesspools and Sewers. A glance at the following examples of waters pol- luted by cesspools, and by soil containing a large excess of decomposing animal matters, reveals immediately the difference in the results obtained. Samples. Grains per Gallon. Milligramme PER Litre = Part per Million. Remarks. Solids. Chlorine Free Amm. Alb. Amm, Water from shallow well near K. H. B. "Water from shallow well at A. L. B. 101 50-4 12-5 6-9 Above 1-0 Above 1-0 •24 . •50 Polluted by leaky- cesspool. Typhoid fever and diph- theria amongst the owners. Accidental overflow into well of cess- pool contents which, having been the reci- pient of the spe- cific poison of typhoid, spread the disease. SAMPLE OF WATEE SUBMITTED TO ANALYSIS. 169 Free Ammonia. — In large excess. Albuminoid Ammonia,. — In excess. Chlorine somewhat in excess, but not so marked as when slop water is the polluting agent. Nitrogen as Nitrates and Nitrites. — If sewage passes directly into a well — none. If sewage travels through some intermediate earth — generally an excess. 8. Waters of shallow weUs ia towns, the soil of unsafe which is, for the most part, more or less filthy, or near churchyards, if found to contain an excess of nitrates and nitrites, solid residue, and chlorides, should be pro- nounced as unsafe, although the amount of free and albuminoid ammonia should be insignificant, for we can never tell when the earth may cease to act as a filter by oxidizing the filth. In forming an opinion as to the condition of a water, we should, ia weighing the evidence afforded by the ammonia process for organic matter, adhere strictly to the standards of purity that have been laid down after infinite toil, for the quantities yielded by it are only fractions, although constant ones, of the total quantity present. We should be extra-exacting as to purity in judging of a river water that has been pol- luted at some points of its course with the manure of fields and indescribable filth, for these river waters contain every now and then undigested portions of human excreta in addition to living organisms visible by the aid of the microscope, and the accompaniments of all life in water — namely, dissolved and suspended organic matter on which these same organisms feed. Septic poisons, or the poisons of the zymotic diseases, attach themselves to organic filth undergoing putre- factive decomposition, in which they find an appro- priate nidus for development. It is questionable opiuion. 170 OPINION AND PEEPAEATION OF EEPORT AS TO whether such rivers should ever be employed as public supplies, for, if the sewage of towns and villages on their banks be diverted and utilized on the land, the washings of manured fields cannot during periods of flood be altogether excluded. If such rivers are used for drinking purposes an extra degree of purity should be demanded of them. B. PEEPAEATION OF EEPOET. Beportof The Opinion of a water having been formed on a sound basis, its delivery is a very simple matter. The modes of statement of the results of water analysis are so various that they produce, even amongst medical men, endless confusion. " Chlorine calculated as chloride of sodium," " Loss on ignition after deducting combined carbonic acid," are samples of the most recent eccentricities. Why other chlorides in drinking water should be entered as common salt, and why combined carbonic acid should be alone excluded from the loss on incineration, are peculiarities for which it is quite impossible to find any valid reason. Some analysts express themselves in parts per 100 or per 100,000, or in parts per million, whilst others make an estimate in grains per gallon or milligrammes per litre. Oxidized compounds of nitrogen are entered by some as nitric acid, by others as nitrates, and by the majority as nitrogen in the forms of nitrates and nitrites.""" In order to prevent such differences in the modes of calculation, which occasion so much annoyance amongst the pubKc, one uniform plan of drawing up reports should be universally adopted. I find that a form, of the accom- * Vide ' ' Eules for Conversion, of Different Expressions of Results of Analysis," in Appendix. SAMPLE OF WATEE SUBMITTED TO ANALYSIS. 171 panying description, is most convenient for conveying my report to the sanitary authority or other applicant : — Sanitary Authority, 187 Analytical Eeport. Date. NAME AND DESCRIPTION or THE SAMPLE OF Water. Grains per Gallon. Parts per MUlion. Hard- ness. ■ Solids. Chlorine Nitrogen from Nitrates aud Nitrites. Free Am- monia. Am- monia from Organic Matter. Degrees. Mem. LONDON WATER SUPPLY (Thames) .... 18-5 1-2 •15 0-01 06 14 73 (New River) .... 17-7 1-1 •17 0-00 0-06 15 w ■A (Kent Company) . 26-5 2-1 •30 0-01 0^02 21 Very bad Water. Thames Water at London Bridge . 4^00 1^02 0-59 ft Pure Spring Water which sup- < plies Village of Woodham Walter 21 2-4 •20 0^00 0-01 6 Good Water from Shallow WeU depth 25 feet .... 30 7 •07 0-01 0-05 13 W Good Waters from Artesian Wells, of different depths, j'106-4 37-7 •03 0-01 0-02 9i which supply a Village . 1 98-0 37-6 •oa 0-63 0^01 4i Memoranda as to "Water Analysis. 1. Any one who wishes to have his or her drinking Water analysed at the Public Expense, shoiild apply to Clerk of the Sani- tary Authority, for an order from this Authority, giving the reasons for his or her request. If the Authority considers that some grounds exist for thinking that the Water has produced disease, or is likely to be injurious to health, the Authority will issue instructions through its Clerk to the Medical Officer of Health, who wiU on receipt of the sample from the In- spector of Nuisances, analyse the water as soon as possible, and communicate the result to the applicant. 2. Any Member of either of the Combined Sanitary Authorities, and any qualified Medical man practising in the Combined Districts who wishes to have iiis own drinking Water analysed, should communicate direct with the Medical Officer of Health. 3. Any qualified Medical man practising in the Combined Districts, who considers it expedient that the Drinking Water of a Patient on whom he is in attendance should be Analysed at the PiiUic Expense, should communicate direct with the Medical Officer of Health. 172 CONCLUDING EEMAKKS. CHAPTEE XVI. CONCLUDING REMAEKS. Concluding Eeaders of the foregoing pages will liave perceived emar s. ^-^^^ j ^^ ^^^ recommend the complicated and tedious process of Frankland and Armstrong, and that I cannot advise the sole unaided adoption of the beautiful pro- cess of WarLklyn, Chapman, and Smith, nor the prac- tice of the quantitative permanganate of potash process which is often misleading. Whilst agreeing with the inventors of the first process as to the necessity of re- garding the amount of nitrogen as nitrates and nitrites in a water, I totally disagree with Mr. Wanklyn in relying solely on the indications of the Nessler process, to the exclusion of an estimation of these products of oxidation and other valuable data on which an opiuion should be based. Fallacies, undoubtedly, attend Dr. Frankland's lengthy method, and Mr. Wanklyn's rapid method ; and still greater errors are associated with the quantitative permanganate of potash processes, whatever those who are disciples of these several methods may think to the contrary. I am myself indebted to each process, more especially to Mr. WanMjm's, in my studies of water analysis. The method which I almost daiLy practise and recommend, and which I have in the foregoing pages attempted briefly to describe, is, it will be perceived, a modified form of the Wanklyn, Chap- KECIPES OF STANDARD SOLUTIONS. 173 man, and Smith process, I am not conscious of ever having made a mistake in water analysis. This suc- cess is not attributable to any exceptional skill, but to the excellence of the process, which I designate the " Medical Officer of Health Method," because it is par- ticularly suited to his wants. Eecipes of Standard Solutions, etc. standard solutions. Nessler Beagent. Dissolve, by heating and stirring, 35 grammes of iodide of potassium and 1 3 grammes of corrosive sub- limate in about 800 cub. cent, of distilled water. Add gradually a cold aqueous saturated solution of corrosive sublimate, until the red colour produced just begins to be permanent. Add 160 grammes of solid caustic potash to the mixture, which is then to be diluted with sufficient water to bring the whole to a litre. To render the test sensitive add a little more cold saturated solu- tion of corrosive sublimate and allow it to settle. This reagent is a rather troublesome one for the medical officer of health to make, and that prepared by different persons varies somewhat. It is desirable that every one should obtain his ISTessler test from one and the same source. Professor Wanklyn, in the interests of the process of water analysis, with which his name is identified, superintends the manufacture of aU that is sold by Messrs. Townson and Mercer of Bishopsgate Street, London, which he guarantees as " quick" or sensitive. Standard Soap Solution, 10 grammes of Castile soap are dissolved in a litre 174 EECIPES OF STAND AED SOLUTIONS. of weak alcohol (35 per cent). If 35 per cent alcohol is not readily procurable, it may easily be prepared by mixing 29 ounces and 15 minims of distilled water with 17 ounces and 30 minims of rectified spirit (generally 84 per cent), which is everywhere obtainable. One cub. cent, precipitates one milligramme of carbonate of lime. This standard solution will not remain unchanged for an indefinite time. It loses strength. It is wise to make a small quantity of fresh solution every three or four months. One and the same water was recently examined by me for hardness with different standard soap solutions of various ages, and the following results were obtained : — (a) 19|^ degrees. (P) 17 „ (c) 16 (d)18 (e) 17 „ It is useful sometimes to verify the strength of a soap standard solution by the help of a solution of pure fused chloride of calcium, 1*11 gramme in a litre of water. One cubic centim. of the standard soap solution should precipitate one milligramme of carbonate of lime, which is the exact amoimt present in one cubic cent, of the chloride of calcium verifying solution. Dilute Standard Solution of Ammonia. Keep two solutions — a strong and a dilute. To pre- pare the strong solution dissolve 3"15 grammes of crystallized sal. ammoniac in one litre of distilled water. EECIPES OF STAND AED SOLUTIONS. 175 To prepare tlie dilute solution place 5 cub. cent, of the strong solution in a half-litre flask, and fill it up with distilled water. Mingle very thoroughly by pouring the mixture several times from the flask into the bottle, and from the bottle back again into the flask. The dilute solu- tion contains ywo Diilligramme in each cub. cent. Permanganate of Potash and Caustic Potash Solution. Permanganate of potash crystallised, 8 grammes ; solid caustic potash in sticks, 200 grammes ; distilled water, 1 litre. Boil the above, so as to thoroughly dis- solve the chemicals in the water, and until about ^ of the solution has passed off as steam, to dissipate all ammonia. Eeplace the water lost in boHing, as steam, by adding sufficient distilled water to bring it back to the Ktre. Standard Solution of Nitrate of Silver. Dissolve 4' 7 9 grammes of crystallized nitrate of silver in 1 litre of distilled water. One cub. cent, pre- cipitates one milligramme of chlorine. SECTION 11. SANITARY EXAMINATION AIR. N THE PURITY OF AIR. 179 CHAPTEE XVII. THE PURITY OF AIR. The examination of air for sanitary purposes by the medical of&cer of health may he deemed by some as work that is needless, and which can be turned to no practical advantage. If preventive medicine and sanitation is ever to become an exact science, we must, as those who are laying its foundations, be able to state in precise language the boundary lines between whole- some air, air to which it is undesirable to be fre- quently exposed, and air which is so impure as to be quite unfit for breathing; and, again, between the latter and that which is poisonous. It is as desirable to know the composition of the air we breathe as of the water we drink. Indeed, it is more important to attend to the cleanliness of a medium in which we are always bathed, and which is continually passing into and out of our bodies, than of that which is only occasionally, and by some rarely, introduced into an organ which contains a fluid possessing a certain anti- septic and destructive power over substances injurious to health. The insidious and indistinctly recognizable deleterious effects on the health of a continued exposure of the human frame is often more marked in the case of impure air than of impure water. The train of evils is so slowly but surely laid as to even escape the obser- 180 THE PUEITY OF AIE. vation often of an experienced medical man, who sees in a case of blood deterioration by impure air one of imperfect or defective assimilation, anaemia, dyspepsia, hysteria, disordered biliary functions, or one of those indefinite and chronic ailments which lead the way to the development of some visceral disease. What a contrast is afforded by placing a representative of the rebreathed and otherwise vitiated air trades, who per- haps rarely sees the sun, by the side of one whose daily occupations are such as to give him the fullest benefit of the purest air and the freest exposure to solar light ! Bookbinders, or factory girls, or miners, from one of our towns and colliery districts, neither of whom are exposed to any distinctly poisonous influences, may, for example, be compared with sailors. The former are pallid, jaded, sallow, afraid of fresh air, with uncertain and capricious appetites, the normal functions of the body liable to continual disturbance, excitable, generally affected with a craving for stimulants — alcohol in the male, tea in the female — to temporarily alleviate their sensations of depression, whose Kves are brief, their average duration being known by all insurance companies with mathe- matical precision; whilst the latter — namely, the jack tars — present a tout ensemble indicative of the highest degree of health and buoyancy of spirits, which is so well known as not to need description. The sailor likes his occasional drinking bout when he goes on shore to enjoy freedom, after the confinement and tedium of a voyage, but is no "soaker." The moral condition of a class is intimately associated with its physical state, but a consideration of this connection would lead us too far away from the scope of these pages. THE PUEITY OF AIE, 181 Medical officers of health should be in a position to state accurately, when required, if any given air is or is not deleterious to the health of the body continually or frequently exposed to its influence. Provided that they could positively lay down the limit beyond which the organic matter and carbonic acid of our rooms, in which the majority of us spend the greater portion of our lives, should not pass, then architects and in- ventors would soon find out some simple, efficient, and economical mode of ventilating our houses and pubKc buildings, which are nearly all afflicted with filthy air ; and our mortality from diseases which we know now to be indirectly preventible, or capable of considerable reduction, such as consumption, bronchitis, and other pulmonary affections, would be materially lessened. Pure air contains the foUowing bodies ; — Composition of Aie. composition or pure air. Oxygen (Ozone, an active form of Oxygen, -^ ^ which varies in amount) . 209'6 I g Nitrogen . . . . . . 790" [ '"' Carbonic Acid . . . . . -4^ -S Moisture varying with temperature. Peroxide of Hydrogen 1 . , ■\Tu 7 ^Tu ■ A ■ 1 c occasional components. JSitrous and Nitric Acids j ^ Organic Matter 1 . . > very rmnute traces. Ammonia j '' The purest air is to be found on mountains, moors, or far away from contamiaating and polluting agencies, such as aggregations of men and animals, manufactories. 182 THE PXJEITY OF AIR. etc. There is an ample provision in nature for destroy- ing the impurities of the air produced by man, especially the organic substances, some kinds of which become, when they decompose, injurious and often dangerous to him. Ozone, peroxide of hydrogen, and nitrous acid, are the three great purifying agents contained in the air, the first named being nearly always present in greater or less quantity, the two latter being the special productions of what the Germans call the "nieder- schlage," or the great cleansing operations of nature, such as the precipitation of the air-washer rain, storms, hail, dew, falls of snow, etc. Oxygen. Oxygeu. — The following results of analyses made by M. Eeynault and Dr.- A. Smith show the deviation from a state of purity of air, as respects its life- supporting constituent, oxygen gas, in different situations and under different circumstances : — Oxygen in Air — Summary of Averages. By Mons. Eeynault. Yolume per cent. 100 from Paris ... from 20-913 to 20-999 9 J , Lyons and around 35 20-918 to 20-966 30 , , Berlin .... J) 20-908 to 20-998 10 , , Madrid .... 3J 20-916 to 20-982 23 , , Geneva and Switzerland 3J 20-909 to 20-993 15 , , Toulon and Mediterranean . » 20-912 to 20-982 5 , , Atlantic Ocean . . 5> 20-918 to 20-965 1 , , Ecuador .... 20-960 2 , , PicMncha, higlier than Mont Blanc Mean of aU foregoing 3J 20-949 to 20-981 20-949 to 20-988 „ „ the Paris specimens . . 20-96 THE PURITY OF AIR. 183 By Dr. Angus Smith. N.E., seashore and open heath. (Scotland) Atlantic, lat. 43° 5', long. W. 17° 12' Top of hills (Scotland) .... In a suburb of Manchester in wet weather Do. do. do. In the outer circle of Manchester, not raining Low parts of Perth .... Swampy places, favourable weather In fog and frost in Manchester . . . . In a sitting-room, which felt close, but not excessively so . ...... Best ventilated wards in three London hospitals — Day Midnight ...... . . Morning ........ In a small room with petroleum lamp Ditto, after six hours . . , . . . Pit of theatre, 11.30 P.M. Gallery, 10.30 p.m. About backs of houses and closets . . . . In large cavities in metalliferous mines (average of many) In currents „ „ „ . . Court of Queen's Bench, 2d February 1866 Ditto at Lantern ....... Under shafts in metalliferous mines (average of many) . In sumps or depressions in do. . . . , When candles go out ...... The worst specimen yet examined in a mine Very difficult to remain in for many minutes By Various Scientific Chemists. Heidelberg (mean of 28 analyses) Bunsen Paris. Dumas and Boussingault * Faulhom „ „ Brussels. M. Stas . Geneva. M. Marignac Bern. M. Brunner Groningen. Verver Copenhagen Volume per cent. . 20-999 . 20-99 . 20-98 . 20-98 . 20-96 . 20-947 . 20-935 20-922 to 20-95 . 20-91 . 20-89 20-92 20-886 20-884 20-84 20-83 20-74 20-86 20-70 20-77 20-65 20-65 20-49 20-424 20-14 18-5 18-27 17-2 20-92 20-86 20-77 20-85 20-78 20-75 20-79 20-81 * Annales de Chimie. 1841. 184 THE PURITY OF AIR. The remarks that accompany Dr. A. Smith's ana- lyses, dealing as they do with a point that I have long wished to press on the attention of the sanitary public, are worthy of weighty consideration. Some people will probably incLuire why we should give so much attention to such minute quantities — between 2 0"9 8 and 20*999 — thinking these small differences can in no way influ- ence us. A little more or less oxygen might not affect us ; but supposing its place occupied by hurtful matter, we must not look on the amount as too small. Sub- tracting 0'980 from 0'999, we have a difference of 190 in a million. In a gallon of water there are 70,000 grains ; let us put into it an impurity at the rate of 190 in 1,000,000 ; it amounts to 13'3 grains in a gallon, or 0*19 gramme in a litre. This amount would be considered enormous ff it consisted of putre- fying matter, or any organic matter usually found in waters. But we drink only a comparatively small quantity of water, and the whole 1 3 grains would not be swallowed in a day, whereas we take into our lungs from 1000 to 2000 gallons of air daily. If, by in- halation, we took up at the rate of 13 grains of un- wholesome matter per day — half a grain per hour — we need not be surprised if it hurt us. Such an amount is an enormous dose of some poisons, and yet this is not above one two-thousandth part of a grain at every inhalation. It is marvellous what small amounts may affect us, even when, by repeated action, they do not cumulate as certain poisons do. We com- menced by assuming very small shades of difference — namely, 1 9 in a million ; but ff we examine the table we shall find much gxeater quantities. Take, for example, the pit of a theatre; we have, by subtracting 20 '74 THE PUKITY OF AIK. 185 from 20 "9 9 9, a difference of 2590 in a million, or 14 times more. And so on, we may go to the lowest, where we have 17*2, which, taken from 20*999, leaves 3*799, or 37,990 in a million, or 200 times more than the first example. Carbonic Acid. — It has been experimentally shown carbonic that the quantity of carbonic acid in the air : (1) is greater in the night than by day on land, due doubt- less to the large amount evolved by vegetation during the hours of darkness ; (2) is slightly increased towards noon and after rain ; (3) is greater in the air collected above the ocean by day (*05 per cent) than by night ('03 per cent). M. Mene ''^ has found that the pro- portion of carbonic acid in the air varies at different seasons, being constant in December and January, increasing in February, March, April, and May, and decreasing from June to August, increasing again from September to November, and attaining its maximum for the whole year in October. Saussure discovered that the carbonic acid of mountain air is in larger pro- portion than in that of plains. The observations made by M. Mari6-Davy at the Montsouris Observatory, which is situated at the junc- tion of Paris with the country, seem to furnish, as a rule, much lower results than are obtained by Mr. Dixon in, and in the vicinity of, Glasgow. Whilst the percentage ranges between "02 and "03 at the former station, it somewhat exceeds "03 at the latter stations. Nor is this divergence whoUy due to differences in the quality of the air around Paris and around Glasgow. There is a very strong probability, almost amounting to certainty, that it is partly owing to the greater * Cowptes Rendus, Ivii. 155. 18b THE PUEITY OF AIK. speed at which the air is passed through the chemical reagent at Montsouris than at Glasgow. M. Mari^- Davy transmits air through his aspirator at the rate of about 10 cubic feet per hour, whilst Mr. Dixon sends 1 cubic foot of air through his absorbing solution in the same space of time. Chemical action consumes a certain definite time, and if we hurry air through a chemical solution, intended to withdraw from it any body which it contains, too rapidly, the air is not thoroughly deprived of the same. Eecent experimenters have found a larger amount of carbonic acid on the summits of high mountains than on their sides at a lower elevation. ( Vide following Table.) The observations made by M. G-. Tissandier in his late ascent in the balloon named the " Zenith," are confirmatory of their results, for he found at an altitude of from 800 to 890 metres that the amount of carbonic acid in the air was '024 per cent, and at 1000 metres ■03 per cent, '"" Although many explanations of what must, I suppose, be admitted as a fact have been attempted, not one has as yet been offered which is altogether satisfactory. As in the case of the amount of oxygen, so in that of the quantity of carbonic acid, in pure or moderately pure air, there is a remarkable absence of discrepancy in the analyses, made by different chemists by dissimilar processes, of air taken under similar conditions in various parts of the world. Per cent. Mean of 18 analyses on Lake Geneva, by Sanssure "j" . '0439 Air of Madrid outside the walls. Mean of 12 analyses by Luna J '045 * Comptes Rendus, 12tli April 1875. + Ann. de Chem. et de Phys., vol. xliv. 1830. t Estudios quimicos sobre et aire atmosfirico de Madrid. 1860. THE PURITY OF AIK. 187 Air of Madrid inside the walls. Mean of 1 2 analyses by Luna . ..... Air of Munich, by Pettenkofer * . . . Air of summit of Mont Blanc, by Frankland t . Air over Irish Sea, July and August (Dr. Thorpe) X Air in Brazil (April and May) Hills above 3000 feet ... (A. Smith) „ between 2000 and 3000 feet . . „ „ „ 1000 and 2000 feet . . „ „ below 1000 feet . . . . „ At the bottom of the same hills On hills in Scotland from 1000 to 4406 feet In the streets of London (summer) In the London parks and open places On the Thames at London At the Montsouris Observatory, near Paris — Mean of results for six months, December 1876 to May 1877 In the streets of Glasgow (E. M. Dixon). Mean of results for May and June 1877 Air of S.W. suburbs of Leicester (Weaver) Per cent. •051 •050 ■060 •030 •032 •0336 •0332 •0334 •0337 •0341 •0332 •0380 •0301 •0343 •0278 •0304 •0460 * Handworterhuch der Chemie — Ventilation. t " On the Air of Mont Blanc ; " Journal of Chemical Society. 1861. J Journal of Chemical Society. 1867. 188 DIFFEKENT KINDS OF IMPURITIES. PAET I. DIFFEEENT KINDS OF IMPURITIES. The air is deteriorated in quality and defiled by — Different 1- Eespiration ""* and Transpiration, modes 2. Combustion. wnereDy air isdeterio- 3. Putrefactive processes, sewage emanations, and ex- ^uStfand cremental filth. defiled. 4. Gases, vapours, and suspended metallic, mineral, and vegetable matters given off by trades and manufactories. 5. Poisons of unknown nature evolved by damp and filthy soil. * The changes that are found to have taken place in pure air that has been respired are roughly the following : — (1.) 100 parts of air contain only 13, instead of about 21, parts of oxygen, the missing 8 parts having been withdrawn by the blood .corpuscles in the lungs. (2.) The °03 or '04 part per cent of carbonic acid is increased to between 4 and 5 per cent. (3.) An increase of watery vapour is noted, which is loaded with organic matter. ORGANIC MATTEE. 189 CHAPTEE XVIIL OKGANIC MATTER. Organic Matter. All air contains some organic matter, wliicli may be of different kinds. It has been divided into (a) the wholesome, (6) the neutral, (c) the putrid, and {d) the organized = dangerous form. I apprehend that, in designating any particular kind of org8,nic matter as wholesome, it is not intended to convey the idea that the presence in air of this variety is conducive to health, but rather that it does not influence health in one way or the other. It would be as well perhaps to combine the " wholesome " and " neutral " into one class, thus making only three varieties. It may be said at the outset that it is quite impossible by chemical means to distinguish one variety of organic matter from another. Organic matter may be of an animal or of a vege- table nature, but the sum and substance of all the most recent observations on air is, that the bodies, the pre- sence of which creates the difference between good or healthful air and bad or deleterious air, are mainly of a nitrogenous organic character. Animal organic matter is thrown off from the Animal. lungs in respiration, and from the skin by transpira- tion, in a state of invisible vapour and of epithelial dust. In 1870 Dr. Eansome read a paper * " On the * Proc. of Manchester Phil. Soc, 22d February 1870. 190 ORGANIC MATTER. Organic Matter of Human Breath in Health and Disease," in which he stated that the vapour of human breath in adults in a state of health, if condensed in a large glass flask, surrounded by ice and salt, and examined by the Wanklyn, Chapman, and Smith pro- cess, yielded about 3 grains of organic matter in 10 ounces of the condensed fluid, a quantity sufficient to make the fluid highly decomposable, and ready to foster the growth of those lowly organisms that we believe to be the intimate companions of the morbific ferments. This animal organic matter decomposes and gives off various volatile nitrogenous compounds, which, although they may not themselves produce disease, undoubtedly lessen the power of the body to resist its attack. Moreover, putrefying animal matter is a favourite pasture for the development and dissemina- tion of the animal poisons. It would seem to exert a distinctly poisonous action on one at least of the lower animals, if we are to accept the experience of Dr. Hammond, who placed a mouse under a bell glass, taking care to supply it with plenty of oxygen, and removing all carbonic acid and watery vapour, per- mitting the organic matter to remain. The mouse died in 45 minutes. Excremental filth, in a condition of impalpable powder, is often present in the air, and is the most disgusting of all the impurities to which man is ex- posed. As many diseases propagate themselves by eliminating their poisons through the medium of the exhalations and excretions of the body, air thus polluted is often the bearer of the organic poisons by which maladies are disseminated. ORGANIC MATTER. 191 Medical men and district visitors, who enter the dwell- ings of the poor in crowded courts and alleys, are per- fectly familiar with the foetid emanations that abound in such unwholesome styes. The peculiar sickening odour of organic matter is especially noticed in crowds of the great unwashed, and creates often, in those unaccus- tomed to such smells, a feehng of faintness, languor, and debility. Vegetable organic matter, if excessive in the air, is vegetable, associated, so far as our present knowledge extends, with a poison productive of ague and other malarial affections.'"'' The quantity of the nitrogenous material (ammonia and albuminoid ammonia) found in air varies, of course, and is a measure of its impurity. Dr. Angus Smith discovered "066 milligramme of ammonia, and "190 milligramme of albuminoid ammonia, in each cubic metre of air in a bedroom at 9 p.m., and "095 milligramme of the former, and "334 milligramme of the latter, per cubic metre, in the same room on the following morning at 7 A.M. t Mr. Moss, I whilst finding as a mean of eight observations "093 milligramme of ammonia and '088, or roughly '09 milligramme of albuminoid am- monia, in each cubic metre of the air of Portsmouth, estimated the proportions present at the same time in the Portsmouth Hospital, iu the officers' quarters, etc. {Vide Table.) Ammonia generally occurs in the air as a salt, such as the carbonate, chloride, nitrate or nitrite, derived * The answer of Dr. C. F. Oldham to the query which forms the title of his work, What is Malaria ? namely, that "Malaria is chiU," and that ague and other malarial diseases are not produced by a specific poison, is not accepted by the medical profession. + " Air and Rain." J Lancet, 2d Nov. 1872. 192 OEGANIC MATTEK. from decomposing animal matters, such as manure, sewage, effete matters from the lungs and skins of men and other animals. Some express the amount of the ammonia, and the ammonia derived from albuminoid ammonia, which they detect in air, in terms of nitrogen, by multiplying by 14, and dividing the result by 17. The nitrogen from both kinds of ammonia being added together, is recorded as the total nitrogenous matter in the sample. The old methods of estimating ammonia, in vogue before the discovery of the Nessler test, yielded most contradictory evidence. The invention of this re-agent, which can be worked with marvellous delicacy and pre- cision, has inaugurated a new era in air and water analysis. The following observations have all been made by its assistance in different ways, which will be described, in connection with the names of the analysts, in the chapter on " The Chemical Examination of Air," page 272:— OEGA^TjQ MATTEE. 193 Air-Washings. By Dr. Angus Smitli, Mr. W. A. Moss, and Dr. C. B. Fox. Milhoeamme in One CoBic Metee of Aib. Sample or Aib. Time and Weather. Ammonia. Albuminoid Ammonia. In Manchester. Laboratory Office, IOa.m . •106 •266 4p.m . •133 •293 Gas-room, 10 a.m. •130 •213 • ,, ,, 4 P.M. •190 •427 Yard behind laboratory Fine,' Oct. 28, 1869 '. •095 •095 J> 5> 5> Freezing, snow on the ground, Dec. 28 . •106 •356 )» 5> )J Damp, Jan. 13, 1870 •059 •213 " J5 >) Fine, Jan. 25, 1870 . •190 •316 " ') >} Foggy, Jan. 26, 1870 •142 •221 Street, open Eaining, and strong Average Bedroom, 9 p.m. wind, Dec. . Feb. 15, 1870 . •071 •261 •122 •266 •066 •190 „ „ 7 A.M. Feb. 16, 1870 . •095 •334 Average Midden Nov. 1, 1869 . Fine, cold, Oct. 27 . •142 •190 •101 •238 •533 •533 ,, t . ,, „ Oct. 28 . •237 •475 J, ... Average In London. „ „ Oct. 29 . •237 •237 •336 •415 Air of the Underground Nov. 11 and 12 (morn- •109 •457 Railway (Metropoli- ing) tan), 1869 Do. do. Nov. 15, 1 to 3 p.m. •034 •289 Chelsea (three places) , Nov. 4, windy . •045 •110 Brompton ,, ,, Nov. 4, windy, and a shower of rain •047 •128 By Dr. A. Smith. 194 OEGANIC MATTEK. Am-WASB.mGS— Continued. Milligramme in One Sample of Air. Time and Weather. Cubic Metre or Am. Ammonia. Albuminoid Ammonia. Hyde Park (two places) Nov. 5, morning, fine •028 •086 King's Cross(two squares) N ov. 8, dull and windy •047 •133 "Woburn Square and off Nov. 11, frosty. •038 •133 Regent Street Space near Holbom Nov. 11, „ . •028 •152 Viaduct Islington, Hoxton, Dal- Nov. 8, showery •061 •149 ston, and Hackney Bethnal Green and Step- Nov. 9, dull . •095 •190 ney Large yard near St. Nov. 9, „ •053 •157 Katharine's Docks London Bridge , Nov. 10,moming, cold and damp •062 •139 The Bank of England . Nov. 9, dull , •066 •142 Westminster Abbey Yard Nov. 6, fine •047 •085 Embankment of Parlia- Nov. 13, windy •048 •164 ment Houses Back street near Lam- Nov. 10, fine . •203 •241 beth Workhouse ' New Kent Road, Plea- sant Place, Kenning- Nov. 10, fine . ^057 •145 ton Park Near Vauxhall Bridge Nov. 6, „ . •038 •152 Cavendish Place, Wands- Nov. 6, ,, . •066 •133 worth Road A field two miles past Nov. 13, very strong Clapham Junction Average In Glasgow. Wind . •067 •271 •061 •150 A green in Elmbank Feb. 26, S., thawing, Street, near St. Yin- snow on the ground •079 •269 cent Street Union Street, near Argyle March 1, W.S.W., Street fine •095 •407 Charlotte Sti'eet, Gal- March 2, fine , •101 •258 lowgate Finnieston Quay Average March 1, W.S.W. . •036 •285 •078 •304 Shore, Innellan, Firth of Clyde March 3, n'.N.e! wind . •052 •137 OEGANIC MATTEE. 195 Am-'WASRmGS—Co7itinued. MiLLIGEAMME IN OnE Cubic Metre of Air. Sample of Air, Time and Weathee, Ammonia Albuminoid Ammonia. In Portsmouth. By Mr. W. Mean of eight observa- Air obtained at eleva- A, Moss, tions at different times tion of 20 feet •093 •088 in open air Rooms (Oificers' Quar- ters) No. 5 Ward of Hospital . ■436 •462 •428 1^307 Do. do. • ■ , , •855 1-018 No. 7 do, do. * •520 •753 Variola Ward . . "1 Rubeola Ward (chil- [- dren) , , .J Both were freely ven- >, tilated,andinboth i disinfectants were 1 •309 •226 •416 •197 freely used , J Room containing medi- » , , , •169 •282 cal stores Do, do. . •210 •138 Respired air in health t > , , , •218 •545 Do, do. •122 •169 Do, do. . •112 •099 Do, do. •144 •177 In Essex. By C, B. Air on banks of Thames Wind flowing from Fox, M,D. after passing over river to shore •03 •10 marshes Air of sitting-room Occupied by on« per- son for several hours. Good iire. Venti- lation by draughts underneath door and windows, which open to ground •066 •265 Air of bedroom after No ventilation of any being occupied by- kind •264 1-367 three persons for nine hours, at 7 a,m. Pure air of meadow , 1 •066 •044 * The amount of impurity found in the air of this ward gives, I should imagine, a fair example of the state of a fully occupied ward under ordinary conditions, — W, A, M, + These analyses show a considerable variation in purity, even in the same individual. It appears probable that a far larger amount of organic matter passes into the air from the skin than the lungs. 196 OEGANIC MATTEK. The observations that are now being conducted on the air of several parts of the city of Glasgow by E. M. Dixon, Esq., B. Sc, show, as regards its organic im- purities, an increase with an augmentation of tempera- ture, which is the principal factor concerned in late summer in the greater activity of aU putrefactive changes in nitrogenized material. Summary of Averages of Ammonia and Albuminoid Ammonia, and their Equivalents in Nitrogen, in 100 Cubic Feet of Air, in the Air of Glasgow, during the Summer and Autumn of 1877. Month. Stirling Square. Calton. Hospital, Kennedy Street. Sailors' Home. Broomie- law Bridge. Western Infirmary. ( d May . Am. •063 •052 Am. •081 =N-. •067 Am. •040 =N. •033 Am. •056 046 Am. •046 =N. •038 Am. •019 =N. •016 June . •064 053 •092 ■076 •023 •019 046 •038 ■015 ■012 July . •232 •191 •155 •128 •049 •040 •064 •053 ■037 •031 r^^ Aug. . •237 •195 •148 •122 •062 •051 •096 ■079 •081 •067 •056 ■046 ■049 1 Sept. . Oct. . •171 •141 •104 •129 •189 •107 •086 •071 •075 ■062 ■074 •070 •058 ■059 E. M. •126 •115 ■070 ■058 •089 •057 •047 •064 •053 sn. •an May . June . Alb. Am. •091 =N. ■075 •088 Alb. Am. •098 =N. •081 Alb. Am. •077 =N. ■064 Alb. Am. •069 =N. •057 Alb. Am. ■061 =N. •050 Alb. Am. ■053 =N. •044 •107 •116 ■096 ■099 •082 ■074 •061 •065 ■054 ^1^ July . •098 •081 •081 •067 ■077 ■064 •089 ■074 ■081 •067 Is^ Aug. . •122 •101 •121 •100 •115 •095 •094 ■078 ■093 •077 ■089 •074 •062 < Sept. . •110 •091 •122 •101 •094 ■078 •143 ■118 •086 •071 •075 Oct. . •060 •052 •058 •048 •059 •049 ■035 •029 •109 •090 •068 •056 The foregoing observations are of great interest, and open out to us a field of research into the large subject of chemical climatology, which is very attractive. The proportion of organic matter in air is also estimated by OEGANIC MATTEK. 197 making examinations of tlie amount contained in that great air-washer, rain. Eain dissipates the deleterious Rain, gases which accumulate and float over towns and cities. It brings down from the higher regions of the atmo- sphere a more salubrious air, and by the flushing of drains and cleansing of the surface of the country, aids in the prevention of the contamination of the air by the exhalations of animals, and by the decomposition of animal and vegetable matter which is incessantly proceeding. The following analyses, made by Dr. Angus Smith, evince very important differences : — Eain Waters collected dueing 1869, Darmstadt, February ..... Do. during a thunderstorm, May 26 Zwingenburg, near Heidelberg, July Heidelberg, June 15 Tyree, May * Kelly, Wemyss Bay, soutb-west wind, June 2 to 1 5 St, Helens, west wind, February 1 8 to March 1 1 Do. AprU 23 ... . Manchester, 30 feet from the ground, August Do. same place, September 12 feet from the ground, February same place, June during a thunderstorm. Eain had fallen heavily just before. Collected about 2 feet from the ground, September 10 2 feet from the ground, behind the Literary and Philosophical Society, September . . . . . Albuminoid Ammonia. Parts per MilUon^Milligr. per Litre. 30 Do. Do. Do. Do. 075 15 087 30 075 15 20 15 30 30 15 •079 •25 A large kelp work exists on the island. 198 OEGAinC MATTEE. The close agreement in chemical composition as re- gards the amount of organic matter of pm-e air, and of rain that falls through country air far away from animal and vegetable satiating agencies, and of well water of aver- age cleanliness, cannot but attract the attention of the analytical student of nature. About "08 of one part per million appears to be the mean amount of albuminoid ammonia contained in air, in rain, and well water that has not received any extra impurities from organic life. The study of the compensatory forces of nature, as manifested in that universal tendency to a restoration to a state of ec|uilibrium of everything that has to some extent departed from it, may well occupy the minds of those whose pursuits lead them to the contemplation of the laws by which this world is governed in special relation to the life and health of its inhabitants. OXIDES OF CAEBON, 199 CHAPTEE XIX. OXIDES OF CAEBON. A. Carbonic Acid. — The discomfort wliicli we experience cartonic in "badly ventilated rooms was formerly considered to ^^^*^- be occasioned by the production of carbonic acid. We now know tbat it is caused mainly by organic matter, and that an excess of carbonic acid can be borne with- out iH effects, if the air be free from deleterious gases and an excess of organic impurity. StiU the amount of carbonic acid is, as a rule, a measure of other accompanying impurities in the air, for it is almost always found in bad company. A confidence in our powers of measuring very accurately the minutest quantities of carbonic acid is established by the harmony that has been already shown to exist on page 187, between the results ob- tained by analysts on air of varying degrees of purity, which is still further increased by our study of such an interesting series of observations of air, of various degrees of impurity, collected together in the following Table :— 200 OXIDES OF CAEBON. Cahbonic Acid m Public and Ppjvate Buildings in Nature or Building. 1. Boot and shoe finisher 2. Framework knitter 3. Ditto ditto 4. Boot and shoe finisher 5. Needlemaker 6. Tailor's workshop . 7. Boot and shoe finisher 8. Tailor's workshop . 9. Elastic weh manufacturer 10. Fancy hosier .... 11. Boot and shoe riveter . 12. Kiveting-room of boot manufacturer 13. National school : Science class-room 14. Ditto Boys' day-room 15. Ditto Girls' day-room Boys' day -room Girls' day-room 16. Ditto 17. Ditto 18. Police Court : The Mayor's parlour 19. Ditto The Town-Hall 20. Private house : sitting-room 21. Worsted spiriner's preparing-room 22. Ditto doubling-room . 23. Town-Hall during Quarter Sessions 24. Prisoners' cell in police station Nnmlser of persons present. 6 14 10 7 6 20 12 25 20 9 13 18 17 100 110 300 160 20 100 7 50 50 300 1 Space for each person in cubic feet. 51 186 321 197 800 367 191 280 483 233 205 200 236 116 139 348 270 230 154 1310 1310 285 * Lancet, July 6, August OXIDES OF CAEBON. 201 Leicester, by E. Weaver, C.E., F.C.S5 Carbonic acid per 100 ot air. Number of gas- lighits burning. Remarks. 528 532 408 460 287 306 259 217 •211 •493 •172 •328 •241 •116 •164 •153 •103 3 14 8 4 6 13 8 25 30 10 10 •309 •204 — •120 •098 •304 1 •106 •174 60 17 ■NT 4.-1 4.- 1, 4- £ 1 ^ Breathing in several of the No ventilation but fireplace. i ° j j Ditto Ditto Ditto Ditto Ditto ditto, ditto, ditto, ditto, ditto. J low rooms was rendered oppressive. In every case a pleasurable sense of relief was experienced in returnrag to the outer air. Small ventilator in ceiling. Ventilators in roof. Small ventilators in side of" wall. Ventilated through window. Ventilated through window. — Nos. 8 and 11 prove that an open window or door wonderfully ameliorates the con- dition of the breathing air, even with diminished space. Ventilated through window. No ventilation. — Considerable cubic capacity is of no avail in the absence of ventilation. Ventilated by door being open. Ventilators closed. ' These ventilators are quite inadequate to secure fresh air to the scholars, and their area is very insignificant compared with the total capacity of the rooms, and out of allproportion. Afewjets of gas would appear to double the air pollution. Very small ventilators in ) The odour of organic matter walls. > was unpleasantly percep- Small ventilators in roof. ) tible in this school. Rotatory ventilators in roof. Ditto ditto. No ventilation. Gas had been burning for three hours. Ditto. Ditto. The sixty jets had been lit for twenty minutes. Owing to absence of ven- tilation, the aerial pollution was in- creased nearly 70 per cent during this short time. Numerous ventilators in roof. VentUated at open grating. On busy occasions, e.g. Saturday nights, when there are seven or eight inmates, with a capacity of 30 or 40 cubic feet per head, the smell is perfectly sickening. 3 and 17, 1872, 202 OXIDES OF CAEBOiSr. Caebonic Acid in Public and Private Buildings in Natuee of Building. Number of persons present. Space for each person in cubic feet. Temp, of building InF. degrees. 25. Police station : Sergeant's office . 26. Prisoners' cell at Town Hall 4 1 120 500 67 55 27. Spring Assizes : Crown Court ; body of hall 28. Spring Assizes : CrowTi Court ; gallery 29. Spring Assizes : Nisi Prius Court ; body ofhall 30. Spring Assizes : Nisi Prius Court ; gal- lery . . . . 350 350 200 J 200 100 100 160 160 60 64 60 62 31. Newspaper office : Compositors' room . 32. Ditto Machine room 33. Ditto Compositors' room . 10 4 10 400 1000 410 65 65 70 34. Private house : One foot from floor of bedroom 4 365 58 35. Private house : One foot from ceiling of same room 36. Private house : One foot from floor of bedroom ...... 4 2 365 730 59 58 37. Private house : One foot from ceiling of same room 38. National school : Infants' room . 39. Ditto Girls' Eoom 40. Private school ...... 41. Ditto 2 75 65 23 14 730 115 125 107 100 60 67 65 62 64 braid room 43. Elastic web manufactory : The upper or weaving room 1 100 J 50 990 1650 64 66 44. Public library : Heading-room 150 700 60 OXIDES OF CAEBON. 203 Leicestek, by E. Weaver, C.E., F.C.S. — Continued. Carbonic Number acid of gas- Bemabks. per 100 lights of air. burning. •203 1 Ventilated by the window. •081 — Ditto at grating. ''The condition of the air proves that the action of the rotatory ventila- tors is from some cause •196 — c Rotatory ventilators in roof. very imperfect. The •290 — Ditto ditto. carbonic acid in No. 28 - -j is very large, consider- | •134 Ditto ditto. ing that artificial lights 1 were absent, and that •169 _ I Ditto ditto. it was entirely due to animal combustion. The odour in this gallery was I strong and oppressive. •111 6 Yentilated by staircase. •123 4 Ditto ditto. •149 13 Small ventilators in walls. Business in full action during experiment. •102 — No ventilation. Door open all night. Four young children slept here. Samples obtained in early •150 — Do. do. do. 1 morning. In each room a small jet of gas was ' •116 ISo ventilation. Door closed biu-ned. all night. Two adults slept here. •164 — . Do. do. do. J •154 — ^ Yentilated by open window. •139 — Ditto ditto. •120 — Ditto ditto. •121 — Ditto ditto. ' ITotwithstandrng the much greater breathing space secui-ed to each occupant of the upper room, the air •178 150 ( Ventilated at side walls is much more contamin- 90 i and ceiling. ated, because of the foolish •328 Ventilated at side walls arrangement of passing the and ceiling. foul air of the bottom apartments into those above, instead of directly . into the outer air. •206 50 Ventilators in ceiling, which are evidently inefficient. [ 204 OXIDES OF CAEBON. Mr. Weaver points out that the condition of the air in the sitting-room of a private house, No. 20, illustrates the condition of a great number of dwellings, occupied by mechanics and clerks, entu^ely unprovided with ventilation. The higher percentage of carbonic acid in the galleries, as shown by the observations No. 27 to 30, testifies to the fact of its ascension with the aerial currents, and that there is no tendency towards accumu- lation in the lower strata of air from superior specific gravity, as has been sometimes argued. Caebonic Acid in London, Manchester, New Yoek, Cornwall, Poetsmouth, and elsewhere. By Drs. Smith and Bernays, F. de Chaumont, and others. Chancery Court, closed doors, 7 feet from ground, Marcli 3 Same, 3 feet from groimd .... Chancery Court, door wide open, 4 feet from ground, 11.40 A.M., March 5 . . . . Same, 12.40 p.m., 5 feet from ground . Strand Theatre, gallery, 10 P.M. . Surrey Theatre, boxes, March 7, 10.3 p.m. „ „ „ March 7, 12 p.m, Olympic, 11.30 p.m. ..... „ 11.55 P.M. ..... Victoria Theatre, boxes, March 24, 10 P.M. . Haymarket Theatre, dress circle, March 18, 11.30 P, Queen's Ward, St. Thomas' Hospital, 3.25 p.m. Edwards' „ „ „ 3.30 p.m. Victoria Theatre, boxes, April 4 . Effingham, 10.30 p.m., April 9, Whitechapel Pavilion, 10.11 p.m., April 9, ,, City of London Theatre, pit, 11.15 p.m., April 16 Standard Theatre, pit, 11 P.M., April 16 Percentage by volume. 193 203 0507 045 101 111 218 0817 1014 126 0757 040 052 076 126 152 252 320 OXIDES OF CAEBON. 205 Percentage by volume. •700 •723 •068 •230 •082 •95 •124 Stable for horses : Ecole Militaire Crowded girls' schoolroom, seventy girls (Pettenkofer) Mean amoiiut in a dwelling-house, during the day , In a bedroom at night with closed windows „ „ „ partly open . Sleeping cabin of Dublin Canal boat (Cameron) Unventilated barracks in London (Roscoe) Tombs Prison (male department), New York (H. Endemann) ....... "147 Fulton Market, New York (H. Endemann) . . •OS 4 Manchester streets, ordinary weather . . . "0403 "V^Tiere fields begin ^0369 During fogs in Manchester . . . . ^0679 About middens -0774 In workshops ....... •SOOO In theatres, worst part, as much as . . . ^3200 In mines, largest amount found in Cornwall . . 2*5000 In mines, average of 339 ..... "7850 Dr. F. de Chaumont's estimations of the amount of carbonic acid in the air of barracks, hospitals, and prisons are interesting : — BarracJcs. Gosport New Barracks •06 Anglesea Barracks .... •14 Aldershot ..... •049 Chelsea ...... •07 Tower of London . . . . •13 Fort Elson (Casemate) •12 Fort Brockhurst (Casemate) . •08 Military and Civil Hospi 5afe, Portsmouth Garrison Hospital •097 „ Civil Infirmary •092 Herbert Hospital , . . •047 Hilsea „ . . •057 206 . OXIDES OF CAEBOK Military and Civil Prisons, Per cent. Aldershot Militarj^ Prison — Cells . , . '165 Gosport „ „ „ ... '13 Chatham Convict „ » ... '169 Pentonville Prison — Cells (Jebb's system) . . "09 Dr. Endemann obtained seventeen samples of air from the public schools of America, and found carbonic acid varying in amounts from '09 to "35 parts in 100 ; or, in other words, from more than twice to nearly nine times the normal quantity. He gives the following tabular results, obtained from some of the public schools in New York: — Schools. Per cent. Elm Street •146 Roosevelt Street •195 Thirteenth Street, near Sixth Avenue . •281 Thirteenth Street, near Seventh Avenue •213 Greenwich Street ..... •176 Vandewater Street *..... •147 Madison Street, near Jackson •242 Dr. Breiting made a series of fourteen experiments on the quantity of carbonic acid contained in the air of some schoolrooms, commencing at 7.45 a.m., and continued to 4 P.M., in a room of 2 5 1^6 1 cubic metres capacity, and contaiaiQg 64 children. The amount of carbonic acid was said to vary from 2^21 to 9"36 per cent (!). Herr E. Schulz found in a clubroom "37 per cent, and in a schoolroom an amount of carbonic acid vary- ing from ^14 to ^35 per cent. Dr. Snow has concluded from his experiments on animals " that 5 or 6 per cent by volume of carbonic acid cannot exist in the air without danger to life, and that less than half this amount will soon be fatal, when it is formed at the expense of the oxygen of the air." OXIDES OF CAEBON. 207 My own determination of the amount of carbonic acid in air of different degrees of purity teaclies no more than do the foregoing analyses, so that I will not trouble the reader at present with any more tabular matter. The purest air — ^namely, that resting on the sea, and on the sides of the highest mountains — is thus seen to possess rather more than "03 per cent of car- bonic acid, which is often increased in the streets of cities to '04, an amount which may be doubled in foggy weather. Much discussion has taken place at various times as to whether carbonic acid is a positive poison or simply an asphyxiatmg gas. It has now been pretty clearly established that this gas is a distinct poison when diluted with air, but that, in a pure or unmixed state, as it is sometimes found in a beer vat or old well, it extinguishes life in a mechanical manner, by immedi- ately suffocating any one who may be immersed in it. The presence or absence of injurious bodies iu air, such as hydrogen sulphide, methyl hydride, hydrogen, organic matter, sulphurous acid, ammonia, ammonium sulphides, and the amount of oxygen it contains, must not be lost sight of in judging of the effects of carbonic acid on the human frame. It has been a subject of wonder that people have been but slightly incon- venienced by an exposure to the air of places where brewing is going on, or soda water is being manufac- tured, where, indeed, the air contains perhaps about •20 per cent of carbonic acid. In such cases the gas diluted with air is unmingled with unwholesome accessories as organic matter, sulphur compounds, etc. Such air in a closed chamber will give to any one who exposes himseK to it a severe headache. We all, in- deed, avoid an atmosphere containing "10 per cent of 208 OXIDES OF CAEBON. carbonic acid in crowded rooms. Animals can be kept alive for a long period in an atmosphere bigbly charged with it if the oxygen be added. The body, when exposed to air containing a large excess of carbonic acid ('30 per cent), suffers a reduction in the heart's action and an acceleration of respiration. These effects have been found to be produced when the influence of the organic matter and other foreign bodies is eliminated. Estimates of the enormous quantities of this gas that are daily and hourly poured forth by our cities would be alarming indeed were we not consoled by the knowledge of the rapid distribution of gases by diffusion, which tends to maintain a state of equilibrium in the constitution of the air. Dr. Smith assures us that 15,066 tons of carbonic acid are daily passed by the city of Manchester into the air that envelopes it,'^'" and Dr. F. de Chaumont states that 822,000,000 cubic feet of this gas are generated in London per day, or more than 9500 cubic feet every second. In consequence of the possession of most wonderful self-purifying pro- perties, which are partly due to its powers of oxidation and partly to the physical changes that are unceasingly occurring in its condition, through the agency of currents, storms, rains, changes of temperature, etc., the vast aerial sea maintains a uniformity of composition so marvellous as to strike with awe the student of the mighty forces of nature. * M'Dougal {Chemical News, ix. 30), under Koscoe's direction, determined on two different days the amount of carbonic acid in tlie air of Manchester. As a mean of 46 analyses, the air from the centre of Manchester was found to contain '039 per cent of carbonic acid (max. "056, min. -028), whilst the air four miles from the city exhibited as a mean of eight determinations "04 per cent. Hence Roscoe con- cludes that in open places the influence of combustion and respiration processes is completely neutralized by the movements of the air. OXIDES OF CAEBON. 209 B. Carbonic Oxide, which is a most poisonous gas, is carbonic a product of combustion, and is to be found in the air of ^ °' towns, where it is so diluted as to do but slight injury. Public buildings, churches, colleges, schools, barracks, etc., are very often heated by means of coke-burning iron stoves, some of which are provided with troughs and pans of water, to counteract the aridity of the air which they are supposed to induce. During the late " Coal famine " the demand for coke for domestic purposes has been perhaps greater than has ever been before known in this country, particularly amongst the labouring classes. In the United States anthracite (called in Ireland "Kilkenny coal" and in Scotland "blind coal"), which bears a great resemblance to coke, and is equally objectionable as ordinarily consumed, is most exten- sively used. Dr. Derby asserts '"' that " ninety-nine dwelling houses out of a hundred in Boston are, in whole or in part, warmed by this fuel, burned in iron stoves, or in the iron fire-pot of a furnace, which is but a stove in another form." Many people of nervous and sanguine tempera- ments, especially the plethoric, most of those indeed who are sensitive to changes in atmospheric states and conditions, are affected injuriously if they remain for some time in a room or ofiice warmed by an iron stove in which coke is consumed. They experience a languor ' and oppression ; in fact, a sense of " malaise," and sometimes a difficulty of breathing, slight dizziness, confusion of ideas, headache accompanied by a feeling as if a tight band encircled the forehead and temples, in one word, the symptoms of narcotic poisoning, which are speedily dissipated on removal tO' the fresh air. * Anthracite and Health. P 210 OXIDES OF CAEBOK Now, what poisonous gases are generated by the com- bustion of coke, coal, etc. ? Carbonic oxide, carbonic acid, the carburetted hydrogen gases, and sulphurous acid. The last named, which is so abundant in the air of coal and gas burning towns ■^'" (where it serves a useful purpose, being a powerful disinfectant), hardly deserves to be placed in juxtaposition with such deadly agents as carbonic oxide and carbonic acid. The light and heavy carburetted hydrogen gases may be excluded from our consideration, for they pass off in comparatively minute quantities in an uncon- sumed state. As the carbonic acid, which is produced by the lower layer of burning matter forming the fire, rises through the heated mass above, it unites with more carbon and becomes changed into carbonic oxide. This latter gas may sometimes be seen burning on the surface, and yielding a pale blue flame. When it burns in contact with air, carbonic acid is reproduced. The presence of carbonic oxide is a sign of imperfect combustion. The loss of heating power when this gas escapes from a stove has been estimated at 67 per cent. Carbonic oxide is believed by all to be a most virulent poison, even in the smallest quantities. As both of these gases are given off in the com- bustion of coke, anthracite, and charcoal ; and as dele- terious effects may be occasioned by either, and especially by the carbonic oxide, any escape of them into the air we breathe is to be carefully guarded against. Claude Bernard and M. Guerard both assure us that a mixture of these gases is more hurtful than either respired alone. * One of the causes of the difficulty which is experienced in culti- vating trees and shrubs in cities is to be found in the presence of this acid, which is highly destructive to certain kinds of plants. OXIDES OF CAEBON. 211 When coke or anthracite, which do not contain the illuminating gases, and which burn without flame and smoke, are used in our fire-grates, we can generally perceive an odour of sulphurous acid on the addition of fresh fuel, by placing the face close to the mantel- shelf. If this acid, which is detected by its irritating fumes, escapes then into our rooms, it may be fairly presumed that the inodorous gases, carbonic oxide and carbonic acid, which are simultaneously developed, are associated with it. Some may enquire, " Is it then unadvisable to burn coke in open fire-grates ? " I will answer this question by narrating an incident that came under my notice when in practice. An extremely delicate child, afflicted with a pulmonary affection, was ordered, during the prevalence of the easterly winds, to be confined to a suite of rooms, all maintained at one temperature, during both day and night, by coal fires in open fire-grates. As coals were very expensive, the mother after a time adopted the economical measure of burning coke. On entering the sitting-room, after the introduction of the coke, to visit the little patient, I experienced a sense of general oppression, of weight about the head, and a difficulty in breathing air which seemed to have lost all fresh- ness. The child was suffering from the symptoms of narcotic poisoning. She complained of great lassitude and of " a feeling as if a band was tightly bound around the forehead." The rooms were not again warmed by this fuel. It is to be observed that those who are unaccustomed to come into the vicinity of iron coke-burning stoves are more liable to be unpleasantly affected than those who are frequently near them. There is a certain 212 OXIDES OF GAEBON. tolerance of the poison of carbonic oxide acquired in time by those who habitually breathe it in small amounts, just as we see in the case of arsenic, opium, etc. Americans appear to be fully alive to the danger of the poisoning of the air they breathe with carbon monoxide, and now employ wrought-iron stoves, which are but slightly, if at all, permeable to gases. They are formed of plates riveted together as tightly as those of a steam boiler, so that the stove is practically of one piece. Stoves constructed of Eussian sheet-iron (rolled iron covered with a siliceous glaze) have also been employed. The Germans appear to be only partially aware of the injury attendant on the use of porous stoves.''^ As the majority of their earthenware stoves are covered with a silicious glaze, they suffer rather from the dryness of the air which they occasion than from the escape of poisonous gases. The English seem perfectly insensible at present to this danger to health, although it has been pointed out by myself t and others for years. The reader may imagine that, as stoves are fur- nished with flues, every provision is made for the removal of all the products of combustion into the outer air. Unfortunately these poisonous oxides of carbon do not all pass away by this outlet, but enter the rooms which the stove is designed to warm in three ways ; (a) through the iron ; (6) at the junctions of the separate pieces of which a stove is made ; and (c) in consequence of downward currents of air. * Vide Haller's "Die Liiftung und Erwarmung der Kinderstube und des Kranken Zimmers." + Coke as a Fuel, in Relation to Hygiene. OXIDES OF CARBON. 213 The second and third modes of exit are readily- comprehensible, but the first requires some explanation. MM. St. Claire Deville and Troost have discovered that iron and several other metals permit, when heated, the passage through them of the gases of combustion. They write, " The porosity results from the dilatation induced by heat in the intermolecular spaces." The researches of Tyndall on the penetration of metals by gases, and of Graham on the absorption of carbonic oxide by iron, corroborate these experiments. M. Dumas has distinctly shown * that a portion of the carbonic dioxide evolved during combustion is changed by heated iron into carbonic monoxide. It is by virtue of the absorptive power possessed by iron that this metal is converted into steel. We learn from Dr. Derby's little work, before alluded to, that so long ago as 1865 Velpeau communicated to the French Academy some observations of Dr. Garret, as to the unhappy influences on the health which attend the use of cast- iron stoves. General Morin interested himself in the matter, and asked MM. St. Claire Deville and Troost to analyse the air encircling a heated stove. These chemists found : (1) that tubes of cast iron are incapable of maintaining a vacuum ; -f" (2) that carbonic oxide, carbonic acid, and hydrogen gases pass through iron, and to a still greater degree through cast iron; and (3) that carbonic oxide, absorbed in our stoves by the internal surface of the cast iron, diffases * Comptes Rendus, August 26, 1872. + The soil in which pipes containing illuminating gas are embedded has often a powerful odour of it, and is frequently much discoloured. This is, without doubt, partly occasioned by loss through the walls of the pipes ; to guard against which, so far as is practicable, gas com- panies test their pipes by submitting them to a powerful pressure. 214 OXIDES OF CARBON. itseK from the external surface into the atmosphere, and that this process goes on continuously. They have besides determined the quantity of the oxides of carbon present in the air surrounding heated stoves, and the proportion of carbonic oxide which permeates through a given surface of a cast-iron stove, as well as that which the metal absorbs and retains. ^'' The passage of the comparatively harmless sulphurous acid through the crystalline structure of cast-iron stoves is often recog- nised by its pungent and peculiar smell. The most pleasant and grateful of all the artificial kinds of heat is obtained by the consumption of coal in open fireplaces, although as at present managed it is exceedingly wasteful. The quality of heat thus im- parted is, according to my experience, more conducive to health than that supplied by any other fuel. Ven- tilation is also promoted by open fire-grates. A brightly burning fire is an enlivening object, and tends much to render home attractive by its stimulat- ing influence on the spirits. These beneficial impres- sions on the nervous system are denied us by the cheerless stoves. Provided there is a powerful draught in a fire- place, coke may generally be burnt in it, mixed in small proportions with coal, without causing a disturb- ance of nervous functions. The draught in a chimney can of course be easily increased, if it is insufficient, by either lengthening the flue or diminishing the size of it near the fire. * The important experiments of these chemists are contained in Comjites Bendus, T. 57, 1863, and T. 59, 1864. PUTEEFACTIVE PROCESSES. 215 CHAPTEE XX. PUTREFACTIVE PROCESSES, SEWAGE EMANATIONS, AND EXCREMENTAL FILTH. Putrefactive changes are accompanied by the pro- Putrefactive dnction of gases and vapours, with which is associated ^^°'^^^^'^^- organic matter and a septic ferment. Warmth and moisture favour, and cold and dryness retard, these putrid decompositions. " The ferments, so far as we know them," writes Mr. Simon,'"" " show no power of active diffusion in dry air ; diffusing in it only as they are passively wafted, and then probably, if the air be freely open, not carrying their vitality far; but as moisture is their normal medium, currents of humid air (as from sewers and drains) can doubtless lift them in their full effectiveness, and if into houses or con- fined exterior spaces, then with their chief chances of remaining effective; and iU-ventilated, low-lying localities, if unclean as regards the removal of their refuse, may especially be expected to have these ferments present in their common atmosphere, as well as, of course, teeming in their soil and ground water." Again, he tells us that the common so-called " septic " ferment the product of putrefaction, which in its stronger action quickly destroys life by blood-poison- ing, can, in slighter actions, start in the body slowly * Filth Diseases, in Report of Medical Officer of Privy Council and Local Gov. Board. New Series, No. II. 1874. 216 PUTEEFACTIVE PEOCESSES, SEAVAGE EMANATIONS, advancing processes, which, will end in general tuber- cular or consumptive disease. Sewage Scwage emanations have been found on analysis emanations, to be somcwhat Variable in composition. The exami- nations of different analysts agree in noting a diminu- tion of oxygen and increase of carbonic acid, with small proportions of hydrogen sulphide, carburetted hydrogen, and sulphide of ammonium. The characteristic foetid odour of sewer gas is due to some organic vapour of carbo-ammoniacal origin, the precise composition of which has not yet been determined. Sewage and cess- pool effluvia are well known to be injurious to the health of animal and vegetable life, even when mixed in small quantities with the air. The only forms of life that thrive in air thus polluted are certain of the bacteria and fungi, and other of the scavenging families of creation. Excrementai As to the fouling of ths air we breathe with excre- flith. mental filth, generally dried and wafted about as dust, and its connection with the spread of such diseases as cholera and typhoid and other of those loathsome filth diseases, the subject is too disgusting to treat of. I would simply refer my readers to two sources for in- formation, if they require any: — First, to disclosures of Dr. Stevens as to the state of Over Darwen when the recent terrible outbreak of fever occurred there, where the people were living with thousands of tons of ex- crementai filth stored amongst their dwellings, exposing a surface of many acres, continually poisoning the air they breathed, and which enveloped them ; secondly, to Mr. Simon's Eeport on Filth Diseases, in which he writes of enteric fever — " Of all the diseases which are attributable to filth, this, as an administrative scandal. AJSTD EXCEEMENTAL FILTH. 217 may be proclaimed as the very type and quintessence ; that though sometimes by covert processes which I ■will hereafter explain, yet far oftener in the most glaring way, it apparently has an invariable source in that which of filth is the filthiest ; that apparently its infection runs its course, as with successive inocula- tions from man to man, by instrumentality of the molecules of excrement, which man's filthiness lets mingle in his air and food and drink." \ 218 POISONOUS GASES AND INJUEIOUS VAPOUES. CHAPTEE XXI. POISONOUS GASES AND INJUEIOUS VAPOUES, Such as hydrochloric acid gas from alkali works, arsenical vapours from copper-smelting works, hydro- fluoric acid from superphosphate manufactories, etc., injure animal and vegetable life, sometimes destroying aU trace of the latter for miles round. Then the air is vitiated by bisulphide of carbon from indiarubber works ; sulphurous and sulphuric acids from bleaching works ; hydrogen sulphide from chemical works where am m onia is manufactured. It is poisoned also by carbonic acid, carbonic oxide, and hydrogen sulphide, from brickfields and cement works ; by organic vapours from glue refiners, bone burners, slaughter-houses, etc.; by the fumes of phosphorus to which lucifer match makers are exposed ; '"' and the fumes of oxide of zinc, producing " brassfounder's ague." f * Vide Eeport on the Maniifacture and Applications of Phosphoras, by Dr. Bristowe, in Fifth Report of Med. Off. of Privy Council, 1862. t An examination of the long list of the manufactures of this and of other countries, which are, without scarcely any cessation, engaged in defiling the air by pouring into it a continuous sti-eam of noxious vapours, gases, and other injurious substances, is alarming. SUSPENDED IMPURITIES, 219 CHAPTEE XXII. SUSPENDED ANIMAL, VEGETABLE, AND METALLIC, AS WELL AS MINERAL IMPURITIES, Are the cause of an immense amount of suffering, the non-poisonous exciting lung disease by the irrita- tion occasioned. After the age of thirty-five the metal miners of Cornwall and Yorkshire are liable to a large mortality from a disease commonly spoken of as "miners' rot." The lungs of colliers become black with coal dust. It may be well to enumerate a few of the trades which suffer in this way : — ""' Potters suffer from the dust, and have what is called " potter's asthma ; " f Knife-grinders are injured by the fine particles of steel, and suffer from what is called " knife-grinder's rot ; " Millers, sweeps, hairdressers, and snuff-grinders, are liable to asthmatic affections ; Buttonmakers ; pin-pointers ; cotton, wool, and silk * Vide Thackrali's work on the Effect of Arts, Trades, and Profes- sions on IlealtJi. Vide also Reports on the Districts with excessive mortality from Lung Diseases, in Third and subsequent Reports of the Med. Off. of the Privy Council, by Mr. Simon and Dr. Greenhow. t It has recently been publicly declared that not less than 60 per cent of working potters die from diseases of the lungs. 220 SUSPENDED ANIMAL, VEGETABLE, METALLIC, spinners ; workers in flax factories ;* cotton weavers ; t stone masons ; grinding and millstone makers | and glass makers ; makers of sandpaper and Portland cement. Apart from the very obvious injury to health, induced by inhaling dust of various kinds, the circum- stances which attend the performance of this injurious work are in many cases highly deleterious. The hot, stuffy, damp, rebreathed air in which large numbers of these artisans are bathed during their hours of labour is enough in itself to predispose strongly to the development of disease. Some of the metallic dust to which some workmen are exposed is poisonous. * What a deplorable state of afiFairs is revealed by Dr. Purdon in his recent report on the flax manufacture of this country ! — Lancet, October 27, 1877, page 630. Rewrites : — "The spinners suffer less from phthisis than other classes of workers, but are much influenced by the moisture and heat of the rooms, which often cause fainting, accidents having occurred by the operatives falling when in this state on the machinery. The temperature in these rooms sometimes reaches 82° F., and the garments of the workers are so constantly wetted by spray from the spindles that they go out into the open air with satu- rated clothes, and are, of course, frequent victims to bronchitis. The weavers sufl"er greatly from chest aff"ections by inhaling the damp air, which has an average temperature of 75° F. Many of them being under 18 years of age, and being obliged to stoop constantly at the looms, get contracted chests, and this, with other circumstances, makes the death-rate very high. The rooms in which the dressing of the flax is carried on require to be kept at a temperature varying from 90° F. to 125° F. No one under 18 years old is employed in these rooms, and, as it is considered that their lives are shortened several years, they are paid very high wages. " t Vide Eeport of Dr. Buchanan's Inquiry at Todmorden, in York- shire. X Vide French millstone-makers' phthisis, by Dr. T. B. Peacock, in Brit. Med. Journal, October 14, 1876. AND MINERAL IMPUEITIES. 221 Manufacturers of white lead inhale the dust of this metallic compound. Plumbers and painters are very often poisoned by this metal in consequence generally of a want of sufficient cleanliness. Workers in mercury, such as silverers of mirrors and water gilders, suffer from mercurial poisoning. Workmen and women, who make arsenical wall papers and artificial flowers, suffer from inhaling the poisonous dust of some compound of arsenic.'"' Many persons who do not gain a living by paper or flower making, but who are unwise enough to adorn the walls of their rooms with papers of gorgeous hues, suffer also, and know not what ails them. Mr. Kerley found that a room, 16 feet square and 9 feet high, will have spread upon its walls, provided any of these arsenical papers are hung, from 52 grains to more than 8 ounces of poisonous green colouring matter. It is a popular mistake to imagine that all green papers are coloured by arsenic, or that papers which are not green never contain arsenic, or that arsenical wall papers and flowers are the only risks to health to which the unfortunate householder is exposed. Lead papers and copper papers are not fanciful dangers. It seems that clothing and furnishing materials are also not exempted from the universal system of poisoning and adulteration that prevails. The above-mentioned analyst estimated the presence of 5-|- ounces of aceto- arsenite of copper or " Paris green " in a green tarletan dress of 1 6 yards. Every sample of tarletan examined * Vide Eeport on the Manufacture and Applications of Arsenical Green, by Dr. Guy, in Fifth Eeport of Med. Off. of Privy Council, 1862. 222 SUSPENDED ANIMAL, VEGETABLE, METALLIC, contained it; the higher priced qualities of this material possessing more poison than the cheaper varieties. Some kinds of muslin are also coloured with this poisonous material. It has recently been discovered that the bright greens of certain furnishing materials, such as chintz curtains and linings, consist of the poisonous compounds — arsenate of iron and chromium. j\ir. Foster, of the Middlesex Hospital, who has drawn public attention to this matter,'"' found in each square yard of bedroom chintz arsenicum, in the form of an arsenate, equal to 45-^ grains of white arsenic, and in each square yard of the chintz lining 20^^ grains of this deadly poison. On estimating the number of square yards of chintz and lining in the bedroom of a gentleman who had suffered for some time from nausea and nervous depression, it was proved that there was arsenicum present in his sleeping apartment equal in amount to 2 6 ounces of white arsenic. This coloured powder being apt to be removed by trifling causes, is, of course, disseminated through the air, and well merits the epithet of " devil's dust." These poisonous furnishing materials have been sold to the public for the last twenty years. The latest surprise for the much-enduring house- keeper is, that children have been poisoned by white arsenic with which " "vdolet powder " has been found to be adulterated to the extent of 25 per cent, and by lead, from inhaling the dust that proceeds from inferior kinds of American cloth, with which perambulators are lined. The poisonous coating of these American cloths presents, after but a brief exposure to damp and sunlight, a countless number of cracks, and gradually * Lancet, August 11, 1877. AND MINEKAL IMPUEITIES. 223 separates from the texture on whicli it is spread in the form of a fine dust. Pollen and the aroma of grasses will produce in some people hay fever. Many contrivances have been devised for the pro- tection of the lungs of workmen who have to support "dear life" by engaging in the foregoing and other unhealthy callings ; but there is in this field a great opportunity for those with talents for invention to exercise them in behalf of these suffering thousands. In addition, the ventilation of workshops should be more attended to, for at present the admission of fresh, and the expulsion of foul, air is about the last thing thought of. Happily something has been done in this direction not only amongst the Sheffield knife- grinders,''^ but in the mines of Durham and Northum- berland, and the greatly diminished death-rate of these poor mechanics and colliers from pulmonary disease proves the advantage of free ventilation. Sufficient evidence has been adduced to show the magnitude and enormous importance of the subject. Medical Kterature and the columns of the medical * "What distressing truths have been for years presented to the public by the late Dr. Hall, of Sheffield, respecting the average dura- tion of life amongst the steel-grinding trades of that city. What fear- ful waste of life is disclosed in Dr. Wynter's summary of Dr. Hall's observations! — "Dry grinders of forks, 29 years; razors, 31 years; scissors, 32 years ; edge tool and wool shears, 32 years ; spring knives, 35 years ; files, 35 years; saws, 38 years; sickles, 38 years." Some improvement has undoubtedly been effected of late years, as the report of the Medical Officer of Health, contained in Dr. Hall's last communi- cation to the profession shows ( ' ' Remarks on the Effects of the Trades of Sheffield," Brit. Med. Journal, October 14, 1876), through the in- troduction of fans, but much still remains to be done. In 1874, 92 grinders died ; average age at death, 46 years. In 1875, 111 „ „ „ „ 42-5 „ 224 SUSPENDED IMPURITIES. press have for years been teeming with instances of the wholesale destruction of health and life by these terribly dangerous occupations. In brief, the injury and fatality induced by impure air charged with poisonous and non-poisonous dusts is simply an ignorant waste of human life. The air that we breathe, we who are not engaged in these unwholesome avocations, is full of dust — a heterogenous mixture of particles of organic and in- organic origin. From the amount of spores (250,000) in a single drop of fluid, Mr. Dancer calculated '"'■ " that 3 7-|- millions of these bodies, exclusive of other substances, were collected from 2495 litres = 88 cubic feet of the ' air of Manchester,' a quantity which would be re- spired in about ten hours by a man of ordinary size when actively employed." It may well be said, " Surely this' dust that we all of us breathe must be hurtful. Is there no provision in nature for counter- acting its baneful influence ? " There is no doubt but that the less of it we have the better for us. We are taught in every possible way, if we will but be guided by the teachings of nature, to be clean. If people win but admit an abundance of Nature's great disinfectant, pure fresh air, into their houses, and at the same time keep themselves and their houses clean, they will not be injuriously influenced by the dust of the air. * Microscopic Examination of the Solid Particles of the Air of Manchester. Proc. Lit. and Phil. Soe. of Manchester, vol. iv., series 3, 1867-68. EMAIfATIONS FEOM THE SOIL. 225 CHAPTEE XXIIL EMANATIONS FEOM GEOUND HAVING DAMP AND FILTHY SUBSOIL SUBSOIL AIE, CHUECHYAED AIE, MARSH AIE. The air of towns, and also that of houses, is often deteriorated by emanations from wet and filthy sub- soil. It has been distinctly proved both in this country and in America that the death-rate of consumption is diminished very considerably by drying the subsoil. Eheumatism and heart-disease, which is so frequent a concomitant of rheumatic affections, is lessened by the same beneficial measure. Emanations from filthy soil produce diarrhoea in that part of the year, namely autumn, when there is a predisposition to intestinal disorders. It is very unwise to allow the soil close to houses to be defiled by filth, for the fires of a house, creating a force of suction, draw into the house the air contained in the surrounding soil, as well as of that on which it is built. The popular impression that the atmosphere ends where the ground begins is a very widely spread delusion. Most soils are more or less porous. A house built on a gravelly soil stands on a foundation composed of a mixture of two parts of small stones, and one part of air. The air may give place to any gas or to water. The porosity of soils may be well illustrated by the following experi- ment devised by Pettenkofer.''"" * Cholera : How to Trevent and Resist it, by Dr. Max von Petten- kofer. Translated by Dr. Hime. 226 EMANATIONS FKOM DAMP " If a person blows, as represented in the figure, on tlie surface of the gravel, the water in the U-shaped tube will be seen to alter its position, the level of the Fig. 9. A, a tall and large glass tube filled with fine gravel, in the axis of which stands a very small tube, B, open at both extremities, the upper being curved, and connected by a piece of indiarubber tubing, C, to a U-shaped tube, D, contain- ing water. E, fine gravel. ) side next the person who is blowing becoming lowered, and the other proportionately elevated. The depres- sion of the fluid is caused by the force of the air blown through the gravel, because it ascends from the bottom of the gravel through the small glass tube, passes through the indiarubber tube, and thus reaches the water." Eemembering the force with which the wind often strikes the surface of the ground, exciting a pressure during a hurricane, amounting, according to some, to 36 and to others of 50 pounds on every square foot, AND FILTHY SOIL. 227 it cannot be a matter of surprise, in the light of the above experiment performed by a simple blowing from the mouth, that foul and pestiferous air from the filthy earth beneath, and close to our habitations, should be introduced into them, aided, as this driving force is, by the suction power created by the fires and lamps, etc. I have encountered instances in which foul air from drains, cesspools, and from leaky gaspipes, has been drawn into houses great distances, and has caused ill-health and death from the continued poisonous con- dition of the air. Pettenkofer, of Munich, relates a case '''■ where gas was found to have travelled a space of 2 0^ feet from the street main into the house. Dr. r. de Chaumont refers f to a case that occurred to Dr. Fyffe, in which the foul air from a cesspool was sucked into a house a distance of 27 feet. It is im- possible for any public health physician to speak in temperate language of the crime of erecting houses, and of allowing houses to be constructed, on filthy and sodden foundations. No one can possibly enjoy for any length of time good health in such buildings, and the diseases from which the inhabitants suffer are generally influenced so unfavourably by the insanitary conditions in which they exist, as to have a tendency to death rather than to recovery. I once visited a little town on the coast, swept by the purest of breezes — the sea breeze — where scarlet fever was prevalent. In one part of the town, where the cottages were kept in a cleanly and wholesome state, and were bmlt on virgin soil, the disease showed itself in the mild form of scarlatina, and not a death occurred. In another part of the town nearly every family lost one or more * Op. cit. f Lectures on State Medicine. 228 SUBSOIL AIR. Subsoil air. children, killed almost immediately by the poison. I went into one of the cottages where all the children, five in number, were destroyed, and talked to the poor afflicted parents. The father, pointing to a loose plank of the floor, moved a portion of it aside. I pushed my walking stick down, and stirred up the soil over which this family had been living. It was fluid filth. The cottages in which these fatal cases occurred had been erected on ground made up of stinking fish, brickbats, earth, and every kind of decomposing debris. Sulsoil Air. — The chemical composition of the air contained in soils has been investigated by many chemists, such as Boussingault and Lewy, Petten- kofer. Fleck of Dresden, Nichols of Massachusetts, and others. A large excess of carbonic acid, an excess of oxygen, a little carburetted hydrogen, a trace of ammonia and hydrogen sulphide (when the ground water possesses sulphates), have been discovered. They aU seem to be unanimous as to the much greater Pig. 10. quantity of carbonic acid in ground air than in atmo- spheric air, and as to its great variability in amount. The former fact is well demonstrated by an experiment and illustration, contained in Mr. W. N". Hartley's Air and its Belation to Life. SUBSOIL AIE. 229 A flask full of clear baryta water is connected by tubes to a vessel filled with earth, and again attached to this is another flask of baryta solution. By draw- ing air through the whole system of bottles the amount of insoluble carbonate of baryta, formed in the first flask by the carbonic acid in the air, may be compared with that in the second flask, produced by the carbonic acid in the soil. Pettenkofer discovered that the amount of carbonic acid in ground air varies in different seasons of the year, that it reaches its minimum from January to May, and then rises steadily to its maximum from July to November. The occurrence of the maximum in autumn, is probably the result of high temperature and excess of decomposing organic matter. The exact period of the minimum has not been so clearly determined. The analyses of the air of soils of various kinds that rest on different formations, the degree of porosity of soils, and the connection, if any, of the same with such diseases as diarrhoea and certain forms of continued fever, is an extremely interesting field for research which has been but barely opened out. That there is a very decided relation between ^the state of the ground air and the continued prevalence in a given locality of diarrhoea at certain seasons is a matter of strong probability. It has been suggested that the amount of car- bonic acid in ground air be taken as indicative of the degree of impurity. As the animal poisons seem to attach themselves always to minute particles of animal and vegetable organic matter in a state of decomposition, a study of the comparative amount of organic matter in the ground air of soils cannot well be omitted. 230 CHUECHYARD AND MARSH AIR. churciiyard Tlu Air of Churchywrds and Vaults is richer in *^'- carbonic acid than ground air, and contains often a putrid organic vapour, hydrogen sulphide, carbonate of ammonia and sulphide of ammonium, and elementary forms of animal and vegetable life. Marsh air. Tlu Air of Marskcs contains also a large excess of carbonic acid and organic matter. Great quantities of living organisms and organic debris, carried upward for a certain distance by the ascensional force afforded by the evaporation of water, are discernible on microscopic examination. Carburetted and phosphuretted hydro- gen gases are evolved by marsh land, and sometimes hydrogen and ammonia. The time to be selected for making observations on the composition of marsh air is in the early morning or evening, when the density of the air and the deposition of dew prevents a free admixture of the impure with the higher strata of pure air, or during a hot, sultry noon when no breeze keeps the air in motion. I have made analyses of the air of marshes that are hotbeds of ague, taken on a fine day, whilst a gentle wind blew over them, and have foimd no more organic matter in such air than in pure air collected simultaneously on high hills. This fact is only another proof of the marvellous purifjring properties of air, and the tendency throughout nature, not only in the air, but in the earth and in water, to self-purification, and to the restoration of an equili- brium. THE AIE OF OUR HOUSES. 231 CHAPTEE XXIV. THE DELETERIOUS EFFECTS ON HEALTH OF THE AIR OF OUR HOUSES. To dilate on such a subject would be indeed need- The air of less to students of preventive medicine, if a general recognition existed of the fundamental principles on which the relations between a state of health and disease, and between a condition of health and the circumstances which tend to promote and deteriorate it, rest. The old notion that disease is a sort of malignant demon that takes possession of the body, and requires to be combated and expelled by some violent means, is still a very wide-spread one, even amongst some of the rural rank and file of the medical profession, and any modern ideas as to the relations of health to the conditions of those surroundings of life, namely, the air we breathe, the water we drink, and the food we eat, which so seriously influence it for good or evil, are often received with a smile of in- credulity. The public surely ought not to require a skilful physician to teach them what common-sense inculcates, that perfect bodily and mental health can- not be enjoyed by those who are inattentive to the cleanliness of the body, and of that which enters it. There is, unhappily, an increasingly exaggerated im- portance attach-ed at the present time, by great numbers 232 THE DELETERIOUS EFFECTS ON HEALTH OF of people, to the injurious effects of impure water. It is the fashion to ascribe almost 'every indisposition to the condition of the water supply. The tendency to run into extremes about most matters, and to ride hobbies, is but too frequently observed. On the other hand, there does not yet exist in the public mind an adequate conception of the extent of the danger to the health which is induced by a continual immersion of the body in impure air, notwithstanding the .efforts that have been made in this direction for the enlighten- ment of the public mind. For years I have, as medi- cal ofi&cer of health, been preaching on this subject, pretty much in the language of my First Annual Ee- port of 1874, which contains the following passages : — The teaching " It shouM not be ncccssary to point out the blessings officers. of puro air, and the evils resulting from the inhalation of a vitiated atmosphere. Excluding from considera- tion the effects of an exposure to the fcetid gases of organic decomposition, which act like other poisonous chemical agents, it may be said that offensive smells, the products of putrefaction, are not only injurious in themselves, but serve as danger signals bidding men to beware. By acting as depressants, and as reducers of bodily vigour, they tend to make the system more prone to be attacked by disease. As the smell of gas in a house warns men of the pre- sence of a body dangerous when diffused through it, so an offensive smell is a signal of the possibility of the presence of the poison of a disease. A stench may or may not be associated with a disease poison, and no one knows when it is and when it is not thus accompanied. As a means of warning to those exposed, an offensive smell is useful, but we must remember THE AIE OF OUR HOUSES. 233 that agents whicti destroy the stink of filth may yet leave all its powers of disease-production undiminished. Disease poisons or ferments, although not always in the companionship of stinks, are often so, and it behoves every one to remove the cause of stinks, and prevent their recurrence. Disease ferments may fatally assail the human body in doses quite, unappreciable to the most acute sense of smell. All unpleasant smells are to a certain extent deleterious, although infinitesi- mally so perhaps. Pleasant odours, if in excess, be- come injurious to some persons. Those who visit the farms devoted to the cultivation on a large scale of the rose and jessamine in France, for the manufacture of scents, experience, after being exposed to these per- fumes for a little time, severe frontal headache and lassitude, symptoms which speedily pass away when they emerge from these odoriferous tracts of country. It should always be remembered, then, that smells which offend the senses, even when not accompanied by disease poisons, act deleteriously on the health of those frequently exposed to them, by depressing the system, thereby lessening the resistance of the frame to the approach of disease, and by diminishing the bodily vigour, rendering the vis medicatrix naturae a less chance of success in preventing disease from destroying those attacked." The effect of all the exertions of that class who have been called sanitary reformers is, that large num- bers of people tacitly acknowledge that the constant inhalation of air rendered impure to the senses of sight and smell is likely to injure. Is it very difficult for i^^suit of ,■■ ttj. iPi 1 on *^® same me puDiic to go a step further and cease to offer oppo- amongst the sition to the belief which is rooted in the mind of^''^^'^- 234 THE DELETEEIOUS EFFECTS ON HEALTH OF every public health physician, that frequent exposure of the body to air that is deteriorated in quality either by having been rebreathed without purification, or devitalised, tends to a reduction of the vital powers, a state which is favourable to the development of a perversion of healthy action, the precursor of disease. Dr. Eichardson has, in his attractive style, most candidly spoken out on this subject in his Diseases Dr. Richard- of Modem Life. " It is this devitalised air in our oftte^uni-^ overcrowded towns and cities, where there is no vege- versai sys- tatiou to rcvivify it, which we distinguish as something deteriort- SO different from the fresh country air that streams tion. Qygp forest and meadow. It is the breathing of this air that makes the child of the close town so pale and lax and feeble, as compared with the child of the country. It is this air that renders the atmosphere of the crowded hospital so deficient in sustaining power. It is this air that gives to many of our public institutions, in which large numbers of our poorer, ill-clad, uncleansed masses are herded together, that ' poor smell,' as it is called, which is so depress- ing both to the senses and to the animal power. " In many private houses, houses even of the well- to-do and wealthy, streams of devitalised air are nursed with the utmost care. There is the lumber-room of the house, in which all kinds of incongruous things are huddled away, and excluded from light and fresh air. There are dark understairs closets, in which cast- off clothes, charged with organic debris of the body, are let rest for days, or even weeks, together. There are bedrooms overstocked with furniture, the floors covered with heavy carpets, in which are collected pounds upon pounds of organic dust. There are dress- THE AIR OF OUR HOUSES. 235 ing-rooms, in which are stowed away old shoes and well-packed drawers of well-worn clothing. There are dining-rooms, in which the odour of the latest meal is never absent, and from the cupboards of which the smell of decomposing fruit or cheese is always emanat- ing. There are drawing-rooms, in which the scent of decayed roses, or of the varnish from the furniture, or of the dye from the table-covers, is always present. There are kitchens in which there is the odorous indi- cation of perpetual cooking. There are sculleries where the process of ' washing up ' seems to be in permanent action, and where the products of change from stored bones, potato parings, recent vegetable green food, and other similar refuse, are abiding. There, are water-closets in which there is at every time of day or night a persistent, faint ammoniacal organic odour. "The process of devitalisation of the air is again effected, locally, in human habitations, by the presence in it of the lower forms of life. When in the dwell- ing-house dogs, cats, tame mice, birds, squirrels, are kept in such numbers that the odours of the animals are perceptible ; when flies cover the ceilings, and a mould collects on the walls, then the air teems with myriads of minute Kving forms, and with organic dust. Every particle of this matter induces deteriora- tion of the air that feeds the lungs." Although many may smile on reading the foregoing extract, every one with any experience of life must admit the truthfulness and fidelity of the sketch. The principles that should be firmly implanted in our minds are involved in the consideration of such golden rules as the following : — 236 THE DELETERIOUS EEEECTS OX HEALTH OF Pi-incipies 1. An exposuie of the body continually to a smell, be the public it a pleasant or an unpleasant one, is deleterious mind should to healtli. be imbued. 2. An odour that is at first pleasant, generally soon becomes objectionable. The little is grateful, but a constant excess of the perfume is hurtful. 3. An unpleasant odour may or may not be in the companionship of a disease ferment, and no one knows when it is or when it is not so accom- panied. The putrid gases of decomposition will not in themselves give rise to the development of either of the zymotic diseases. 4. When an unpleasant odour is not associated with a poison of a disease, it is nevertheless deleterious to the health of those constantly subjected to its influence. I know that this statement will be doubted by some. Several instances of its truth have occurred to me. For example, a man in good health took a house close to one of those pubhc trade nuisances where the smeU. of melted tallow taints the air, and suffered in consequence severely from nausea and diarrhoea. Here no septic ferment could have existed, such, for example, as is supposed, with good reason, to be mingled with the odours of the dissecting-room. 5. The healthy human body often becomes inured, after long exposure, to unpleasant odours, and at length hardly notices them, if always immersed in them. Those actively injurious effects of im- pure air, such as nausea, diarrhoea, etc., often gradually pass away. If a man is possessed of exceptional powers of vigour, which enable bim to maintain a successful warfare with those de- THE AIR OF OUR HOUSES. 237 pressing influences that surround him, he may live for a great many years in tolerable health, although defying the laws of nature. The large majority become affected in course of time, if not suddenly attacked by a passing epidemic (to which a person living under unhealthy conditions is especially prone), by the insidious progress of a chronic disease. 6. Air, which is not defiled by the offensive produc- tions of decomposition, may contain organic matter in the form of dust or vaporous emanations, as carriers of the specific poisons. A cursory examination of these dicta may lead some one who is indisposed to remove a nuisance from his pre- mises to urge that the whole question as to whether an odour is or is not injurious to health, rests on the point as to whether it does or does not annoy the person con- tinually exposed to it. Anything which persistently worries, disturbs, and irritates, is undoubtedly dele- terious to health, although the injury may be so in- finitesimal that it cannot perhaps be measured or demonstrated. It will probably scarcely incommode the resilient disposition of the young and healthy animal that is naturally cheerful, and disposed to look on everything with a couleur de rose hue. The human body by acclimatization can adapt itself to wondrously different circumstances, although a certain injury is received by so doing, but it never reaches the period of old age if continually bathed in impure air, although that air may have long ago ceased to offend the olfactory nerves. The comparative freedom of the sewer men of Paris from cholera and other zymotic 238 THE DELETERIOUS EFFECTS ON HEALTH OF diseases, an assertion which has encouraged the opinion that a constant exposure to morbific ferments or contagia diminishes the risk of "being injured by them ; the absence of any marked injury to health during the year that the Thames was so odoriferous ; and of any excess of zymotic disease in the neighbour- hood of MontfauQon, in Paris, where much of the filth of that city is stored preparatory to its conversion into manure for agricultural purposes : will perhaps be urged as contradicting these views. It is a well- established rule, however, notwithstanding the existence of certain much-talked-of supposed exceptions, which is recognised by the whole of the medical profession, even to its humblest member, that there is a greater mortality amongst those who are exposed continually to impure air than with others who are not so circum- stanced, and that the diseases from which the former suffer are of an asthenic type tending to death rather than to recovery. Air of the The amouut of oxygen in the air is diminished, toTOs\nd ^^^ ^^^^ 0^ ^^® carbonic acid is increased by respira- citiesisnot tiou, and combustiou and decay of organic matter, the has bLn^^ ^^ former, to speak in popular language, being the life- generaiiy giving and purifying principle, and the latter its noxious substitute. Thanks to the diffusive powers of gases, and the effects of wind, and to the currents produced by the fires of large towns, and last, but not least, to the wonderful cleansing properties of fresh air, the air of the streets of our towns is not so impure Air of our as might be expected. The air of our houses, on the e^tbits^the ^^^^^ hand, is generally very impure, because the con- presence of tinuous admission into them of pure air, and expulsion of that which has been used up, is rarely thought of, THE AIR OF OUR HOUSES. 239 or if so, is seldom efficiently managed. In respiration amounts of we deteriorate an enormous quantity of air (about a agents. gallon a minute), and we are continually throwing off carbonic acid and organic matter. Every time we breathe, and we breathe about eighteen times per minute, we expel 30 cubic inches of air, which amount contains 1'29 cubic inch of carbonic acid, or 16"1 cubic feet in the 24 hours. In the 16 cubic feet of carbonic acid, there are about 7| ounces by weight of charcoal. Others say that the amount of charcoal is 160 grains per hour = 8 ounces in 24 hours. Air which has been once breathed should never be breathed again until it has been mingled with fresh air, in order that the impurity which it has acquired may be removed from it, and that it may regain a wholesome amount of moisture. Architects design houses, local boards pass the plans, builders erect places which are totally devoid of all provision for the admission of fresh air, and may be likened to Holes of Calcutta on the small scale. As for arranging for a change of air by the passage through a room of warmed fresh air in winter, and cooled fresh air in summer of a healthful degree of humidity, such a proceeding is never dreamt of. The drowsiness which often oppresses our congregations may frequently be more correctly ascribed to the absence of Absence of any attempt at ventilation than to the cause to which it is to ve^ntarte generally attributed. Who is there not acquainted with buildings Y-, 1 ^ 1 ^ , except in the unwholesome atmosphere to be met with m nearly the cmdest every public building ? whilst our drawing-rooms, ™^^^^^- dining-rooms, and bedrooms, even in the best houses, are too often in a most disagreeable state of what is termed " closeness." On once remonstratino; with the 240 THE DELETEEIOUS EFFECTS ON HEALTH OF verger of a churcli in a suburb of London with respect to the oppressive state of the air during the Sunday afternoon, and on suggesting to him the propriety of opening freely the windows during the interval between the first and second services, he expressed his dis- approval of my proposition by informing me that if he "followed my advice the church would catch a chill." I have always maintained, and increased experience has only confirmed my previous conviction, that the impure condition of the air of our houses, be they fac- tories, public buildings, or dwelling-houses, has much to do with the great prevalence of such diseases as phthisis pulmonalis, bronchitis, and pneumonia, which together make up nearly one quarter of the total mor- tality ; and if we could strike a telling blow at that great universal evil — namely, poisoning by impure air — we should do much to save life. Unventilated and overcrowded workshops and schools are, moreover, the nurseries of strumous diseases in general, which sap the strength of the community. During the decennial period 1865 to 1874, not less than half a million individuals died of phthisis, and three-quarters of a million of people were destroyed by other diseases of the lungs in England. The depend- ence of these diseases on vitiated air was maintained by Dr. Alison'"' as long ago as 1824, by Baudelocque in 1834,t and very likely long before those years. That air vitiated by respiration is the one great cause of pulmonary consumption, which may be trans- mitted from parents to children for generations, needs no proof, as it rests on such a mass of evidence. * Edinlmrgh Med.-CMrurgical Transactions, vol. i. t Uhides sur la maladie scrophuleuse. THE AIR OF OUE HOUSES. 241 The facts that an increase of this disease occurs pari passu with an increase in the density of a popu- lation ; that in manufacturing centres, where the males are the chief workers at indoor employment, the male death-rate is the highest ; and in others, where females are principally required at indoor work, they suffer most; that in agTicultural districts, where the men spend nearly all their lives in the open air, and the women scarcely ever leave their cottages, the female death-rate from this disease is higher than the male : — are all corroborative of this inevitable conclusion. Dr. Parkes mentions a remarkable circumstance illustrative of this connection as having occurred in Vienna. In the badly-ventilated prison of Leopold- stadt, 51 '4 per 1000, whilst in the well-ventilated House of Correction of this city, 7*9 per 1000 died of consumption. Dr. Guy's evidence before the Health of Towns Commission contained most striking statements as to the journeymen printers of London. He divided them into three classes : — The 1st Class consisted of men who worked in rooms where they had less than 500 cubic feet of air per head. Of these 12 1 per cent had spat blood, and a like proportion had been subject to catarrh ; The 2d Class comprised men who had between 500 and 600 cubic feet of breathing space per individual, and amongst them intermediate effects were noticed ; The ?>d Class was composed of men who worked in shops where they had more than 600 cubic feet per individual, and amongst these only 4 per cent had suffered from spitting blood, and only 2 per cent from catarrh. 242 THE DELETEEIOUS EFFECTS ON HEALTH OF The published opinions of Dr. Farr, Dr. Marcet, Mr. "Welch, """ Dr. Eansome, f Dr. Parkes, Dr. Austin Flint, and Sir James Clark, are all to the same effect. The continued employment of rebreathed air for respiratory" purposes, and its bearing on the develop- ment of that terribly fatal strumous disease, pulmonary consumption, has been vigorously brought before the world by Dr. MacCormack, of Belfast, | who, to show his enmity to used-up air, is said to sleep always, during winter and summer, as do also his family, with the windows of their bedrooms widely opened. The testimony of the most able physicians of this and other countries ; the results of enquiries as to the prevalence of this disease amongst the picked men of the armies and navies of the world; the reports of hospitals for consumption, and of commissions and committees appointed to make special investigations as to jails, workhouses, and schools : all, in various degrees, point to this one conclusion. There are one or two apparent exceptions to this rule in Iceland and the Hebrides, which are worthy of attentive consideration. ^ We have evidently something to learn as to the effect of sea air, the air of high latitudes and elevated regions, on this disease. * "On the Nature and Yariations of Destructive Lung Disease, as seen amongst Soldiers, and the hygienic conditions under which they occur." + "Foul Air and Lung Disease." J " Consumption, as engendered by rebreathed air." § Vide Dr. Morgan, on the " Non prevalence of Phthisis in the Heb- rides and along the N.W. Coast of Scotland." — Brit, and Foreign Medico-Chirurgical Review, 1860, vol. xxvi. page 483. Controversy in Medical Periodicals, during 1868 and 1869, between Dr. MacCormack, Dr. Leared, Dr. HjalteLin, and others, as to whether Phthisis is or is not indigenous in Iceland. THE AIR OF OUE HOUSES. 243 Some animals that are kept for a long time in con- finement are affected in a manner similar to man. The monkeys of our Zoological Gardens are well known to die in great numbers from this disease. Dairy cows that are kept immured in close, ill-ventilated sheds in cities and towns also suffer from it.* As regards the connection between the other strumous diseases and overcrowding, abundant proof is to be found if looked for. Scrofula once prevailed to such an extent in the Asylum of the House of Industry, Dublin (so Carmichael affirms), that it was regarded as a contagious complaint. The air was so impure in consequence of the excessive overcrowding as to be unendurable when the wards were first opened in the morning, and to be " but little better " during the day- time. The communicable eye disease, so common in asylums and schools for children, is another of the legacies of our overcrowding. The injurious effects of rebreathed air, and the want of any provision for ven- tilation, is not only seen in the public schools for the poor, but in private schools for middle classes. I recently visited a " College for Young Ladies," which contained rooms 12 ft. X 9 ft. x 8 ft. high, where slept six girls, between the ages of 10 and 17, in two beds. Not a fireplace or other means of ventilation existed. This school, which was a popular one, had, like a concertina, a wonderful power of expansion — those who could not be accommodated with beds being stowed away on floors and in day rooms. That young women, at the most delicate period of their lives, should be thus injured by thoughtless parents, who care more * Vide Annates d'HygUne, vol. ii. page 447. 244 THE DELETEKIOUS EFFECTS ON HEALTH OF for cheap accomplisliments than a healthy frame, is a great evil. Every school should be under the super- vision of the Health Authority of the district in which it is situated, so that a guarantee may be afforded to the State that the young be not subjected to the cruelty of slow poisoning by foul air. The relation between such lung diseases as bron- chitis and pneumonia, and the unwholesome condition of the air of our dwellings, has not been sufficiently recognized by the medical profession and the public. One of the most common causes of an attack of bron- chitis is a sudden exposure of the bronchial mucous membrane to extreme conditions of air. A man who breathes for some hours the hot and dry vitiated air of an unventilated room is prone to be thus affected on passing out into cold damp night air. If debilitated from any cause, the inflammation may affect the sub- stance of the lung, and the man will have pneumonia. Eapid alternations of temperature and moisture are apt. to be attended with risk to health to those who have passed the period of youth during which the body quickly adapts itself to altered atmospheric conditions. The body, in the middle-aged and old, always experiences a difficulty in suddenly accommodating itself to extreme ranges of temperature. By substituting for the over- heated and impure air of our houses and public build- ings a pure wholesome air, of a temperature adapted to our sensations of comfort, by the establishment of an efficient system of ventilation, we shall avoid the danger of sudden and extreme changes which continually menaces those organs in which the blood and air meet. A Fellow of the Eoyal Society has recently publicly declared that there is not a perfectly healthy dwelling- THE AIR OF OUE HOUSES. 245 house in the country. Although that at first sight seems an exaggerated view, yet it is not far short of the truth. I only know of one room in this country one weii- in which there is any good ventilation, namely, the ^^^^"^^^^^ House of Commons. AU the patents that have ever country, yet been devised are worthless. Amongst the dozens useiessness of contrivances that are described and figured in F. niunberiess Edwards' book, entitled Ventilation and Seat, not popular ventilators. one fulfils the requirements of a good ventilator, namely, the constant passage into each room of pure air of a healthful degree of humidity — warmed in winter and cooled in summer, with an accompanying provision for the immediate removal of that which has been breathed, in such a manner that no draught is created. To intercept the fuliginous particles of the air by gauze curtains ; to pass the inflowing air through an atmosphere of spray ; to artifically warm it in winter, and cool it in summer with ice : all this preparation of the air can be carried out in public buildings like the Houses of Parliament, but such arrangements are quite impossible in the case of the majority of private houses. As regards cottages, the mere hint at such a project is absurd in the extreme. An American architect has expressed the opinion''^ that a building cannot be supplied with cool air of a pleasant degree of humidity when the external air is hot and damp, for the cooling would be attended by the condensation of the moisture, and the formation of a mist. This change cannot, I admit, be produced without a preparation of the air in underground cham- * " On tlie Eelation of Moisture in Air to Health and Comfort," by Eobert Briggs, C.E., in Quarterly Journal of Science. April 1878. ances. 246 THE DELETERIOUS EFFECTS ON HEALTH OF bers adapted for the purpose, such as are available beneath pubUc buildings or large houses. In the case of the majority of houses, air, when hot and moist, can be passed through a room with greater rapidity than usual, and the occupants will experience the cooling effects produced by the more frequent renewal of air. The establishment of a comfortable uniform loss of heat by the system is the point to be arrived at in our efforts to determine the requisite speed for the passage of the air. R6ieof Physicians are waiting for inventors to deal with ^ to 'excite this difficult subject of providing the habitations of the the demand people, poor as Well as rich, with some efficient and for efficient \ ^ , "^ ., . , , , . , , ventilating Simple vcntilatmg methods, remembermg the above m- contnv- dispensable requisites. There is no difficulty as regards public buildings, such as churches, meeting halls, con- cert rooms, theatres, baU rooms, etc. They can all be ventilated and lighted in the same manner as the House of Commons. An exposure of the body, and especially of that part of it named the pulmonary surface, to sud- den and extreme ranges of temperature, as in coming out into the cold air from a hot ill-ventilated church or other public building, should be regarded as attended with a certain amount of risk to aU, and a positive danger to the aged and weakly. The role to be played by the Medical Officer of Health and other sanitarians in the public interest, is to urge Local Boards of Health to refuse to pass the plans of houses in which there is no efficient provision for the removal of used-up air, as well as of other effete and noxious matters. When a great demand is in this way excited, a vigorous attempt will be made by those who devote their energies to the invention of con- I THE AIR OF OUR HOUSES. 247 trivances for our health and comfort to supply that want. The standard of pure air for our dwellings and for all places of public resort, which we should endeavour to reach, may be considered to be thus constituted : — Active Oxygen, Ozone, and other air purifiers, in recog- standard of nizable quantities. pure air. Organic Matter, as Alb. Ammonia, as near "08 milligram. per cubic metre as possible. Carbonic Acid — Not more than '06 per cent. Temperature to be determined by the sensations of the majority as to comfort.* Moisture — Eelative humidity 70 to 75 per cent. A difference between the dry and wet bulbs of about 5 or 6 degrees. To approach this standard as closely as possible should be the aim of all who study the construction of healthy homes for the people. The practical question arises — How are we to make an attempt to arrive at any point on the road to this standard amongst the cottages of the poor? The difficulties are enormous in many cases. In the rural districts, where the houses are surrounded generally by pure air, we insist on every inmate (age not considered) having at least 200 cubic feet of air by night. In * The temperature of comfort of air indoors has been variously stated : — 65° to 58° F. Hood's Treatise on Warming Buildings. 59° F. Peclet's Traite de la Chaleur. 56° to 62° F. Tredgold's Principles of Warming and Ventilation. 62° F. Box's Practical Treatise on Heat. 65° F. Eeed's Illustrations of the Theory and Practice of Ventilation. 48° to 60° F. Parkes' Mamual of Hygiene. 59° F. Nurseries and Schools ; 61° to 64 F. Hospitals ; 66° to 68° F. Theatres and Assembly Halls.— Morin's Etudes sur la Ventilation. 248 THE DELETEEIOUS EFFECTS ON HEALTH OF tramps' lodging-liouses 300 cubic feet of air in a sleep- ing-room, and 400 cubic feet in a room used for sleeping and as a day room, are the minimum quantities sanc- tioned by the Local Government Board. In towns, where the air is more or less impure, a larger quantity of air per individual should be insisted on. We should gradually aim at obtaining not only the largest amount of breathing space that is practicable, but some ef&cient provision for the change of air to the extent of from 2000 to 3000 cubic feet per hour, or about 10,000 gallons of air per head, per hour. How is this to be accomplished ? Happily, for the sake of ventilation, the majority of our cottages have an abundance of chinks and crevices that admit air from without. Fortunately, also, a considerable change of air is effected through the walls of our dwellings, if they are composed of brick, or mud, or tufacious limestone, or wood. Permeabiii- Profcssor Pettcnkofcr has, by experiments, shown '"" ty of walls. ' •' ^ ' that through a room made of brick walls, of the capacity of 2650 cubic feet, every crack and hole in which was thoroughly plugged up, 1060 cubic feet of fresh air passed per hour, by virtue of the difference of temperature (34° F.) between the outer (32° F.) and the inner (62° F.) air. He found that, with a difference of temperature of 9^° F. between the outside and the inside of a room, the spontaneous ventilation through each square yard of the free wall amounted to about 7 cubic feet, or 43 gallons per hour. Marker's and Schultze's experiments on the spon- taneous ventilation of stables confirm these observations. They discovered that with a difference of temperature * The Air, in relation to Clothing, Dwelling, and Soil. THE AIE OF OUE HOUSES. 249 of 9|-° F., the passage of air through each square yard of free wall was — With walls of Sandstone . 4*7 cubic feet per hour. „ „ Quarried Limestone 6 '5 „ , „ Brick . . 7-9 „ „ Tufacious Limestone 10*1 „ „ „ Mud . . 14-4 „ „ All the ordinary building materials, such as plaster, wood, cement, etc., are more or less porous, and admit the passage of air through them in such a manner that we are not conscious of the movement. We are in- sensible to the passage of air if the velocity of the same is less than 19 inches per second. It will, perhaps, be considered by some that to change the air of a cottage at the rate of between 2000 to 3000 cubic feet per hour per individual, at a velocity, to avoid draught, of less than 19 inches per second, is to supply an enormous and unnecessary amount of fresh air, and is, moreover, a thoroughly impracticable project. Frenchmen do not consider this amount excessive, if we may judge from the following table, given by Petten- kofer, of their demands as to change of air in their buildings per hour per person : — Hospitals for ordinary cases „ for wounded „ for epidemics . Prisons Workshops — ordinary „ unhealthy Barracks^ — day „ night . Theatres Large rooms for long meetings „ for shorter Schools for adults . „ for children Provided we keep our walls dry, for then we main- . 2120 — 2470 cubic feet. . 3530 }j . 5300 5J . 1766 J> . 2120 }> . 3530 55 . 1060 55 . 1410 — 1765 55 . 1410 — jj 55 s 2120 55 1060 55 880 — 1060 55 424 — 530 55 250 THE DELETEEIOUS EFFECTS ON HEALTH OF tain them in a porous condition, as moisture renders them impermeable, so long we can draw a very large quantity of air through our walls, with but little dif- ference of temperature between the inside and outside of the house, ventuation. If this spoutaucous Ventilation is supplemented by some simple contrivance, which cannot be interfered with, for admitting fresh air in so broken-up and divided a state as that its flow shall be unfelt by the occupants, all that can be done will have been accom- plished for the majority of our old isolated cottages in the coimtry districts, the repairs of which often consume the whole of the yearly rental. Pettenkofer rightly says, " It is a waste of ventilation if it is directed against avoidable pollutions of the air . . . the proper domain of ventilation begins when cleanliness has done its best." We ought not, however, to let matters rest here as regards the rows of cottages in our towns and cities, which have but Kttle free wall sur- face, and are often merely foul caves with no opening at the back to allow of the free passage of air. Thousands and thousands of these urban dwellings of the poor are caricatures of what cottage homes should be, namely, a healthful place for rest, refresh- ment, and cheerful intercourse after toil, and would be more truthfully designated human piggeries. Who is there amongst medical men that is not familiar with the appalling infanticide that prevails amongst these •districts which have been designated " Herodian," mainly due to the foul air (for young lives are the most sensitive tests of the existence of an infraction of sanitary laws), and partly, no doubt, to improper feeding and neglect. That noble appeal of Charles Dickens for legislation for the poor cannot but be remembered I THE AIR OF OUR HOUSES. 251 in thinking of this sad subject : " If those who rule the destinies of nations would but think how hard it is for the very poor to have engendered in their hearts that love of home from which all domestic virtues spring, when they live in dense and squalid masses, where social decency is lost, or rather never found, — if they would but turn aside from the wide thorough- fares, and great houses, and strive to improve the wretched dwellings in byeways, where only poverty may walk — many low roofs would point more truly to the sky than the loftiest steeple that now rears proudly up from the midst of guilt and crime and horrible disease, to mock them by its contrast.". What a picture is sketched of these dreadful places by Dr Buchanan, one of the travelling inspectors of the local government board ! " In small closed courts, surrounded by high buildings, and approached by narrow and perhaps winding gangways, houses of the meanest sort stand, acre after acre of them, with but privies and dust bins to look upon. And surely such cannot be accounted fit for human habitation, while the standard of that humanity is low. Nothing short of a tornado can effectually ventilate these courts ; in still weather the atmosphere in them is unchanged and unchangeable. Can it be a matter of surprise that such regions should be the favourite pastures or hunting-grounds of filth diseases, and that moral, as well as material deterioration should be invariable accompaniments ? It may be truly said of many evil things, that ' like goes to like.' Happily the Artizans' Dwellings Bill, alias the Eookeries Bill, has been passed, which aims at the demolition of these nests of disease and crime ; and which wiU, it is to be hoped, gradually diminish the most depraved and unhealthy modes of Life." 252 DETECTION OF IMPURITIES IN AIE. PAET II. THE DETECTION AND ESTIMATION OF THE AMOUNT OF THE MOST IMPORTANT IMPURITIES FOUND IN THE AIR. Two methods of discovering the condition of the air, as to purity, a direct and an indirect one, have been in vogue : the direct having for its object the detection and estimation of the quantity of impurities, such as the organic and other solid bodies, and the carbonic acid present in the air ; and the indirect one being to ascer- tain its departure from a state of purity by the estima- tion of the amount of ozone and other purifying agents which have not been used up by the organic matter and by the various noxious gases with which it is contaminated. SOLID BODIES IN THE AIR. 253 DIRECT METHOD. CHAPTEE XXV. MODES OF OBSERVING SOLID BODIES IN THE AIR, AND OF SEPARATING- THEM FOR EXAMINATION. As far back as 1830, Ehrenberg worked and pub- som bodies lished on this subject. He showed the actual existence ^"^ of an atmospheric kingdom of life, animal and vegetable. He was followed by M. Gaultier de Claubry, who passed air from various localities through water that had been exposed to a high temperature. During the cholera epidemic in England of 1849, the dust of air was much examined, in consequence of the supposed discovery of certain bodies termed cholera fungi in infected air. M. Quatrefages, Pouchet, Pasteur, IsT. Joly, and Charles Musset, Boussingault, Baudrimont, and Gigot, are foreigners who have all severally laboured at this subject from different points, the first five being especially interested in it in relation to spontaneous generation. Devergie examined the air in the vicinity of a case of hospital gangrene, and detected an enormous quantity of organic matter in it. Bits of wool, cotton, particles of hair, and epithelial cells and starch, were most common. 254 MODES OF OBSEEVING In the Army Medical Eeport for 1867, is an account of an experimental investigation made by Dr. F. de Chaumont into the ventilation of the new barracks at Chelsea. He passed 120 cubic feet of air through a freezing mixture, and 4' 7 c. c. of fluid condensed from it, which contained epithelium in large amount, hair and various fibres, sand, soot, crystalline substances, and chloride of sodium, together with sporangia of fungi, and monads in considerable quantity. In the air of a back yard of a London hospital he found con- siderable quantities of epithelium ; and in the " dirty linen area," where the foul linen was kept in crates until washed, pus globules and a quantity of fatty crystals apparently from dressings, bacteria both free and in the zooglseal form. In the Accident Ward of St. Mary's Hospital, Paddington, he discovered pus cells in the air near some beds which had a bad repu- tation for erysipelas.""'' The Army Medical Eeport for 1868 contains similar observations by Dr. E. T. Wright on the air of the barrack-room, Eoyal Victoria Hospital, Netley. In 1861 MM. Eiselt and Bechi published the result of some experiments. In the same year an investigation was undertaken on behalf of the Lancet on the dust of town houses in dry weather. The result of this enquiry showed that it consisted of pul- verised horse dung, and the grindings of shoe leather, and starch corpuscles. In 1862 Eeveil and Chalvet made some observa- tions on the air of the surgical wards of the hospital of St. Louis. * "Three Eeports on the Sanitary Condition of St. Mary's Hospi- tal, 1875-1876." SOLID BODIES IN THE AIR. 255 Dr. Jefferies Wyman and Dr. Salisbury were the earliest of American workers on atmospheric dust. Samuelson and Balbiani have also made experiments on this subject. Dr. Salisbury's observations especially related to the air of the low marshy valleys of the Ohio and Missis- sippi in connection with the causation of intermittent and remittent fevers.* M. Lemaire's researches, com- municated to the French Academy in 1863, partly related to marsh air in the neighbourhood of Sologne, which was a very malarious district. Selmi and Balestra have both made observations on the air of swamps, and both describe the presence of myriads of spores of algse. The experiments of the latter were made on the air of the Pontine marshes. A great many examinations were made of the dust of the air during the cattle plague epidemic of 1866. It was collected in most cases by passing it through cotton wool. In 1867, M. Poulet reported that he found a number of bacteria in the condensed vapour of the breath in whooping cough. Mr. Metcalfe Johnson describes f a method of col- lecting solid articles from the air by means of an " air sieve," which consisted of a glass plate in a small deal box, over which a stream of water trickled down and was collected in a trough beneath. A current of air was allowed to impinge on it. The subject of the great controversy as to the origin or the beginnings of life, with which the names of Pasteur and Pouchet, Tyndall and Bastian, have been for so long associated, from which great changes in surgery * American Journal of Medical Sciences, April 1866. + Monthly Microscopical Journal, vol. ii. p. 100. 256 MODES OF OBSERVING have flowed, especially under the leadership of Lister, must be strenuously avoided if this section is to be confined within its legitimate limits. If we permit ourselves to drift to the smallest degree into it, the indulgence of the gratification will be fatal to the con- ciseness and brevity requisite in this work. A rough-and-ready way of observing the dust of air is by admitting a ray of sunlight into a darkened room, when the " motes in the sunbeam," as the par- ticles of dust have been popularly called, are visible to us. Professor Profcssor Tyudall has employed the very powerful experi- beam of the electric light for the purpose of render- nients. jjjg ^j^g (j^g^ Qf ^jp more apparent, with which he associated the flame of a spirit lamp that created an appearance, when applied to the beam, of the ascent of dark wreaths of intensely black smoke. A large hy- drogen flame produced the same effect. The blackness proved to be due to the absence from the track of the beam of all matter capable of scattering its light, which had in fact been burnt. He said, in his lecture, de- livered in the Eoyal Institution at the end of 1869 or commencement of 1870 : — " Nobody can without repugnance place his mouth at the illuminated focus of the electric beam, and in- hale the dirt revealed there. ISTor is the disgust abolished by the reflection, that, although we do not see the nastiness, we are churning it in our lungs every hour and minute of our lives. If, after inspiring a quantity of common air, a long expiration is made through a glass tube across the electric beam, the lumi- nous track is at first uninterrupted. The breath im- presses on the floating matter a transverse motion, but SOLID BODIES IN THE AIE. 257 the dust from the lungs makes good the particles dis- placed. After a time, however, an obscure disc appears upon the beam, and at the end of expiration the beam is, as it were, pierced by an intensely black hole, in which no particles whatever can be discerned. The air in fact has lodged its dirt in the lungs. A handful of cotton wool placed over the nose and mouth during inspiration makes the dark hole in the beam of light appear from the beginning of expiration. A silk hand- kerchief '"" answers nearly as well." Mr. C. Tichborne communicated to the British Association, in 1870, an account of his experiments on the air of Dublin. Street dust, he said, was mainly composed of stable manure and triturated stones. The dust of New York has been examined by the ISTew York Officers of Health by exposing glass plates to the air. The same substances were present in all of the specimens; street dust, particles of sand and carbon, fibres of cotton, fragments of vegetable tissues, granules of starch, three different kinds of pollen grains, and fungal elements. The latter were abundant, ranging in character from a micrococcus to mycelial * The old-fashioned practice amongst the public, often witnessed by medical men, of holding a handkerchief to the mouth and nose on approaching the bedside of a person suffering from an infectious disease, may, in the light of recent investigations, have been a wise proceeding, and was doubtless intuitively arrived at and found by experience to be protective to the health. Sometimes scents were employed, not only in the handkerchief but in the sick-room (Vide " Perfumes and Ozone," in Ozone aoid Antozone, pages 121 and 122). People very commonly apply a handkerchief also to the nose and mouth when they come into contact with a stench, to prevent the offensive odour from annoying them. The linen or cotton fabric no doubt acts as an imperfect filter, which strains off the solid particles floating in the air, with which that unpleasant odour is associated. S 258 MODES OF OBSEKVING filaments. When water was added to the specimens, bacteria and vibriones invariably made their appearance within a few hours. Mr. Blackley '"'" has devoted his attention to that particular kind of air dust that produces hay fever, namely, the pollen of certain kinds of grasses, f A good account of the great variety of particles of which atmospheric dust is composed is contained in Charles Eobin's TraiU du Microscope. The space at my disposal will not permit me to enter on that very large field as to the presence of those organic substances in air which have in past times fallen in showers, giving rise to the belief that blood and sulphur have descended from heaven. I must refer my readers to a little book, named Odd Showers, which is published by Kerby and Son, of Oxford Street, for much interesting information as to these records. The observations of Messrs. Tichborne, Blackley, and others, would lead one to think that the spores of fungi and other light bodies are to be detected in the air at very great heights, and that they are conveyed by aerial currents and storms from one part of the earth to another over vast tracts of country. The air dust, such as we breathe, may be conveniently collected, for either microscopal or chemical examination, in several ways : — * Experimental Researches on the Causes and Nature of Catarrhus (Estivus, by C. H. Blackley, 1872. f He refers to one species, the pollen of which, is so small that it would require 37 millions to make a grain ; whilst 6 millions are re- quired of the particles of pollen of the English meadow grasses. He considers that 1760, or the 3427th part of a grain, is capable of pro- ducing the severest form of hay fever. SOLID BODIES IN THE AIR. 259 1, By means of Pouchet's aeroscope, '" which con- Pouehet's sists of a glass tube hermetically closed at either '*-^''°^'^<'p^- extremity by a copper ferule. The upper ferule was fixed to the glass, and was connected with a tube of copper, terminating externally in a small funnel, and internally in the inside of the glass tube, in a very finely drawn point, not more than '5 m, m. in diameter. The other ferule was removable, and allowed of the introduction of a circular glass plate into the interior of the instrument, which was placed at 1 m. m. from the point of the tube connected with the upper ferule. This plate was covered with adhesive matter ; and, if • necessary, the point of the tube was made to terminate in a minute perforated diaphragm like the rose of a watering pot, so as to secure the dispersion of the atmospheric particles over the surface of the plate. Dr. Maddox's "aeroconiscope" differed from Pouchet's Dr. aeroscope in the fact that a current of air was made to ^g^ttonf traverse it without the aid of an aspirator, as employed scope, by that observer. In Dr. Maddox's apparatus the movement of the air was secured by means of a vane, which, when the instrument was exposed to moving air, kept the mouth in the direction of the current, by causing the whole apparatus to rotate on the spindle that supported it. When, on the other hand, still air was to be examined, a current was ingeniously secured by means of a chimney conveying heated air from the flame of a spirit lamp. The apparatus employed by Dr. D. D. Cunningham, f * Moyen de rassembler dans xm espace infiniment petit tons les corpuscles normalement invisibles contenus dans un volume d'air determine. — Comptes Rendus, T. i. p. 748. + Microscopic Examination of Air, by Dr. D. D. Cunningbam, Surgeon, H. M. Indian Med. Service. Published by Government, 1874. 260 MODES OF OBSERVING Cunning- hain's apparatus. Fig. 11. in his numerous observations on atmosplieric dust, was an improvement on that with which Dr. Maddox's name has been coupled. It con- sisted of three thin brass tubes (A), two of which slipped over the third central one, and came into contact with the opposite sides of a projecting rim on its circumference. This rim was formed by the margin of a diaphragm, which divided the centre tube into two chambers. It was of sufficient thick- ness to allow of a spindle passing up through it (B). The latter terminated in a pointed extremity, which came in contact with the upper end of the bearing, and provided for the free rotation of the system of tubes. Eound the margins of the diaphragm there was a set of perforations to allow of the passage of air through it, and, on the centre of its anterior surface there was a square plate of brass, with a slightly projecting rim on its lower margin. The anterior of the two lateral tubes was provided with an expanded orifice, and contained a small, finely-pointed funnel in its interior ; the pointed extremity opening immediately in front of the centre of the diaphragm plate. The posterior tube was quite simple, and had a good-sized fish-tail vane fitted into a slit on its extremity. At each locality selected as a site, a stout teakwood post, about 4^ feet in height, was firmly fixed in the ground. A brass spindle. SOLID BODIES IN THE AIE. 261 fitting the bearing in the diaphragm of the apparatus, was screwed into the top of each of them, and served as an axis of rotation, securing the exposure of the expanded orifice to the prevailing currents of wind. Preparatory to taking any observations the appar- atus was well washed with spirits of wine, and heated over a spirit lamp. A microscope cover glass of suit- able size was then carefully cleaned, and one surface smeared with pure glycerine. A minute drop of the same medium was placed upon the diaphragm plate, and the dry surface of the cover glass applied to it, leaving the smeared surface exposed. The glycerine on the diaphragm secured the glass adherent in a vertical position, and obviated the necessity for a spring, the use of which was found inconvenient from its coming in the way, and interceptiag more or less of the atmospheric dust. The anterior tube was next slipped on, bringing the pointed extremity of the interior funnel imme- diately in front of the glass, and the whole apparatus was finally set on the spindle, where it remained during a period of 24 hours. The mouth of this apparatus, when in situ, was at a level of about 5 feet from the gTound. The stratum of air at this height is that breathed by a man when erect, and is there- fore likely to show the nature of the atmospheric par- ticles commonly entering the air passages. At the close of 24 hours the instrument was taken down, the anterior tube removed, and the cover glass transferred to a clean slide, a little fresh glycerine being added if necessary. The magnifying power employed was one of 400 diameters, but whenever necessary in the exami- nation of specimens, such as minute fungoid cellules or bacteroid bodies, this was replaced by others ranging from 800 to 1000 diameters. 262 MODES OF OBSEEVING The great objection to the three foregoing varieties of the same method, is, that it is difficult to obtain glycerine perfectly free from foreign bodies. 2. A glass tube is heated to redness, and, when it has cooled, is surrounded by a freezing mixture. Air is then drawn by an aspirator through the tube. The great cold condenses the moisture of the air, and arrests its solid particles, which is in both cases col- lected and examined for nitrogenized compounds. 3. Dr. Watson employs fine glass threads, soaked in glycerine or powdered glass, as traps for catching the solid substances, which he afterwards washes with pure water. Perhaps the substance known as glass wool would prove a still more effectual air filter. 4. I use a mineral named asbestos, which is a fibrous and woolly substance, composed of a silicate and aluminate of magnesia and lime, for arresting the dust of the air. A U-shaped platinum tube about ^ inch in diameter, and 7 inches long, having been filled at the bend with this inorganic wool, and Kttle caps of fine platinum gauze being inserted at each end of the asbestos to prevent the loss of any of its particles, a known volume of air is drawn through the tube by means of an aspirator. The tube loaded with asbestos is weighed in a delicate balance, both before and after the air is passed through it. The increase in weight, after the experiment, of course indicates the amount of solid particles contained in the quantity of air drawn through the tube by the aspirator. The platinum tube is then exposed to the flame of a Bunsen's burner, in which it soon becomes red hot. When all the volatile solid bodies, such as organic matter, nitrates, etc., have been burnt off, the tube having been again weighed is ready for a fresh experiment. SOLID BODIES IN THE AIK. 263 5. By taking the rain, which is the great air washer, and removing, by means of a pipette, the solid particles that subside in it after a few hours' rest. 6. M. Pasteur filtered a certain quantity of air through perfectly pure pyroxyline (free from any residue insoluble in alcohol and ether), which is soluble in a mixture of strong alcohol and ether. A tube contain- ing a plug of this material was attached to a water aspirator, from the exit portion of which the amount of air drawn by the instrument per minute, can be easily collected and measured. The cotton plug, on removal, was treated with its solvents, and the dust then allowed to subside. The complete removal of the pyroxyline was effected by adding, and after a time removing, fresh quantities of alcohol and ether. The dust is then transferred to the microscope slide for examination. 7. M. Mari^-Davy of the Montsouris Observatory collected the dust of the air in a receiver which was connected with an aspirator such as is represented in figure 12. The receiver was composed of a bell glass, the roughened lower edge of the large opening of which rests on a piece of plate glass also roughened. The upper and small opening is closed by a cork, which is perforated by two glass tubes : one of them, marked c, is connected with the as- pirator ; the other, h, terminates at one ex- Fig 12. tremity in the air, and at the opposite, within the bell glass, in a tapered point, a short distance from a glass plate covered with glycerine or syrup. 264 mCKOSCOPICAL EXAillNATION OF CHAPTEE XXVI. MICEOSCOPICAL EXAMESTATION OF THE DUST OF THE AIE. Dust derived The air contaiiis such an immense variety of substan- ve°^tab™^ ' ces in the form of dust, invisible to the naked eye, that and mineral their bare enumeration, without enterino; into any de- kingdoms. . . „ , ' ^ °. ^ , , "^ scription 01 them, would occupy a considerable space. Minute particles of anything and everything that exists on the earth, are liable to be mingled with the air that rests on it. As this air, in which we are always plunged, invariably contains more or less of these minute objects, our bodies '" are naturally invaded by the same. These suspended matters are furnished by the animal, vegetable, and mineral kingdoms. From the animal kingdom is derived the debris of little creatures who have been born and have lived and died in the atmosphere, germs and small eggs. From the vegetable kingdom, spores of fungi, the pollen of plants and seeds of all kinds, particles of finely pulverized straw, minute fragments of rags, etc., are obtained. From the soil, dust of inorganic composition, such as sand, oxide of iron, lime, etc. ; from volcanoes, sand and mud, and small particles of carbon ; from the sea, * M. Lemaire finds not only in the air that passes from the lungs, but also in the perspiratory fluid, abundant indications of animal and vegetable life. — Comptes Bendus, October 14th, 1867. THE DUST OF THE AIE. 265 chloride of sodium which is lifted by the spray and conveyed by the wind vast distances : — are contributed. It is with the dust and impurities in the air, created by man and animals, and by vegetation, in which we are at present most interested, as they relate more especially to public health. Excluding, then, a consideration of the solid particles diffused through the air in manufactories, and mines, to the injurious influ- ence of which so many of our fellow- creatures are un- happily exposed, let us ask ourselves the question " What appearances do the minute solid impurities contained in the air of our dwellings and public build- ings, and of our streets, present under the microscope?" Air dust has been divided into the light, which floats and is wafted about by currents, and the heavier par- ticles that settle. The dust of our houses consists largely of light organic matter, either living or dead, whilst that of public buildings would appear to con- tain a larger proportion of the heavier kinds. Dr. Percy found that the dust on the walls of the British Dust of the Museum consisted of 5 per cent of incombustible ^^^^^ matter. The principal objects which we see in the dust of rooms and hospitals with high powers are little por- tions of (1) scaly epithelium (the dust of the skin), (2) particles of soot, (3) small round and oval cells, which, when multiplying, have an appearance Kke the number 8. These little bodies have been named '' putrefaction cells," and by some microzymes, and have been described by Trautman, Lemaire, and B^champ. Their growth is accelerated by hydrogen sulphide and other vile smelling gases, and is arrested by carbolic acid which is one of our most valuable dis- infectants. 266 MICROSCOPICAL EXAMINATION OF Lemaire found tliem in immense quantities in the air of dirty prison cells. They belong to that border land which is midway between the animal and vege- table kingdoms. We know not whether they are ani- mals or vegetables. They bear a strong resemblance to certain kinds of bacteria found in impure water. These organic impurities in air are favourite pastures for the growth and development of the animal poisons that pro- duce the zymotic diseases, such as typhoid fever, scarlet fever, etc. The poisons of these diseases rejoice and luxuriate in filth of all kinds, especially in filthy air. The air of sick rooms and hospitals that are not ventilated efiiciently, is loaded with organic impurities, which, in certain diseases, furnish different odours, — for example, a medical man usually recognizes the pre- sence of small-pox or rheumatic fever in a house by The organic their characteristic odours. The smell of a room f^mfehed by occupicd by a person who is suffering from abscesses different is almost distinctive of this class of malady. In iseases. gniallpox wards minute scales and dust of dried pus- tules, which, if introduced into the system of one unprotected by vaccination, would reproduce the disease, are found floating in the air. In hospitals devoted to skin diseases, that contain patients suf- fering from favus, ringworm, etc., which depend on the growth in the skin of little parasitic plants or fungi, the spores or seeds of these plants may be found suspended in the air. The air of the streets and gardens of our towns and cities contains soot, crystals of certain salts, starch granules, linen, cotton and wool fibres, bits of wood, and particles of food, the hairs of man and animals (dogs and cats). THE DUST OF THE AIK. 267 The organized particles contained in the dust col- lected in Paris by M. Pasteur ° ^ ® in the manner described on page 1^ " ^ 263, having been well washed ^ © * and treated with a drop of a solu- 8 * ^ tion of potash, presented, under o ^ the microscope, the appearance © © represented in fig. 13. ^^^- ^^- The size and shape and gene- ral appearance of these organized corpuscles show ex- treme variety. They range in dimensions from a size infinitesimal to bodies having a diameter of "Ol to •015 millimetre or more. After a series of fine spring days Pasteur exposed a plug of pyroxyline for twenty-four hours to a current of air passing at the rate of a litre a minute, and found myriads of organized bodies. His pyroxyline Fig. 14. Fig. 15. Dust collected on June 25-26, 1860. Dust collected during an intense fog in February 1861. filter extracted the organized and amorphous particles depicted in figs. 14 and 15 on the days specified, which were moistened with sulphuric acid, that dis- solves starch but does not affect the spores of fungi. The character of the dust of the air that is found between the pure air of the country and the impure 268 MICEOSCOPICAL EXAMINATION OF air of a large city has been well observed by M. Marie - Davy and bis associates at the Montsouris Observatory, in the neighbourhood of Paris. Dust furnished by 582 litres of air on September 29th, 1875, after the air had undergone purification by rain during the preceding day, x 1000 : — Fig. 16. DESCRIPTION OF PLATE OF MICROSCOPIC OBJECTS FOUND IN AIR. 1. PoUen. 2. Fungi 3a. Starch granules. 36. Starch granules polarized. 4. Protocoecus pluvialis. 5. Epithelium. 6. Vegetable spores. 7. Spores? 8.f,Fungi ? 9. Particles of soot. 10. Crystals of chloride of sodium. 11. Crystals of chloride of ammonium ? 12. Crystals of sulphate of soda. 13. Mineral particles. 14. Desmids ? SOLID BODIES IN AIR _ THE DUST OF THE AIR. 269 "The majority of the bodies appear to be the spores of cryptogams with a few grains of starch, which iodine coloured blue." Bodies collected on glycerine from December 30, 1875, to January 2, 1876, x 1000 : — Fig. ir. 1 and 2, Pollen ; 3, Starch ; 4, Three of these reddish black bodies were attracted by the magnet, and are granules of meteoric iron, which have been de- scribed by M. Tissandier. The 4th is a spore, as it is uninfluenced by dilute sulphuric acid. 270 MICROSCOPICAL EXAMINATION OF Dust furnished by the air during the month of February 1876, collected on glycerine: — Fig. 18. " The quantity of the colourless bodies, No. 9, which were only seen by the aid of an immersion lens, was enormous. They consist probably of zoospores and germs of infusoria." From February 11 to 16 a large number of the filiform sporules, No. 11, were noticed. Dr. Cunningham has made a vast number of drawings of solid bodies found by him in the air, by the aid of his apparatus described and figured on THE DUST OF THE AIE. 271 page 260. Here are some representative speci- mens : — Fis. 19. M. Pasteur suggests tlie institution of comparisons between the kind and quantity of organized corpuscles disseminated in the air at one place during the several seasons of the year before and after rain^ etc., and at different places at the same time, with the object of increasing our knowledge of the zymotic diseases, especially when epidemics are prevalent. He found in the winter months, during a period of very low temperature, ranging from 15-8° to 6 '8° F., that a very small number of germs could be collected from the air. 272 CHEMICAL EXAMINATION OF AIE. CHAPTEE XXVII. THE CHEMICAL EXAMINATION OF AIE. Chemical The description of the modus operandi in making analysis of sanitary estimates of the degree of impurity or purity air. of the air must necessarily be restricted to those bodies which are the principal and universally observed in- jurious agents, to the exclusion of others, such as sulphuric and hydrochloric acids, arsenic, etc., that are the local and special products of certain manufacturing industries. Organic matter and carbonic acid stand prominently forward beyond all others as the bodies which require our attention : the former because it is, if in excess, the pabulum on which animal poisons feed, amongst which they increase, and through the medium of which they spread ; the latter because, whilst itself being noxious if in any large amount, it is nearly always in bad company. Dr. A. Carpenter, in his Lectures on Preventive Medicine and Fuhlic Health, writes : " Wherever you have excess of carbonic acid from the action of animal life, there you have also an excess of other debris, such as the organic matters which pass off from the respiratory organs ; septic matters given off from the pulmonary membrane, very manifest in some diseases to the sense of smell; impure matters in the insensible perspiration ; ammoniacal CHEMICAL EXAMINATION OF AIR. 273 compounds from retrocedent decompositions — all of which are the most injurious of such impurities." The presence of sulphurous acid from the combus- tion of coal in an overcrowded city, and free chlorine in the air of a manufacturing centre, may certainly tend to purify to some extent the atmosphere, which is so heavily laden with animal emanations. As the existence in air of an excess of organic matter keeps the oxygen, or its active form ozone, low, for it is always being used up in oxydizing it, so the presence of such objectionable intruders as sulphur or chlorine compounds, takes the place of this vitalizing gas. The purification of air by disinfectants after defilement reminds one of the purifi- cation of the water supply of a town that receives sewage by filtration — an unwise, and, at the best, an imperfect proceeding, and, moreover, a great waste of power. Far better and wiser is it to keep both these media pure, rather than, after permitting them to become impure, to then expend force (money) in en- deavouring to restore them to a state of purity. Dr. Ballard, and other eminent men, have been diligently collecting information as to the fearful pollu- tion of air that is unceasingly proceeding, and valuable materials have been and are now being brought together for consideration by the Eoyal Commission that has been deputed to investigate the subject of air pollution. The aid that such a Commission requires before a recommendatory report can be issued as a basis of any legislation, is partly that which scientific chemists and partly that which medical officers of health should be able to furnish. The scientific chemist must be in a position to represent on paper, in the form of figures, the differences in the degree of impurity of various kinds of polluted air. This first step towards the T 274 CHEMICAL EXAMINATION OF AIR. definite and precise having been gained, it then devolves on the health officer to clearly lay down, with exacti- tude, the connection that exists between these degrees of impurity and certain forms of disease or ill health. If the scientific chemist and medical officer of health can push our knowledge so far as to be able to prove to demonstration that, if the human body is persistently exposed to air contaminated by a polluting agent to a degree represented by a certain figure, it will be, in the majority of instances, injuriously affected, then the Legislature will have some basis on which to work. A Grovernment would, whether in accordance or not with its own wish, be compelled to act consistently with the principles of past sanitary legislation, the burden of which is that a man shall do nothing which is injurious to the health of his neighbour or to the public welfare. Those enlightened and humane men who govern cannot avoid deploring, as do the governed, that great manufactories that defile the air exist, which sustain in their vicinity hundreds and thousands of work-people, whose vital energies are lowered (thus rendering them a more ready prey to disease), and whose offspring are stunted and depraved by the medium which the industry that supports them is always and needlessly rendering unwholesome. A. — Organic Matter. Organic Organic matter which is given off from the skins and matter. ^ . ,^ lungs of all animals, and gives that peculiar, indescrib- able odour noticeable in ill-ventilated bed-rooms occu- pied by many or by dirty people, is very easily detected in the air, but there has always been a considerable difficulty in estimating its amount, by reason of the CHEMICAL EXAMINATION OF AIE. 275 interference of other substances contained in air, which is a mixture of so many different extraneous bodies. Of the chemical composition of organic emanations we know very little. Dr. Odling found that the vapours arising from sewage were of a carbo-ammoniacal nature, similar to such bodies as methylamine, or tri- methylamine and ethylamine. Beyond this point there is nothing but a terra incognita as to this very in- teresting subject. One of the first processes adopted for the estimation Permangan- of the amount of organic matter was to expose a solution Method, of permanganate of potash to the air, as the oxygen of the salt has a powerful oxydizing effect on organic matters. A burette was fiUed with a very weak solution, and an attempt was then made to ascertain how much of it was necessary to drop into a bottle of a certain capacity, before it arrived at the point when it was no longer c^ecolorized by the air of the bottle. The amount ne- cessary to reach this point having been found, it was a matter of easy calculation to ascertain how much of the permanganate of potash salt was expended. Another plan was the following : — The test solution is placed in a bottle of known size, attached to an aspirator, and is violently shaken with the air in the bottle. This air having been washed, the bottle is re- filled by the aspirator, and a fresh quantity of air is washed, etc., the object being to discover how much of any given sample of air is necessary to ^gcolorize the pink solution. It will be seen that in both modes of applying this permanganate of potash test the object is the same, namely, to remove the pink colour of a solu- tion of known strength by a known quantity of air shaken with it. It was ascertained, however, that the nitrous acid often present in the purest air ; that the 276 CHEMICAL EXAMINATION OF AIR. sulphurous acid, which is very abundant, and the hydrogen sulphide gas, which is generally found in minute quantities, in town air ; and the chlorine com- pounds, which often exist in the air of our manufac- turing cities : — also decolorize permanganate of potash. This process, therefore, never unquestionably proves the presence of any organic matter, but merely indicates the relative quantities of oxidizable matter contained in different samples of air. Better modes have since been devised, having for their object the conversion of the organic matter of air into ammonia, the amount of which can easily be calculated. Water is prepared of great purity by distilling it twice in perfectly clean vessels. A definite quantity, generally 50 c. c, is placed in a Win- chester quart bottle, or any other of known capacity. A little bel- lows, ■^''" the capacity of which is ascertained, with a vulcanized india- rubber tube, is employed for pumping fresh sup- Fig. 20. Dr. A. Smith's latest method of air-washing. A. Small hand-bellows, with India-ruhber -. . r • " ^- +V. T^ 4- tube attached. It possesses a valve at P^ISS 01 air lUtO tUC DOt- one extremity, which admits air when ^]^g q^ fgj. withdrawing air is pumped into a vessel. If it is ' . . wished to withdraw air from a vessel the air Contained 111 the this aperture is closed by a large cork, "bottle, SO that fresh air B. A Winchester quart bottle. ' may rush in and take its place. (Fig. 20.) * Mine was procured at a surgical instrument maker's, such as is employed for inflating air beds. CHEMICAL EXAMINATION OF AIE. 277 The bottle and bellows are taken to the place, the air of which it is proposed to analyze, and the washing of the air is proceeded with by blowing air thrice into, or sucking air three times out of, the bottle, replacing the stopper, and violently shaking the bottle. This performance has to be repeated 100 times, and is, as may be supposed, sufficiently laborious. In order to refill the bottle with air, an air-pump is sometimes used until the required point is obtained on a mercury gauge, this being found to indicate a known amount of air, which is then allowed to enter in order that it may be washed. Some few, such as Dr. Angus Smith, have gone through a series of these air-wash- ings, and the results arrived at have been found satisfactory. The cumbrousness of the apparatus, and the labour involved, have been great obstacles to the general adoption of this process. Mr. A. Moss' experiments on the nitrogenous organic matter in air, referred to on page 195, were made by passing a certain quantity of air, by means of " an accurately graduated aspirator," through four wash bottles, each being of a capacity of 1 c. c, and each containing 5 c. c. of pure distilled water. In the first bottle of the series, 50 c. c. of pure hydrochloric acid was also poured. The air-washings are, in either case, distilled with the caustic potash and permanganate of potash so- lution, and the distillates are treated with IsTessler re-agent. Although all the organic nitrogen of the air is not in this manner converted into ammonia, that which is most easily decomposed, such as is theoreti- cally capable of producing disease, is secured. A fourth method, which has been suggested as 278 CHEMICAL EXAMINATION OF AIK. applicable to the detection and estimation of atmos- pheric impurities, is to pass a known quantity of air by means of a swivel aspirator, graduated into cubic centimetres or cubic inches, through distilled water to catch the organic matter, and through standard solutions of nitrate of silver and chloride of barium, to retain respectively the chlorine and sulphur compounds. This plan is perfectly useless, for the amounts of these bodies secured in this way are too small for estimation. If success is to be achieved in air analysis, it is absolutely essential that a very large quantity of air be washed in a very small quantity of water, so large indeed, as to be able to obtain results which are alto- gether beyond the reach of being affected by the expe- rimental errors that are inseparable from all delicate analytical operations. A fifth method, already mentioned as adopted for extracting the solid particles contained in air for microscopical examination, consists in drawing a measured quantity of air by means of an aspirator through a clean curved tube (which has been previously heated and cooled), surrounded by a freezing mixture. The moisture contained in the air is condensed, and with it much of the organic matter. The tube is then washed out with -pure water and the washings are analyzed. The elaborate series of analytical observations on the impurity of air that have been in progress for some time at the Montsouris Observatory, near Paris, under the superintendence of M. Mari^-Davy, and the valu- able analytical work on the air of Glasgow, that is now at the present time carried out by Mr. Dixon, B. Sc, with the co-operation of the medical ofi&cer of health. CHEMICAL EXAMINATION OF AIK. 279 are the most complete and perfect that have yet been attempted on a large scale. The arrangements of the latter gentleman are in many respects precisely the same as those conducted by M.Mari^-Davy,with some improvements that he has, through the light of English methods of analysis, made. The apparatus which is used at the Montsouris Observatory, not only for the estimation of the amount of organic matter, but of that of carbonic acid, ozone, etc., consists essentially of two distinct parts, one being a pump or aspirator, of a peculiar construction, which draws a known quantity of the air operated upon through a certain solution, and the other being an arrangement for holding the absorbing solution and exposing it fully to the influence of the air. The aspirator is composed of a glass tube, about 2 cen- timetres in diameter, and 1 centimetres long. This tube is tapered at its lower ex- tremity, which is connected '^' with a vertical india-rubber or glass tube B, about 5 millimetres in diameter and 2 or 3 metres in length. 280 CHEMICAL EXAMINATION OF AIR. The glass tube A is closed at its upper extremity by a cork, through which two tubes D and C pass. The tube D communicates with a water service pipe ; a stopcock at the junction serves to regulate the flow of liquid which, running into A, descends through the ringed portion (b) of the tube B, carrying bubbles of air derived from the tube C, similar in appearance to the manner in which the mercury of a Sprengel's pump draws the air. (Fig. 21.) The water and air both enter the displacement gauge E, where they separate. The water flows away by the curved spout F, and the air escapes by the tube G, which terminates in an air meter that measures its volume. The " aspiration pipe," C, is attached to the set of absorbents intended to remove the body to be collected from the air. Where, in other analy- tical experiments, a larger quantity of air is required, the observers at Montsouris combine together 8 of these twisted tubes, arranging them in a parallel manner — Vide fig. 24. This more powerful aspirator delivers 80 litres of water and 200 litres of air per hour. A set of absorb- ents consists of two or more elements, each element being thus formed : A straight tube of platinum, 1 centimetre in diameter, and 14 or 15 centimetres in length, open at its upper end, is dilated at its lower extremity, where it is closed by an arrangement re- sembling the rose of a watering can, pierced in its centre by 5 or 6 holes of | millimetre in diameter, to facilitate the washing of the tube. At the upper part of the rose the enlarged portion of the tube is perforated with 20 holes of -§- of a millimetre in diameter, dis- posed in two circular rows. This tube is arranged in the axis of a deep cylindrical glass, about 4 centimetres CHEMICAL EXAMINATION OF AIE. 281 Fig. 22. A Set of Absorbents. a a. Platinum tubes with in diameter, and 11 or 12 centimetres in depth. Here it is retained in position by a gutta-percha cork, which is also traversed by a bent glass tube of a diameter of 1 centimetre. If we place some water in the glass and draw air through the bent tube, air will enter the pla- tinum tube and escape through the liquid in the form of numer- ous fine bubbles — Vide fig. 22. When the amount of organic matter in the air is sought to be determined, M. Mari^-Davy and his assistants roses at their extremities. -I r\ r\ 1 • T hbh. Absorbing solutions. pass 100 cubic metres = about cc. india-rubber tube connec- 35311 cubic feet of air, through "°'''- distilled water, and examine it by the permanganate process. The ammonia in the air is determined at this ob- servatory in a manner which will not be imitated in this country, where we employ so universally the Nessler test. A vessel of two litres capacity, fitted at its base with a tapered glass tube, and filled with distilled water, is fixed at a certain distance above the terrace of the staircase. This quantity of water escaping from the jet in exceedingly minute drops, and descending through 4 metres of air, furnishes about 1 litre of this " artificial rain," which is collected, mixed with lime water and distilled. The product of distillation is then treated with a definite quantity of a standard diluted sulphuric acid, is concentrated by evaporation, and at length rendered neutral by a standard solution 282 CHEMICAL EXAMINATION OF AIE. Air examiDa- tions at Glasgow. of ammonia, which determines the remaining amount of acid. The difference between the amount of acid employed in the first instance, and that found by the standard solution of ammonia to have been unacted upon, furnishes the ammonia contained in the collected water. The quantity of ammonia in 1 cubic metres of air at the time of the experiment is ascertained by the help of a table prepared by M. Schlcesing, in which the relation between the amount of ammonia detected in the analysis, and the weight of ammonia present in a litre of water " en equilibre ammoniacal avec I'air " is shown. In Glasgow, which is well known to be a city of smoke and manufactories, 6 or 7 stations have been established in its various parts, and one has been organised in pure air at Eaglesham, which is 12 miles distant ; at all of which the amount of ammonia and albuminoid ammonia, carbonic acid, sulphuric acid, and chlorine, coupled with certain meteorological phenomena, such as rainfall, temperature, etc., are observed. Every station in the city is provided with (1) sets of " absorbents," each " set " being furnished with a distinct solution containing glass Mi^ beads, adapted to withdraw one of the above named substances from the current of air that passes through it ; (2) a water injec- tion aspirator — Vide, fig. 23 ; (3) a gas meter to measure the amount of air passing through the aspirator ; and (4) a water-gauge to keep the aspirators at all the stations as nearly as possible at one and the same speed. A set of absorbents for ammonia and albuminoid ammonia, which are estimated together as Kg. 23. CHEMICAL EXAMINATION OF AIR. 283 ammonia, is thus prepared. The glasses having been thoroughly washed, about three ounces of glass beads {vide Fig. 22) and some twice distilled water are placed in each. They are allowed to remain in the water for a short time in order that any impurities adhering to the beads may be removed by the water. The distilled water having been poured off, 10 c. c. of diluted sulphuric acid, and 70 c. c. of distilled water, free from ammonia, are introduced in the following proportions : — Dilute Sulphuric Acid. Distilled Water. Glass. 5 c. c. 3 c. c. 2 c. c. 30 c. c. in 30 c. c. 10 c. c. No. 1 2 „ 3 The roses being inserted, the set of absorbents is attached to an aspirator for 48 hours, in which space of time about 200 cubic feet of air are passed through this dilute sulphuric acid. At the end of this time the contents of the glasses, beads included, are poured into a copper flask made out of a very large ball cock, into which 1 5 c. c. of a solution of carbonate of potash (240 grammes in a litre of distilled water) has been previously poured. The washings with twice distilled water of the glasses and tubes are added, so as alto- gether to just exceed | litre. The copper flask is then attached to a condenser, and distillation is performed exactly as has been described on pages 38 and 40, in the analysis of water, the first i litre yielding the ammonia and the remaining i litre, after the addition of 50 c. c. of the caustic potash and permanganate of potash solution, furnishing the albuminoid ammonia ; the amount in each case being estimated by a standard ammonia solution precisely as has been there indicated. 284 CHEMICAL EXAMINATION OF AIE. Fig. 24. I am not aware that beads are employed at the Montsouris Observatory for min- utely subdividing the streams of air. This addition has been made, I be- lieve, by Mr. Dixon — Vide fig. 22. And to it is partly, in all probability, to be ascribed the higher results which he obtains. At the station at Eaglesham he uses an aspirator formed of a com- bination of twisted tubes, the inter- nal orifice of each having a slit. — Vide fig. 24, There are a great variety of aspirators, and it is difficult to de- cide as to which is the best form. Some are more adapted for certain purposes than for others. Descrip- tions and sketches of many of the most favourite kinds are to be found in Ozone and Antozone, pages 2 5 to 2 5 9. It is not my intention to give a description of the mode of carrying out these valuable determinations. Mr. Dixon will soon himself furnish the scientific world with a fuU and complete account of the whole process, and the exceedingly interesting results which he has obtained after the expenditure of a wonderful amount of toil and ingenuity. There would seem to be some divergence in the results as derived by the bellows pump and shaking (described on page 277) when compared with those procured by aspiration with rose-ended tubes.* * Proc. of Eoyal Society, Dec. 13, 1877. CHEMICAL EXAMINATION OF AIR. 285 Manchester, Dec. 2, 1876, dull, damp morning . Ditto, Dec. 4, raining By Shaking. Aspiration, 3 bottles. Milligramme in 1 Cubic Metre of Air. Free Ammonia. •093 Alb. Ammonia. •160 •159 Free Ammonia. •070 Alb. Ammonia. •053 •124 The organic matter has been obtained for examina- Mr. a. h. tion from air, by collecting the moisture that is seen to attach itself to the walls and windows of crowded ill- ventilated halls, which has been condensed by the cold air outside. Mr. A. H. Smee '"" employs a glass funnel drawn to a point, and filled with fragments of ice. The aqueous vapour in the air is deposited as a dew on the sides of the funnel, which runs down and is received in a vessel underneath. This air moisture, in whatever way procured, is examined for nitrogenous compounds. The process, which will now be described, is pre- ferred by me to all that have yet been adverted to : — 1. Because it is the most rapid and reliable one puivenza that has been devised. 2. Because the air-washing apparatus required is portable, and can be readily carried in the hand by any one in a small box. * Soc. Science Transactions, 1875, page 486. Fig. 25. tion of water Method. 286 CHEMICAL EXAMINATION OF AIR. It consists in "bringing continually fresh quantities of air into intimate contact with a small quantity of very pure water, which is reduced to a minute state of subdivision by pulverization. The tools required are the following : — 1. A glass cylinder about 7-|- or 8 inches long, Fig. 26. A. Cylinder. B B. Wash-bottles. C. Black india-rubber ball pump. D. Black india-rubber J oz. ball, to ■which a glass tube, tapered to a fine point, is attached. E. Black india-rubber cork, through which passes the air pipe of a Bergson's spray producer and a straight glass tube, one end of which stoppers into a wash- bottle. F. Level of fluid in cylinder. and 2 inches in diameter, furnished with a large black india-rubber stopper perforated with two holes, into one of which the air-pipe of a Bergson's spray pro- ducer is fitted, the other being intended for the passage of a straight glass tube about 12 inches inch in diameter. long and i CHEMICAL EXAMINATION OF AIK. 287 2. Two stoppered WouKe's wash-bottles, of a ca- pacity of about 130 c. c. ISTo corks should be employed for connections. The tubes are stoppered into the necks of the wash- bottles. 3. A stoppered flask, of the capacity of 100 c. c, with a mark at about 70 c. c. 4. A black i oz. india-rubber ball, to which a glass tube, drawn to a fine point at its extremity, is fitted. The point is protected by a cap formed of an inch of the smallest black india-rubber tubing, sealed at one end. The steps of the process are as follows : — The several parts of the apparatus having been thoroughly cleansed in the laboratory with twice-dis- tilled water, which gives no colour whatever with JSTessler test, by the aid of the ball injection tube, the several parts are securely attached to one another. The cylinder with its spray producer, the wash-bottles, the ball pump, and flask filled up to the 70 c. c. mark with twice-distilled water, are packed in a small practically air-tight box, and conveyed to the place, be it a public building or a private dwelling-house, or some marsh land, where it is intended to make an air- washing. Pour a little of the 70 c. c. of the distilled water contained in the flask into the glass cylinder, so that when inverted its level may be just below the jets of the spray tubes. The remainder of the 70 c. c. is poured in about equal proportions into the two wash- bottles. Air should then be pumped into the glass cylinder 288 CHEMICAL EXAiMENATIOX OF AIR. SO as to produce in its interior a fine spray or mist by means of the india-rubber pump, the capacity of which should have been previously ascertained by the help of an air or gas meter. The greater part of the spray returns to the water at the bottom of the cylin- der to be reconverted into spray with fresh portions of air, but a small quantity passes down'rt'ards through the straight tube into wash-bottle Xo. 1, and a still smaller portion reaches wash-bottle Xo. 2. At the exit tube of the latter no spray can be perceived. The india- rubber pump which I employ delivers 3 "2 cubic inches of air every time its sides are approximated by the pressure of the hand, so that if it is emptied 540 times, an operation which altogether consumes about 1- of an hour, one cubic foot of air is injected into the glass cylinder. At the termination of the stage of air- washing, the distilled water in the cylinder and in the wash-bottles should be immediately poured back into the flask, and the apparatus having been restored to the box is returned to the laboratory; where the interior of the cylinder, and wash-bottles, and glass tubes, should be at once washed out, by the aid of the ball injection tube, with twice-distilled water. The great point to be aimed at is to wash the several parts of the apparatus most thoroughly with as little distilled water as possible, as if indeed this fluid was most costly. The washing of the apparatus can efficiently be accomphshed with 30 c. c, which should be poured also into the flask, thus filling it up to its 100 c. c. mark. The mere washing of the apparatus with distilled water both before and after the operation is sufficient to heighten the experimental error, which is insepar- CHEMICAL EXAMINATION OF AIE. 289 able from all these delicate experiments. Accordingly, it is necessary to know the average amount of nitro- genous matter, whether in the form of ammonia or albuminoid ammonia, which is present in the air in which these cleansings are made. If we know the average experimental error which occurs when blank experiments are made in our laboratory, there is nothing easier than to make the necessary deduction from the results furnished by an air- washing. The average experimental error of manipulation when the preliminary and terminal cleansings of the apparatus are made in my laboratory is about '006 of albuminoid ammonia for a cubic foot of air, a quantity which is consequently always deducted by me from any result obtained from an air analysis. The contents of the flask, namely, the air washings and the cleansings of the cylinder and wash-bottles, are analyzed for ammonia and albuminoid ammonia in a manner precisely similar to the mode adopted in a water analysis. A small stoppered retort, of a capacity of 2 cub. cents, connected with a glass Liebig's condenser, about 18 inches long is necessary. By means of a little copper basin, containing sand or oil, placed on a large ring of a retort stand, heat can be applied more gently than with a naked flame. I often, however, use the naked flame with the chimney, as figured on page 87. The retort, condenser, etc., should, after copious ablutions with tap water, be first thoroughly washed internally by distilling through the apparatus some twice-distilled water. The 1 c. c. of air-washings contained in the flask should then be introduced into the retort, and distillation begun. u 290 CHEMICAL EXAMINATION OF AIR. A dozen test-glasses that will stand without sup- port, about 4 inches long, and -|th inch in diameter, Kg. 27. the bases of which have no colour, should have been previously marked with a file at the height which is reached by 10 c. c. of fluid. No corks should be used. The retort and condenser can be imited by a packing made of a strip of common writing paper. The fi-rst distillate of 10 c. c. that passes over should be Nesslerized by introducing into it -|- c. c. of Nessler re-agent, and shaking the mixture. We should not blow into the pipette so as to mingle the contents of the Nessler glass, as is not uncommon in water analysis. The second, third, and fourth distillates, each of 10 c. c, may be thrown away, and a third of the quantity of ammonia found in the first distillate be added as in water analysis, page 40. The con- tents of the retort are then to be allowed to cool. After it has become reduced to a state of tepidity, 10 c. c. of the solution of permanganate of potash and caustic potash are added, and the distillation again proceeded with. Each of the three distillates should be tested with -|- c. c. of ISTessler re-agent, and then the estimation of the coloration of the single ammonia CHEMICAL EXAMINATION OF AIK. 291 distillate, and the tliree albuminoid ammonia distil- lates, should be made. A burette with the subdivisions of each cubic cen- timetre widely apart is necessary. Mine is 1 foot long, and j^th inch in diameter, and with it xtjths of a c. c. can easily be read. The very dilute standard ammonia solution used is half the strength of that found most convenient in water analysis, and is prepared by mixing 5 c. c. of the strong standard solution of ammonia (1 milli- gramme of ammonia in 1 c. c.) with 995 c. c. of twice- distilled water. Accordingly 1 c. c. of it contains "005 milligramme of ammonia. 1 c. c. „ -0025 „ „ x% c. c. „ "0015 „ „ ^c. c. „ -0005 It is necessary to make up standards exactly as in water analysis. The test-glasses should be cleansed with twice-distilled water by the aid of the pipette before they are employed. If Gmelin's wash-bottle is used, organic impurities from the breath may be intro- duced. The test-glasses containing the standards and the distillates, the colour of which it is necessary to imi- tate, are placed on a sheet of white paper. It is often very convenient to stand them in a common test-tube rack. The differences between the tints of each ^trth of a c. c. of the very dilute standard ammonia solution are distinguished with great precision by one who has had some practice with these delicate analytical ope- rations. The great objection to the employment of so smaU. a quantity of air as one cubic foot is, that the experi- 292 CHEMICAL EXAMINATION OF AIR. mental error falls so heavily on the results. This difficulty can be overcome by practice and the greatest attention to cleanliness, and the minute details with which every practical scientific chemist is conversant. Blank experiments on pure air, or the effects of simply washing the apparatus with twice-distilled water, will give confidence to the operator in his tools, and by giving him practice will help him to obtain reliable results of air of different degrees of impurity. A¥hichever of the foregoing plans be adopted for extracting the organic matter from the air, its washings are treated in the same way. These washings are examined by the Wanklyn, Chapman and Smith process, in a manner precisely similar to the mode in which the organic matter contained in water is detected and estimated, which has already been described. {Vide page 36.) B. Caebonic Acid. As I before stated, carbonic acid is not the worst impurity in the air of our houses, for it stands second to the organic matter in its evil effects, yet an estimation of its amount is an index of the foulness of air of a very valuable kind. There are several modes of detect- ing its presence and calculating its amount in any given sample of air. The method known as Pettenkofer's is a good one, but requires the expenditure of much time and labour. It consists essentially in washing a certain measured quantity of air with a definite quantity of lime water or baryta water, and noting the loss of causticity that either of these waters (whichever is used) has under- gone; in other words, the amount of lime or baryta CHEMICAL EXAMINATION OF AIE. 293 that has united with the carbonic acid. The process is conducted thus : — A large glass vessel is taken of known capacity (1 oz. = 1"733 cubic inches). The air to be examined is pumped into it, or the air con- tained in it is drawn out (so ensuring the admission of fresh air), by a hand bellows. The causticity of the lime water to be used in the experiment is first ascer- tained by mixing with it a certain measured quantity, say 30 c. c. of a solution of oxalic acid to neutralize it. The oxalic acid solution is made of such a strength that 1 c. c. will exactly neutralize 1 milligramme of lime. Turmeric paper is employed for noting the exact point of neutralization. The stain produced on the turmeric paper when there is an excess of lime is of a dark brown colour, which becomes paler as the oxalic acid solution is added. As soon as the mixture ceases to give a brown stain the neutralization is effected. The same quantity of lime water, namely, 30 c. c, is placed in the bottle of air to be examined, and is shaken with it, and is allowed to remain in it for not less than six or eight hours, at the end of which time the causticity of the lime water, or, in other words, the quantity of oxalic acid solution required to bring it to the point of neutralization is determined. The caus- ticity of the lime water that has been exposed, and that has not been exposed, to the air operated upon being known, the difference will furnish us with the amount of lime that has become united with carbonic acid. From this datum the percentage of carbonic acid in the air under examination is easily calculated. Corrections have to be made for temperature and baro- metric pressure. This process is fully described in Parkes' Hygiene (fifth edition). 294 CHEMICAL EXAMINATIOISr OF AIK. The determinations of the amount of carl)onic acid The in the air are thus made at the Montsouris Observatory : obsfwato^ A set of absorbents, consisting of three elements, each Method. of course furnished with its platinum rose, is charged with a 20 per cent solution of potash, coloured blue with a few drops of litmus. The elements are con- nected with one another, all being in commTmication with the aspirator depicted in fig. 21. Fig. 28. The last element serves to show if all the carbonic acid has been extracted by the preceding ones. After the passage of 1 cubic metres of air the contents of each element is submitted to analysis. The platinum tube through which the air has entered is attached to CHEMICAL EXAMINATION OF AIK. 295 a graduated burette containing hydrocliloric acid. The glass tube through which the air has passed out is connected with a cylindrical receiver full of water, covered with a layer of petroleum oil, and furnished with an exit tube, the upper extremity of which is always at the same level as the layer of petroleum. A definite quantity of hydrochloric acid is allowed to flow into the solution of potash, sufficient, indeed, to convert the blue colour of the litmus to a red tint. The carbonic acid evolved displaces a volume of the water equal to itself. This water is received into a burette graduated into cubic centimetres. The method which has until recently been pursued at Glasgow by Mr. Dixon, consisted of the passage of 1 cubic foot of air per hour, for 48 hours, through solu- tions of caustic potash contained in three wash-bottles (a set of absorbents). To their contents a solution of barium chloride was added, and the precipitate was, after washing, drying, and ignition, weighed. Dr. A. Smith has lately found '"" that three washing-bottles containing a solution of barium hydrate, were insuffi- cient to absorb all of the carbonic acid from the air aspirated through them. Yolumes, COg per million volumes of air. Exp. 5. Exp. 6, 1st tottle gave 80 115 2d „ }} 62 71 3d „ j> 62 66 4tli „ jj 53 62 5tli „ )5 18 62 6th „ 5J 45 62 Total . 320 438 in series of 6 bottles. * Proc. of Royal Society, Dec. 13, 1877. 296 CHEMICAL EXAMINATION OF AIK. WanMyn's Metliod. Captain Abney's Method. Another good method, proposed by Wanklyn, based on the same principle, is to make a standard by dis- solving 4' 7 4 grammes of dried carbonate of soda in one litre of water — a solution which contains a cubic centimetre of carbonic acid {= 1'97 milligrammes of carbonic acid) in every c. c. of liquid. A bottle capable of holding 2000 cubic centimetres of air, or, failing one of exactly the right capacity, a stoppered Winchester quart bottle, having been washed clean, is rinsed with distilled water and allowed to drain. It is filled with the air to be tested by sucking out the air of the bottle with a glass tube, or with a bellows, like that in fig. 20, when air from without immediately takes its place. 1 c. c. of baryta water are introduced, and the bottle is shaken for two or three minutes. The baryta water, on being poured out into a glass cylinder, is found to be more or less tur- bid, being slightly so if the air is good, and like milk if it is very impure. We then proceed to imitate the degree of turbidity in the following manner : — The standard soda solution is measured by drawing out the number of c. c. required from a burette graduated to deliver tenths of a cubic cent of solution. We take 100 c. c. of baryta water and introduce into it 1 c. c. of soda solution. If the turbidity thus occasioned is about equal to the turbidity produced in the 100 c. c. of baryta water by the air under examination, we know that the air contains '05 vol. of carbonic acid per cent. If two c. c, or more than two, are required to imitate the turbidity occasioned by the air, the air is bad and ventilation is defective. Dr. Notter advocates the trial of the delicate pro- cess of Capt. Abney, which is thus described in the Sani- CHEMICAL EXAMINATION OF AIR. 297 tary Record, Sept. 9tli, 1876 : — "A Florence flask of known capacity is . fitted with a stopper, and into the stopper is inserted an U tube half fiUed with spirit, which may be coloured with any convenient pigment, also a smaller tube, bent at right angles, and drawn out to about twelve inches from the flask. A small bulb of very thin glass, made by heating to redness the end of a test tube and blowing it, is constructed, and this is filled with a saturated solution of caustic potash, and sealed by the flame of a gas get ; several of these can be made at the same time, and put by for future experiments. Our flask is now taken into the room, the air of which we wish to examine, and one of the small bottles containing the caustic alkali carefully placed in the bottom, and air blown in by a beUows. The flask is allowed to remain undisturbed for some time, say half an hour, to acquire the temperature of the air in the room. The U tube should have appended to it a scale of half an inch or less ; this can be made of paper and pasted on the back. When the flask has acquired the temperature of the room, the long thin glass tube is sealed by dipping it into parafiin or wax. The spirit in the U tube should then stand on the same levels. The flask is then taken and jerked sud- denly, so as to smash the little bulb within it. This sets free the caustic potash, which absorbs the carbonic acid, and causes a partial vacuum in the flask, depend- ing on the amount of carbonic acid present, the result being that the spirit in the U tube is depressed on one ■side. The difference in the reading will give the difference in pressure due to the absorption of the gas, and from this can be easily calculated the amount of carbonic acid present in the flask. 298 CHEMICAL EXAMINATION OF AIE. Household Method. Simpler, but somewhat less accurate, modes, called the household and minimetric processes, which are sufficiently exact for all practical purposes, have been proposed by Dr. Angus Smith. "'^ The outside air contains an amount of carbonic acid, varying between "03 and "06 per cent, but is most frequently -04 per cent, which rises in crowded Fig. 29. buildings and other close, ill-ventilated places to '25 per cent. The way to estimate the amount roughly is "to wash different measured quantities of air with ^ oz. of lime water in such bottles as are here depicted. The lime water is prepared by slaking lime with water, stirring the slaked lime with the water, and then allow- ing the lime to subside. The clear fluid is, after 1 2 or 24 hours, poured off, and is ready for use. A table has been prepared to facilitate the use of this plan : — Op. cit. CHEMICAL EXAMINATION OF AIR. 299 Size of Bottle. Ounces. 20-6 . Poi Ca Lime Water. nt of observation is 710 precipitate. rbonic Acid in air per cent. •03 15-6 . •04 12-5 . •05 10-5 . •06 9-1 . •07 8-0 . •08 7-2 . •09 6-5 . •10 6-0 . •11 5-5 . - •12 5-1 . •13 4-8 . •14 4-5 , •1§ 3-5 . •20 2-9 . ■25 2-5 . •30 2-0 . •40 1-7 . •50 1-5 . •60 1-3 . . -70 1-2 . •80 The rule to remember is that the air around houses generally contains about "04 per cent of carbonic acid, and that our rooms should always be kept so that a 10^ oz. bottle full of air, when shaken with ^ oz. of lime water, gives no precipitate. We then know that the air does not contain more than "06 per cent. It is often difficult to keep the air of a room below "07. If a precipitate is observed we know that the air does contain more than "06 per cent, and we take a smaller bottle, say a 9 oz. bottle, the air of which, when shaken with -|- oz. of lime water, gives, perhaps, no precipitate. We then say the air is worse than -06, and not worse than "07; accordingly, the amount must 300 CHEMICAL EXAMINATION OF AIK. rougKly be '07. If we wish to test the air as expe- ditiously as possible, and are not particular to ascertain the exact percentage, we may take a bottle of a size indicative of alternate hundredths. Instead of taking a 9 OK. bottle we may take an 8 oz., and treat 8 oz. of air in the same manner. If we obtain no precipitate we know that the air is not worse than "08 per cent. Having already ascertained that the air is worse than •06 we conclude that the air is contaminated with "07 or "08 per cent of carbonic acid. If no turbidity is occasioned on commencing with our 1 0^ oz. bottle, and we would like to know whether the air contains as much as '06 per cent, we must take a larger quantity of air, for example a 12^ oz. bottle. If, when this quantity of air is shaken with -|- oz. of lime water, no precipitate is procured, we know that the air does not possess more than "05 per cent, and if a precipitate is occasioned, we know that "06 per cent is the amount. The air to be examined is best introduced into the bottles by sucking out the air already contained in them with a glass tube. Fresh air enters to supply the void we create. The greatest care should be taken not to breathe into the bottle, for our breath is full of car- bonic acid. The bottles should be wide-mouthed, so that the sides can be- wiped dry and clean. If the lime cannot be readily removed, they should be rinsed out with strong hydrochloric acid, followed by an abundance of water. There is great difl&culty in ob- taining bottles of exactly the capacity required, but this could be overcome if there was any demand for such measures, by the special manufacture of bottles to hold accurately the quantities of air indicated. CHEMICAL EXAMINATION OF AIE. 301 Minimetric Method. — This method is more accurate, Mmimeti-ic and involving but few tools, which can be conveniently ^^®*^°^- disposed of in one's pocket, is more handy. It consists essentially in ascertaining the smallest or minimum amount of air required to produce a precipitate of given density — hence the name. Baryta water, which is very poisonous, is employed, because it is more sen- sitive than lime water. A standard precipitate is ob- tained by shaking ^ ounce of baryta water in a 23 oz. bottle in pure air, which generally contains "04 per cent of carbonic acid. The liquid is turbid and still translucent, but so that you cannot read through it. The endeavour is to ascertain the smallest amount of the air to be tested which is necessary to produce this standard degree of turbidity. We take a bottle which holds exactly 2-|- oz., and place in it -|- oz. of baryta water, having first changed the air in the bottle by a few strokes of the finger pump ; we then shake the 2 oz. of air contained in the bottle baryta water, and count one. — Vide fig. 30. with the ^ oz. of Pig. 30. We then pump 2 oz. of air through the liquid and 302 CHEMICAL EXAMINATION OF AIE. again shake violently and count two. When the tur- bidity is such that the words written on the slip of paper ■^''' affixed to the outside of the bottle become in^ distinguishable, we stop, and refer to a table that has been prepared to economize the labour of calculation. Volumes of Carbonic Acid Number of in 100 of air. ballfuls With 2 oz. With i oz. of air. baU. ball. 1 •44 2 •22 3 •14 4 •11 5 •088 6 •074 7 •063 8 •055 9 •049 10 •044 •17 11 •040 •16 12 •037 •14 13 •034 •13 14 •032 •12 15 •029 •116 16 •11 17 •10 18 •098 19 •093 20 •088 21 •084 22 •08 23 •077 24 •074 The I oz. ball enables us to estimate greater degrees of impurity than the 2 oz. one. When the air of a place, which it is wished to test, * The words written with a lead pencil on the label must be of such a depth of shade that the turbidity of the standard liquid just prevents them from being seen. CHEMICAL EXAMINATION OF AIR. 303 Fig. 31. to '5 per cent, the feels close on first entering, I use the 2 oz. bottle, and if very close I employ the ^ oz. ball and bottle. As the silk valves are rather liable to get out of order, I dispense with them, and simply make a slit in the tube con- necting the ball and bottle, which allows of the expulsion of air, but prevents its in- gress. — VideG.g. 31. A weak solution of baryta (-1 exact strength being unimport- ant) is employed, which is made by dissolving caustic baryta in distilled water. It must be stored in such a way that, on removing portions of it, air un- deprived of carbon dioxide shall not enter the store bottle. The arrangement here sketched, which is in constant use in the Board of Health Laboratory, Glasgow, and is to be found in Sutton's Vohimetric Analysis, is a most convenient one for with- drawing any quantities that are required of baryta water, or, in- deed, of other standard solutions, in such a manner that air entering is freed from whatever body the contained solution is designed to extract from it. — Vide fig. 32. Fig. 32. A. Store bottle containing solu- tion of caustic baryta. B. U tube filled with fragments of pumice stone moistened with caustic potash, through which air passes in order to enter the store bottle. C. Burette graduated in any manner that is required. D D. Shelves. E E E. Black india-rubber tubes. F. Clip. G. Rod ,'or support ot burette. 304 CHEMICAL EXAMINATION OF AIE. It will be found very handy to have a dozen ^ oz. stoppered bottles with wide mouths, and to fill them from this store bottle. It is needful to carry a stop- pered and capped bottle of hydrochloric acid to clean the little apparatus after each experiment, before it is washed thoroughly with water. In the air of a room which, at first pure, is gradu- ally vitiated by the presence of persons, the smell of organic matter begins to be perceptible to one entering it from tlie fresh air when the carbonic acid reaches •06 or '07 per cent. When the carbonic acid amounts to -09 or -1 per cent, the air is termed "close" or " stuffy." The foetid odour of organic matter becomes very disagreeable when the carbonic acid exceeds *! per cent. When the carbonic is as much as from '15 to "S per cent, headache and vertigo are experienced, as the result of the vitiation of the air by this gas and its accom- panying impurities. When people speak of good ventilation, they mean air with less than '07 per cent. Detection of A rough and ready mode of detecting the presence suipude, of hydrogen sulphide in the air, which is a gas produced Ammonium jj^ ^j^g dccay of orgauic matter — for example, in some and ' marshes, in sewer gas, etc., is by means of acetate of lead papers. Ammonium sulphide, which, with hydrogen sul- phide, is a constituent of sewer gas, is detected by nitro-prusside of sodium tests. Ammonia, a product of putrefaction and decomposition, is, if in large amount, observed by means of logwood papers. Ammonia. METALLIC POISONS. 305 ■CHAPTEE XXYIIL METALLIC POISONS : ARSENIC, COPPEE, AND LEAD. Copper and lead are sometimes found in the air in copper and the neighbourhood of smelting works, etc. The deter- mination of the amount of these metals, which, when diffused through the air, exercise injurious effects on animal and vegetable life, faU rather within the scope of those legislative enactments that concern the con- tamination of the air by manufactories, such as the AlkaK Act of 1863, under which scientific chemists are appointed as inspectors. The human system itself, when continually exposed to the poisonous influences of copper and lead, affords an excellent test of an exposure to an injurious amount in the case of those who work with these metals, such for instance as miners in copper mines, or painters. The effects on the body of these metals, even in the smallest doses, are so well known to every physician, that he requires but little chemical aid. It is different in the case of arsenic, for the effects of the metal give rise in minute doses to such obscure and incomprehensible symptoms, of such great variety, that they often cannot be assigned to their rightful cause without chemical assistance. A description of the several poisonous colours used to tint the cheeks, the hair, etc., to avert the appearance of old age and to dye articles of wearing apparel, will X 306 METALLIC POISONS, not fall witliirL the province of this work, because they exert their poisonous effects hj coming into contact with the skin. Arsenic, mercury, lead in the form of magenta, coraline,"'' and other of the new dyes, are some of the most common poisons thus used. The receipt of injury from the poisoning of the air by burning arsenical tapers, so rarely happens, that we need scarcely delay to consider it. Arsenical lustauces of the terrible suffering, misery, and even wau papers, (^ga^]^^ that havc occurred from the use of arsenical wall papers, from the preparation for sale of feathers, artificial flowers, leaves, fruit, etc., swarm in medical publications. The poisonous greens, such as Scheele's, Schweinfurth's, Brunswick, Emerald, Paris, which are all confounded together by work people, are used in enormous quanti- ties, partly because they are very attractive in appear- ance and partly because they are cheap. Not less than 700 tons of these deadly greens are consumed in trade annually in this country. Many wall papers that are not green are loaded with arsenic, especially pale or white dravsdng-room papers, with an enamelled or opal white ground, which have yielded 15 to 25 grains of arsenic per square foot. Mr. Wigner, on recently examining samples of aU the papers in a ten-roomed house, none of which were green, discovered that five of them con- tained arsenic in such quantity as to be injurious to health. The medical of&cer of health, in his inquiries after the causes of vague and obscure forms of illness, may often have occasion to examine the air of rooms poisoned by arsenic papers and furnishing materials. * Bulletin de V Academic Imjperiale de Medicine, February and March 1869. METALLIC POISONS. 307 The public will not unfrequently bring him portions of wall paper with which their rooms are adorned^ in order that he may examine them and express an opinion there- on. It is as well, therefore, for him to be acquainted with a simple means of testing for arsenic, not only to aid him in his own investigations, but to assist the public and their medical attendants. If it is wished to ascer- tain whether a paper does or does not contain arsenic, the paper is scraped with a pen-knife, and the dust that is removed is tested. If we desire to find out whether particles of dust have detached themselves from the paper, and poisoned the air of the room, the dust that lies on the articles of furniture may be collected for examination. The dust of the paper, in whatever way obtained, is mixed with an equal bulk of bicarbonate of soda (dried over a spirit lamp) and a little powdered charcoal. The mixture is placed in a dry test tube and heated characteristic odour of garlic is perceived, and a mirror of me- tallic arsenic is ob- tained as a ring on the sides of the tube. If the test^ tube is large, so as to allow of free access of air, octahedral crystals of If arsenic is present, the Mg. 33. arsenious acid, easily recognised by the microscope, will be found instead of the mirror. Eeinsch's test may be employed to show the presence of arsenite of copper in a paper. The paper having been soaked in a solution of ammonia, which wiU. dissolve the arsenite of copper 308 METALLIC POISONS. forming a blue liquid, is acidified with hydrochloric acid and then boiled in a test tube with one or two strips of brilliant untarnished copper. The copper is washed, dried on filter paper, and heated in a small test tube over a Bunsen's burner or spirit lamp, when arsenious acid in octahedral crystals, readily diagnosed by the microscope {vide Fig. 34), will be deposited in the cool part of the tube, if the paper contains arsenic. Or the green colouring matter may be scraped off the paper and dissolved in pure hydrochloric acid and water, and examined by Marsh's test. Granulated zinc, or zinc foil infragments, are introduced into a flask with some water, and a Kttle pure sul- phuric acid is poured down the funnel. A few minutes should be allowed to elapse for the removal of aU the air from the flask. The gas evol- ved should then be collected in a test tube, and a lighted Fig, 35. — Marsh's Test. A. Flask containing dilute sulphuric acid and zinc free from all traces of arsenic. B. Test tube for coUecttng small quantities of the gas evolved. C. Tube of hard Bohemian glass that wiU not rnatch be aDnlipd tfJ fuse, drawn out to a point so as to form a jet. ^" METALLIC POISONS. 309 the tube to ascertain whether a mixture of hydrogen and atmospheric air is escaping, or whether hydrogen is alone given off. If air is still being expelled from the apparatus the gas in the test tube on being lighted will explode harmlessly. The gas escaping at the jet should on no account be ignited until two or three of these trials have been made. When the gas collected in the test tube does not explode, it is safe to light the jet. Having ascertained the purity of the chemicals employed, by depressing a piece of porcelain on the flame, the solution of the green colouring matter may be passed down the tube funnel and the flame again tested. If it consists of arsenic there will be a dark mirror of arsenic deposited on the porcelain. If it is wished to ascertain the amount of arsenious acid (the common white arsenic of commerce) contained in a paper, a rough estimate may be easily formed. If the pattern of the paper consists of groups of green leaves, as is often the case, scrape off all the green arsenite from a single leaf and weigh it. The number of leaves in each square foot of surface of the paper having been counted, and the dimensions of the room haAdng been taken, the number of leaves in the room is easily ascertained. If the green colouring matter is equally distributed over the surface of the paper a square inch of the paper should be operated on in place of a single leaf. A measurement of the room will readily give the number of square inches of surface. Two or three green leaves of a wall paper were recently sent to me with the request that I would ascertain whether the green pigment contained arsenic, and, if so, the quantity of the same. It had been estimated by the applicant thattherewereabout22,8001eaves in the room. 310 METALLIC POISONS. All the green colour having been scraped off from a single leaf, by the help of a penknife, was found to weigh 16 milligrammes. Arsenite of Copper. Arsenious Acid. 2 Cu. 0., H 0., Asa O3 Asa O3 375 : 16 : : 198 16 1188 198 Arsenious Acid. 375 I 3168 I 8 J 3000 [' To convert the 8 milKgrammes of arsenious acid into fractions of a grain, a weight that is more readily understood by the public, it is simply necessary to multiply by 15*5 and divide by 1000. Milligram. Milligram. Grs. in 1 gramme. 1000 : 8 : : 15-5 1000)l24-0(-124 Ans. One leaf contains '124 of a grain, which is equivalent to 124 grains of white arsenic in every 1000 leaves, or nearly 6 ounces in the room. It is always wise to perform a blank experiment, in order to be perfectly certain that the chemicals em- ployed are quite free from the metal. Some wall papers contain compounds of lead and copper (non-arsenical), but, although their employment is undesirable, we have but little evidence at present which would forbid their use. OZONOMETKY INDIRECT METHOD. 311 INDIRECT METHOD. CHAPTEE XXIX. OZONOMETRY. The whole subject is so vast that it is extremely ozone, difficult to know how to concentrate it without omit- ting salient points of great interest. • Ozone is condensed oxygen, or a very active, lively, and energetic form of this life-giving gas. Its object in nature is to destroy, or, to speak more correctly, to render harmless by oxidation all offensive noxious products that, if permitted to accumulate, would pro- duce disease and kill life. Take, for example, a little blood, and keep it in a warm place for months, until it putrefies. When the odour is something horrible, sufficient indeed to create nausea, or sickness, send a stream of ozone over it, and its freshness, purity, and sweetness, wiU. be restored. Neither ozone nor the other air purifiers are to be found in the air of unventilated inhabited rooms or hospitals unless the windows are open, being speedily used up, and not replaced as they should be by the admission of fresh air, which nearly always contains them in greater or less quantity. Ozone can be prepared in a great variety of ways. It is perhaps most conveniently made by mixing three parts of sulphuric acid with two parts of permanganate of potash. This mixture will continue to give off ozone 312 OZONOMETRY. for several months. It is associated in the air with other purifying agents, such as peroxide of hydrogen and acids of nitrogen. Peroxide of hydrogen, called also oxygenated water, is produced by a combination of the oxygen of the air with water. It is found sometimes in rain and snow. It also is a powerful oxidizing agent, for it very freely parts with its excess of oxygen. Its oxidiz- ing powers render it useful for bleaching, as it attacks vegetable colours vigorously. Young ladies used to purchase it for bleaching their hair, under the name of "auricomus," when it was the fashion for every one to ex- hibit flaxen locks. It so readily parts with its oxygen that a temperature of 68° F. is sufficient to disengage it, the warmth of the hand to the bottle which holds it being often dangerous. Nitrous acid is a product of the thunderstorm, and is produced whenever an electric spark passes through air. It is one of the most valu- able gaseous disinfectants and deodorizers known. It acts most energetically on organic impurities, removing the unpleasant odours of the dead-house more readily (so it is said) than any other gas. This rapid action arises from the facility with which it gives up its oxygen. For deodorizing purposes, it is made by mixing nitric acid and water with copper turnings. It is used more on the continent than in this country. The amount of ozone, peroxide of hydrogen, and nitrous acid, which are all powerful air purifiers, are measured by exposing to the air paper dipped in a solution of iodide of potassium. They aU. have the property of breaking up this salt and setting free the iodine, which gives the paper a reddish brown colour, of greater or less depth, according to the amount of these disinfec- tants present in the air during the time of its exposure. OZONOMETEY. 313 Sometimes, instead of all the iodine being set free, some of it goes to form a higher oxide of potassium, called the iodate which is a colourless salt. It is therefore always necessary to spray these tests after exposure with a solution of tartaric acid which sets free the iodine from the iodate, but does not interfere with the unacted upon iodide of potassium. We are then sure of obtaining all of the iodine set at liberty by the air purifiers. If we wish to ascertain the amount of ozone present in the air to the exclusion of the other air purifiers, we employ a paper which is alone acted upon by ozone, such as the iodized litmus paper. With this test we do not take any notice of the amount of iodine set free, but we observe the amount of potash formed by the union of the ozone with the potassium. Potash, being an alkali, of course has the property of turning red litmus blue, whilst an acid turns blue litmus of a red colour. The greater or less conversion of the red litmus into blue, shows a greater or less quantity of ozone in the air. Scales have been prepared for estimating the depth of colour of the iodine papers in testing the amount of the three air purifiers, and of the iodized litmus papers for showing the amount of ozone. It was formerly the practice to employ starch tests, iodized which are composed of a mixture of iodide of potassium Tests. and boiled starch, which became blue on exposure to the air from the formation of the blue iodide of starch. There are many different kinds, which may be looked upon now as curiosities ; for example, Schonbein's, Lowe's, Jame de Sedan's, Lender's, Moffat's, etc. They are all more or less disposed to play mad pranks ; now they colour, then they bleach ; sometimes they tint in 314 OZONOMETRY. a uniform manner ; at other times they become marked with lines like a Scotch plaid, or with spots ; whilst they very frequently fade. Hence the records of ob- servations appear most contradictory, forming a mass of almost inextricable confusion. In support of this assertion, the opinions of a few who have made ozone a subject of study may be quoted : — "At the present time the modes of determining ozone, and the tests for ozone in the external air are very unsatisfactory." — Dr. Bichardson. " The greater part of the countless observations on the amount of ozone in the air are worthless." — Professor Heaton. "The determinations which have hitherto been made are very vague and unsatisfactory." — Dr. Wetherill. " Tests prepared from the same recipe, by different persons, give varied results." — Boekm. " If we expose the tests of Schonbein and Moffat together we do not get the same result, and even tests made by the same persons at two different times will not read alike." — Mr. Lowe,, of Nottingham. "All the methods employed are more or less de- fective." — Dr. Scoresby-Jackson. " Until more certain means are discovered for estimating ozone, present observations must be received with great caution." — Davies. " The estimation of ozone is in a very unsatisfac- tory state. The great imperfection in the tests makes it desirable to avoid all conclusions at present." — Professor FarJces. "No clear and consistent results have yet been obtained. Variations of Light, wind, time, and paper. OZONOMETRY. 315 may cause changes attributed only to ozone, and there are no reliable means of checking them." — Admiral Fitzroy. " No trustworthy observations on ozone are made in the United States of America." — Dr. Henry, of the Smithsonian Institution. These views refer to the antiquated practice of estimating atmospheric ozone with the iodized starch test, by suspension in a cage or box, and subsequent comparison with a scale containing gradations of colour. The exposure of any kind of test papers in cages is a most fallacious mode of observation, for they are measurers of the velocity of the wind, and may be called anemometers rather than ozonometers. The higher the wind the deeper the colours they assume, for the simple reason that more air passes over them. There is a special fallacy attendant on the employ- ment of starch tests in ozonometry, because there is every reason to believe that the iodide of starch is not a true chemical compound. M, Duclaux declares that its formation is purely physical, and results from the adhesion of the molecules of its constituents. It appears that M. Personne and M. Guichard expressed the same opinion some years ago. The latter chemist, who examined the iodide of starch by the aid of the dialyser, writes — "The so-called iodide of starch is simply starch tinted with iodine." Watts considers that " the blue coloration is due to the formation of a loose combination of starch and iodine, or perhaps to the mere mechanical precipitation of the iodine upon the starch." The various circumstances which affect 316 OZONOMETRT. and modify tlie colour of the iodide of starcli have been pointed out by Gmelin.'" Then, again, all of the iodine set free in the starch test does not sometimes combine with the starch. Some of the iodine set free occasionally forms a colour- less iodate. It is, moreover, very difficult to obtain pure starch, and samples of the same kind of starch often vary much in strength. The errors associated with the employment of iodide of starch tests are indeed legion. Notwithstanding the existence of these irremedi- able defects inherent to the employment of iodide of starch in atmospheric ozonometry, which were brought by me before the scientific world in a prominent manner three or four years ago, the officials at the Montsouris Observatory have been throwing away their time and labour by employing cotton wool im- pregnated with iodide of potassium and starch. They have at length, it seems, discovered that what I told them years ago is but too true — namely, that the iodide of starch test is wholly unreliable. M. Mari^- Davy writes : — " La difficulte de la methode consiste en ce que I'iodure d'amidon manque de stabilite, qu'il se d^colore a I'air, et qu'en presence de la potasse formee une partie de I'iode mis en liberte pent se transformer en iodate. D'un autre cote, I'amidon s'alt^re au contact de I'air et des produits pyrogen^s qu'on rencontre toujours dans 1' atmosphere des grandes villes." They have now forsaken this untrustworthy iodide of starch reaction, and estimate the quantity of oxygen employed in the conversion of an arsenite into an arsenate, and efforts have been made to bolster up * Handbook of Chemistry, xv. 97 (German edition). OZONOMETRY. 317 the belief in the starch tests of Schonbein, by making it appear that Schonbein's starch tests — plus certain corrections of their own — agree in their indications with the results determined by the oxidation of an arsenite. Having had such an immense experience with starch tests, my intimate acquaintance with their comic behaviour would incline me to think that if there is any harmony between them and the process with the compound of arsenic, the latter must be worthless also. According to the most approved recent mode of observing ozone, and of estimating the amount of the air purifiers (ozone, peroxide of hydrogen, and nitrous acid), it is necessary to pass a known quantity of air over test papers of two different kinds at a known and unvarying velocity by means of aspirators, of which there is a great variety, such as Mitchell's aspirator, the tube aspirator, Dancer's aspirator, the injection aspirator, Andrews' aspirator, the Montsouris aspirator, and the clockwork fan aspirator. The test papers are exposed in a box of a peculiar form, where they are protected from dust, Kght, and moisture. It would be impossible to give the reader in this handbook an adequate description of the mode in which ozone and the other air purifiers should be esti- mated. The fullest information as to how these bodies should be observed has already been published by me in my work on Ozone and Antozone in which it occupies 136 pages. The errors associated with the Errors con- 11 ,• J.^ T I' • j_ij_j. nected with old ozonometric method of exposing starch tests may ^m method. be here summarized. 1. Impurity of chemicals ) employed in the manu- 2. „ „ paper j" facture of the tests. 318 OZONOMETEY. 3. Formation of the iodate of potash. 4. Non-union with the starch of the whole of the liberated iodine. 5. Changes in the force of the wind. 6. Bleaching and fading of coloured tests from — A. Formation of the iodate of potash. B. Excess of moisture in the air. C. A high temperature of „ D. A great velocity of „ E. A long exposure to „ E. Sulphurous acid in „ 7. Light. 8. Ozonometers (= chromatic scales) faulty in con- struction. 9. Differences of aspect and elevation. I must refer to that work for the blue and red chromatic scales, the ozone register and diagram, which in like manner cannot possibly be copied into this publication. After a thoroughly accurate estimation of the amount of ozone present in the pure air of different climates, and during the various atmospheric changes of each climate, we shall be in a position to attempt an elucidation of the following and many other questions which are of immense interest and importance to the human race : — 1. What are all the sources of atmospheric ozone ? 2. How is it formed, and in what circumstances does it arise ? 3. What is its precise action on animals and plants ? 4. Has an excess or deficiency of ozone any effect on the public health ? 5. If so, what is the nature of that influence ? OZONOMETRY. 319 6. What is the effect of the presence of epidemics on its amount, as calculated by the improved ozono- metric method ? 7, Does ozone oxidize one only, or aU of the different kinds of organic matter found in the air ? The elucidation of that very interesting mystery respecting the supposed relationship between an excess of atmospheric ozone and an epidemic of influenza is one which demands special attention, because of the fact that an excess of ozone artificially prepared will originate a catarrh. As an outbreak of this disease has not occurred since 1847, it seems probable, from the experience of the past, that no long time will elapse before an opportunity will be afforded. 320 METEOEOLOGICAL VARIATIONS IN RELATION PAET III. SKETCH OF RELATION BETWEEN CERTAIN METEOROLOGI- CAL VARIATIONS m THE CONDITION OF THE AIR, AND STATES OF HEALTH AND DISEASE. In the consideration of " all influences affecting, or threatening to affect, the public health within his dis- trict," the medical officer of health should not neglect observations on those climatic and topographical pecu- liarities wMch are likely to exert any action on health. The variations in the temperature, humidity, pressure, and electric state of the atmosphere, as well as the effects of these changes on the moral and physical con- dition of nations and individuals, form a most exten- sive field of study, and one, moreover, of the highest possible interest. The influence of climate on the sani- tary condition of all animals, and especially of the most highly organized being in the scale of creation, has occupied for more than 2000 years, and. still engages, the attention of scientific men. The great subject of weather and disease has been worked at ever since the times of Pythagoras, whose doctrines were supported by Hippocrates,* the father of medi- cine. These distinguished philosophers divided nature into four qualities — viz. cold and warmth, dryness and moisture. They considered cold with moisture to be * Fide " irepi aepuv, vdaroip, rorruv. " TO STATES OF HEALTH AND DISEASE. 321 hurtful, and warmth with dryness to be beneficial qualities. The three following rules have long been accepted by the few, and unrecognised by the many, for hun- dreds of years : — ■ 1. A preternaturally dry air, with a high tempera- ture, predisposes to the development of fevers and intestinal disorders. 2. A very moist atmosphere, accompanied by a low temperature, is apt to induce bronchial and rheumatic affections. 3. A very dry atmosphere, when associated with a low temperature, has a tendency to excite inflamma- tions of the respiratory organs. The labour of the past has borne, however, but little fruit. With our present improved means of meteorological observation, a fresh impetus has been given to this pursuit, especially in connection with our increased knowledge of the influences of the seasons on, and the physiological changes in, the human body. That a certain amount of disease can be prevented by guarding against many of the effects of changes of * climate is indubitable. It will be useful to consider : first, the effects of differences of temperature, moisture, and barometric pressure, direction of the wind, etc., on health ; and, secondly, the meteorological conditions which appear to favour or retard the development of those diseases that seem to be influenced most by climatic variations. 322 THE TEMPEKATURE OF CHAPTER XXX. 1. THE INFLUENCE OF DIFFERENCES OF TEMPERATURE, MOISTURE, AND BAROMETRIC PRESSURE OF THE AIR, DIRECTION OF THE WIND, ETC., ON HEALTH. A. The Temperature of the Air. The Tern- The following dicta may be regarded as aphorisms : the Aj^.^ ° I^ summer, during which season there is a tendency to intestinal affections, a rise of mean temperature above the average increases the number of cases and the mortality from them. In winter, during which season there is a predispo- sition to lung diseases, a fall of mean temperature below the average increases the number of cases of, and the mortality from, these affections. When the temperature in London falls from 45° to 27°, the Eegistrar-General calculates that about 400 * persons perish of bronchitis. The valuable reports of the Eegistrar-General con- tain much information as to the connection of mortal- ity from various diseases with temperature. As his reports are quite accessible to sanitarians, I shall not make any further quotation from his calculations. Dr. Ballard concludes,* from a comparative study of the meteorological observations made at Greenwich for * " On the influence of some of the more important elements of weather upon the absolute amount of sickness." — British Medical Journal, June 12, 1869. THE AIR AND HEALTH, 323 the six years from 1860-65, and on the amount of paro- chial sickness in the parish of Islington and in two large metropolitan dispensaries, and in the Pentonville con- vict prison, that — (1.) " Comparative warm weather is more deleterious to public health in the colder than in the warmer half of the year," which is certainly opposed to the general opinion; (2.) In the colder months of the year the mean temperature is, on the whole, much more important as a condition determining the absolute quantity of sickness than the extent of the diurnal range, and that, in these months, the higher the mean temperature the more important is the influence of the range ; (3.) In these colder months a low range is more injurious to public health than a high range, whether the mean temperature be comparatively high or comparatively low, which is a conclusion contrary to the received opinion that an equable temperature is the most favourable to health ; (4.) That in the warmer months of the year the diurnal range of temperature is, on the whole, more important as a condition determin- ing the absolute quantity of sickness than the mean temperature ; and (5.) That, in these warmer months, a high diurnal range of temperature is much more injurious to public health than a low range. The very sensible discomfort and illness in some, induced by sudden and extreme ranges of temperature, must often press itself on the notice of the health officer. The healthy body in the prime of life shows a wonderful ability to adapt itself to extraordinary ranges of temperature, even to differences of as much as 72 degrees. The very young, the aged, the feeble, the sickly and diseased, are generally more or less dis- turbed by the sudden variations of our fickle climate, 324 AIE TEMPERATUEE AND HEALTH. and it is sometimes found almost impossible to pro- vide against the rapid alternations of heat and cold, moisture and dryness, etc., with suitable clothing. As regards the climate of this country it has been recommended : '"' — 1. That no chUd too young to walk or run should be taken out of doors when the external tempera- ture is below 50° T. ; 2. That the rooms in which children live and sleep should never be below 58° F. ; and 3. That the dayroom should be three or four degrees warmer than the bedroom. The relation between certain varieties of coup de soleil or heat apoplexy, as well as other affections, and the indications of solar and terrestrial radiation ther- mometers, is a subject that, if worked at, will probably yield valuable results. B. The Eygrometric state of the Air. The WhUst the air is never without some moisture, the Moisture of , j. • j.i ■ • i i i j. -j. j. the Air. amouut present in the air is largely due to its tem- perature. The capacity for retaining moisture in an invisible gaseous form is greater when the temperature is high than when it is low. For example : — Air of a temperature of 55° D. B., and 50° W. B., contains 3"4 grains of vapour per cubic foot ; and Air of a temperature of 85° D. B., and 80° W. B., contains 9*7 grains of vapour per cubic foot. The aching of rheumatic joints and of corns, the * "The effect of cold on children." — British Medical Jonrrml, December 25, 1875, HYGEOMETEY AND HEALTH. 325 extraordinary noises that sometimes proceed from chairs and tables, and the condition of certain epithelial struc- tures, such as the hair and sldn, are often signs to the public of the approach of rain, all being the result of an excess of humidity in the air, due to the great alter- ations in size which fibrous, epithelial, and ligneous bodies undergo by the addition or subtraction of moist- ure. How cleverly did the great Jenner embody in a few lines of verse " On the Signs of Eain," the effects of this atmospheric change. " Hark ! how the chairs and tables crack, Old Betty's joints are on the rack." The decrease of the pressure of the air which gene- rally accompanies an excessive hygrometric condition has doubtless, however, much to do with the paiuful condition of that old lady's joints. We know but little of the influences of varying degrees of humidity of the air on animal life. It is unquestionable that an excess or deficiency of the normal amount of moisture in the au' exerts a very decided action on the state of the public health. People in health merely feel slightly depressed when the air is rather damp, and somewhat irritable when it is unusually dry, but to invalids even a change of two or three per cent in the humidity is perceptible. An excess is the more pre- judicial, because aqueous vapour possesses a powerful affinity for organic matter, and serves both to preserve and diffuse it. We all of us have frequently experi- enced the enervating effects of fogs and mists, and the return of our usual mental and bodily vigour on their removal. When we remember that all depressing agents predispose to disease, the subject of humidity in relation 326 HYGEOMETEIC STATE OF to hygiene, connected as it is so intimately with, that of climate, cannot be too diligently examined. Insular climates, in the temperate latitudes, are necessarily humid to a certain extent, especially if the temperature is low, "\ATien there is in addi- tion an excessive rainfall, a damp, foggy, and relaxing climate is produced, which often exercises an injurious influence on the health of those unacclimatized to it. The voice of Grassini was reduced nearly an octave by the relaxing effect of the air of this country. Her vocal organs were restored, however, to their normal condition on her return to the drier climate of Italy, The view has been expressed that the degree of moisture of the air is intimately associated with the degree of beauty in the human female, and especially with its duration. The average hygrometric state of the air is but one of the many factors concerned, which, by their union, form the climate of the country, by which the female body is undoubtedly influenced to a considerable extent in its development. Tem- peratm-e unquestionably exerts an effect wliich is per- haps scarcely if at all inferior. Warm moist climates, in the temperate regions of the earth, have been considered to produce more beautiful women, whose beauty endm^es longer than countries possessing dif- ferent qualities of climate. As we leave the tem- perate climes for the sunny south, where development is more rapid, and the period of puberty earher, we notice that female beauty is very evanescent, and is soon on the wane. As the temperate latitudes are left for the nor- thern, colder, and drier climates, there is a coarseness, and want of softness and delicacy which is so characteristic of the women of the south. Modes of life, differences of THE AIR AND HEALTH. 327 race and character, as well as the kind of climate, have, of course, some considerable action on the grace and love- liness of the female. This subject is one of great magni- tude, on which there will necessarily be a divergence of opinion, as the question of taste is very much involved. I only allude to it as one deserving of thought. An excess of aqueous vapour in the atmosphere has not only a depressing effect on the nervous system, but it interferes with the cutaneous and pulmonary exhala- tions. If the temperature is high (65° to 80° E.), saturated air is sultry and oppressive. If low {e.g., a Scotch mist of 36° F.), its chilling influence pene- trates aU clothing. At least one haK of the patients which apply for relief during the winter months to the physicians of the metropolitan and provincial hospitals of this country, are afflicted with colds, coughs, bronchial and rheumatic affections. The prevalence of these dis- orders at this season is, without a doubt, due partly to the coldness, and partly to the excessive moisture of our very changeable climate. Above 80° F., air of excessive humidity becomes injurious ; and it has been doubted as to whether life can be prolonged ia such air at a temperature between 90° F. and 100° F. A very dry air is considered by some as less dele- terious to health than a very moist air. Assistant- Surgeons Lauderdale and Eoss, in a report relative to Fort Yuma, California, write:* — "With the thermo- meter at 105° F., the skin becomes dry and hard, and the hair crisp, and furniture falls to pieces. Newspapers, if roughly handled, break. Eggs that have been on hand for a few weeks lose their watery contents by evapora- tion, and the remainder is tough and hard. A tempera- * Quarterly Journal of Science. April 1878. 328 HYGEOMETEIC STATE OF ture of 100° F. may exist for weeks in succession, and there will be no additional cases of sickness in conse- quence. We kave none of the malarial diseases." Dr. Ballard's'" inferences as to the effect of varia- tions in atmospheric moisture, as represented by the readings of the hygrometer, and the estimation of the rainfall on the public health of a portion of London, are thus given by him : — First. As to the readings of the hygrometer. " 1. That in the colder months of the year the mean tem- perature is, on the whole, more important as a condi- tion determining the absolute quantity of sickness than the amount of accompanying atmospheric moisture. 2. That in the loarmer months of the year, on the other hand, the amount of atmospheric moisture is more im- portant as a condition determining the absolute quan- tity of sickness than the mean temperature. 3. That, both in the colder and warmer seasons of the year, a comparatively dry condition (for the season) of the atmosphere is more damaging to public health than a comparatively moist condition of the atmosphere." Secondly. As to the rainfall. "1. That in the colder months of the year the mean temperature is, on the whole, more important as a condition determining the absolute quantity of sickness than the amount of rain- fall. 2. That in the warmer months of the year the amount of rainfall is more important in determining the absolute quantity of sickness than even the tem- perature. 3. That the amount of rainfall is more im- portant at comparatively low than at comparatively high temperatures, in regulating the absolute quantity of sick- ness, both in the colder and warmer months of the year." * Op. cit. THE AIK AND HEALTH. 329 The artificial cKmates whicli we manufacture in our houses and public buildings are far more deleterious to health than any atmospheric vicissitudes as to moisture. The air of our rooms has a tendency to be preternatur- ally dry, and when so is often oppressive and unwhole- some. The degree of moisture of air is shown by the hygrometer, which consists of two thermometers, one the dry bulb and the other (covered with muslin and attached by a lamp wick to a feeder of water) the wet bulb. The difference between these bulbs is about five or six degrees in a healthful atmosphere. In rooms warmed by radiant heat it reaches often eight degrees ; whilst in rooms heated by hot air a difference of fifteen to seventeen degrees is often noticed, which is unwhole- some and unpleasant. Although so many different kinds of stoves and other appliances, such as hot water pipes, etc., for heating rooms, have been devised, that important point seems nearly always to have been over- looked, namely, the maintenance of a healthful amount of moisture in the air. I have seen pans of water placed on iron stoves to counteract the unpleasant effects caused by the dryness of the air, and have seen the water steaming, and even boiling. In such an apartment there was an excess of moisture in the air which made me feel very uncom- fortable, creating the disagreeable sensation which one experiences on entering the house of a laundress ; the hygrometer in such a case giving a difference of only one or two degrees, showing that the air was almost saturated with watery vapour in an invisible form. The air sometimes becomes almost saturated with the aqueous vapour that proceeds from the pulmonary and cutaneous surfaces in crowded halls or rooms. 330 THE PRESSUEE OF THE AIR Professor Sanders relates * an anecdote, narrated to him by a Kussian of&cer, of the production of a shower of snow that fell on the audience in a concert room by the sudden opening, in very cold weather, of a window, for purposes of ventilation. Even now, when the study of health and the influ- ences which deteriorate and promote it, coupled with the prevention of disease, are the great subjects of the day, rivalling in interest the kindred one of the cure of disease, there seems a complete ignorance or apathy in regard to this subject amongst physicians and leading architects. On recently visiting the completed portion of the New Edinburgh Eoyal Infirmary, which is fitted with all the most approved and recent appliances for heat- ing, ventilation, etc., and which, when finished, will take the place now occupied by St. Thomas' Hospital, London, and the Lariboisi^re in Paris, of the modern pattern hospital, I was astonished to find that no provision whatever existed for supplying moisture to the air dried by the coils of hot water pipes that are seen in so many places. If gardeners were to treat their greenhouse plants thus, healthy life and gTOwth would be impossible. Horticulturists always furnish their hot water pipes with long troughs, filled with water, that rest on the pipes, and thus maintain an artificial climate, closely resembling that to which the plants have been accustomed, in which air is enabled to lick up as much water as its temperature will permit. C. The Pressure of the Air. The There is a strong popular belief that old wounds, in- Pressure of the Air. * Handbucli der offentlichen Gesundheitspflege. AND A STATE OF HEALTH. 331 juries, diseased bones, and rheumatic joints are the seat of discomfort, or even pain, on the approach of a storm, which, speaking generally, means in this country a sudden decrease of at least ^ inch of the mercurial column. Eichardson and others tell us that when the body is exposed to low barometric pressure there is a tendency to exudation of fluid from wounded sur- faces, a feebleness in the healing of wounds, a suscepti- bility to disturbance in the body generally, and a proneness to the production of secondary fever by the absorption of discharges which have undergone some decomposition. The outcome of these facts has been the establishment of the law that no important sur- gical operation should be performed when the baro- meter is low, or when it is steadily falling. The principal effect of diminished pressure of the atmos- phere is distension of the capillaries. We all recognize, as one of the exciting causes of apoplectic seizures, a rapid diminution of atmospheric pressure producing a sudden capillary engorgement. Mr. Wood, of King's College Hospital, introduced the question in the British Medical Journal in the spring of 1872, as to why cases of joint disease are invariably worse during the warm, moist days of winter ? It was curious that his attention should have just at that time been particularly called to the connection, for the pressure of the air in London had been less early in that year than had been noted for nearly 30 years. Indeed, it was stated, on the authority of the editor of the Meteorological Magazine, that only on two occasions during the present century had the barometer been so low as on January 24th, 1872. An exacerbation of the symptoms in cases of joint disease may be due to low barometric pressure, 332 THE PRESSUEE OF THE acting in a manner which may be thus explained : — In the solid, inelastic articular expansions of the bones, which are surrounded by firm inextensile textures, forming the joints, the minute nerves, shown by Kolliker and others to permeate the cancellous and compact structures in company with vessels, are pressed by these vessels, when enlarged, against the unyielding walls of the channels through which they pass. Although the nerves of bones do not generally afibrd healthy individuals any conscious sensations, yet, in diseases of the joints, the bones, when congested or the seat of inflammation, become painful. Tissues, not supplied with rigid canals like bone, yield to pressure during any temporary increase in the si^e of the minute vessels. In such tissues, vascular distension, from a diminution of the pressure of the air, is unassociated with pain, because the nerves accompanying the vessels are uninterfered with. Low barometric pressure and an excess of humidity of the air offer conditions most unfavourable for the removal of heat by evaporation and radiation from a congested or an inflamed joint. Teeth, which have a nutrient system very similar to that possessed by bone, become painful when the pressure of the air is suddenly lessened, for the same reason. The nerves of the tooth being in a morbid condition from caries, are temporarily irritated by the capillary enlargement. How is it that joints which are not diseased ache when the barometer is low ? I am not aware that this occurs in the young and healthy. Experience teaches us that old rheumatic people often complain of this symptom. Such persons, whose joints are not in a perfectly healthy state, are generally worse AIK AND HEALTH. 333 during damp weather, in consequence, I presume, of imperfect elimination by the skin, and of the lowering of the vitality of parts (whereby the action of a morbid condition is favoured), — changes undoubtedly induced by the meteorological conditions, the effects of which we have been considering. It has for a long time been held that iacreased atmospheric pressure artificially applied exercises an anoemiating and compressing action in the peripheric tissues; that it diminishes the frequency of the pulse and the calibre of the small vessels gene- rally, thus increasing the obstacles which the vascular walls oppose to the current of blood from the heart. The haemorrhages and peripheric congestions observed in aeronauts, and the opposite facts noticed in divers and miners, are in this mechanical manner accounted for. M. Vivenot states that this diminution of the vessels may be seen on the conjunctiva, on the ear of the rabbit, and on the vessels of the retina, and that rarified air produces contrary effects (Virchow's Archiv. 1866). M. Bert, in recent numbers of the Comptes Bendus, and Forlanuai, ''^ have impugned the correctness of this view, and state that the calibre of the capillaries does not undergo change under the action of compressed air. The therapeutic employment of compressed air, which is given at a pressure of from 1 to 1 atmospheres, in bronchitis and other affections, is now a recognized mode of treatment at some places, as, for example, at Ben Ehydding, in Yorkshire, and at some establishments on the Continent. The physiological effects are said to be the following : — 1. Augmentation in the ampli- tude of the inspirations ; 2. Diminution in the number of respirations in a given time ; 3. Prolongation of the * Gazzetta Medica Italiana, Lombardi, March 31st, 1877. 334 AIR-PRESSURE AND HEALTH. expiratory act ; 4. Gradual augmentation of the capa- city of the lungs ; 5. Superoxygenation of the blood, increased activity of the organic combustion, and eleva- tion of temperature. The effects of diminished pressure of the air are an increase in frequency of the respiratory and circulatory acts, and a reduction of the activity of the nutritive processes, as shown by the amount of urea eliminated. The subject of the effects on health of changes in. atmospheric pressure, '"' should be more clearly ascer- tained, and it offers a wide and encouraging field for exploration. The stumps of amputated limbs appear to be very sensitive to meteorological vicissitudes. Persons vsdth these painful stumps sometimes get into a morbid and hysterical state of mind ; and in their prospective study of their discomforts, this hypersesthetic condition gives rise to fanciful imagmary ideas. It is the experience of those who have the care of the insane, that a sudden and great decrease in atmos- pheric pressure is generally accompanied by an in- creased excitability, more apparent amongst some forms of mental disease than others. Attacks of neuralgia and other nervous maladies seem often to recur during the fall of the barometer, especially when this culminates in rain. Dr. Weir Mitchell gives the following result of his observations on this connection between the neuralgic attacks in a painful stump of a Capt. Cathn, U. S. A.f "It was * The observations of M. Bert on" Barometric Pressure," in recent Nos. of the Comptes Rendus, should he perused. Vide also Effets Physiologiques et Applications TMrapeutiques de I'Air Comprimi, by Dr. J. A. Fontaine, 1877. t American Journal of the Medical Sciences, April 1877. AIE-PEESSURE AND HEALTH. 335 rather the fact of a storm, or the disturbance of pres- sure, that induced, or at least accompanied pain, than its depth, duration, or extent." The number of hours during which neuralgia was endured was greater in the spring and autumn quarters than during the summer and winter. He writes, " The amount for spring, which is in America the season of greatest depression of health tone, when choreas return, and epilepsies are difficult to control, but little exceeds the autumn pain crop." This army officer noticed also that his neuralgia was apt to prevail when the northern lights were intense. As auroras are generally followed by storms this coincidence is not improbable. Dr. Mit- chell adds, " A still more valuable and novel conclusion has arisen out of the study. Every storm, as it sweeps across the continent of America, consists of a vast rain area, at the centre of which is a moving space of greatest barometric depression, known as the storm centre, along which the storm moves like a bead on a thread. The rain usually precedes this by 550 to 600 miles, but before and around the rain lies a belt, which may be called the neuralgic margin of the storm, which precedes the rain about 150 miles. This fact is very deceptive, because the sufferer may be on the far edge of the storm-basin of barometric depression, and seeing nothing of the rain, yet may have pain, due to the storm. It is some- what interesting to figure to oneself thus a moving area of rain girdled by a neuralgic belt 150 miles wide, within which, as it sweeps along in advance of the storm, there prevail in the hurt and maimed limbs of men, and in tender nerves, and rheumatic joints, renewed torments called into existence by the stir and perturbation of the elements." 336 DIEECTION OF WIND AND HEALTH. The Direction of the Wind. D. Tlie Direction of the Wind. West and north-west winds are considered more favourable to health than south and south-west winds, which are generally warm and soothing to invalids, and others with an irritated pulmonary surface. North and north-east are not considered unfavourable to health, and are generally enjoyed by those who are robust. East winds are proverbially deleterious, except to the strong and healthy, by reason of their coldness and dryness. East winds have been especially connected with the production of neuralgic affections, and the moist warm relaxing winds from the south-west have to a less extent been blamed. Dr. W. Mitchell found that of 50 cases of ampu- tation of limbs less than half felt unusual sensations upon the coming of or during an east wind. Of the rest, two-thirds insisted on their power to predict such a change of weather, but said they were unaffected by a thunderstorm or by rain coming from the south. Dr. Ballard's observations, to which allusion has already been made,""'' lead him to believe that westerly, southerly, and south-westerly winds, are associated with a larger amount of sickness than northerly and north- easterly winds. No .of Sum of Sickness in Mean. Weeks. new cases. w.s.s. 2 984 497 s.w. . 103 48,550 471 w. 7 3273 467 N.W. 5 2312 462 N. 3 1382 460 Var. 47 21,660 460 N.E. 33 14,952 453 KN.E. 4 1790 447 O^y. cit. SEASONAL METEOROLOGY AND DISEASE. 337 CHAPTEE XXXI. 2. THE METEOROLOGICAL CONDITIONS WHICH APPEAR TO FAVOUR OR RETARD THE DEVELOPMENT OF CERTAIN DISEASES. 1. Surgical fever and shock after operations. 2. Small pox. 3. Measles. 4. Whooping cough. 5. Scarlet fever. 6. Fever. i Diarrhoea. Dysentery. Cholera. 8. Bronchitis, pneumonia, and asthma. 9. Phthisis. 10. Hsemorrhages, apoplexy, abortion, neuralgia. 11. Hydrophobia. 12. Erysipelas and puerperal fever. 13. Insanity. 14. Rheumatism. 1. Surgical Fever after operations. — Dr. Richardson surgical shows '""■ that there are differences in the mortality of g^^^^ certain diseases which are attended by fever or incre- ment of animal heat during the several seasons of the * "On Meteorological Readings in relation to Sui'gical Practice." — Medical Times and Gazette, January 29tli, and February 5tli, 1870. Z 338 METEOROLOGICAL CONDITIONS WHICH FAVOUR year. He found, from an analysis of 139,318 deaths from all diseases, during the years between 1838 and 1853, that the mortality from three of the diseases of this class, held the following proportions : — First Quarter. Jan. Feb. March. Second Quarter. April, May, June. Third Quarter. July, Aug. Sept. Fourth Quarter. Oct. Nov. Dec. Scarlet Fever . 20-809 18-978 26-234 33-976 Erysipelas 25-144 23-444 22-337 29-174 Carbuncle 29-771 19-685 24-409 29-133 He points out that the last quarter is the central quarter of the year in which these diseases are most fatal, and that December is the centre of a period of seven months which commences in September, during which there is occurring in the animal organism a marked modification in the nutrition, as compared with the five remaining months from April to August. '''' Admitting that whenever there is any considerable increase of the animal temperature, there is danger, unless there be established a compensation by radiation and specially by evaporation of water from the body, we find that the fourth quarter of the year is more distinguished than the other quarters for those meteor- ological conditions which are most unfavourable to equalization of heat by evaporation and radiation, namely, low barometric pressure, excess of humidity of air, and a temperature low, but not low enough to com- * Mr. Milner's experiments on the weight of the body during the various months of the year amongst the convicts at Wakefield, led him to the following conclusions : — 1. The body becomes heavier during the summer months, and the gain varies in an increasing ratio ; 2. The body becomes lighter during the winter months, and the loss varies in an increasing ratio ; 3. The changes from gain to loss, and the re- verse, are abrupt, and take place about the end of March and the beginning of September. . OE EETAED CERTAIN DISEASES. 339 pensate for increase of heat by arrest of oxidation or by abstraction of heat. Dr. Eichardson has accordingly drawn up certain rules for the guidance of surgeons in the performance of operations which will admit of delay, until natural conditions arise favourable to operative work, whereby surgical fever, which often creates such fatality, may be prevented. The time is favourahle for operation — {a) When the barometer is steadily rising. (h) When the barometer is steadily high. (c) When the wet bulb thermometer shows a read- ing of five degrees lower than the dry bulb. {d) When, with a high barometer, and a difference of five degrees in the two thermometers, there is a mean temperature at or above 55° Fahr. (e) When the wind is west or north-west. The time is unfavourable for oferation — (a) When the barometer is steadily falling. (6) When the barometer is steadily low. (c) When the wet bulb thermometer approaches the dry bulb within two or three degrees. id) When, with a low barometrical pressure and approach to unity of reading of the two thermometers, there is a mean temperature above 45° and under 55° Fahr. (e) When the wind is south or south-west. Dr. A. Hewson has published"'' the results of the observations made in the Pennsylvanian Hospital by * Pennsylvanian Hospital Reports, vol. ii. 1869, 340 METEOROLOGICAL CONDITIONS WHICH FAVOUR the surgeons, on the relation between certain meteoro- logical conditions and the mortality after surgical opera- tions. They agree in the main with the conclusions of Dr. Eichardson, and elicit the additional fact that death from surgical " shock " is associated with a high barometrical pressure and a dry air, conditions opposite to those accompanying fatal pyaemia. Dr. Hewson writes, " We obtained a mortality, when the operation was performed with the barometer ascending, of 10"7 per cent, of 20*6 per cent with it stationary, and 2 8 '4 per cent with it descending." smaUpox. 2. Smallpox has been found by Dr. Ballard* in Lon- don, and by Dr. Wistrand in Sweden (in which country there is a registration of disease), to prevail more from November to May, than from May to November. The former physician noticed that it has assumed an epidemic form soon after the mean temperature of the air has persistently fallen below 50° for the winter season, and has begun to decline in May, when the mean temperature of the air begins to rise above this line, and gives place to higher temperatures. The curve for smallpox in London for a period of Smallpox — for all Ages and both Sexes. Jan. Feb. March April May June July Aug. Sept. Oct. Nov. +50 p. ct. J:i I I I 1 I J 1 1 1 I III III 1111 111 I 1 [ I II I I III MI Mean Line. —50 p. ct. thirty years (1845 to 1874), represented in Mr. Alexander Buchan's and Dr. A, Mitchell's interesting * Medical Times and Gazette, March lltK and 13th, 1871. OE EETARD CERTAIN DISEASES. 341 research on The Influence of Weather on Mortality from Different Diseases and at Different Ages, endorses these views. ■ The dotted line represents the mortality from which that of the abnormally high epidemic of 1870-72 has been withdrawn. This abstraction has simply reduced the sensitiveness of the curve. The straight black line in this and in the following figures containing curves, indicates the mean weekly death rate on an average of 52 weeks. The curve, as it rises above and falls below the straight black Kne, represents the average death rate of each week, calculated in per centages of the mean weekly death rate for the whole year. Dr. Moore has confirmed these observations in Dublin, where a well-marked tendency to an epidemic was noticed in March 1871; but the disease appeared to be kept in check by the increasing temperature, notwithstanding the importation from England of many cases, until, with the advancing autumn it blazed into an epidemic. He has also noticed'"'' that abundant rainfalls seemed to be followed by remissions in the severity of the epidemic, and that the acme of the epidemic closely followed a period of comparatively dry weather and lower humidity. 3. Measles. — Sydenham, in his medical observations, Measles, states that cases of measles are generally most numerous towards the end of March, and that they then gradually decline in number and disappear by midsummer. The observations of Dr. Eansome and Mr. G. V. Vernon would indicate roughly that measles increases with a fall and diminishes with a rise of temperature ;t that * Manual of Public Health for Ireland. \ " On the Influence of Atmospheric Changes upon Disease." — Proc. Lit. Phil. Soc, Manchester, vol. i. Series 3, 1859 to 1860. 342 METEOEOLOGICAL CONDITIONS WHICH FAVOUE barometric pressure fluctuates more when it is prevalent than when it is not rife ; and that the period of its re- currence is about every five or six years* This disease, which prevails especially during the spring and summer quarters of the year, would seem, according to the observations of Drs. Moore,t Ballard, | and others, to be unfavourably influenced by a temper- ature of the air above 60° in summer, and to be checked by a fall of temperature during winter below 42°. Its mortality is governed by other influences than those of a meteorological nature. Cseteris paribus, measles would seem to be more destructive amongst those who live in total disregard of all hygienic rules than amongst those who obey the laws of health, and to be more fatal to native tribes amongst whom the disease has been previously unknown. The recent severe epidemic in the Fiji Islands affords a fresh proof of the truth of this last-mentioned statement. The measles curve, representing the fatality in Lon- Measles — for all Ages and both Sexes. Dec. -1-50 p. ct. Mean Line. — 50 p. ct. D 1 I 111 111 don from this disease, is remarkable, according to Mr. Buchan and Dr. A. Mitchell, in showing a double maxi- * "Epidemic Cycles." — Brit. Med. Journal, Sept. 1, 1877. + Op. cit. t Eleventh Report of the Medical Officer of the Privy Couucil, 1868, No. 3, pages 54-62. OR EETAED CERTAIN DISEASES. 343 mum and minimum during the year, a rapid fluctuation taking place from Christmas to the middle of February, when the weekly deaths fall from 42 to 21. 4. Whooping Cough. — Extremes of heat and cold whooping appear to affect not only the prevalence of this disease, ^°"^^- but much more so its mortality. It generally seems to progress hand in hand with measles, increasing with a falling and diminishing with a rising temperature. During the hot weather of summer it is rarely heard of; and during the period when the cold, dry, east winds blow in spring, it is generally most fatal amongst the insufficiently clothed and ill fed. "We usually re- gard it as a winter and early spring disease. Dr. Moore thinks that intense cold checks the disease^ whilst moderate cold favours its spread. The London curve for thirty years agrees pretty closely with these views. Whooping Cough — for all Ages and loth Sexes. Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. ) p. ct. I) 1 1 1 1 1 M !J_ -^ 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ' 1 ■ C an Line. - N ^ p. ct. J 1 1 1 1 1 1 1 II 1 1 1 1 1 1 ill! " N 1 ! 1 1 i 1 >rTr TTT 1 1 1 I 1 1 L Kg. 38. 5. Scarlet Fever. — Sydenham considered that this scariet . Fever. disease appears most frequently towards the end of summer. 344 METEOEOLOGICAL CONDITIONS WHICH FAVOUR r F. Temperature. Humidity. Pressure. Authority. Moderately Excessive. Sudden fluc- low. tuations. -►J PI a O U. Above the Diminished pressure. Dr. Ransome. average. F. Between 56° Not above t and 60°. 86, or much ^ less than 74. • F. When it rises s fe much above 50°. fe" U. A fall of mean tem- perature below 50° in autumn. Dr. Moore. The Eegistrar-General of England has noted a tendency in the mortality from this disease to increase in London during the last six months of the year, attaining a maxunnm in December. Dr. Moore has observed it always to be most prevalent and fatal in Dublin during the last quarter of the year. Dr. Wistrand considers that this disease is most prevalent in Sweden in November, and least so in August. The habits of the people have much to do, doubt- OR EETARD CERTAIN DISEASES. 345 less, with the determination of the particular time of the year, when the impact of the disease is most felt. My own experience teaches me that it increases with a rising temperature, spreading like wildfire in very hot weather in agricultural villages, during the times when children congregate together, as, for example, during hay-making, pea-picking, gleaning, hop-picking, and school fetes ; and that this highly infectious disease spreads in towns and cities in very cold weather amongst the poor, who, with their scanty supplies of fuel, huddle together for mutual warmth, diligently closing every chink whereby fresh air might possibly enter their overcrowded dwellings. The thirty years' curve for London would, accord- ing to Mr. A. Buchan and Dr. A. Mitchell, show the maximum death-rate to occur from the beginning of October to the end of November (when the mean tem- perature of the air of London is 48*2, and its relative humidity is 85), and the minimum to be in March, April, and May (during which months the mean tem- perature of the air of London is 4 7 '3, and its relative humidity is 77). Scarlatina — for all Ages and both Sexes. +70 p. ct. Mean Line. Sept. Oct. Nov. Dee. ' P- ct. b 1 1 III! Fig. 39. The curves of whooping-cough and scarlet fever 346 METEOEOLOGICAL CONDITIONS WHICH FAVOUK Fever. form striking contrasts, the maximum for whooping- cough and the minimum for scarlet fever both occurring in spring ; whilst whooping-cough reaches its minimum in autumn, when scarlet fever is at its maximum. As to the cycle of scarlet fever, Dr. Eansome has noted ''^ that a small wave has appeared about every five years, and a great wave every fifteen or twenty years. ( Typhus. 6. Fever. — < Enteric. (^ Intermittent and continued. Typhus, according to most observers, is only in- directly influenced in its prevalence by temperature. When the weather is very cold cases are generally more numerous, because the overcrowding and the defective ventilation of the dwellings of the poor is worse than usual. The height of an epidemic has occurred in some instances during hot weather (as, for example, in Glasgow during July 1847). Jan. +40 p. ct. n I r Mean Line. 40 p. Ct. LI 1 Typhus — for all Ages and both Sexes. (Bloxavi's MetJiod) .f March April May I 1 il II 1 I 111 1 I 1 ] I [ I Fig. 40. ill 111 i 1 I I III I I 1 II II LJ Mr. Buchan and Dr. A. Mitchell remark respecting * Op. dt. t This metliod of dealing with, the percentages in laying down the curves is convenient in arriving at an approximately true average when a small number of years are available, as in the case of typhus and typhoid figures (for which diseases figures extending over six years OK EETAED CEETAIN DISEASES. 347 tlie London curve — " It is probable that this curve has two maxima, the larger in the early months of the year, and the smaller in the height of summer," Enteric. — Autumn is generally considered the season Enteric or par excellence for the development of this disease, hence pgYer*^ it has been called in America " autumnal or fall fever." It would be more correct to call it a late autumn or winter-autumn fever, and diarrhoea a summer-autumn complaint. It has been noticed to be more prevalent after dry and hot summers than after those which are cool and wet. Warm, damp weather, in autumn and winter, when there is much decomposition of vegetable matters, is favourable to an outbreak. Heavy rains, by cleansing the air and the drains, is unfavourable to its appearance, except when filth is washed by these downfalls into the wells. The London curve for tjrphoid fever resembles Typhoid Fever — for all Ages and both Sexes. {Bloxavi's Method). Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. +40 p. ct. D I I III I I I I III 111 II I I III III I I II Mean Line. —40 p. ct. that for scarlet fever as to the period of its maximum death-rate, but the minima of these two diseases widely differ in character from one another, only are obtainable), or when few deaths occur from any particular disease, such as gout or ague. The method consists in assuming the average, for instance, of the second week of January, to be not the actual average of that week, but the average of the iirst, second, and third weeks ; the average of the third week is assumed to be the aver- age of the second, third, and fourth weeks, and so on. 348 aiETEOEOLOGICAL CONDITIONS WHICH FAYOUK Intermittent Fever ^= Ague. — The popular idea in aguish districts that outbursts of this disease generally occur when sudden changes of weather, from hot to cold or the reverse, take place, and especially during the prevalence of a dry east wind with a scorching hot sun, is interpreted by the knowledge that we at present possess, as to the tendency of such meteorological in- fluences to conduce to the congestion of the liver, the spleen, and other internal organs. r Diarrhoea. 7, ■< Dysentery. ( Cholera. Diarrhma. — The following memoranda have been offered to the profession by Dr. Eansome * respecting these two diseases : — A mean temperature above 60 predisposes to this disease when continuous, causing a rapid in- crease in the number of cases. A temperature below 60 appears to be unfavourable to its progress. Dysentery. — This disease seems to be increased by a high mean temperature and diminished by a low mean temperature, but to be influenced by variations of temperature to a less extent than diarrhoea. High readings of the barometer are nearly always accompanied by diminished prevalence of dysentery. Dr. Moffat has expressed the opinion that, as regards simple diarrhoea, there is a decrease in the pressure of the air and an increase in the force of the wind on the days on which diarrhoea occurs, and to a less extent on the days after its occiuTence. * Op. cit. OE KETAED CEETAIN DISEASES. 349 Dysentery, Diarrhoea, and Cholera — for all Ages and hath Sexes. Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. +500 p. ct. +300 „ +200 „ 350 METEOEOLOGICAL CONDITIONS WHICH FAVOUR Cholera. ChoUro,. — The history of past epidemics has gene- rally taught uSj with but two or three exceptions, that the mortality from this disease usually increases until September, when it reaches its maximum, after which it begins to decKne. A sudden diminution in the extent of its ravages is often ushered in by some great natural cleansing process, such as a storm of wind, or hea\y downfall of rain, or sudden descent of tem- perature diminishing decomposition of organic matters. The London curves for these diseases show the close relationship that the progress of mortality from them bears to temperature. The speed at which they suddenly increase during the hottest weeks of the year, and rapidly decline on the fall of the thermometer, is very striking. The dotted line. Cholera, No. 1, indicates the fatality from Asiatic Cholera. The line not dotted. Cholera No. 2, represents simple or British cholera. The maximum and minimum of diarrhoea is seen to be a month earlier than the maximum and minimum of dysentery. Mr. Buchan and Dr. A. Mitchell point out that the four curves seem to group themselves in pairs — diarrhoea and British cholera on the one side, and dysentery and Asiatic cholera, which pass through their annual phases a month later, on the other. BroncMtis, g. BroncMUs, Pueumonia, and Asthma. — These Pneumonia, i • n andAstiima. discascs are greatly mnuenced by mean temperature. They increase in prevalence as the temperature falls, and diminish as it rises. The London curves strikingly exemplify this fact. The percentages of the mean weekly death rate at different ages are — OR EETAED CERTAIN DISEASES. 351 From Bronchitis. 1-5 I 5-20 I 20-40 AGES. 40-60 I 60-80 Above 80 I Total. 38 17 34 6 100 From Fneitmonia. 61 j 6 I 10 I 13 I 9 I 1 I 100 Broncliitis is thus seen to be most fatal to children under 5 years, and to the old; whilst pneumonia, although specially fatal to children below this age, is of rare occurrence amongst the aged. Bronchitis, Pneumonia, and Asthma — for all Ages and hoth Sexes. Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. + 130 p. ct. The principal maximum of pneumonia in November- December, is chiefly determined by the large number of deaths amongst children under five years, whilst the secondary maximum occurs in March. Dr. William Squire does not apparently recognize the existence of two maxima, but contends that the annual maximum of pneumonia, unlike that of bronchitis, is always in spring. 9. Fhthisis Fulmonalis. — This disease destroys, on Phtwsis an average, 148 individuals in London every week, 352 METEOEOLOGICAL CONDITIONS WHICH FAVOuxi and its fatal assaults are directed against those in the prime of life, differing in this respect entirely from bronchitis. Fhthisis — for all Ages and loth Sexes. +30 p. ct. Mean Liue. — 30 p. ct. Jan. -| I I b 1 1 Feb. I I I I I March. I I M I I I 1 April I I I I I I May I I I I I 1 June I I I I nil Fig. 44. July 1 I I I I 1 Aug. I I I I I Sept. I I I I I 1 Oct. I I I I I I Nov. I I I Hsemorrha- 1 0. HcBmorrliages, Apoplexy, Ahortion, and Neuralgia. ttontnd^' — I^ consequence of the statements of Dr. Moffat as Neuralgia, to the important effects produced by fluctuations of atmospheric pressure on these diseases, Dr. Eansome made an enquiry into the matter, from which he drew the following conclusions, which were embodied in a paper read by him before the Manchester Philosophical Society : — * 1. That a high degree of barometric pressure is favourable to the production of neuralgias, less evidently so to apoplexies and other hsemor- rhages, and that abortions are not shown to be aftected by it ; 2. That increasing readings of the barometer are as frequently accompanied by cases of these diseases as decreasing readings ; 3. That a small extent of diurnal oscillation of the barometer seems to be favourable to neuralgias, no effect on haemorrhages being traced to this source. Hydropho- bia. 11. Hydroplio'bia. — The hot " dog days" of summer * " On Atmosplieric Pressure and the Direction of the Wind, in Eelation to Disease, especially Hemorrhages and Neuralgias. " OK EETAED CERTAIN DISEASES. 353 are generally considered to be those during which this disease is most prevalent, and this ancient belief is justified to some extent by facts, although we must remember that it shows itself to be independent in its spread of a high temperature, as the following curve of the mortality in London during 30 years proves. Eydrojphohia — for all Ages and both Sexes. Feb. March April May June July Aug. Sept. Fig. 45. The number of cases in December is there seen to be as numerous as those in August. More persons are doubtless bitten by dogs in hot weather, because dogs are more irritable during this season. We want an answer to the query as to the percentage of cases of hydrophobia in those who are bitten in each month of the year, before we can determine with certainty the influence of meteorological conditions on the disease. 12. Erysipelas and Puer;peral Fever. — The curves of Erysipelas. mortality for 30 years in London from these two diseases, wonderfully resemble each other, and are highly suggestive of a more intimate relationship between them than is generally conceded. Erysipelas— foi' all Ages and both Sexes. Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. +40 p. ct. R" 1 1 i 1 M 1 1 1 1 1 1 1 1 1 II 1 1 1 1 1 t 1 II 1 1 1 1 'W K"a i^ A^ f\ r -^, rJ \/- —40 p. ct. :i 1 1 1 II II II I 1 1 1 1 1 F It 1 1 g. 46. 2a 1 1 i 1 1 1 1 1 II 1 1 1 1 1 1 1 1 1 L 354 METEOKOLOGICAL CONDITIONS WHICH FAVOUR Puerperal Fever. Puerperal Fever or Metria — for all Ages. {Bloxam's Method). Jan. Feb. March. April May June July Aug. Sept. Oct. Nov. +50 p. ct. n I I Mean Line. —50 p. ct. D I Ll i M Dec, I 1 Fig. 47. Insanity. 13. Insanity. — The London curves for diseases of the nervous system are interesting. That of insanity may be taken as a sample of the others. Insanity — for all Ages and both Sexes. (Sloxam's Method). Jan. Feb. March April May June July Aug. Sept. Oct. Nov. +40 p. ct. p^l 1 Mean Line. —40 p. ct. L' Dec I I Rheuma- tism. This curve shows three maxima, the largest being in December and January, the next in June, and the least marked in March and April. 14. Eheumatism. — Eheumatic fever was said by Sydenham to be most common during the autumn. The London curve does not confirm his view. Eheumatism — for all Ages and both Sexes. Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec +40 p. ct. n I ; Mean Line. —40 p. ct. U I I I I I I 1 1 IN Ml Ml I I I I M Fig. 49. OR EETAED CERTAIN DISEASES. 355 Sub-acute rheumatic affections of joints would seem to be more uncomfortable to their possessors when the barometer is low, and the air is warm and moist, and chronic cold rheumatic affections of the aged, in whom the skin is inactive, are apparently benefited by this " muggy " condition of the air. Both kinds of rheum- atic joints are incommoded by a sudden diminution of pressure and perhaps by a low atmospheric pressure. — Vide page 331. The curve of pericarditis closely resembles that of Periear- rheumatism, as every medical man would of course conjecture. Pericarditis — for all Ages and both Sexes, (BlooMm's Method). Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. -30 p. ct. i;;^! i ] [ean Line -30 p. ct. D 1 I 1 1 I i I ] I I II Before concluding this sketch of the influence of meteorological conditions on mortality, it would be in- structive to consider briefly : — (1) The influence of weather on the mortality at different ages ; and (2) The influence of weather on the mortality of the two sexes, as shown by curves of Mr. Buchan and Dr. Mitchell, for the 30 years period in London 1845 to 1874. The most striking fact exhibited in Fig. 5 1 is. Mortality that the large excess of mortality in summer is due to the deaths amongst children under one year, which is shown by the enormous development of the diarrhoea curve. The months of June and September are seen at different 356 METEOEOLOGICAL CONDITIOiSrS WHICH FAVOUE to be those attended by least infantile mortality. The deaths from respiratory diseases during the winter and spring months are shown, by the maintained excessive height of the respiratory diseases curve at those seasons, to be enormous in young childi^en. The mortality curve at the opposite end of life, in persons upwards of Mortality at different Ages, for both Sexes and all Causes. Jan. Feb. March April May June July Aug. Dec. 80, appears to be a very simple one, having its maxi- mum in cold and its minimum in warm weather. Cold and heat are the great destroyers of the infant life, and cold and not heat of the aged in London. Mortality of The period of the year when females have a higher death rate than males is when diseases of the respira- «y tory organs are most fatal, and the period when females OR RETARD CERTABT DISEASES, 357 have a lower death-rate than males is when diseases of the nervous system are most fataL Deaths of each Sex from all Causes — Males being represented by the solid line, and Females by the dotted line. Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec. The curve of the mortality of each sex consists of three distinct portions, a^ c(? the respiratory disease mortality ; h h the nervous disease mortality, and c the intestinal disease mortality. The respiratory disease mortality during the commencement of the year, a^, js higher than that of the end of the year, after undergo- ing this excision, because it is held up by the two maxima of the nervous disease mortality. Nearly the whole of the intestinal affection mortality is created by the death of infants under one year. If we could diminish the mortality to any considerable extent from these three kinds of disease, namely, the respiratory, the nervous, and the intestinal, the curve of mortality would become very much flattened and approach in appearance the curve of old age. Here the end gene- rally comes, it would seem, from some respiratory affec- tion, fig. 53. 358 SEASONAL METEOROLOGY AND DISEASK Old age. +50 p. ct. Mean Line. Old Age — for both Sexes. Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Hi —50 p. ct. D I I III I I I I III III 11)1 Ml III I I I I 111 111 II Fig. 53. No more space can be allotted for the consideration of the relations of atmospheric states and conditions of the air to disease, as it is necessary to describe the mode of observing meteorological variations according to the most recent and approved methods. MODE OF OBSEK"\aNG CONDITION OF THE AIE. 359 PAET IV. MODE OF OBSERVING THE METEOROLOGICAL STATES AND VARIATIONS IN THE CONDITION OF THE AIR. In commencing a series of meteorological observa- tions, it is necessary to know the heiglit above the sea of the place of observation. This is readily found by making a search for the nearest bench mark of the Ordnance Survey, and ascertaining by a rough estimation, or by the help of a surveyor and his spirit level, the difference between the level of that bench mark and the station where our instruments are exposed. As the publi- Fig- ^^^ cations of the Ordnance Survey are not readily accessible, it will afford me much pleasure to give any applicant the height of any bench mark. The hours of observation that are best, if two ob- servations are taken daily, are 9 a.m. and 9 p.m. 360 THE ATMOSPHEEIC PEESSUEE. CHAPTEE XXXII. 1. THE ATMOSPHEEIC PEESSUEE. Barometers. Theee are thiee principal classes of barometers — the syphon, the aneroid, and the cistern. The wheel baro- meter, so common in the passages and haUs of houses, is an example of the first class, and is useless for all scientific purposes. The aneroid is not a thoroughly- reliable instrument, unless checked frequently by means of a good mercurial barometer. It varies very much in excellence according to the sMll and delicacy of workmanship bestowed on it. Fortin's cistern baro- meter is the instrument for the scientific man. The bulb of its attached thermometer should always enter the cistern. A long strip of white porcelain, fixed to the board at the back of the scale, facilitates accuracy of reading. There are three points to be remembered in making an observation with one of these instru- ments, and they should be attended to in the order in which they are mentioned. Firstly. The temperature of the attached ther- mometer should be noted and recorded. Secondly. The screw at the base of the cistern should be adjusted until the point of the ivory cone visible within it meets the reflec- tion of the same that is seen on the surface of the mercury. A piece of looking-glass placed THE ATMOSPHEEIC PKESSUEE. 361 at the back of the cistern is a great aid to the observer in dull weather. c ■! s 1 \\e '''' t LEVEL OP MERCURY a. Interior of cistern. h. Mercury. c. Tube containing mercury. d. Ivory point fixed to top of cistern. «. Reflection of same, seen on surface of mercury. /. Screw for elevating or lowering the level of the mercury in the cistern. Thirdly. The vernier should be adjusted so that its lower horizontal edge forms a tan- gent to the convex curve of the mercurial column, and not an arc to that curve. There are corrections to be considered in making barometrical observations, namely, those for index error, capacity, and capil- larity, furnished by the certificate of verifi- cation from the Kew Observatory, which should accompany every good instrument ; the correction for height above mean sea level ; and the correction for temperature. Three simple arithmetical calculations have then to be made for every reading. (a.) Correction of Kew certificate. Fig. 56. 362 THE ATMOSPHERIC PEESSUEE. (b) Eeduction to mean sea-level. (c.) Eeduction to 32** Fahr. Application Tables are published by the help of which both of tions'^r' these reductions are accomplished easUy and rapidly.* readings. Vide Appendix. For example : — Observed reading ... . 29*900 Kew correction ..... —•01 5 29-885 Deduct temp, correction for 68° F. (attached therm.) and 30 inches . . . . --106 Reading at 32° F. . . . . 29779 Correction for height (350 ft.), the air, as shown by dry bulb therm., being 50° F. . . +-380 Observed reading corrected and reduced to 32° F. at mean sea level .... 30"159 Adie's barometers are useful instruments, in which allowances are made for the capillarity and capacity errors in their construction. There are two kinds, one adapted for a house or observatory, and the other, the marine variety, which will work efficiently when exposed to the motion of the ship. In making an observation with an Adie's baro- meter, it is simply necessary to read the height by the help of the vernier, and apply to the observed reading the necessary corrections for height and temperature. Mode of YhA exact height of the column of mercury is read reading. ° •' thus : — In Fig. 5 6 the zero of the vernier is on a level with the line indicating 29|, so we record of it 29-50. * A lengthy barometric table for the reduction of observations to the mean sea level has been published by E. J. Lowe of Nottingham. THE ATMOSPHEEIC PEESSUEE. 363 30 If the zero of the vernier and the scale occupy such relative positions as are sketched in Fig. 5 7, we read the barometer to one thousandth of an inch in this way : 1. We see that the reading is somewhere between 29 and 30, so we write down 29. 2. We perceive that the zero of q the vernier is on a level with a part of the scale somewhere between 1 and 2 tenths, counting upwards, and that it is more than 1 1 or *! 5, so we write down 29*15. 3. We then glance down at the subdivisions of tenths on the scale and on the vernier, in order to discover which sub- division of the scale lies in one and the same straight line, with a subdivision on the vernier. In the accom- panying example we perceive that this takes place at the line on the vernier just above figure 3, namely, at "034, which, when added to the scale reading 29*15, equals 29*184, which we call the observed reading. With a little practice barometer readings to the 1000th of an inch ° ^ f ^f 1 °f *^' ^^^'^ " ^ scale of the barometer, can be taken with the greatest ease and a b is the sliding T • ^•^ scale or vernier. and rapidity. It is occasionally desirable to ascertain whether the 29 c Fig. 57. 364 THE ATMOSPHEEIC PEESSURE. space above the mercurial column is devoid of air. By gently inclining a barometer, so as to allow the column of mercury to strike against the top of the tube, a sharp metallic click should be heard. If such a sound is not audible, air is present where a vacuum should exist. If the air cannot be expelled by inverting the barometer, it should be taken to an instrument maker. THE TEMPEEATUKE OF THE AIE. 365 CHAPTEE XXXIIL 2. THE TEMPEEATUEE OF THE AIE. The thermometers required are the following : — The dry bulb thermometer of Mason's hygro- ihermome- meter, described on page 379^ furnishes the tern- *®'^' perature of the air in shade. A mercurial maximum self -registering thermometer, for indicating the highest temperature reached by the air in the shade. I prefer the pattern made by Negretti and Zambra, but those of other makers are very good. The maximum tempera- ture of the twenty-four hours generally occurs about 3 P.M. A self-registering minimum thermometer for record- ing the lowest temperature of the air in shade. Many attempts have been made to manufacture mercurial minimum thermometers — (a) Because in spirit minimum thermometers there is a ten- dency to the evaporation of the spirit, and a con- densation of it at a distance from the column, and to the breaking up of the column into dis- tinct portions ; (h) It would be desirable, if possible, to employ the same fluid mercury for registering minimum temperatures as that for recording maximum and other temperatures. 366 THE TEMPERATURE OF THE AIR. Casella's mercurial self-registering minimum ther- mometers are most beautiful instruments, but cannot be recomimended for general use, as they require the most delicate manipulation, and they cannot, it appears, be made so as to stand wear and tear. I have had one in use for many years, and it has never once been deranged in its action, but it was selected from amongst many. Negretti and Zambra have sold for years a mer- curial minimum thermometer with a bulb of very large dimensions. This firm has, I believe, improved upon it, and recently patented another, which I have not yet seen or tested. The extra-sensitive self -registering spirit minimum thermometer of Casella, with a forked bulb, is an excellent instrument. If the column of spirit should happen to separate, it can be reunited by taking the thermometer in the hand farthest from the bulb, and giving it one or two sharp swings. The thermo- meter should then be hung in a slanting position, so as to allow the rest of the spirit still adhering to the sides of the tube to drain down to the column. If this method of restoring union is unsuccessful, gentle heat should be applied very carefully to the end of the tube where the detached portion of the spirit is lodged, so as to drive it towards the column. The minimum temperature of the twenty-four hours generally occurs some time before the sun rises. The mean Xhc mean temperature is calculated by taking the ^empera- a,verage of the maximum and minimum readings, which is so near the true mean as to be practically correct. It is almost as important from a public health point Its daily of vicw to uote the daily range of temperature as to observe the extremes to which the temperature occa- sionally reaches. The mean daily range of tempera- ranse. THE TEMPEKATUEE OF THE AIR, 367 ture is obtained by deducting the average daily maxima from the average daily minima temperatures. The thermometers which have been adverted to Themome- being employed to indicate the temperature of the air ^'^ ^ ^^ ^' in the shade, it is necessary, if we would obtain correct information, to protect them from the sunlight, wet, etc., whilst at the same time permitting the freest access of air. Accordingly, cases, called thermometer stands, of which there is a great variety, are employed, in which the instruments are suspended. There are Lawson's, ■^'* Glaisher's,t Martin's, | James', | Morris', j| Stevenson's, II Griffith's, IF Stow's, IF Welsh's Kew stan- dard,'"''"" Pastorelli's,'"'"''" and the Meteorological Society's stand. The last named, which appears to be the outcome of an investigation into the relative merits and demerits of all the existing thermometer stands, most resembles Stow's, but is superior. Fig. 58. * Described in Met. Mag., Oct. 1868, page 127. + Described in Met. Mag., Nov. 1868, page 155, i Described in Met. Mag.., Dec. 1868, page 169. § Described in Met. Mag., Dec. 1868, page 170. II Described in 3fet. Mag., Jan. 1869, page 187. H Described in Met. Mag., Feb. 1869, pages 1, 2, 3, and 4, ** Described in Met. Mag., March 1869, pages 17, 18, and 19, 368 THE TEMPEEATUEE OF THE AIE, {a a a a) The uprights, 1|- by f inch, serve for the suspension of the maximum and minimum ther- mometers. LONGITUDINAL SECTION Fig. 59. (b) Piece of thin board 1 inch thick, against which Mason's hygTometer is fixed. It stands in the centre of the interior at an equal distance from the front and back of the stand. I have three of these stands, and have but three faults to find with this form, as originally proposed, two being easily removed, and the third being appar- ently inseparable from every ther- mometer stand that has yet been devised. The side boards were not sufficiently thick and strong, and the most external board that forms the roof is apt to warp unless made of a hard, very well-seasoned wood, or of greater thickness. An external coating of canvas rather increases the mischief. In the above design these defects have been rectified. The irremedial evil is, that when the wind and rain blows against the front of the stand from the north Fig. 60. THE TEMPEEATUEE OF THE AIE. 369 or south, the thermometers are liable to receive a wetting. Thermometer stands should always be fixed in an open place, far away from buildings and trees, so as to face due north, and so that the bulbs of the thermometers shall be at a distance of exactly 4 feet above the ground. 4. Solar Maximuin Radiation Thermometer. — Com- soiar Maxi- parative observations with solar radiation thermometers have been in the past distinguished for their discre- pancy, due in part to imperfect construction of the instrument, and partly to the want of uniformity in mounting and observing it. The most modern and best thermometer of this class has its bulb, and one inch of its stem of a dull black. Its jacket is provided at each extremity with a platinum wire to test by the aid of a Euhmkorff's coil the degree of rarefaction of the air. If the interior of the jacket be perfectly clean, free from moisture, and sufficiently ex- hausted, a pale white phosphor- escent light, with faint stratifi- fications and an appearance of transverse bands will be visible. Mr. Stow has drawn up the following suggestions for ob- servers, which have been almost universally adopted : — 1. Adjust the instrument four feet above the ground in an open space, with its bulb directed towards the S. E. 2b Fig. 61. It is 370 THE TEMPERATUEE OF THE AIE. Terrestrial Minimum. necessary that the globular part of the exter- nal glass should not be in contact with, or very near to any substance, but that the air should circulate round it freely. Thus placed, its readings will be affected only by direct sunshine, and by the temperature of the air. 2. One of the roost convenient ways of fixing the instrument, will be to allow its stem to fit into and rest upon two little wooden collars fastened across the ends of a narrow slip of board, which is nailed in its centre upon a post, steadied by lateral supports. 3. The difference between the maxima in sun and shade is a measure of the amount of solar radiation. It has been found that solar radiation attains its maximum in most parts of the country during May, and its minimum during December, and that it is greater on the western than on the eastern side of England.'" 5. Terrestrial Minimum Thermometer. — The spirit minimum with a bifurcated bulb, exactly similar to the minimum thermometer for shade temperatures, with a * Vide " Solar Radiation 1869-74," by Rev. F. W. Stow, in Quar- terly Journal of Meteorological Society, October 1874. THE TEMPEEATUEE OF THE AIE. 371 substitution of a jacket for protection in place of a porcelain scale and hard wood back, is an excellent instrument. This therniome'ter is exposed on grass which is kept closely cut, and should be surrounded by some arrangement for protecting it from dogs and other animals. A circular wire-fence, similar to that de- picted in Fig. 63, is the best with which I am acquainted. The obscurity produced by a condensation of moist- ure within the jacket, and the destruction of the material employed for rendering the divisions on the stem dis- tinct from the same cause, have sorely troubled observers in the past. Fig. 63. As received from the instrument maker a terrestrial minimum thermometer is generally attached to its jacket by a stuf&ng of strips of india-rubber. Many remedies have been proposed. A packing of chloride of calcium, or of putty and sealing wax, or a bored cork painted over on its exterior with 2 or 3 layers of asphalte, or an air-tight ground joint. Some have bored a hole at the closed end of the jacket, and others have discarded the jacket altogether. I would recommend that this last named plan be adopted, or that a bored india-rubber cork be employed, painted externally with several coats of asphalte, or 372 THE TEIIPERATUEE OF THE AIK. Verification of Thermo- meters. that the thermometer be fitted to the jacket like a stopper to a bottle. In either case the markings on the stem should be rendered indelible, in the manner described on page 376. Every thermometer should be numbered and gradu- ated on the stem, and should be verified by comparison with standard instruments. A special department at the Kew Observatory occupies itself with the verification of meteorological instruments, charging a small fee for the labour. No one should buy a thermometer or barometer unless it is provided with a recent certificate of the verification of the same. Proof of the Necessity for the Verification of Ther- mometers. — The inaccuracies in the readings of ther- mometers, which render a verification of all a necessity, are due partly to the difference in the diameter of the bore throughout their entire length, which defect appears to be inseparable from their manufacture, and partly to the tendency which thermometers have to read higher from age. It is sometimes difficult indeed to find two thermome- ters, out of a large number, that read exactly alike. Here is a certificate of verification from the Kew Observatory, which belongs to a thermometer in my possession : — At 32° ... 0-0 42° 52° 62° 72° 0-0 + 0-1 —0-1 + 0-1 N.B. — When the sign of the correction is -f- the quantity is to be added to the observed scale reading, and when — to be subtracted from it, ■ THE TEMPEEATURE OF THE AIE, 373 They may in truth be likened to human faces, for scarcely two are to be found very closely resembling one another. Dr. Prior, of Bedford, in a paper on " The Thermometer in Disease," read before the South Midland Branch of the British Medical Association in 1867, relates an experiment of comparison which he made with five thermometers, three of them being medical instruments. He placed them all in water at a temperature of 105° or 106°, and allowed it gradu- ally to cool. The result is here given in his own words : " No two of them precisely corresponded at any time." A mercurial maximum thermometer was some time ago purchased by one of my friends, of each of the most eminent meteorological instrument-makers. They were compared together, and all found to differ from each other. Mr. Alexander Buchan states * that he recently com- pared a number of first-class high-priced thermometers, every one of which was from 1*2° to 1*7° too high. Some thermometers have been offered to the public with the assurance that " every instrument is carefully verified by a Kew standard thermometer;" which simply means a well-made thermometer that has been verified at the Kew Observatory — one, in fact, whose errors are known. A thermometer which had been thus verified has recently been sent by me to this observatory. The certificate returned with it contained the following cor- rections : — At 90° . . . — 0-2 „ 95° . . . —0-2 „ 100° . . . —0-1 „ 105° . . . — 0-0 * Randy Booh of Meteorology. Blackwood. 1867. 174 THE TEMPEEATUEE OF THE AIE. Another thermometer sent out by a different maker is in my possession, which was " guaranteed accurate in its indications, having been compared, degree by degree, with a standard thermometer verified at Kew." It is about '4 of a degree in one part of the scale, and •5 in another part, higher than is correct. Here is the certificate of a third thermometer, which was supposed to be perfectly accurate before returned from the Kew Observatory : — kt 85" . —0-3 „ 90'' . — 0-4 „ 95° . —0-5 „ lOO'' . —0-4 „ 105" . —0-4 It is not by any means an easy matter to verify thermometers with precision. The verification can only be satisfactorily conducted by means of instruments specially adapted for the purpose, such as are to be found in the great observatories. It should be done, moreover, with the greatest care, by men who are accustomed to the work. The following memoranda, which were published in a paper * read before the British Medical Association in 1869, may be advantageously repeated: — (a.) Mercurial thermometers which are two or three years old are always to be preferred. (b.) No instrument should be purchased without a certificate from an observatory of its recent verification. Mercurial thermometers are liable to read higher than is correct through age ; and this change especially * " Eemarks on Clinical Thermometers. "- Gazette, Oct. 16, 1869. -Medical Times and THE TEMPEEATUEE OF THE AIE. 375 occurs during the year or two immediately succeeding their period of construction. The bulb having been formed by the action of heat, undergoes contraction after its manufacture, the fibres of the glass taking some little time to assume their permanent position. Hence it has been usual amongst some makers of meteorological instruments to lay down their ther- mometers, like their port, for improvement with age, before engraving the scale on their stems. " By quite a recent discovery in the manufacture of these instru- ments," writes one who sells thermometers, " the glass bulb of the thermometer is reduced to its ultimate degree of contraction before the stem is diAdded, thus obviating the necessity of keeping the tubes filled for the space of one or two years before dividing them, and rendering it possible to make an absolutely accu- rate instrument in a week." With the object of ascer- taining the truth of this statement, I made a careful examination of one of these thermometers, and dis- covered that it was incorrect. Its readings were about two-fifths of a degree too high, , The verification of a two or three-year-old mercurial thermometer at an observatory should not be relied on as a guarantee of the perpetual accuracy of an instru- ment. The authorities of the Kew Observatory conse- quently append to their certificates the following amidst other notes : — " This instrument ought, at some future date, to be again tested at the melting-point of ice, and if its reading at that point be found different from that now given, an appropriate correction ought to be applied to all the above points." The markings on the stem of thermometers which Markings of indicate the degrees and parts of degrees, are exceed- T^Smo-°^ meters. 376 THE TEMPERATUEE OF THE AIR. ingly apt to crumble away and disappear after but a short exposure to the air, for the reason that instru- ment makers do not know of a durable composition with which to form them. The markings of the divi- sions may be replaced by the observer in either of the following modes : — The stem of the thermometer having been thoroughly cleansed by scrubbing it with an old tooth-brush dipped in a mixture of strong aqueous caustic soda and methy- lated spirit in equal proportions, is washed with water and dried. Silicate of soda is mixed with water suf- ficient to produce a syrupy solution. A little of this fluid is mingled with some lampblack, so as to form a paste, which is brushed over the divisions as a coating. The thermometer is rolled between a flat piece of wood and a strip of cardboard, so as to remove all of the black coating from the stem except that which fills the grooved lines of the divisions. By means of another brush dipped in the clean syrupy solution, a coating of this artificial glass is rapidly spread over the whole of the stem of the thermometer, which is then allowed to dry. Some mix with the syrupy solution of sodic silicate some common precipitated manganic dioxide, to which a little lampblack has been added. Others smear over the scale of divisions on the stem some compound of lead, converted into a paste with a solution of silicate of soda. The paste which does not fill the lines is rapidly removed by rubbing the stem of the instrument between two smooth sur- faces. The divisions containing the paste are then brushed over with a Kttle ammonium sulphide, which forms with the lead the black sulphide of lead. THE HYGROMETEIC CONDITION OF THE AIE. 377 CHAPTEE XXXIV. 3. THE HYGROMETEIC CONDITION OF THE AIE. The hygrometric state of the air is determined by Moisture of — 1st. An estimation of the amount of water which ^y i^^^. reaches the earth in the form of rain, hail, snow, and ^^auge, Hy- fog ; and 2d. A consideration of the indications of the and spec'tro- hygrometer, an instrument for determining the amount ^°''p®- of aqueous vapour present in the air, near the surface of the earth. The amount of moisture in the higher and distant strata of the atmosphere may be roughly indicated by the degree of development of the atmospheric lines of the solar spectrum, close to D, on its red side and c^, as seen by a simple waistcoat-pocket spectroscope.* The degree of humidity of the air is affected by many circumstances — such as direction of the wind, temperature, season of the year, distance from masses of water, and configuration of the land over which it lies. Eelative humidity at Halle, found by Kamtz,t as a mean of several years' observations, during each month of the year, and for each wind : — * An article, entitled " Rain-Band Spectroscopy," by Professor P. Smyth, in tlie Trains. Scottish Meteor. Sac, Nos. 51-54, contains some information on this subject very useful to those who have not worked at the spectroscope in connection with meteorology. + Cours Complet de M4t6orologie, p. 92. 378 THE HYGEOMETEIC CONDITION OF THE AIE. Jan. Feb. Mar. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 85-0 79-9 76-4 71-4 69-1 69-7 66-5 61-0 72-8 78-9 85-3 86-2 In Halle December has most liiimid air, and August the driest. N. 78-5 S. 73-6 N.E. 77-5 S.W. 74-8 E. 73-0 W. 74-4 S.E. 74-8 K.W. 76-5 Rain Gauge. A Bain Gaiige, quite good enough for all practical purposes, can be purchased for about half-a-guinea, the glass measure, which is divided into ^-^ths of an inch, being included. It should be fixed, by means of four or more wooden stakes, firmly into the ground, so that its sum- mit is 12 inches above the surface. The farther removed the site is from buildings and trees the bet- ter. It should always be as far from a neighbouring object as that object is high. Snow should be melted be- fore it is measured. Printed directions for making observations gener- ally accompany these in- struments. Any informa- ^^ tion as to the estimation of ^'' the rain is freely given by Mr. Symons, of Camden Square, London, who is at the head of all rainfall regis- tration in this country. The form for the registration is to be found in the Appendix. Eain Gauge. Fig. 64. THE HYGEOMETEIC CONDITION OF THE AIE. 379 Dr. French, the late Medical Officer of Health for Liverpool, was strongly impressed with the beKef that there is an inverse ratio between the rainfall and the amount of mortality from infantile summer diarrhoea. If this disease is dispersed, or rendered less virulent by an excessive rainfall, it is often superseded by catarrhal and rheumatic affections, which, although less mortal, are often exceedingly intractable, and sometimes lead to serious results. The amount of aqueous vapour present in the air is determined by instruments called hygrometers, of which there is a great variety. Eeynault's and Mason's hygrometers are generally Hygro- preferred ; but, as the working of the former instrument ^^ ^^^' with ether and an aspirator is troublesome, the latter has almost entirely supplanted it in every-day practice. It consists of two verified thermometers, fixed side by side ; the bulb of one being kept always damp by a covering of muslin connected with a little reservoir of dis- tilled water by means of a lamp wick. Great mistakes are commonly made in the adjustment of the muslin, lamp wick, and water reservoir. I have seen a hygro- meter in the observatory of a Philosophical Society with the wet bulb arranged in the manner here depicted : Mason's Hygrometer. Pig. 65 The Improper Mode. The Proper Mode. Bulbs of Mason's Hygrometers. 380 THE HYGROMETRIC CONDITION OF THE AIR. In the first sketch the wet bulb is smothered in wet muslin, to which is attached a piece of lamp wick as large as one's little finger, whilst close below the bulb is an open vessel full of water. Every provision would seem to be made here for producing an artificial local dampness of air around the bulb, and for rendering it simply impossible that the thermometer should really furnish us, by indicating the temperature of an evapor- ating surface, with the true hygrometric state of the air in the neighbourhood. The finest muslin, which generally contains starch, should be boiled in distilled water to extract it. Lamp wick should be boiled in distilled water and a little carbonate of soda to remove all grease. The smallest thread of lamp wick that will keep the muslin per- manently damp should be employed, and the little reservoir of water should be fixed away from the bulb, so as not to create a local artificial climate. The first drawing represents the ignorant and care- less use, and the second drawing the intelligent employ- ment, of the hygrometer. The hygrometer is fixed against a thin board that occupies the centre of the thermometer stand. Like the other shade thermometers it should face the north. If the air is saturated with moisture there is Kttle, if any, difference between the readings of the dry and wet bulb thermometers. The readings of the wet bulb are, as a rule, lower than those of the dry bulb ther- mometer. The generally accepted statement that the greater the difference between the dry and wet bulbs, the less is the amount of watery vapour present in the air, requires some qualification. An increase of temperature, by expanding the air, THE HYGROMETEIC CONDITION OF THE AIR. 381 and thus separating the particles farther from each other, increases, whilst a fall of temperature, hy draw- ing them closer together, diminishes the capacity of the air for moisture. Air of a temperature of 5 7 "2 dry bulb, and 51 wet bulb, with a relative humidity of 64, may contain exactly the same amount of vapour in grains per cubic foot (3-4), as air of a temperature of 70-5 dry bulb, and 56*8 wet bulb, with a relative humidity of 42. The semi-diurnal rise of temperature is more frequently accompanied by an increased capacity of the air to absorb moisture, than an actual increase in its amount. The relative humidity of or percentage of moisture in the air, is afforded by reference to a table in the Appendix. '"'' One of the best, if not the best, hygrometer for popular use, as it requires no tables and calculations, is one that was designed by Mr. Lowe of Boston, U.S., and is employed in France. It is especially adapted for the sick room, as it can be easily managed by an intelligent nurse in accordance with the instructions of the physician. Fig. 66. It consists of two thermometers precisely alike, the bulb of one being dry and the other kept always moist. On the inner side of the dry bulb scale is a third scale, on which two indices move up and down. In the central portion of the lower part of the hygro- meter is a screw head with a pointer attached to it. * The fullest information as to the use of Mason's hygrometer, and the calculation of the dew point, etc. , is to be found iu James Glaisher's Hygrometric Tables, adapted to the dry and wet bulb thermometers. 3d edition. Taylor and Francis, Fleet Street, London. The tables prepared by William Bone, which are obtainable from Negretti and Zambra, are also useful. 382 THE HYGROilETRIC CONDITION OF THE AIR. By the help of the vertical, oblique, and horizontal lines the relative humidity, dew point, and elastic force of vapour of the air may be seen at any moment at a Fig. 66. glance. The instructions as to the mode of working the instrument are thus given in the Meteorological Magazine of December 1877 : — Lowe's " (1) I^ead the dry bulb thermometer and raise the Hygrometer, screw head in order to set the upper index on the extra scale at the dry bulb temperature; (2) read THE HYGEOMETKIC CONDITION OF THE AIR. 383 the wet bulb, and turn the screw head until the lower index is at the wet bulb temperature. The extremity of the long hand will then point to {a) the relative humidity ; (b) the dew point ; and (c) the elastic force of vapour, according as one reads the vertical, oblique, or horizontal lines." The only objection to this instru- ment is that very common one which has already been adverted to in referring to Mason's hygrometer, as to the position of the reservoir of water, etc. This defect can, of course, be easily removed. 384 THE DIRECTION AND STRENGTH OF THE WIND. CHAPTEE XXXV. 4. THE DIRECTION AND STRENGTH OF THE WIND. Anemo- meters and Pressure Plates. The direction of the wind is easily ascertained by noting the movements of the lowest stratum of clouds. Upper strata of clouds are sometimes to be seen travelling in opposite direction to those in which the lower are moving. The strength of the wind is estimated by its velocity or pressure. Instruments named anemometers are employed to register its velocity, and pressure plates its force. The belief of meteorologists in anemometers has suffered a rude shock by the investigation made by the Eev, Fenwick Stow, on a simultaneous comparison of the behaviour of different anemometers."'" He dis- covered that the results were discordant, and that the indications of the only instrument which comes within the reach of the purses of most of us, namely, Eobinson's cup anemometer, are very fallacious. Pressure plates are open to several objections, and are generally costly contrivances, arranged with vanes, so as to keep the surface of the plate always at right angles to the flow of the wind. The cheapest and simplest which I have seen is one * " On Large and Small Anemometers. " — Quarterly Journal of the Meteorological Society, April 1872. THE DIEECTION AND STEENGTH OE THE WIND. 385 that has recently been introduced by Mr. Thomas Stevenson, which can be obtained for 24s.'"" Fis;. 67. A is a wood box, -| inch thick, attached to the top of a stake fixed in the ground, which turns with the wind on a vertical axis. & is a small disc, fixed on a light brass tube, ^ inch in diameter, which rests on two brass rollers. B is a larger disc, fixed on a light brass tube, ^ inch in diameter, which rests on two brass rollers. When acted on by the wind the brass spring S is lengthened, the maximum elongation being recorded by a fine thread attached to the rod, which is pulled through a small hole in a brass plate (t) fixed to the side of the box. The rods are graduated by weights, each division corresponding to the elongation of the spring, due to a weight of 1 ounce. "To ascertain the maximum elongation that has taken place in the observer's absence, press the thread against t, then push in the disc until the part of the thread which had been drawn through the hole in i! is * Scottish Meteorological Journal, July 1874-July 1875, p. 266. 2c 386 THE DIRECTION AND STRENGTH OF THE WIND. again drawn ' taut,' and read off the result from the graduated tube." Pressure in lbs. per sq. ft. Remarks. July 3 2-54 4 • 7-50 Stormy winds witli sudden gusts. 5 3-44 7 1-05 8 •80 31 ■62 Aug. 1 1-54 2 12-00 Weather described in news- paper as a heavy gale.' When the disc is 6 inches, the factor for reducing the divisions (due to pressures of 1 oz.), to the stand- ard of lbs. to the sq. ft. is . '318 Do. 3 do. do. . 1-273 Do. li do. do. . 5-09 This variety of pressure gauge has been constructed for storm stations with one disc of 3 inches diameter, and the other 11 iuch, but admitting of a 6 inch one being put on at any time when the winds are light. One great objection to these, as to almost all other wind pressure plates, is, that they only move in a hori- zontal line. Supposing the wind to descend upon them, or ascend towards them, in sudden gusts, they do not feel and therefore cannot register its force. Table for J havc bccu in the habit of employing the accom- mate offeree panying table (extracted from Buchan's Meteorology) for of wind. many years, and think it can hardly be improved upon as a guide to the formation of a rough estimate. The scale is to 6, representing a calm, and 6 a hurri- cane, a violence of wind which is unknown in this country. THE DIEECTION AND STEENGTH OF THE WIND. II 5 • 'it 2 Si > Popular Designation. ri li "it i * ^^ ■ |E. > PopiUar Designation. 0-0 0-1 0-5 1-0 1-5 2-0 2-5 0-00 0-01 0-25 1-00 2-25 4-00 6-25 0-0 1-4 7-1 14-1 21-2 28-3 35-4 Calm. Lightest breath of air. Very light air. Light air. Light breeze. Fresh ,, 3-0 3-5 4-0 4-5 5-0 5-5 6-0 9-00 12-25 16-00 20-25 25-00 30-25 36-00 42-4 49-5 56-6 63-6 70-7 77-8 84-8 ■ Very fresh. ) Blowing \ hard. Blowing a gale. Violent gale. Hurricane. 388 THE ELECTRICAL STATE OF THE AIR. CHAPTEE XXXVI. 5. THE ELECTRICAL STATE OF THE AIR. This subject may be discussed under two beads : — (1) As to the mode of collecting atmospheric elec- tricity; (2) As to the mode of determining its kind, whether positive or negative, and its tension. Mode of (1.) Mode of collecting atmospheric electricity. collection. tt • j • t ^ i i i Various contrivances nave been employed — such as an insulated metal point ; a kite ; a pole, ynth an insulated pointed wire, or bundle of copper wires, or conducting ball on its summit, connected by an insulated wire with an electrometer ; a rod with a burning fuse or match ; a copper tube, with an oil lamp always burning attached to its extremity ; an insulated can of water, with a fine discharging tube dropping minute quantities of water through the air;"*'^ baUoons with wire coverings ;t a spirit lamp on an insulated stand ; a gas jet, so con- structed that it cannot be extinguished by the wind ; etc., etc. The insulated can of water is, of course, useless in frosty weather, and troublesome when it is desired to * A description of this may be found in Deschanel's Natural Philo- sophy, by Professor Everett, part 3, page 604. + Nouveau ProciM pour Etudier L'Mectrieite Atmospherique, par M. Monnet. Published by the Societe des Sciences IndustrieUes de Lyon. THE ELECTKICAL STATE OF THE AIK. 389 make observations at different places ; otherwise the water dropper is a most convenient apparatus. Sir Wm. Thompson employs for travelling, in con- nection with his portable electrometer, blotting paper steeped in a solution of nitrate of lead, dried, and rolled into matches, which are attached to a brass rod project- ing from the instrument. (2). Mode of determining its kind, whether positive Determina- or negative, and its tension. w ^id^ The electrical condition of the air has been most tension. frequently determined in the past by the employment of an electrometer, which is figured in almost every meteorological work and catalogue of instruments. It therefore needs no description, beyond stating that its essential parts are gold leaves and a brass rod two feet long, with a lighted fusee composed of nitrate of lead to collect the electricity. As a glass rod, when rubbed, produces ^positive, and a stick of sealing wax, when thus treated, negative electricity, and as all bodies similarly electrified repel each other, whilst those oppositely elec- trified attract one another, the custom has been in employing this instrument to apply the excited sticks in turn, in order to ascertain the kind of electricity with which the gold leaves diverge. It will indicate the presence of the electric fluid on almost any fine night, and will show by the aid of the rod of glass or wax the positive or negative character of it, but the intensity of the same is not referable to any accurate scale. It is now almost abandoned for investigations as to the electrical condition of the atmosphere. The only instruments with which I am acquainted that are of any service in these delicate investigations as to the 390 THE ELECTKICAL STATE OF THE AIR. nature and tension of atmospheric electricity are Sir "William Thompson's portable electrometer/'' Messrs. Elliott and Co.'s modification of Thompson's quadrant electrometer, Peltier's electrometer, f Lament's electro- meter, and Palmieri's electrometer. Thompson's port- able electrometer is easily managed, but if it is once out of order, or has been neglected, is almost hope- lessly ruined. Its price is £10 : 10s. Elliott and Co.'s TJieWceferDrcppiTrff CoUecfor A. The needle -with mirror. B. The Leyden jar. C. Electrode in commtmica- tioa with body to he tested. C Electrode ia connection, with the earth. D. Cop- per vessel containing water. B. Brass pipe, with tap, tapered to discharging orifice. F. Glass stem. G G. Pumice moistened with Bulphuric acid. H H. Brass case lined with gutta percha. 1 1. Section of wall. modification of Thompson's quadrant electrometer is not at all portable, but is cheaper, being £5 : 5s. It * Obtainable in this country from James White of Glasgow. t Both obtainable from Messrs. Elliott and Co., 112 St. Martin's Lane, London. THE ELECTEICAL STATE OF THE AIE. 391 requires a collector wMch, if an insulated can of water, costs an extra three guineas. Some excellent drawings of the former or the portable instrument are to be found in Noad^s Students' Text-Book of Electricity, pages 466 and 467 and in DeschaneVs Natural Philosophy, by Professor Everett, part iii. page 593. The latter has nowhere, to my knowledge, in conjunction with the in- sulated can of water collector, been delineated. Peltier's electrometer has been employed for more than 30 years at Brussels by M. Quetelet, and is described in the Annuaire Meteorologique de France, 1850, p. 181. Palmieri's electrometer is hardly known in this country, but is valued iu Italy, Austria, and France. M. Branly's modification of Thompson's electrometer is also employed by the French. The medical officer of health who contemplates making a special study of this subject, and it affords in relation to health and disease a boundless field for research, which has up to the present time been scarcely cultivated, would do well to acquire a prac- tical familiarity with the principal electroscopes, elec- trometers, and distinguishers that have been at various times in use. He will find the works of Saussure and Schlibler, of Quetelet, ''''' Lamont, f Duprez, Thompson's reprint of papers on electrostatics and magnetism, and the bulletins of the Observatories of Kew and Green- wich, of service. They contam records of the annual, seasonal, monthly, and diurnal changes in the electrical condition of the atmosphere of great value. A com- * "Observations des Phenomenes Periodiques, " extracted from Memoires de I'Academie Jiayal de Belgique, vol. xxix. t " Entnommen aus dem Jahresberichte der Mlxnclmer Stern warte, page 72, und aus dem vii. Bande der Annalen der K. Stemwarte zn Bogenhausen bei Miinclien. " 392 THE ELECTEICAL STATE OF THE AIE. parison between the monthly electrical observations at different observatories in relation to the development of atmospheric ozone is to be found in Ozone and Antozone, page 6 7, etc. M. Mascart's TraiU de VMec- triciU is a book which will be also found useful by the student. The quality of the electricity present in the air is ascertained by obser^dng the attraction or repulsion of the needle. If the jar is charged positively, the needle will be repelled when a positive charge is in the air, and attracted by a negative charge. It is not easy to charge the jar exactly to the same potential. To obtain accurate quantitative results from exami- nations of the electrical condition of the air requires some practice and skill. The insulated cans are constructed so as to run for twenty-four hours. It should be remembered that the proximity of houses, trees, etc., will influence the read- ings of the electrometer very much indeed. ]\Iedical officers of health might very fairly be excused from attempting to deal with a subject which is confessedly a very difficult one, seeing that the officials at the Kew Observatory are continually ia trouble with their atmospheric electrical apparatus, were it not that health officers are moraUy, if not legally, bound to neglect the study of no influence which is likely to affect the public health. Some one has said very truly that a man must be a brave one indeed who ventured in the present day to attribute any morbid or incomprehensible action to electrical influence, as the whole subject of electricity has suffered so much from the hands of the teachers of THE ELECTEICAL STATE OF THE AIE. 393 popular science. Just as the old-fashioned medical man ascribes aU obscure affections to that much-abused viscus, the liver, so every phenomenon which could not be readily explained has in the past been attri- buted to electricity, and its first cousin, magnetism. The observations made at the Kew Observatory tend to show that the atmosphere always contains free elec- tricity, which is positive in far the great majority of cases at a certain height above the ground (at 5 feet on flat ground). Out of 10,500 observations made during the years 1845-1847, only 364 showed the presence of negative electricity. In damp or rainy weather it is occasionally negative. The lowest stratum of air close to the earth's surface generally furnishes negative electricity. Quetelet, who carried out a series of observations at the Observatory of Brussels from 1844 to 1848, only observed the elec- tricity to be negative twenty-three times, and these exceptional indications either preceded or followed rain and storms. Beccaria recorded a negative state of the atmosphere only six times during a period of fifteen years. It has always been accepted as an article of belief that positive electricity, like ozone, is never to be found in a dwelling-house. "We now know that both can be detected in rooms, although the latter is soon used up, unless the windows are open, or some efficient system of ventilation exists. Sir William Thompson, by means of his delicate instru- ments, has shown that either positive or negative elec- tricity may be carried even through narrow passages from one room to another by air. 394 THE ELECTEICAL STATE OF THE AIK. Registration of Meteorological Observations. Begistration There IS a great variety of registers for recording tions!^'^^^' nieteorological phenomena, but they do not teach the eye much, unless arranged in the form of curves. Per- haps the most useful is that represented at the end of Ozone and Antozone, or the meteorological diagram of observations made at the Kew Observatory, which appears in the Times once a week. SECTION III. SANITAEY EXAMINATION OF FOOD, THE PUEITY OF FOOD. 397 CHAPTEE XXXVII. THE PURITY OF FOOD. It will be observed that the eighth duty {vide page 4), which especially relates to the examination of food, simply imposes on the medical officer of health the obligation, when required, of delivering an opinion as to whether any given sample of either of the three great solid necessaries of life, namely, flour, meat, and vegetables, is or is not injurious to health. On the wholesomeness of these substances the health of the great mass of the public, to a large extent, depends. That teas are faced, to give them a bloom, with ferrocyanide of iron, considered by the majority of physicians to be deleterious to health ; that ales are salted to make customers more thirsty; that nearly every sherry is plastered ; that fusel oil is a frequent accompaniment of raw spirits ; that sugar often con- tains iron and sand ; that preserved vegetables are frequently coloured with copper ; that lemonades, beer, and porter not uncommoidy contain lead ; that tea is weighted with iron, and weakened with leaves of the thorn and other plants ; that butter is sometimes made without cream; that coffee is adulterated with rotten figs, which have been roasted and ground to powder ; that ports are manufactured at chemical works : — are 398 THE PURITY OF FOOD. all facts whicli are now pretty well known to the pnb- Kc, who have the remedy in their own hands. Not one of these articles is a necessary of life, and therefore does not fall within the scope of the work laid down by law as devolving on the medical officer of health. INSPECTION OF ANIMAL FOOD OF MAN. 399 CHAPTEE XXXVIII. INSPECTION AND EXAMINATION OF ANY ANIMAL INTENDED FOR THE FOOD OF MAN. The possession bj tlie medical officer of health of some knowledge of the diseases of animals is of great value to him, not only in guiding him in the formation of an opinion which may be required of him as to the whole- someness of their flesh for food, but as opening out to him a field which has hitherto been barely worked as to the relation between certain diseases of man and those of his humble associates. The writings of Gam- gee, Fleming, and Williams, will be found to be of great service to those who are engaged in the study of veterinary medicine. It is wise to take every oppor- tunity that offers of making oneself conversant with the diseases of animals, and of encouraging the performance of post-mortems in all doubtful cases. During my studies, cases of cattle plague, pleuro- pneumonia, typhoid fever in pigs, foot-and-mouth disease, splenic apoplexy and other forms of anthrax, glanders, fever of a puerperal description following parturition, ringworm, hydrophobia, distemper, etc. etc., have come under my notice. It is only for the medical officer of health to look out for samples of these maladies, and many chances will present themselves in rural dis- tricts of making a practical acquaintance with them. 400 IXSPECTIOX AND EXAMINATIOiST OF AJSTY ANIMAL The diseases of live stock in their relation to public supplies of meat may be summarized in the following manner :- * 1. Contagious Fevers. 2. Anthracic and Anthracoid diseases. 3. Parasitic Diseases. 1. Contagious Fevers. (ft) Epidemic Pleuro-pneumonia or lung fever, peculiar to horned cattle ; (&) Aphthous fever, or foot-and-mouth disease (murrain), which affects horned cattle, sheep, and swine ; (c) Smallpox of sheep (Variola ovina) ; {d) Cattle plagTie (Einderpest, Typhus Con- tagiosus). 2. Anthracic and Anthracoid Diseases = milz BRAND of German pathologists. They prevail as epidemic diseases localized in par- ticular sections of the country, and are known as — (a) Splenic apoplexy of horned cattle and sheep ; (b) The braxy of sheep ; (c) The black quarter of horned cattle and sheep ; {d) The gloss anthrax or tongue carbuncle of almost exclusively horned cattle ; (e) The forms of anthrax which affect the mouth, pharynx, and neck in swine ; * Vide Public Health Report of Medical Officer of Privy Council. No. 5. 1862. INTENDED FOE THE FOOD OF MAN. 401 ( /) The apoplexy of swine and their so-called blue-sickness or hog-cholera; {g) The parturition fever of cows, etc. etc. etc. 3. The Paeasitic Diseases, such as — " Measles " of the pig ; the various, chiefly visceral, diseases of stock which depend on larvse of the tsenia marginata and tsenia echinococcus ; the " rot " of sheep ; the lung disease in calves and lambs ; and the easily overlooked, but highly important, disease of swine, which consists of an in- festation of their muscular system by the minute immature forms of the " trichina." 2d 402 INSPECTION AND EXAMINATION OF MEAT CHAPTEE XXXIX. INSPECTION AND EXAMINATION OF CARCASES OF ANIMALS, MEAT AND FLESH EXPOSED FOE SALE, OE DEPOSITED FOE THE PURPOSE OF SALE, OE OF PREPARATION FOR SALE, AND INTENDED FOR THE FOOD OF MAN. This section of tlie duties of the medical officer' of health as to food would seem to rank first in im- portance, and to comprehend a consideration of the suitability not only of the beef, mutton, lamb, veal, and pork that may be prepared for the food of the whole community, but the wholesomeness of those kinds of animal food which are employed by certain special classes of the people, such as game, poultry, and fish. Mr. John Gamgee expresses his belief that as much as one-fifth part of the common meat of the country — beef, veal, mutton, lamb, and pork — comes from animals which are considerably diseased. Mr. Simon, in the report already alluded to, gives the following digest of Mr. J. Gamgee's investigations, made at the request of the Government : — " Horned cattle affected with pleuro-pneumonia are much oftener than not slaughtered on account of the disease, and when slaughtered are commonly (except their lungs) eaten, and this even though the lung disease has made such progress as notably to taint the carcase ; that animals affected with foot-and-mouth INTENDED FOR THE FOOD OF MAN. 403 disease are not often slaughtered on account of it, but, if slaughtered, are uniformly eaten ; that animals affected with anthracic and anthracoid diseases, espe- cially swine and horned cattle, are (except their gan- grenous parts) very extensively eaten ; that the presence of parasites in the flesh of an animal never influences the owner against selling it for food ; that carcases too obviously ill-conditioned for exposure in the butcher's shop are abimdantly sent to the sausage- makers, or sometimes pickled and dried ; that specially diseased organs will often, perhaps commonly, be thrown aside, but that some sausage-makers will utilize even the most diseased organs which can be furnished them ; that the principal alternative, on a large scale, to the above-described human consumption of diseased carcases is, that in connection with some slaughtering establish- ments, swine (destined themselves presently to become human food) are habitually fed on the offal and scavenage of the shambles, and devour, often raw and with other abominable filth, such diseased organs as are below the sausage-maker's standard of usefulness." Characters of Good and Bad Meat. The appearance and odour of good fresh meat is known to most people. The medical officer of health, however, should possess a critical knowledge which may enable him to guide a sanitary authority in cases of doubt, where, from disease or otherwise, the ordinary characters of good meat are partially absent, or attended by some irregularity. The muscle of young animals is pale and moist, and that of old ones is dark-coloured. A deep purple tint is suggestive that the animal has 404 INSPECTION AND EXAMINATION OF MEAT not been slaughtered, or has suffered from some fever. The characters of good and bad meat are generally thus laid down. Good. Good. — Fkm and elastic to touch ; marbled appear- ance ; should scarcely moisten the finger ; no odour, beyond that peculiar to fresh meat, which every one knows ; upon standing, a small quantity of a reddish juice oozes from it, and it becomes dry upon the surface ; marrow of bones is of a light red colour. Bad. Bad. — Wet ; sodden ; flabby ; purulent fluid in intermuscular cellular tissue ; fat resembling jelly, or wet parchment, or exhibiting heemorrhagic spots ; sickly or putrefactive odour ; on standing it becomes wet ; marrow of bones of a brownish colour, sometimes with black spots. It should be remembered that meat may not reach the standard of good meat and yet be perfectly whole- some, so difficult is it to lay down rules to which there shall be no exceptions; for example, a perfectly fresh leg of mutton is tough and by no means pleasant eat- ing. If kept until it begins to lose some of the char- acters above enumerated as indicating good meat, which may be a long time if the weather be cold, and espe- cially if the air be dry, it is tender and digestible. If an opinion cannot readily be formed, the lungs and their coverings, the liver, brain, and other viscera of the suspected animal should be carefully examined. Signs of inflammation are to be found in the lungs and pleura ; hydatids may be present in the brain and liver. The condition of the mouth, stomach, and in- testines should be examined, if there is a probability of rinderpest, and that of the feet, teats, and mouth when there is a suspicion of aphthous fever. INTENDED FOE THE FOOD OF MAN. 405 There never can be any doubt as to the propriety of condemning meat that has become putrid, for it produces violent gastro-intestinal disturbance, until the offending matter has been removed either by vomiting or purging. Numerous cases are to be found in medical records of fatal results following the ingestion of animal substances in a state of advanced putrefaction. Certain damaged meat, such as moiddy veal, musty bacon, decaying mutton, sausages, bacon,"^" pork pies, brawn, t potted meats J in a state of incipient putrefac- tion, cheese, etc., have acted like irritant poisons, pro- ducing great nervous depression and collapse. It has been supposed that these defects are owing to the for- mation of a rancid fatty acid, or a poisonous organic alkaloid, or to the development of a fungus, termed Sarcina hotulina. The smell, appearance to the naked eye and under the microscope, will readily reveal the condition of meat in this state. The detection of decomposition in sausages is found to be more difficult. It has been recommended to mix the sausage with water, to boil and add freshly pre- pared lime-water, when an offensive odour will be ' evolved if the sausages are unwholesome. The exist- ence of an acid reaction to litmus paper, an unpleasant odour and a nauseous taste, are signs of their unfitness for human food. Beaction with Litmus Paper. — Good meat is acid, ^eid, alkaline and therefore turns blue litmus paper to a red colour. Bad meat is alkaline or neutral, and accordingly changes * Medical Times, March. 7th, 1845. + British Medical Journal, May 10th and 17th, 1873. ' + Medical Times and Gazette, August 5th, 1854. 406 INSPECTION AND EXAMINATION OF MEAT Degree of resistance. Smell. Amount of moisture. red litmus paper to a blue colour, or neither the blue nor red litmus paper are altered by it. Degree of Resistance of various parts when pressed. — Plunge a long clean knife into the flesh. In good meat the resistance is uniform; in bad meat some parts are softer than others. Smell of Meat- — The knife after removal should be smelt. If the meat is chopped up into small portions and some hot water thrown on it, its odour can be readily determined. An unpleasant odour indicates disease, or incipient putrefactive changes. Meat which has a smeU of physic is generally condemned. Loss of Weight in drying at 212° Fahr. — Good meat, if dried for some hours on a water bath, will not lose more than 70 to 74 per cent of its weight. Bad meat will often lose 8 per cent. ( Vide Pre- cautions to be adopted in estimating loss of moisture, on page 442.) If there is any reason to think that an animal, the meat of which is suhjudice^hsiS been drugged, although the appearance and smell of the meat are unobjection- able, it is sometimes necessary to cook and taste it, for the fat of a drugged animal, after cooking, has often a peculiar bitter taste. Such drugged meat sometimes creates illness. As to the meat of an animal respect- ing which there is any suspicion of poisoning by arsenic, antimony, or strychnine, a rough and ready test is the physiological one of giving a portion of the meat to a cat or dog, or to the butcher who is selling it, and to note if symptoms of poisoning are produced, and if so, the exact nature of the symptoms, for each of those poisons produces characteristic effects, which are fully INTENDED FOE THE FOOD OF MAN. 407 laid down in all books on toxicology. Such cases of poisoning of meat are rare. Mr. Gamgee reports one"'"'' in which an animal had been excessively drugged with tartar emetic (about ^ij-) Of 321 persons who ate of the flesh, 107 suffered from violent gastro-intestinal disturbance, one case proving fatal. Antimony was chemically found, both in the flesh of the ox and in the interior of the individual who died. Doses of the flesh, which were given experimentally to animals, pro- duced signs of poisoning. The following analyses of Letheby and Eanke may prove interesting : — Beef. Mutton. Roast Meat. Veal. Fat Pork. No dripping lost. Lean, Fat. Lean. Pat. Nitrogenous matter . 19'3 14-8 16-3 18-3 12-4 y-8 27-6 Fat. 3-6 29-8 15-8 4-9 31-1 48-9 15-45 Saline matter 5-1 4-4 47 4-8 3'5 2-3 2-95 Water 72-0 51-0 63-0 72-0 53-0 39-0 54-00 The Frevalent Diseases of Stock in relation to the su;pply of Meat for Human Food. Theoretically the meat of the healthiest animals that have been slaughtered is alone fit for the food of man. Practically meat that has been obtained from sickly and even diseased animals has been eaten with impunity, and no proof has been afforded that such meat has always been injurious to health, although abundant * " Fifth Report of Medical Officer of Privy Council, 1862." 408 INSPECTION AND EXAMINATION OF MEAT evidence is on record wkLcli shows the occasional evil results of its consumption. To understand this fact, which has been deemed incomprehensible, it is necessary to make a distinction between the diseases from which our stock suffers, and between the meat furnished by animals at different stages of these diseases. 1. Contagious Fevers. pieuro- The Epidemic Pleuro-Fneumonia of Cattle is an Pneumonia. jjjfgQ^^JQ^g digeasc, the poisou of which is eliminated through the lungs. The divergence of opinion that has prevailed in the medical profession as to what is and what is not wholesome meat, has expressed itself chiefly in connection with the flesh of pleuro-pneumonic cattle. Some would condemn meat that exhibited evidence of perverted nutrition far short indeed of actual disease, whilst others would allow unsound meat to be eaten unless it exhibited such signs of disease as to excite disgust in the consumer. These are the two extremes of opinion, and both parties have much to urge in sup- port of their opposite views. These unfortunate differ- ences have led to great variations in practice, meat in precisely the same condition being confiscated in one part of London, for example, which is permitted to be eaten in another part. They have led also cattle- dealers, farriers, and other interested individuals, to rebel against the opinion of scientific medical ofiicers of health, of which we have recently had an instance in DubHn. In September 1877 the Public Health Committee of the Corporation of this city addressed a circular INTENDED FOR THE FOOD OF MAN. 409 letter, at the suggestion of the medical officer of health, Dr. Cameron, to a great number of medical men in the United Kingdom, including medical officers of health, and to veterinarians, containing the following queries : — 1. Do you consider the flesh of oxen killed whilst suffering from contagious pleuro-pneumonia fit for food for man ? 2. If you consider that such flesh may be used under certain circumstances, please state whether or not it is fit for food in the second stage of the disease, in which the lungs are usually much increased in size, partially hepa- tized, and sometimes more or less infiltrated with pus ? 290 repKed that under no circumstances should pleuro-pneumonic beef be used as food by man ; 45 stated that it might be used, but, with two exceptions, they believed it to be unwholesome in the advanced stages of the disease.'"* In October 1877 a report was prepared for the Cattle Trade Association of Ireland by Drs. Macnamara, Macalister, and Eeynolds, who gave it as their opinion — " That the consumption of the flesh of cattle slaugh- tered in early stages of pleuro-pneumonia is perfectly harmless, and the destruction of such meat is a waste- ful expenditure of a material which is capable of sup- plying a perfectly wholesome animal food." The flesh of cattle markedly reduced in condition is expressly exempted from this conclusion. This report called forth a rejoinder from the Dublin Sanitary Association, drawn up by Drs. Hayden, Grim- * " Report on the use of Flesh of Animals affected with Contagious Pleuro-Pneumonia as Food for Man," hy Dr. C. A. Cameron. 410 INSPECTION AND EXAMINATION OF MEAT shaw, Moore, Harvey, and Woodhouse, wMch concludes as follows : — " 1. That epidemic pleuro-pneumonia is a specific contagious fever, and therefore affects the whole system of the animal, including its flesh and milk. " 2. That the flesh of animals affected with the disease, except in the earliest stages, is known to pre- sent unhealthy appearances. " 3. That the flesh is specially prone to become putrid, and therefore dangerous as an article of food. " 4. That it is not known with certainty at what stage of the disease the flesh first shows signs of infec- tion. " 5. That there is no evidence of a scientific charac- ter to prove that the flesh of oxen affected with the disease has not produced injurious effects. " 6. That there is some evidence to show that the flesh when eaten has produced injurious results. " 7. That the proposal to sell the flesh at a reduced price, and to make it less prone to putrefaction by careful bleeding, is, if carried out, calculated seriously to endanger the health of the consumers, especially the poor, and to leave a loophole for the sale of all kinds of diseased flesh. "We are, therefore, of opinion that the flesh of animals which have suffered from pleuro-pneumonia in any stage, should not, under any circumstances, be permitted to be sold for human food." In opposition to these views it should be recorded that Loiset affirms* that during nineteen years 18,000 oxen affected with pleuro-pneumonia were killed and used as food by the 150,000 inhabitants of Lille, or * Reynal's TraiU de la Police Sanitaire. INTENDED FOR THE FOOD OF MAN. 411 nearly 1000 carcases every year, without any apparent injury to them. Other authorities have made similar observations as to its innocuous character."^' My own opinion is, that until it can be shown that the meat of animals in the congestive and inflammatory stages of the disease is deleterious to health, a medical officer of health has no right to have it destroyed. I could not, however, sanction the employment of the meat of an animal that had reached the suppurative and advanced stages of the disease. Foot-and-Mouth Disease. — Although this specific Poot-and- eruptive fever, which runs a definite course and is Disease, accompanied by eruptions in the mouth, on the teats, and on the feet, is rarely fatal, it has created greater ravages, and has caused a more heavy loss than cattle plague. The loss of milk, the abortion of cows in calf, the loss of time and produce, interferes greatly with the meat-produciag powers of the country. One of the witnesses before the Select Committee of the House of Commons in 1873 stated that in 1872 the country lost £12,000,000 from foot-and-mouth disease alone. There is no evidence on record to show that the flesh of cattle affected with this disease has injured health. There is a very strong suspicion, however, that the milk of these animals has produced " sore " or " festered " mouths, especially amongst children. Vide page 485. Small-Pox of Sheep.— The flesh of animals thus smaii-pox of affected has an unpleasant smell, and does not possess * " Eeport to Board of Trade," by Dr. Greenhow, 1857. 412 INSPECTION AND EXAMINATION OF MEAT some other of the characters of good meat. It produces, if eaten, sickness, diarrhoea, and febrile symptoms. Cattle- Cattle Plague {Rinderpest). — When this disease Rinderpest, ravaged Italy in 1 711 the Government of Venice con- sulted the Faculty of Padua as to whether such flesh was unwholesome. The decision arrived at was that it was unattended with danger. In 1714, when the disease prevailed, no evil consequences were observed. In 1775, when the plague raged in the southern pro- vinces of France, the flesh of diseased animals was consumed by three-fourths of the inhabitants, and no instance of inconvenience was recorded (Fleming). This author also informs us that the same freedom from any injurious effects was noticed at Hong Kong in China in 1860. During the recent invasion (1865- 66-67) by rinderpest of this country, there can be no question but that a vast quantity of animals suffering from this disease has been consumed as food, and we, as medical men, are unable to prove that any great injury has resulted to the pubKc. The meat thus em- ployed was doubtless that of animals in the early stage of the disease. If such meat is consumed the greatest precautions should be taken as to thorough cooking. It is a matter of doubt whether the flesh of an animal in the advanced stages can be eaten with safety. 2. Anthracic and Anthracoid Diseases. Splenic SpUnic ApopUxy. — G-reat differences of opinion have Apoplexy, prevailed as to whether animals thus diseased should be used as human food. Large quantities of this meat have been eaten, and with apparently no injurious effects, but so many disastrous occurrences have INTENDED FOE THE FOOD OF MAN. 413 followed its employment as to, warrant the medical officer of health in condemning such meat. The poison of this diseased meat resembles some others in acting with greater virulency when inserted sub- cutaneously than when taken into the stomach. A butcher cuts his hand in dressing an animal that has suffered from this disease, and rapidly dies of pyaemia. A carrier was recently packing some of this diseased meat for the London market, and a splinter of bone entered his hand. Phlegmonous erysipelas, which ended speedily in blood-poisoning, terminated his life in a few hours. A man was engaged during a dark night in resurrectionizing a diseased animal that had been buried. He hoisted some of the meat in a sack over his back, which was alone covered by his shirt. In some way or other the juices of the meat passed through the sack and shirt, and came into contact with the skin of the back, on which there was probably some abrasion. Erysipelatous inflammation of the skin, attended with intense depression of the vital powers, rapidly set in, and the man expired. I cannot think that meat containing such a deadly poison should ever be sold to the public. The Braxy of Sheep, which kills 5 per cent of ite Braxy the young sheep of Scotland,"'" is readily recognized by "^^ ^^^^p- the shepherds by a short staggering gait, blood-shot eyes, rapid breathing, fever, scanty secretions. The braxy mutton is preferred to salt mutton by the hardy Highland shepherds, but it is not, as a rule, cooked and eaten until it has been steeped in brine for two months, and has been suspended for some time from the kitchen * Vide the Prize Essay on Braxy, by Mr. Cowan of Glasgow, in " Transactions of the Highland and Agricultural Society, 1863." 414 INSPECTION AND EXAMINATION OF MEAT Autliiacic Diseases. Parturient Apoplexy. roof. Dr. Letheby writes '" — " Every now and then, however, when perhaps the diseased parts have not been entirely removed, or when the salting has not been sufficiently prolonged, or the cooking has not been thoroughly effected, the most serious consequences result from it, insomuch that many medical practi- tioners, who are acquainted with the habits of the Scotch shepherds in this respect, and have seen the mischief occasioned by the meat, declare that braxy mutton is a highly dangerous food for man." Anthrax, Black Quarter, Gloss Anthrax, Sog-clwlera. — The literature of the past teems with examples of the poisonous nature of the flesh of animals that have suffered from anthracic diseases, although many in- stances can be adduced, showing the escape of people who have been imprudent enough to risk their health and lives iu consuming it.f The malignant pustule of the human subject is produced by these anthracic diseases of stock, which are included by the French under the head of " Charbon," thus named, because the regions of the body, where the disease is localized, are coloured black. In this country the development of carbuncles, boils, and other forms of blood-poisoning, has been attributed to the use of meat from animals affected with anthracic diseases. All such meat should be condemned. The use of the milk of animals suffer- ing from anthracic diseases should be interdicted. Parturient Apoplexy {Milk Fever, Dropping after Calving). — The condition of the meat should govern the medical officer of health iu the formation of an * Vide Dr. Letheby's Lectures on Food. t Vide Fleming's Manual of Veterinary Sanitary Science, vol. ii. page 195. INTENDED FOE THE FOOD OF MAN. 415 opinion as to whether the flesh of such animals is or is not fit for human food. Mr. Gamgee writes '"'' — " Not- withstanding the sporadic nature of parturient apoplexy in cattle, it is marked by the development of a poison -capable of inducing a similar disease in other animals, of affecting the human frame, and hence of rendering the flesh of animals affected by it unfit for human food." Professor Williams writes f — " If this assertion were correct, the number of the human race would, ere this, have been much reduced, for it is a well-known fact that the flesh of cows, slaughtered whilst suffering from parturient apoplexy, is a common article of diet, and that no bad consequences result from it, provided the animal has been slaughtered early, before the system has been empoisoned by the excessive doses of medicines, which are so generally prescribed in this malady, and antecedent to a general vitiation of the animal solids and fluids by the accumulation of effete materials." Convictions in such cases have been obtained. Vide, for example, one reported in Sanitary Record, March 2d, 1877, p. 144. Tubercular Diseases. — Large quantities of meat that Tuiiercuiai r> 1 • • 11 c • 1 Diseases. finds its way mto our markets has come irom animals more or less affected with pulmonary or mesenteric phthisis, called by cattle-dealers "grapes." In the early stages of the disease the meat does not present any of the characteristics of bad meat, and cannot be rejected, for no proof exists that such food has injured health. If it is eaten, care should be taken that it is well cooked. In the advanced stages it should be destroyed. * Our Domestic Animals in Health and Disease. + The Principles and Practice of Veterinary Medicine. 416 mSPECTIOX AND EXAJtflNATION OF MEAT Scarlet, ScarUt FcvcT, Pig TypliiLs, Sjpotted Fever, Typhoid T^h^d^'^ Fever. — Coii\dctions are obtained for the destruction of Fevers. anjmals that have suffered from these blood diseases.'"" The carcases exhibit appearances so different from those of good meat as readily to fall under condemna- tion. It is stated that whole families have been made seriously ill by eating the flesh of " soldier pigs/' as pigs suffering from typhus are termed in Ireland. Accidents. Accidents, Fractures, Wounds. — The flesh in these cases may generally be utihzed as inferior meat, except in the neighbourhood of the injury. If gangrene has set in, its use should be prohibited. The flesh of overdriven animals has been stated by Gamgee to have produced eczema of the skin, and other unpleasant effects. Arguments Arguments against the Employment of Diseased Meat. against em- pio>Tnentof The arguments that are employed by those who Meat would perpetrate such raids on our meat markets as to condemn not only all diseased meat, but even that of animals whose nutrition is temporarily perverted, are : — 1. That cases of apparent poisoning sometimes arise in a quite indefinable manner ; and that, if such cases prove fatal, no known poison can be detected by the toxicologist. It is true that cases of blood poisoning occasion- ally occur which have equally been ascribed to * Sanitary Record,, 5 an. 6th, 1877, p. 12 (scarlatina). „ „ Feb. 5th, 1876, p. 96 (typhoid fever), „ „ Oct. 26th, 1877, p. 270 (spotted fever). „ „ Aug. 31st, 1877, p. 145 (scarlatina). INTENDED FOR THE FOOD OF MAN. 417 the air from drains and cesspools, or to filthy water. 2. That there has been a great increase of carbun- cular diseases ever since 1842, the year in which the infectious blood disease of cattle, known as pleuro-pneiunonia, was first recog- nized in this country. An increase in this class of disease occurred during the years from 1842 to 1854; but since this latter year there has been a decline. 3. That Dr. Livingstone had remarked that those African tribes that fed on cattle which died of pleuro-pneumonia, were often affected with malignant carbuncles. If Dr. Livingstone was correct as to the nature of the disease from which the cattle suffered, which appears very doubtful, it would seem that the meat was eaten in the most advanced stages of the disease. If, as is highly probable, the cattle died of some form of anthracic disease, the result that followed is only that which would be expected. 4. That the Eegistrar-General of Scotland had noticed that since lung disease in animals was introduced into Scotland, there had been a gradual increase in the proportion of deaths from carbuncles. Arguments in favour of the Employment of Diseased Arguments ■n/r s f°'^ employ- Meat. ment of The arguments used by the opposite section in the Meat. profession, who would not confiscate meat unless it was almost repulsive, are : — 2e 418 INSPECTION AND EXAMINATION OF MEAT 1. That our animal food is exposed to so lugh. a temperature as to kill parasites, and coagulate and render inert any albuminous morbid con- tagium. 2. As the venom of the cobra and the rattlesnake is rendered innocuous after exposure to the dis- infectant chemistry of digestion, so the poisons of such diseases as small-pox, etc., probably undergo similar destruction. "These two protective influences do not," as Mr. Simon has pointed out,"^^' "cover the whole field of danger : — " {a) Meat is often only half cooked ; and, " (&) Complete coagulation of albiunen may leave some morbid poisons in operation." We are, one and all, aware that terrible outbreaks of disease have occurred from the use of meat, other than that which we are unanimous in condemning. Here are two out of many instances : — ■ Severe and Professor Gamgec has given evidence with reference extensive ^q ^ couvict establishment, containing 1500 inmates, outbreaks of . , , . , • i i disease. in which diseascd meat was permitted to be used, out of which number 40 or 50 cases of boils and carbuncles occurred per month. The late Dr. Letheby's sausage case, of November 1860, was remarkable. "A fore quarter of cow beef was purchased in Newgate market by a sausage manu- facturer who lived at Kingsland, and who immediately converted it into sausage meat. Sixty-six persons were known to have eaten that meat, of which sixty-four were attacked with sickness, diarrhoea, and great prostration of the vital powers, and one of them died. Dr. Letheby • Fifth Annual Report, 1862. INTENDED FOR THE FOOD OF MAN. 419 found that the meat was diseased, and that it, and it alone, had been the cause of the mischief." It is extremely difficult to trace cases of illness to the use of diseased meat, for such does not generally produce such striking and alarming effects as have been referred to in the foregoing examples, but is slow and insidious in its action, unless in a state of putrefaction, when it often induces symptoms of gastro-intestinal disturbance. The Medical Officer of Health of Dublin, where diseased meat has, until recently, been disposed of to the public in an unblushing manner, states that he has received complaints from at least 100 persons with respect to the quality of the meat — nearly always beef — which they alleged had caused them nausea and severe diarrhoea.^' He most thoroughly endorses my own views when he writes, " As a rule, bad water and vitiated air do not kill like arsenic or strychnine, neither does the flesh of diseased animals." People are often to be found who habitually drink water which is highly contaminated with sewage ; whilst others are almost always immersed in a vitiated atmosphere, and exhibit no sudden and easily perceived injury thereby. Now, although this is imdeniably true, yet the views of the public on this question should have their weight ; for, without a con- sideration of the subject in its breadth, it is possible to be led into unpractical conclusions. The loss to this country from the contagious diseases Pecuniary of animals is over one million a year, which is felt by all classes of the community in the increased prices of * Vide Eeport on Pleuro-pneumonic Flesh as Food, and Dublin JouttmI of Medical Scierice, 1871. 420 INSPECTION AND EXAMINATION OF MEAT meat, milk, butter, etc. WMlst every effort is being made by the Legislature, with a due regard to the in- jury to trade of too many or of too severe restrictions, to prevent the spread of these diseases, the confiscation of animal food should not be attempted unless we possess evidence that such meat is likely to be in any way prejudicial to health, for meat is already so expen- sive as to be almost beyond the reach of the agricul- tural labourer. Then, on the other hand, it cannot be right, as Dr. Cameron says, for the flesh of diseased animals to be palmed oif on the public as that of healthy animals, even if such meat is not considered injurious to health, for the flesh exposed for sale in the shops is presumably derived from healthy animals. The practice in the city of London is to condemn the flesh of animals that have been suffering from all febrile and wasting diseases ; and of any animal that has been killed immediately before, during, or after parturition, for the reason that an animal would not be slaughtered at that time unless death appeared to be imminent. Much meat finds its way into the market which is simply inferior meat, or that of ill-fed, half-nourished animals ; or of cattle that have died as the result of accident, such as rupture of the stomach from eating too much clover, etc. Sheep often die of exhaustion or mechanical impedi- ments in parturition. These animals are much disposed to over-eat themselves. They distend themselves to such an extent that they at length fall down in a stupe- fied condition or in a fit — they " drop," as the agricul- tural people express it. The farmer generally cuts the animal's throat in haste, before it dies, and rapidly sends it to the butcher. The meat, in such cases, must INTENDED FOE THE FOOD OF MAN. 421 be judged of by its characters when dressed by the butcher for food. The flesh of animals that have died, and of those that have been over-driven or fatigued, will not keep long, and their flesh is very prone to rapidly present an unwholesome appearance. All such inferior meat is sold at a low price, without apparent injury to health, if it does not exhibit the characters of bad meat. It is a matter open to great doubt as to whether it is justifiable for a Medical Of&cer of Health to attempt to interdict the use of any meat of inferior quality that does not exhibit the characters of bad meat, respecting which there exists on record no evidence showing that the flesh of animals similarly affected has proved un- wholesome to man. 3. Parasitic Diseases. "Measles" of the Pig, Ox, and Sheep. — Professor 'Measles.' Fig. 69.— Measly Pork, by Dr. Lewis. (After Parkes.) Gamgee states that 3 per cent, and probably 5 per cent. 422 INSPECTION AND EXAMINATION OF MEAT of the pigs of Ireland are affected with this disease. The flesh of these animals is infested with a parasite named Gysticercus cellulosus, which is generally visible to the naked eye. They are sometimes so mimerons that when such flesh is cut a crackling sound is emitted. The measles of cattle is produced by the Gysticercus hovis, which becomes the Tcenia mcdio-canellata of man. Mutton is liable to the presence of the Gysticercus ovis, of which, in its mature form as a tapeworm, we have but little knowledge. "Wlien meat thus infested is swallowed, the outer coat of the vesicle is dissolved by the digestive juices, liberating an animal which is seen to possess a bladder- like tail and a crown of booklets, with which it attaches itseK to the coats of the intestines. Here it develops into the Tcenia solium or common tapeworm, each joint of which contains large numbers of ova which are often eaten by animals. The origin of the echinococcus or hydatid disease is thus described by Drs. Woodman and Tidy {Forensic Medicine) : — " A piece of diseased offal is eaten by a dog which passes by the bowels, either in the field or in the stream, segments of the developed worm (Tcenia echinococcus). Cattle and sheep swallow these seg- ments. At last the animal that has swallowed them be- comes the food of man, and then the larval tapeworm becomes a bladder-like hydatid. In the ox it goes to the peritoneal cavity ; in the sheep to the brain, pro- ducing ' staggers ;' and in the man to the liver." The " sturdy," " turnsick," or " gid " of sheep, is in- duced by the presence of a hydatid in the brain, named Ccenurus cerehralis, the mature form of which is named INTENDED FOE THE FOOD OF MAN". 423 Taenia canuris. The Strongylus filaria is a parasite that is found in the lungs of the calf and lamb, where it produces what has been termed phthisis pulmonalis, verminalis, or parasitic bronchitis. In diagnosing the presence of cysticerci in meat, it is necessary to recognize the booklets. The treatises of Cobbold, Leuckart, and Kiichen- meister, may be advantageously consulted by those in- terested in the study of the transformations of these parasites. The trichina spiralis (^/>*f » ^ hair) is found most TrieWna frequently in the flesh of the pig. It has been declared^' ^^"^ to have been found in mutton and frequently in beef, and, that the reason that this parasite has always been associated with pork is, that in the flesh of the pig its cysts are most easily seen. The symptoms of trichinosis, being enumerated in many books which are easily accessible to medical men, require no description. During the progress of the disease they arrange themselves in three stages, as has been pointed out by Dr. Eichardson : — (1) A stage of intestinal irritation, corresponding with the full develop- ment of the trichiua ; (2) a stage of moderate fever attended with pains in the muscles, like those of rheu- matism, corresponding with the time when the embryos find their entrance into the muscles and are becoming encysted; and (3) a prolonged and chronic stage of unpaired muscular movement with emaciation, corre- sponding with the period when the larvae are entirely encysted in the muscle, and are fixed in position. If the case proceeds to a fatal termination, death either results from coma or from severe pneumonia. This * Public Health, Feb. 23d, 1877, p. 131. 424 INSPECTION AND EXAMINATION OF MEAT disease is happily scarcely known in this country, being apparently confined to our raw sausage-loving neighbours, the Germans. The first recorded epidemic of this disease was observed in 1862 at Plauen,'"'" in the Yoigtland, in which 30 persons were seized, of whom one died. Soon afterwards outbreaks occurred at Calbe au der Saale, Burg near Magdeburg, in Anhalt, Stolberg am Harz, Leipsic, Jena, Eisleben, Quedlinburg, Dessau, Stassfurt, Weimar, and Hettstadt.f At the last-named place 103 persons were affected, and 83 died. I In Germany about 2 per cent of swine are considered to sufi'er from trichinosis. Modes of Modes of DetecMoTh. — Sausage manufacturers in Ger- many are said to have the eyes of all pigs after slaughter detection. ■*'*lfl Fig. 70. — Ti-icliiua Spiralis x 250. examined microscopically by a medical man, as the muscles of the eye are the first affected. Meat suspected to contain Trichinae may be examined * Annal. d' Hygiene, Oct. 1863. t Brit. 3fed. Jour., Jan. 16, 1864. X Vide Report by Dr. Tliudichum on the "Parasitic Diseases of Quadrupeds used for Food," in Seventh Report of Medical Officer of Privy Council, 1864. INTENDED FOE THE FOOD OF MAN. 425 thus : — A thin section having been made with a Val- entine's knife is immersed for a few minutes in a mixture of liq. potassse, 1 part and water 8 parts, until the muscle becomes clear. If they are present white specks appear, in which the worm is seen by the aid of the microscope, coiled up. A drop or two of weak hydrochloric acid will often render the parasite more visible. A little ether may be added with the same object in fat meat. A ready way of detecting these animals in flesh, is that of soaking it in a strong solution of logwood, which dyes the meat but does not colour the trichina. Care must be taken to avoid confounding these Rainey's Corpuscles (Psorosper- mia). Fig. 71. — A Psorosperm lying loose among muscular fibres. parasites with Eainey's corpuscles or capsules (Psoro- 426 IXSPECTION AND EXAMINATION OF MEAT spermia), whicli have on their surface minute hair-like markings."" These bodies were observed in the flesh of cattle that died of rinderpest, when the disease en- tered the country and destroyed our herds in 1865, by some who were not accustomed to examine meat micro- scopically, and who discovered in their presence, so they thought, the cause of the disease. An instrument, termed a harpoon, was devised and employed some years ago in Germany, when such large numbers of people suffered from the disease, for diag- nosing the presence of the parasites in the human muscles, and for notirig their increase or diminution. It resembled a trocar with a minute forceps at the pointed extremity, which was plunged into the living muscle. The small pincers having been opened by the aid of some mechanism in the handle, a bit of the muscular tissue was seized and withdrawn. This minute portion of muscle was examined microscopically, and if present, the number of trichinae in the quantity were counted. The Fluke. The, FluTce (I>istoma hepaticum = the rot) — is a para- site that is found in the livers of men and animals, especially the sheep. Many regard sheep's liver, thus infested, as a dainty dish. The eating of garden snails, whelks, mussels, shell fish, etc., is considered as another mode by which men become affected with this disease, which occasions hsematuria and dysentery. The rot is the name given to this disease as it occurs amongst sheep, thousands of which it kills annually .f Salting does not kill cysticerci, although a high * Phil. Transactions^ 1857. + A good description of the transformations tmdergone by this para- site is to be found in Aitken's Practice of Medicine. INTENDED FOE THE FOOD OF MAN. 427 temperature and smoking are said to do so. In India such meat is allowed to be eaten if well cooked. Cook- ing, salting, and smoking simply lessen the danger, even if efficiently performed, and do not remove it. Much meat that is eaten is very unwisely consumed in a raw state, and more frequently in a half-cooked condition. Salting, like cooking, is generally performed in an irregular ever-changing manner, the hrine sometimes being used so many times as to have become actively poisonous. All meat which contains cysticerci, trichina, flukes, and all other animal parasites which are apt to infest man, should be condemned as unfit for human food. In the reign of Henry III. butchers who sold measly pork were placed in the pillory. 428 INSPECTION AND EXAMINATION OF POULTRY, ETC. CHAPTEE XL. INSPECTION AND EXAMINATION OF POULTRY, GAME, ETC. As violent gastro-intestinal disturbances are often ex- cited by the consumption of game in a very " high " condition, a medical officer of health would be warranted in pronouncing any birds, especially poultry, and hares exhibiting this decomposed state in an extreme degree, as injurious to health. It should be remembered that the flesh of game is apt to be rendered unwholesome by the food eaten, and even poisonous, as, for example, when wickedly destroyed by arsenic, etc. The flesh of hares fed on the rhododendron chrysanthemum, and after coursing,'''' has been found to exert poisonous effects. Pheasants fed on the laurel have created illness when eaten. A case is recorded where the flesh of a turkey proved poisonous,! and no poison could be found on analysis. Birds, like mammals, are subject to a sort of variola which is contagious. Fowls, turkeys, and geese are sometimes affected by it. The presence of pustules on the body of the bird renders it for the time unsaleable. Cholera and anthrax in poultry, are diseases that are not known to render them injurious to the health of man when eaten. It is often necessary to have rabbits confiscated, as they are frequently offered for sale in a putrid state. * Lancet, September 27, 1862. t Medical Times and Gazette, March 18, 1871. INSPECTION AND EXAMINATION OF FISH. 429 CHAPTEE XLI. INSPECTION AND EXAMINATION OF FISH. Although the quantity that is annually condemned throughout this country is very great, an immense amount of unwholesome fish is consumed by the poor, and creates diarrhoea, nettle rash, and other affections. Mackerel cannot be eaten in too fresh a state ; whilst whiting is improved by hanging for a short time, when the weather is not hot. When fish has changed colour, and has an offensive or ammoniacal odour, it should be seized as unfit for human food. A bright red colour of the gills cannot be relied on as a sign of freshness, for they are often tinted by the salesman. Some fish in the tropics are always poisonous, whilst others are poisonous to some, but not to all persons, and others are at times only injurious. Pilchards, mussels,'"' eels,t crabs,| lobsters, oysters, mackerel,^ turtle, and sar- dines, || have at times produced very unpleasant, or dan- gerous, and even fatal results. Most commonly dys- pepsia, swelling of the tongue and fauces, itching of the * Medical Times and Gazette, November 1, 1862, April 30, 1864, and Guy's Hospital Eeports, October, 1850, and Lancet, March 7, 1846 and May 5, 1866. t Lancet, June 21, 1873. % Lancet, October 27, 1866. § Lancet, July 30, 1864. || Medical Times and Gazette, Dec. 13, 1862. 430 INSPECTION AND EXAMINATION OF FISH. eyes and eyelids, an eruption resembling nettle rash, with great irritation, are the symptoms complained of. Less frequently numbness of limbs, feeble action of heart and coma, and, in rare cases, death has resulted. The nature of the animal poison contained in these fish is unknown. It is, in some cases, thought to be due to some particular food in which the fish has indulged, and in others to be developed only during the breed- ing time. DESTRUCTION OF CONDEMNED FLESH. 431 CHAPTEE XLIL DESTRUCTION OF CONDEMNED FLESH. The question often arises as to how flesh, which is con- sidered to be unfit for human food, should be disposed of. If it is handed over to the knacker to be sold as food for cats, there is a risk lest the meat should ulti- mately find its way to the butchers' stalls of the low parts of our cities and towns, and be sold to the poor. If the meat is not unsuitable for dogs, it may, with greater safety, be sold as food for packs of hounds. If meat is buried,"'lij[cre is a dap "•'^"^_ lest it may partly be brought to light by dogs- kcj- If it is buried too deep to allow ot such intt^xerencC; the meat is still liable to get into the market by the aid of a resurrectionist. Interesting cases of the resurrection of diseased pigs Resurrectiofi are recorded in the Sanitary Record of February 16 th, ^gg^^^^^^^ 1877, p. 105, and February 5th, 1876, p, 96. Ee- membering that every part of an animal, even to its bones and hoofs, whether diseased or not, possesses a distinct money value, the disinterment during dark nights of such bodies is not to be wondered at. Perhaps the best mode of preventing the sale of condemned meat as human food, is to impregnate it with some substance that will render it unsaleable. 432 DESTRUCTION OF CONDEMNED FLESH. In the city of London, where vast quantities, as much sometimes as 35 tons (=100 oxen), of putrid and diseased meat, dressed for sale, are seized in one day, the meat is plunged into a bath of the following composition, preparatory to its conveyance in carts to Deptford, where, by the help of machinery, it is sepa- rated into meat, fibre, fat, and bone, and subsequently utilized in trade : — Br. Sedgwick Saunders^ Chemical Bath. Cooper's salts (a mixture of chloride of calcium and chloride of sodium), 2 cwts. Sulphate of iron (green copperas), ^ cwt. Picric acid, 2 lbs. ..... Water, 300 gals The chlor^''^"s deodorize j. itrid and stinking meat, whilst the picric 1 and sulphate of iron discolour it, and rex der it so disgusting to the taste, as to remove all fear of its appropriation for human food."'" In country districts, where seizures of meat are few and far between, condemned meat may be most con- veniently rendered unsaleable by making deep incisions into the flesh, and pouring therein im;pure carbolic acid, which possesses a disgusting odour. Creasote and oil of turpentine have also been used. Instruments have been invented for introducing such fluids readily into various parts of a carcase. Defays * " Eeport upon various Methods of dealing with Meat seized as unfit for human food in the City of London," by Dr. Sedgwick Saunders. Yalue. 12s. Od. 2 , 3 , 17 DESTEUCTION OF CONDEMNED FLESH. 433 made a tube with a lancet point, provided with a flask containing the fluid ; and Kopp recommended a spatula with sharp edges, grooved on the surface, which is dipped into the fluid each time that it is plunged into the flesh. 2r 434 IXSPECTION A2v'D EXA]MIXATION OF FEriT, ETC. CHAPTER XLIII. IXSPECTION AXD EXA]\riNATIO]Sr OF FEUIT AND VEGETABLES. Half decomposed fruit and vegetables are deleterious to health, exciting diarrhoea. Every now and then the opinion of the ^ledical Officer of Health is sought by the Xuisance Inspectors, as to whether quantities of fruit and vegetables are or are not injurious to health. Siniply damaged and stale fruit and vegetables cannot, of course^ be so regarded ; but all decomposing and offensive vegetable matter should be condemned. The poor are the chief consumers of this unwhole- some food. "With vast numbers fresh fruit and vege- tables are impossible luxuries. I cannot but think that an immense profit is to be made by any enterprising company that would undertake to supply the wants of the poor of a great city with fresh vegetables, at prices within their reach; for the present arrangement, whereby the poor are supplied with stale vegetables, is attended with such an enormous waste of these important neces- saries of life. INSPECTION AND EXAMINATION OF COEN. 435 CHAPTEE XLIY. INSPECTION AND EXAMINATION OF COEN. CoEN is generally understood to comprehend the grains of wheat, barley, and oats, to the exclusion of those of rye, maize, etc. The differences between the appearance of different kinds and samples of wheat and barley, as indications of YSLijing degrees of quality, can be better learnt from any farmer than from a description; whilst almost every medical man necessarily acquires practical experience in diagnosing good oats. Grains of corn are sometimes damaged and rendered of little value by a " growing out." When such corn is ground the flour is known in trade as " weak." Such flour cannot strictly be said to be injurious to health, except as taking the place of an equal quantity of more nutritious material. Grains of corn should be free from smell, sprouting, discoloration, and any evidence of insects or fungi. The insects sometimes found in corn are the weevil The weevu. 1^ and the Acarus farince, the former visible to J. the naked eye, and the latter by the aid of Fig. 72. g. microscope. If grains are seen to be Calandra grau- ^ o ariaorWeevu. pierced with minutc holes, and are found to have been deprived of their contents, the weevil is the culprit. 436 INSPECTION AND EXAMINATION OF COEN. "Ear- cockle.' "Earcockle," "Purples/ Fig. 73.— Vibrio tritici, x 100 diam. ton-like substance in place or " Peppercorn," are names applied to a blighted condition of ears of corn, in which the grains become gTeen and afterwards black. The grains are filled with a cot- flour, which, when The Wheat Midge. Ergot. m place of moistened, is seen to be composed of animalcules in a state of great activity {VihHo tritici). The wheat midge {Cecidomyia tritici) is a great enemy of the farmer, who sometimes sees, early in June, myriads of these little flies hovering about the wheat, for the purpose of depositing its eggs within the blossoms. The caterpil- lars that are produced from these eggs in- terfere with the development of the ovary, so that abortive grains are alone found. Small birds happily prey on the midge, and thus lessen the mischief. Certain vegetable parasites also de- teriorate corn in value, and sometimes render it poisonous. Ergot (Oidium arbortifaciens) is a fun- gus which shows a decided preference for rye, but also attacks the ears of wheat. In countries where rye bread is eaten to a large extent, a peculiar disease, named Fig. 74. ergotism, has prevailed epidemically. This faciens or Er- disordcr has bccu noticed in two distinct got (after Has- ^ ,■, j • v sau). lorms — the one a nervous disease, char- INSPECTION AND EXAMINATION OF COEN. 437 acterized by spasmodic convulsions ; and the other, wMch is known in France as gangrenous ergotism, and in Germany as the creeping sickness. The symptoms of each form are well described in Christison's work on Poisons. There are two chemical tests for ergot — the first by Laneau, and the second by Wittstein. Make a paste of the flour with a weak alkali ; add dilute nitric acid to slight excess, and then neutralize with an alkali, when a violet red colour is produced if ergot be present, which becomes rosy red when more nitric acid is added, and violet when an alkali is intro- duced. The second test for ergot is to add liquor potassse to the flour, which develops a herring-like smell if it con- tains ergot. Smut {Uredo segetum) is a fungus that exhibits a"Smut.' partiality for barley and oats. Kg. 75.— Uredo segetum, x 420 diam. Fig. 76. — Uredo caries, x 420 diam. Bunt or Brand (Uredo caries or fostida) is a fungus Bunt or only met with in wheat grains. As its name indicates ^^^^- it possesses a disgusting smeU. It is questionable whether or not the consumption of flour containing this fungus is deleterious to health. It is chiefly em- ployed in the manufacture of gingerbread. Bust (Puccinia graminis). — This fungus infests the Riist. 438 nsrsPEOTiON and exajmination of corn. chaff, stem, and leaf. In its young state it was formerly- known under the name of Uredo rvMgo and linearis. Fig. 77.— Puccinia graminis, x 500 (after Hassall). INSPECTION AND EXAMINATION OF FLOUR. 439 CHAPTEE XLV. INSPECTION AND EXAMINATION OF FLOUE. In the inspection of flour we should note the colour, smell, taste, and feel, for we may then receive a valu- able hint as to its wholesomeness or quality. Weevils {Calandra granaria, vide fig. 72) are often found by this rough scrutiny. The examination of flour that devolves on the medical officer of health is of two kinds : chemical to determine its quality ; and microscopic to discover the presence of adulterants and of animal parasites, which are often found in damaged flour. The adulteration of wheaten flour with that of cereals of less nutritive value, or with vegetables that are deficient in nitrogenous principles, may be consi- dered by some as one of fraud, which does not concern a guardian of the public health. The weakening of the strength of the "staff of life," on which the poor man has principally to lean for the support of himself and family, is an undoubted injury of very serious import. The substitution of fat-form- ing for flesh-producing principles into the staple article of diet, cannot but be regarded as a wrong that is cal- culated to diminish the working powers of labourers of all classes. The regulations for the government of King Henry 440 INSPECTION AND EXAMINATION OF FLOUE. VIII.'s houseliold ordain that "his highness's baker shall not put alum in the hread, or mix rye, oaten, or bean flour with the same, and, if detected, he shall be put in the stocks." The nutritive value of the different farinaceous articles of food, especially of those with which flour is apt to be adulterated, is well seen in Dr. Letheby's Table of Analyses, an abridgment of which may be use- fully inserted for reference. NUTRITIVE YALUES IN ONE HUNDEED PARTS. Nutritive Values of the principal Farinaceous Foods. a S M 1 i 1 i Total per Cent. i a i-g 1 Bread 37 15 1 15 15 14 13 15 18 75 83 82 91 8-1 10-8 6-3 12-6 8-0 11-1 6-3 23-0 2-i 1-3 1-1 1-2 47-4 66-3 69-4 58-4 69-5 64-7 79-1 55-4 82-0 18-8 8-4 9-6 5-1 3-6 4-2 4-9 5-4 3-7 0-4 0-4 2-0 3'-2 61 5-8 2-1 1-6 2-0 2-4 5-6 2-0 8-1 0-7 2-1 6 -2 0-2 0-5 2-3 17 2-0 3-0 1-8 1-7 0-5 2-5 07 1-0 1-0 0-6 8-1 10-8 6-3 12-6 8-0 11 -1 6-3 23-0 2-1 1-3 1-1 1-2 55-00 75-50 80-30 77-80 78-20 85-35 81-25 62-65 82-00 22-50 15-00 16-65 7-20 Wheat flour Barley meal Oatmeal Eice Peas Arrowroot Potatoes Carrots Parsnips Turnips If wheaten flour is made by grinding together the whole of the grain, it contains more flesh -forming material than any other of the cereals, sometimes reaching to 22 per cent. The finer the flour the less of nitrogenous matters, of fat and of mineral matters, and the more of starch. The most nutritious portions INSPECTION AND EXAMINATION OF FLOUE. 441 of the grain are the outer or coarser, whicli, contain- ing a larger proportion of cellular fibre and woody matter, are less easily digested by persons of weakly constitution. Bread and puddings made of whole meal flour are highly nourishing, if they can be easily digested, and do not exert a too great laxative influence on the intestines through the mechanical irritation of the small portions of husk or bran. The most distinguished dentists of the day tell us that one great cause of the caries of teeth is the substi- caries of tution of the fine and delicately prepared for the ^^ ' coarser and rougher foods that belonged to a former and less civilized state of society. Whole meal bread, potatoes undeprived of their skins, etc., etc., are sug- gested as preferable. Whether or not such coarse foods act beneficially on the teeth in a mechanical manner by scouring them, and so preventing accumula- tions of food and tartar, does not transpire. Chemical Examination. Wanklyn's analysis of fine wheaten flour is as follows : — Water .... 16-5 Ash . 0-74 Fat . 1-2 Sugar, Gum, and Dextrine 3-3 Albuminous matters (Gluten, etc.) . 12-0 Starch .... 66-3 loo-o Water. — Place a little flour in a smaU platinum Amount of dish (such as is employed for obtaining milk residues) ™°^^*'^®- of known weight, and weigh it. Place the dish thus 442 INSPECTION AND EXAMINATION OF FLOUE, charged over a hot water bath for one hour and a half to drive off moisture. Weigh and then replace the dish on the bath, and after the interval of half an hour again weigh. The object of weighing twice is to be sure that all water is expelled. For example : — Sample of flour and dish 9-959 Platinum dish . 7-978 Weight of flour 1-981 After Exposure on Hot Water Bath. 1st Weighing. 2d Weighing. Flour and dish 9-680 . 9-650 Dish . 7-978 7-978 1-702 1-672 To obtain percentage- — Weight of flour taken. ° of flour after expulsion )f moisture. 1-981 : 1-672 : : 100 100 1*981)167-200(84-4 100 — 84-4 = 15-6 per cent. Good flour contains on an average from about 14 to 16 per cent of moisture. The more water that is present the greater the liability to change, and the less nutriment in a given weight. Professor Partes counselled that flour containing over 18 per cent of water should be rejected. Weight of Ash. — Burn the dried contents of the dish by ^^ applying the flame of a Bunsen's burner. The coke formed requires to be stirred with a piece of thick platinum wire. It is at length reduced to an ash, which should be weighed. Por example : — INSPECTION AND EXAMINATION OF FLOUE. 443 Weight of ash and dish . 8-035 dish . . 7-978 Weight of ash . '057 Weight of flour taken. Weight of ash. 1-981 : -057 : : 100- 100 l-98l)5-700(2-87 Ash 2-87 per cent. The average weight of ash is '7 to -8 per cent. Wanklyn states that if a sample of wheaten flour yields more than this amount there is something wrong about it, and the presence of a mineral is suspected. The inorganic substances with which flour is most commonly adulterated are carbonate of lime or magnesia, sulphate of lime, bone dust, etc. If the ash exceeds 2 per cent, add hydrochloric acid. If distinct effer- vescence is produced, chalk has been probably added. The ash of flour consisting of ground leguminous seeds, is heavier than that of wheat-flour, and is strongly alkaline. The ash of flour is composed mainly of the three phosphates of potash, magnesia, and lime. To detect mineral substances shake the flour with chloroform in a test tube. The flour floats, and inor- ganic bodies subside. The ash of pure oatmeal does not exceed 2-36 per cent. Sugar, Dextrine, and Gum. — Weigh out 100 Sugar, Dex- p n T 1 • 1 T -J ■ 1 trine, and grammes or nour, and, havmg placed it m a large Q-^m. porcelain evaporating dish, introduce some water, and mix the water and flour thoroughly together with the 444 INSPECTION AND EXAMINATION OF FLOUE. fingers, so as to ensure the complete admixture of every particle of the flour with the water, This semi- fluid mixture is poured into a half -litre flask, and water is added until the mark is reached denotiag that quantity. The contents of the flask are filtered. After rejecting the first portions of the filtrate, 50 c. c. of the filtrate are collected and evaporated to dryness in a platinum dish of known weight on a water bath. Weight of dish, and substance after evaporation 26*875 dish . . . 26-210 •665 As a tenth (50 c. c.) of the 500 c. c. (half -litre) which contained the 100 grammes of flour was taken, it is necessary to multiply by 10 to obtain the percentage : •665 X 10 = 6-65. A cold aqueous extract should not exceed 4*7 per cent. The Albuminous principles are divided into those which are soluble and those which are insoluble in cold water. The former, which include vegetable albumen, are calculated in the last-described estimate of the cold water extract. The latter are known under the name of gluten, a mixture, according to Eitthausen, of gliadin, gluten-casein, gluten-fibrine, and mucedin. Gluten. Gluten. — This compound body is estimated by two methods — the rough one of mechanically sepa- rating the gluten, and the more delicate adaptation of the ammonia process {vide page 453). It is wise to employ both, so that one may confirm or negative the other. Place 100 grammes or 100 grains in a Berlin evaporating dish, and mix it thoroughly with a little INSPECTION AND EXAMINATION OF FLOUR. 445 water, so as to make a dougli. Add water to it, mean- time kneading it well with the fingers. Pour off the water and add fresh. This addition and removal of water is carried on until the water ceases to be milky in appearance, when, all starch having been thus re- moved, only a tenacious mass of gluten remains, which is to be dried on the water bath and weighed. Good flour contains from 8 to 12 per cent of gluten. Professor Parkes says that flour should be rejected in which it falls below 8 per cent. Accidental and intentional admixtures of arsenic MetaUic with flour sometimes but rarely occur. I have only p°^°^®- encountered one case, although I have been in the pro- fession twenty years. A remarkable case of an outbreak of lead poisoning, in which between fifteen and twenty persons were simultaneously affected, has recently been published by Dr. Alford.* It was traced to the admixture of lead with the flour in the process of grinding the corn. The millstone being of a very loose nature, large spaces existed in it, which had been filled up by pouring into them quantities of molten lead. There were ten pounds of lead upon the surface of the millstone, and the cavi- ties were all filled with the same metal. The ordinary tests described in the text-books on chemistry roughly applied are sufficient to identify either of these poisons as they occur in flour. Microscopic Examination. The most common animal found in flour that has been kept in a damp place, or been otherwise damaged, * Scmitary Record, May 25t]i, 1877, page 321. 446 INSPECTION AND EXAMINATION OF FLOUE. is the Acarus farince, which multiplies with great rapidity. The Acanis Farinse. Fig. 78.— Acarus farinse, x.SSdiam. (after Parkes). Wheat Starch. Barley Starch. Barley-meal, beans, potato, maize, oat, rye, and rice, are the most common adiilterants of wheat flour, which may all be detected by the microscope. 1. Barley. — The starch granules of barley so closely resemble those of wheat that they cannot readily be dis- Pig. 79. Wheat starch tinguished from one another. Barley X 420 diam. (after » '' Cameron). starch consists rather of small and large grains, with very few of an intermediate size ; whereas this peculiarity does not exist in the case of wheat starch. INSPECTION AND EXAMINATION OF FLOUE. 447 When mingled together, as in the adulteration of Testa of Wheat. Fig. SO.— Testa of Wheat, X 200 (after Hassall). Transverse Section of Testa of Wheat Grain. — d. Cells of substance of grain contain- ing starch gi-anules. The testa consists of 3 coats, 2 longitudinal and 1 transverse. Longitudinal Coat — Outer Layer. — Margins of cells, distinctly beaded. Transverse Coat. — Margins of cells, beaded, but to a less extent. Longitudinal Celh of Surface of Grain = c. consists of only one layer. wheat with barley, it is thus almost impossible to distinguish the two starches. As the finest flour con- Testa of Barley. Fig. 81.— Testa of Barley, x 200 (after HassaU). Transverse Section of Testa "of Barley Grain. — The cells of substance of grain containing starch granules are not here depicted. The testa consists of 4 coats, 3 longitudinal and 1 transverse. Longitudinal Coat — Outer Layer. — Margins of cells not beaded, but slightly waved. Transverse Coat. — Margins of cells not beaded or waved. Longitudinal Cells of Surface of Grain = c. consists of 3 layers. tains portions of the investing membranes of the grain, 448 INSPECTION AND EXAMINATION OF FLOUR. the presence of "barley meal is diagnosed by an examina- tion of portions of the testa, which should be sought for. The cells of the substance of the grain of barley are seen when emptied of starch to be of more delicate structure than those of wheat, and to present a fibrous appearance. Bean starch. 2. Bean. — The addition of beans can easily be detected by a microscopic examination. Fig. 82. — Bean Starch (after Parkes). If a little boiling water be thrown on flour thus Fig. 83.— Potato Starch not polarized, x 285 (after Parkes). INSPECTION AND EXAMINATION OF FLOUK. 449 adulterated the characteristic smell of beans is evolved. Donne's test consists in pouring successively a little nitric acid and ammonia on the flour. If it is not, adulterated with beans no marked reaction is apparent ; but if bean meal is present a deep red colour is observed. 3, Potatoes. — If pota- to starch is found in flour the dilution is as much a fraud as that of water with mUk. The pyriform appearance and eccentric hilum are characteristics of this starch. Potato Starch. Fig. 84. — Potato Starch polarized, x 200. 4. Maize. — The starch granules on the outer part of Maize Starch. Fig. 85.— Maize Starch (after Parkes). 2 G- 450 INSPECTION AND EXAMINATION OF FLOUR. Oat Starch Adultera- tion of Oatmeal. the grain are of hexagonal, and in the centre of a spherical or oval form. 5. Oats. — The granules of oat starch, unlike those of the other starches, do not exhibit the black characteristic crosses under the influence of polarized light. As oats is a very highly nitrogenous material, the admixture of a little oatmeal, with other farinaceous foods, cannot be ob- Fig. 86.— Oat starch, X jectcd to ou Sanitary grounds. ameron). Octtvieol contaius more fatty matters than wheaten flour. Where, as in Scotland, oatmeal, to a very large extent, takes the place of wh eaten flour, the toning down or weakening of oatmeal with the less nutritive barley meal, is a practice which is much to be objected to.'^^" The microscope shows the presence of starch granules, which may be either wheat or barley. As wheat is not employed as an adulterant, the granules will almost certainly be those of barley .f It is asserted that retail dealers mix barley meal with the somewhat buff-coloured oatmeal, to impart a white and cleaner hue. The presence of about one per cent of barley in oatmeal may be charitably looked upon as accidental, but as much as 5 per cent must be regarded as a fraud. As a mode of estimating the percentage of barley in oatmeal that is adulterated with it. Dr. Muter sug- gests the measurement of the starch granules by the aid of a ^ inch objective, and a " B " micrometer eyepiece. Oat granules measure "00037 inch. Bar- * Conviction for adulterating oatmeal with from 25 per cent to 35 per cent of barley meal. Sanitary Eecord, January 20, 1877, p. 42. t English, barley is of course dearer, but foreign barley is cheaper, than oats. INSPECTION AND EXAMINATION OF FLOUR. 451 ley granules measure -00073 inch, and a few of them four times this size, namely "00292 inch. He writes'"' — " The best criterion to go on for the estimation of the percentage is the number of granules measuring •00292 inch, which are found in barley to bear a very constant relation to the "00073 inch granules." 6. By&. — The peculiar rayed hilum of rye starch Rye starch, serves to distinguish it from any other. Fig. 87.— Rye Starch, x 420 (after Cameron). Fig. 88.— Rice Starch, x 420 (after Cameron). 7. B,ice. — Inferior rice is sometimes fraudulently Rice starch. mixed with wheaten flour to render bread whiter and heavier, for rice retains much moisture. Lolium temulentum, or Darnel Grass. — The seeds of Damei this grass are apt to become accidentally or fraudulently ^^^^*' * mixed and ground with the grains of wheat. As the seed of this grass is a poison of the acro-narcotic class^ it is necessary to be able to diagnose the dangerous admixture. Giddiness, tremor, convulsions, and vomit- ing, are the symptoms commonly produced by eating bread containing the flour of darnel grass. Many accidents from consuming flour thus poisoned are recorded.! In the well-known case of poisoning at the Cologne prison, in which sixty persons were affected, * Analyst, January 31st, 1877, p. 190. + London Medical and Physiological Journal, xxviii. 182 ; Biichner's Toxikologie, 174 ; Annalen der Pharmacie, xvi. 318. 452 IXSPECTION AXD EXAMINATION OF FLOUE. one and a liaK draclims of darnel were found in every six ounces of the flour. The starch granules of the darnel closely resemble those of oats, but the difference in the appearance of the testa of the two grains is very striking. Pure flour, when mixed with alcohol, forms a straw- coloured solution, which possesses an agreeable taste. Fig. S9.— Testa of Oat Grain, x 200 diam. a, outer ; 6, middle ; c, inner coats (after Hassall). Fig. 90. — Testa of Lolium temulentum, (Darnel) Grain, x 200 (after HassaU). Flour which contains darnel is said to give a greenish solution, with a disagreeable repulsive taste, and on evaporation a resinous yellow green extract is left (Parkes). If some difficulty is experienced in forming an opinion, the physiological test of administering a small quantity to a dog, and noticing the effect, is admissible. Some rare cases of poisoning have occurred from the mixture with flour of vetches named Lathyrus sativus, and cicera, and of the pollen of the male catkin of the hazel. If, whilst inspecting a specimen of flour with the microscope, particles possessing a resemblance to frag- ments of bone are noticed, the appearance of -which, when magnified, is well known to every medical man, ESrSPECTION AISTD EXAMINATION OF FLOUK. 453 a drop of a solution of nitrate of silver should be added, and tlie flour again examined by tbe microscope. If tbese minute objects really consist of bone dust, they will become yellow under the influence of this reagent. The principal proteine substances occurring in the vegetable kingdom are gluten, legumin, vegetable caseine, and vegetable albumen. An estimation of the proteine value of the different TheProteine p . o -I 1 • l.^ 11 1- Value of the farmaceous foods may be conveniently made by a modi- principal fication of the ammonia process of Wanklyn, Chap- farinaceous man, and Smith. Its adaptation to this purpose is estimated described in the Philosophical Magazine, May 1 8 '^'^^ Ammonia which, with certain improvements that have suggested Process, themselves in working it, will be here described. Place a gramme of the vegetable substance, which should be in a state of fine powder, in a litre flask, and add 20 cub. cent, of a decinormal solution of caustic potash (1'4 gramme of caustic potash in ^ litre of dis- tilled water) ; pour a little distilled water into the litre flask and shake ; add a little more distilled water and again shake vigorously the contents of the flask ; con- tinue the addition of the distilled water, occasionally stopping to shake, until the litre mark is reached by the level of the liquid. If the shaking has been thor- oughly performed the farinaceous substance will be equally diffused throughout the litre of water, other- wise there will be small lumps that will settle at the bottom of the flask. The retort and Leibig's condenser that are employed in water analysis are arranged for a distillation. Pour into the retort a ^ litre of distilled water and 5 cub. cent, of the permanganate of potash and caustic potash solution {vide page 175), and distil 454 INSPECTION AND EXAMINATION OF FLOUE. until the distillates that pass over are quite free from ammonia, wMcli is of course ascertained by the Nessler reagent. Then add to the contents of the retort 10 cub. cent, of the liquid in the litre flask that contains the vegetable substance (10 miUigrammes) to be ex- amined, and proceed with the distillation. Each 50 c. c. that distils over is to be Nesslerized, and the depth of tint estimated by a standard solution of am- monia, exactly as in water analysis. The amount of ammonia found, if multiplied by 10, yields the per- centage of proteine compounds. Messrs. Wanklyn and Cooper give the following determinations in the paper above referred to : — ] Percentage of Ammonia. Percentage of Proteine Compounds. Wheaten flour . . 1-00 to 1-13 . 10-00 to 11-3 Pea flour . 2-30 23-0 Eice . 0-62 6-2 Maize 1-03 10-3 Oats . 1-00 10-0 Barley 1-10 11-0 Malt . •50 5-0 Rye . 1-45 14-5 Ajrowroot . •08 •8 INSPECTION AND EXAMINATION OF BEEAD. 455 CHAPTEE XLVI. INSPECTION AND EXAMINATION OF BEEAD. An inspection of bread will often afford many suggest- ive hints as to its condition. It is quite unnecessary to describe the appearance, taste, and smell of good bread, for every one is familiar with it. How few, however, have any notion as to the unwholesome manner in which the greater part of the bread that is eaten is manufactured. Pure bread is rarely procurable in our towns and cities, under the present system that pre- prevails of " flesh dough-kneading." The cellars em- ployed as bakehouses in London and other cities are generally filthy places, with drain smeUs, infested with beetles, mice, and rats, which make playful incursions into the kneading-trough and flour-sack. The work of Mode of kneading is so laborious as to excite profuse perspira- ™^i"*'a^tur- o _ jr jr jr mg our daily tion, which drops into the dough. The flour rises in tread, clouds, and the workers begin, to cough and sneeze. When the process is almost finished, the dough adhering to their arms is scraped off, and the flour that has settled on their hair is brushed off with a coarse brush into the kneading-trough. This cast-off epithelium from the skin, hairs, head scurf, nasal and pulmonary excretions of men, the majority of whom are dirty and unhealthy, are mingled with the dough that forms our daily bread. Fifteen years ago these 456 INSPECTION AND EXAMINATION OF BREAD. revolting disclosures were made apropos of the griev- ances of journeymen bakers, and are to be found in Government Blue Books * Notwithstanding the pub- licity given to these facts, the manufacture of nearly all bread is carried on at the present time in the same disgusting way.f Eorgetfulness would appear to be bliss no less than ignorance. As guardians of the public health, it behoves medical officers of health, not only in the interest of the journeymen bakers themselves, whose lives are so terribly shortened by their unwhole- . some avocation, but in those of the public at large, who are suppKed with foul bread, to bring about the employ- ment of machine-made bread. The apparent failure to substitute the machine dough-kneading for the flesh dough-kneading is principally due to the cost of the machine, namely £60 or £70, to which expenditure bakers are naturally averse. Microscopic Examination. The presence of fungi in bread, such as the several varieties of Penicillium or common mildew, which gives a greenish or brownish or reddish hue, in patches, or the Oidium orantiacwn, which is distinguished by yellow spots, shows that it is unfit for human food, for there is good reason to believe that illness has been produced by such bread. As cooking so greatly alters the appearance of starch granules, the flour from which the bread is made should be examined. * Vide Report of H.M. Special Commissioner, H. S. Tremenlieere, Esq., C.B., to the Secretary of State of the Home Department. + Vide Medical Uxaminer, July 12, 1877, and July 19, 1877. INSPECTION" AND EXAMINATION OF BKEAD. 457 Adulterations of Bread. The most common adulterants of bread are — Alum. Terra alba (hydrated sulphate of lime) and whiting (fine carbonate of lime). Sand. Sulphate of copper. Eice. Potatoes. 1. Alum. — If the grain of wheat is subjected to Aimn. warmth and moisture — as, for example, from long expo- sure in the field, or from storage in warm damp granaries — a certain degree of germination occurs, an action which is accompanied by the conversion of the albuminous matters into diastase (a substance that changes part of the starch into dextrine), and a saccha- rine body called glucose. In the manufacture of bread from this damaged or partially fermented flour, a larger quantity of sugar is formed from the starch under the influence on it of the diastase than is desirable, a sweet- ish, unpleasant, dark-coloured loaf being the result. Alum, if added to damaged flour, checks the action of the diastase on the starch, and thus prevents its con- version into dextrine and sugar, at the same time improving the colour of the bread. Damaged flour being apt to create dyspepsia and diarrhoea, this astringent salt is found to neutralize to some extent these ill effects. The scoundrels who thus swindle the public by passing off as a superior food of the first quality, at a high price, an unwholesome and inferior doctored article, are happily amenable to the law. One unfortunate stumbling-block in the way of 458 INSPECTION AND EXAMINATION OF BEEAD. preventing this extensive system of fraud, -whicli is so injurious to that part of the community that depends so largely for its sustenance on bread — namely, the agricultural labourer — has been the difference of opinion amonsst scientific men as to whether or not alum is injurious to health in the quantities in which it is generally detected m bread. The view that prevails amongst physicians is that a daily dose of alum, even if in minute quantities, is not by any means conducive but rather deleterious to health. Dr. Dauglish holds that the efficacy of alum in the prevention of the solu- tion and decomposition of starch in the loaf is more or less continued in the stomach; for the alum, whilst neutralizing the action of the diastase, will further neutralize the influence of the gastric juices, the result being imperfect digestion, with the consequent elimina- tion from the system of substances which should other- wise meet with ready assimilation as true food, includ- ing a large proportion of gluten and unaltered starch.* Many scientific chemists, who have but a smattering of medical knowledge, consider that alum in bread is harm- less, except perhaps when present in large amount. In many districts, where the only water obtainable is muddy, it is the practice to place a pinch of aliun in a large butt of water to clarify it by a precipitation of the suspended impurities. The men in such parts drink nothing but beer. I have never seen amongst the wives of these men who drink such water a perfectly healthy woman. Sulphate 2. Terra Alba {Hydratecl Sulphate of Lirns^^ Plaster Carbonate of Faris) and Wliiting {Carbonate of Lime). — The pre- of Lime. scuce of this and other mineral substances in bread is * "Bread and Bread Stuffs," by B. Dj'er; Sanitary Record, Dec. 34, 1877. INSPECTION AND EXAMINATION OF BEE AD. 459 suspected if the ash is excessive. It should not exceed 2 per cent. The flour from which the bread has been made should, if possible, be procured, for flour can be reduced to ash far more rapidly than bread. Care should be taken not to mistake the coke for the ash. Ee-ignition will diminish the weight of the coke, but not that of the ash. The ash of flour which is unadul- terated with mineral matter does not exceed 7 to 8 per cent. The prompt action of the Eussian Government during the recent Eusso-Turkish campaign, on discover- ing that the flour furnished by the head of the Commis- sariat Department contained a large percentage of terra alba, is to be commended. The man who endangered the success of the enterprise was immediately shot for his dishonesty. 3, Sand. — The admixture of sand with bread is sand. easily shown by the silica determination. The average amount of silica in good bread is about '025 per cent. 4. Sulphate of Copper is used by bakers on the sulphate of Continent in small quantities to give a white colour and *^°pp®^- otherwise improve the appearance of bread manufactured from damaged flour. The continual use of bread thus adulterated cannot fail to be injurious to health, what- ever the quantity of the poison may be. Modes of Detection. — 1. Cut a smooth slice of bread and draw across its surface a glass rod dipped in a solution of ferrocyanide of potassium. If copper be present, the streak wiU be of a brownish-red colour. 2. Burn a quantity of bread (or flour, if it is desir- able to test it) to an ash. Boil the ash in a platinum crucible with a few drops of strong sulphuric acid, which should afterwards be 460 INSPECTION AND EXAMINATION OF BEEAD. Rice. diluted witli water. Place in the solution a piece of copper or zinc. If copper be present, it will be deposited on the surface of the platinum. 5. Potatoes are generally added when they are cheap, in a mashed form, to dilute the flour and render bread heavier, for they contain between 70 and 80 per cent of water. Bread thus adulterated has a damp appearance and taste. Many housewives add a few boiled potatoes to the flour in making their bread, with a view to prevent the bread from soon beco m ing dry. Mode of Detection. — Make a solution of bread. Test it with red litmus paper. If it is not alkaline, burn some of the bread, and test the ash with litmus paper. If the ash, instead of being neutral, is alkaline, potatoes are probably present. The percentage of water in the bread and its appearance must also be noted. 6. Bice is added to bread to whiten it and to render it heavier, as it contains a large quantity of water. Mode of Detection. — The ash of rice is necessarily low, namely "85 per cent. An excessive percentage of moisture, an unnatural whiteness of the bread, and a low ash, are suggestive of this adulteration. The flour with which the bread is made should be examined microscopically, for the granules of rice are different from those of any other starch. Chemical Examination. Water Water. — The mean amount of moisture found by exceed Dr. Odliug in good bread was 43 '4 per cent, the maxi- atout45 xnnm of aU the 25 specimens examined yielding 46'7 per cent of water. Place a small portion of bread in a platimun dish per cent. INSPECTION AND EXAMINATION OF BKEAD. 461 of known weight. Weigh. Dry over water bath for some time. "Weigh. Expose the dish on the water bath for another half-hour, and again weigh. Calculate the percentage. For example : — Bread and dish Dish bread lg at 212° F. First weighing. 27-810 26-205 28-910 26-205 Weight of After dryii Bread and dish Dish . 2-705 Second weighing. 27-665 26-205 Weight of bread 1-605 2-705 : 1-460 : : 100 100 1-460 2-705) 146-00000 (53-£ 100-00 53-97 of solid. )7 46-03 of moisture. Kesult 46'03 per cent of water. The addition of mashed potatoes, or boiled rice (starchy foods that are deficient in the nitrogenous elements) is to be suspected if the percentage of water is excessive. If bread possesses an unnatural white- ness and no alum or terra alba can be detected, rice is the probable adulterant. Ash.- — Take 100 grammes of bread (crust and Ash should crumb in about equal proportions) and, having cut it s^perTeiif up into fragments, burn it in a Berlin dish of about 5 inches in diameter. The coke that forms should be broken up by the help of a platinum rod. It is not 462 INSPECTION AND EXAMINATION OF BEEAD. advisable to employ a persistently intense heat, as there is a danger of volatilizing the alumina of the alum, and of cracking the dish. When the cinder and ash cease to glow, and when they exhibit a grey colour, the burning may be considered complete. The ash should not be thoroughly decarbonized for fear of volatilizing the alumina. The burning of 100 grammes of bread consumes four hours. This process can be accomplished in half the time by employing 5 grammes, but in that case greater care and accuracy are required in working. The ash is transferred to a platinum dish, for weighing, by the help of the feather end of a quill pen, with which the interior of the porcelain dish can be very thoroughly cleaned. Before the weight is taken, it is desirable to complete the incineration by heating the contents of the platinum dish to redness for a short time, -to ensure a thorough burning. If the operator is pos- sessed of a large £5 platinum dish, the employment of the Berlin dish is dispensed with. The ash should be weighed. It does not in pure bread exceed 2 grammes in 1 grammes of bread, or 2 per cent. For example : — Ash and platinum dish. . 27770 Platinum^dish . . 26-205 Ash . 1-565 Result 1*5 per cent of ash. Silica varies SUica. — Add 5 c. c. to 10 c. c. of strong hydro- teeTdfrom chloric acid (pure) to the ash in the platinum dish. •018 to -032 Add 20 c. c. to 30 c. c. of distilled water, and boil, taking care to avoid splashing. The hot liquid is passed through a small Swedish filter paper into a beaker, Place some distilled water in the platinum per cent. INSPECTION AND EXAMINATION OF BKEAD. 463 dish and heat to boiling point, nsing a feather or glass rod to detach any solid particles adhering to the sides of the dish. Pour these washings through the filter. Finally wash the precipitate on the filter with hot distilled water by the help of a wash bottle. The well- established rule of avoiding the addition of the wash water to the filter before the mother liquor has entirely passed through it should of course be remembered. As the precipitate on the filter has, like many other precipitates, a tendency to clamber up the sides of the filter and pass down between the filter and the funnel, it is necessary to wash it down the sides of the filter by the help of a jet of water from the wash bottle. A great bulk of liquid is to be avoided in making these washings. Several successive washings with small quantities of hot distilled water are preferable to the practice of using two or three large quantities. Let the filter drain and dry, by suspending the funnel containing it in a ring of a retort stand, at such a dis- tance above a Bunsen's burner, or a spirit lamp, as to prevent the possibility of ignition or charring. The filter and the precipitate on it will soon dry. Fold the filter and carefully transfer it into a little platinum or porcelain crucible provided with a cover (or into a platinum milk dish), and burn the filter to an ash, and weigh. It is advisable to employ round Swedish filter papers yielding definite and known quantities of ash, as, for example, one or two milligramme filter papers. If none are at hand, cut a filter of the requisite size out of a sheet of filter paper and weigh. The weight of the ash is always -|- per cent the weight of the filter paper ; therefore, a filter paper weighing 500 milligrammes 464 INSPECTION AND EXAMINATION OF BKEAD. has an ash of 2-|- milligrammes. We have now arrived at the weight of the silica in the total ash. For example : — Platinum dish and ash . 7-8200 Dish . . . 7-7700 Weight of ash . . 1-0500 „ of filter . -0015 -0485 Eesult '0485 per cent of silica. The following process for the determination of the amount of alum in bread was invented by Dr. Dupre, and has been improved upon by Mr. WanM}Ti. Alumina. AlumincL — The filtrate from the silica estimation is now rendered strongly alkahne by the addition of about 5 c. c. of pure liq. ammonife fort, to precipitate the phosphates. Finally, mix gxadually with this alkaline water, stirring all the time, sufficient pure acetic acid,"^^" strong (not glacial), to neutralize the alkalinity, a point which is easily determined by means of litmus paper. The usual quantity of acetic acid reqmred is about 10 c. c. It is advisable, after having thoroughly neutralized the alkalinity, to add about 10 c. c. of acetic acid more to ensure an excess. Boil and filter through a Swedish filter paper of known weight. (It is better to allow the precipitate to subside a little before commencing the filtration.) Wash well the beaker with hot distilled water, detaching the adherent jelly-like matter by the aid of a feather of a quill, and pour the washings on to the filter. Dry the filter in the manner already described. Place it in a platinum dish, or into a platinum or porcelain crucible with a * The phosphates of alumina and iron are insoluble in acetic acid. INSPECTION AND EXAMINATION OF BREAD. 465 lid, whicli is far better; ignite and weigh the ash, which is a mixture of the phosphates of alumina and iron. The washings of the precipitate in the foregoing manipulations should be occasionally tested as they pass out of the funnel, by allowing a drop to fall on a piece of platinum foil, or a platinum spatula, and evaporating it to dryness to see if it leaves any residue. The washings should be continued until no residue is left. The amount of phosphates of alumina present in pure bread varies from 5 to 10 milligrammes ("005- •01) per 100 grammes of bread. The amount of phosphates of iron generally present in pure bread does not exceed two or three milligrammes (•002 or '003) per 100 grammes of bread. 100 grammes of pure unadulterated bread has been found to yield as much as "010 milligranimes of phos- phate of alumina and of iron, which is equivalent to 1 grains of alum in a 4 lb. loaf. If the ash does not exceed 'OlS milligrammes of this mixture of phosphates of alumina and iron in 100 grammes of bread, there is no adulteration of the bread with alum. For example, a bread containing alum yielded — Weight of dish and ash . 7-8490 Platinum dish . . 7-7690 ■0800 Weight of ash of filter . -0020 Weight of ash . -0780 Deduct average amount of phos- phates of alumina and iron found in good unalumed bread . -0055 Grains . -0725 in the 4 lb. loaf. Eesult 72^ grains in a 4 lb. loaf. 2h 466 INSPECTION AND EXAMINATION OF BREAD. Horsley'i Test for Alum. The following analyses of loaves of bread, containing known quantities of alum, have been recently made in my laboratory by Mr. Slater : — Alumed Bread. Samples. Pound in 100 parts by weight. Quantity of alum added to bread. Ash. Silica. Alum. Grains. Grains. 1 1-5 •048 18-0 15-5 2 1-19 •0475 7-6 7-7 3 1-19 •046 3-3 3-1 4 1-1 •027 1-2 1-5 Horsley's test for the detection of alum in bread is employed as a qualitative auxiliary test by many analysts. It is prepared thus : — " 1. Make a tincture of logwood by digesting for eight hours 2 drachms of freshly cut logwood chips in 5 ounces of methylated spirit in a wide-mouthed phial, and filter. " 2. Make a saturated solution of carbonate of am- monia in distilled water. " A teaspoonful of each solution mixed with a wine- glassful of water in a white ware vessel forms a pink- coloured liquid. Bread containing alum, immersed in in this liquid for five minutes or so, and then placed upon a plate to drain, will in an hour or two become blue on drying ; but, if no alum is present, the pink colour fades away. If, on drying, a greenish tinge appears, an indication of copper is afforded, as carbonate of ammonia produces that colour, but never a blue." Mr. Allen and Mr. E. W. T. Jones both consider that, if the logwood test gives a blue colour, something INSPECTION AND EXAMINATION OF BKEAD. 467 is wrong with, the bread, although it would he rash to say that this coloration indicates that the bread has been adulterated with alum. The amount of alum generally found in bread adulterated with this substance varies between 20 and 3 grains in a 4 lb. loaf, although more than 100 grains have in exceptional cases been discovered in the same quantity of bread. It does not necessarily follow, that because bread on analysis proves to have been alumed, the baker has mingled it with his flour in the manufacture of his bread. Some millers alum the flour before they supply it to their customers. Accordingly, when a loaf is purchased for analysis, a sample of flour from each sack found on the premises should also be taken for examination. In rare cases, salt, which is, of course, freely used in bread making, has been found to contain alum. 468 INSPECTION AND EXAMINATION OF MILK. CHAPTEE XLYII. INSPECTION AND EXAMINATION OF MILK. Milk contains the three classes of principles which are required for human food — namely, the Albuminous or ^Nitrogenous, the Oleaginous, and the Saccharine — and is the only article supplied by nature which combines all the elements requisite to secure healthy nutrition in a form suited to the young animal. It must not be omitted, therefore, from the category of the necessaries of life to which the attention of the medical officer of health is restricted, although, if he does not hold the post of public analyst, he may not find it requisite to make an official exam,ination of a milk, except as a guide for himself in his own investigations as to the origin and spread of diseases. In milk outbreaks of typhoid fever not a single link in the chain of evidence should be neglected. If the health officer finds on analysis that the water used in the dairy contains ex- cremental filth, and traces the pollution to its source, which has been infected with the specific poison of the disease, it is still desirable to ascertain whether or not the milk has been diluted with water. Here is an example of the assistance that such an examination may afford a medical officer of health : — Fever once appeared in a large public school, and as no mode of the entrance of the poison could be discovered, it was INSPECTION AND EXAMINATION OF MILK. 469 at first supposed to have arisen sud sponte. The water supply on analysis proved to be pure. The milk was supplied from two or three sources, and was not com- plained of. On making an analysis of the milk it was found to have been manipulated with water. An analysis of the water from each of the three farms, whence the milk was derived, was made, and one of these waters was discovered to be polluted with animal excrement, whilst the other two waters were of un- doubted purity. On visiting the dairy farm possessing the polluted water supply, it transpired that the closet and well were in affectionate proximity, and that the former had recently received the specific poison of the disease from one of the labourers. If milk under such circumstances should not evince by chemical examina- tion any decided departure from the normal state of the secretion, due regard being paid to its variation in composition, by reason of the age and food of cow, time after calving, weather, etc., it must not be con- cluded that the poison of the disease has not been communicated to the milk through the medium of water, for there is every reason to believe that the smallest quantity of water contaiuing the specific poison, such as may be introduced by merely rinsing the milk-cans, is suf&cient to infect a large quantity of milk. An analysis of milk in suspected typhoid out- breaks affords only negative evidence. The undoubted admixture of water with milk introduces us to a fresh scent in our endeavours to trace the introduction of the poison, although the absence of signs of any decided adulteration does not preclude the possibility that the milk may have been poisoned through the medium of water. No ray of light, however feeble, should be 470 INSPECTION" AND EXAMINATION OF MILK. neglected in tracking this prevalent and wholly pre- ventable disease. The microscope affords also aid which is not to he despised. In milk outbreaks of scarlet fever a comparison should be made with this instrument between milk that has been exposed to in- fection — aS; for example, from being stored within a few yards of persons suffering or recovering from this disease — and the milk of the same animals that has not been thus endangered, with the object of discovering epithelial scales, for its poison would seem to be mainly distributed through the air by the aid of the dust of the skin to which it attaches itself. Good milk, the chemical composition of which is to be found in every physiological work, is slightly acid or neutral, or very feebly alkaline to litmus paper. Its specific gravity is about 1"029 or 1"030. Microscopic Appearance. Milk is seen to consist of a number of oil globules of different sizes, called milk globules, and a Kttle epithe- lium suspended in a somewhat turbid fluid. Immediately after calving are sometimes perceived large yellow com- pound bodies termed colostrum corpuscles. The secretion of the colostrum immedi- ately after birth is, as every one knows, designed to purge the young animal. OO (^ oo -, Fig. 91. — Milk containing colostrum corpuscles, at a and elsewhere (after Carpenter). INSPECTION AND EXAMINATION OF MILK. 471 In the milk of a woman suffering from an acute disease, colostrum corpuscles, and large granular cells rich, in fat are visible.""" Foreign bodies are sometimes noticed by the micro- scope in milk ; for example, blood and pus corpuscles, epithelium, etc. ; also, mineral matters, such as chalk, starch, vegetable organisms. Milk coagulating during or immediately after milk- Fresh MUk ing, especially after it is warmed. — The secretion of '■°*° this acid milk may be owing (1) to inflammation of udder, (2) to digestive disturbance or a febrile state. Yelloiv Milk. — This colour, when not due to the YeiiowMiik. colostrum of newly-calved cows, is observed when there is irritation or congestion of the udder. Dairymen colour their milk with annate. When milk is boiled the colouring matter remains in the whey. An un- natural yellow colour of cream is sometimes produced by an organism called by Verheyen the Vibrio xantho- genus. The eating of orchids by cows has been said to render the milk of a yeUow colour. Viscid Milk, which is stringy and mucus-like when viscid Miik. poured from one vessel to another, and has a stale un- pleasant taste, has been found to contain a large pro- portion of albumen, as well as carbonate of ammonia. Microscopically it resembles colostrum, but it is distin- guished from it by its power of producing the same alteration in a large quantity of healthy milk. The viscidity of milk has been ascribed to a half -starved condition of cows, and to damp unwholesome dairies. The colours of Uue, red, and green milk or cream, are aU probably due to the development of organisms, the nature of which has not been made out. The * Lehman's Physiological Cliemistry. 472 INSPECTION AND EXAMINATION OF MILK. ferment produced will give rise to the same alteration when a small portion of either of these milks is added to a large quantity of good milk. Happily these peculiar growths are engaging the attention of Professor Lister, so we may confidently hope that we shall soon possess some knowledge respecting them."^^ Blue Milk. Blue Milk has a disagreeable taste, and has been found to produce diarrhoea and severe febrile gastritis.! Pigs, rabbits, and sucking calves suffer from diarrhoea after feeding on it. A distinction has been drawn between milk which is blue when drawn and that which is blue when coagulated or in the condition of cream, the former being supposed to be not injurious and the latter in- jurious to health. The probability is that the colour is due to one and the same organism, which becomes poisonous only at a certain stage of its development. The blue colour has been attributed to the consump- tion by the cows of certain plants, as the Myosotis jpalustris, Mercurialis perennis, Fagopyrum, Polygonum aviculare, etc. Milk is a fluid which is extremely liable to be affected, as to its odour and taste and quality, by the food of the cows that secrete it, and by chemical changes that are due to foul conditions of air to which it may be exposed, and to the special ferments which attach themselves to it. Changes in We are aU. familiar with the taste of turnips in our odom-*'^'^ milk and butter during the depth of winter. Vine and chestnut leaves will render milk bitter, and beech leaves * Opening Address at King's College, London, 1877 ; British Medical Journal, October 6tli, 1877. + Virchow's Archiv, Band xliii. page 161 (1868), INSPECTION AND EXAMINATION OF MILK, 473 will diminish the supply of milk. Milk is also bitter if bitter medicines have been administered to the cow, and in disease of the liver. Milk has been found to possess a sweet or bitter unpleasant taste and a " rotten " disagreeable odour when suppHed by cows badly kept on damaged forage and filthy water, and when kept in dirty, unwholesome, damp dairies.'"'' Mr. Smee exposed milk to sewer gas, but could find no change in composition on making a chemical analysis. On distilling the milk at a temperature not exceeding 120° F., a distillate was obtained which had an unpleasant taste and an offensive smell. " Tasting the distillate set up intense headache, vigorous rapid pulse, and was followed by severe diarrhoea." f Milk exposed to the vapour arising from animal matter undergoing putrid decomposition, similarly treated, was offensive and produced results dangerous to health. Cliemical Examination. The average composition of good country and town fed milk is thus given by Wanklyn : — 100 cub. cent, contain — Country. Water . . , 90 '09 grammes. Fat . . . / Caseine Milk solids 12-81 j 3-16 ij 4-16 )) \ Milk solids. Milk-sugar (lactin) . \ Ash . . . ( 4-76 5? > not fat, 0-73 )> ) 9-65. 102-90 * I visited a dairyman's establisliment once where the water in the cowshed, with which the milk was confessedly adulterated, was sewage water, and the cans of milk Avere stored in a bedroom redolent of organic matter, + 31ilk in Health and Disease. 474 INSPECTION AlsB EXAMINATION OF MILK. Town. The Lacto- meter. Water . . *. Fat . Caseine Milk solids 14'47 Milk-sugar (lactiii) Ash . 8 8 "43 grammes. 4-12 5-16 „ ] Solids, not 4-43 „ > fat, 10-35. 0-76 „ J 102-90 The lactometer is simply an instrument for ascer- taining the specific gravity of milk. The more milk- sugar, caseine, and other mineral matter contained in milk, the greater the specific gravity. The effect of these solids is more or less counteracted by the fat globules, which tend to lower the gravity, because fat is lighter than water. As the addition of fat tends to diminish, its abstraction (skimming) must increase, the specific gravity. The practice in the milk trade is to rob the fresh milk of cream by pouring into it skimmed milk. The specific gravity having thus been raised abnormally high, is toned down to the specific gravity of good rich milk by dosing it with water. The creamometer is an instrument which is eq^ually fallacious. ]\iilk should always be analysed in a fresh state, for when sour or otherwise decomposed, correct deter- minations are more difficult. Certain allowances in such cases have to be made which introduce discre- pancies, and analysts differ as to what those corrections should be. The determination of the amount of water in milk is made by the estimation of the amount of milk solids thus : — Procure (1) three or four little platinum dishes 12-81 to 14-47 each of which is numbered; (2) a copper water bath Water in milk. Average milk solids, INSPECTION AND EXAMINATION OF MILK. 475 resembling that depicted in Fig. 6, provided with holes grammes in corresponding to the number of little platinum dishes, ^^^ in place of the large holes there exhibited ; and (3) a bulb pipette graduated to 5 c. c. Weigh the dish and place it on the water-bath. Having shaken the sample of milk, place 5 c. c. of it, measured with the pipette figured below, in the dish. Light the Bunsen's burner, and boil the water in the bath vigorously. Complete Fig. 92.— Milk Pipette. evaporation to dryness will consume three hours. At the end of this time remove the platinum dish, wipe it, and weigh it immediately. For example : — Milk solids and platinum dish. . 8 '40 8 Platinum dish. . . . 7*768 Milk solids '640 Multiply by 20 to obtain the amount present in 100 c. c. of the milk — - -640 X 20 = 12-80 grammes in 100 c. c. of milk. As 100 c. c. of average milk weigh 10 2' 9 grammes, it is necessary, if it is wished to obtain a percentage statement, to divide by 1'029. 12-80 grammes in 100 c. c. of milk -i- by 1-029 = 12*44 per cent of milk solids. The average amount of milk soKds in country and town fed milk is shown in the foregoing complete analyses. The milk solids of the milk of well-fed cows has 476 INSPECTION AND EXAMINATION OF MILK. never been known to fall below 11 "8 grammes in 100 c. c* Ash in 100 The adulteration of milk with chalk or other mUk°^7^-°8*^ inorganic substance is easily detected hj an estimation gramme. of the ash. TMs determination also serves to confirm or otherwise the examination as to water adulteration, for a milk highly adulterated with water gives too low an ash. Place the platinum dish containing the dried milk solids on a pipe triangle, and incinerate with the flame of a Bunsen's burner. Allow the dish to cool, and weigh. Subtract the weight of the dish from that of the dish and ash, and multiply the result by 20 to obtain the amount of ash in 100 c. c. of milk. For example : — Ash and platinum dish . 7 "807 Platinum dish (No. 3) . 7768 •039 •039 X 20 = •78 gramme of ash in 100 c. c. of milk. If a percentage statement t is required, divide by 1^029. •78 -f- 1-029 = -75 per cent of ash. Average of If it is cousidercd desirable to know the extent of frol^"i6to watering to which a milk has been subjected, it is 4-12 grains ncccssary to estimate the amount of fat in the milk, of milk. This determination is somewhat troublesome, and is attended with a very sensible error from loss of fat, unless performed in the following manner : — 5 c. c. of * Pay en asserts that goats' milk contains 14 '4 per cent, and asses' milk 9 "5 per cent of solids. + The results of an analysis are nearly always recorded in the form of a percentage, as such a mode of statement is more easily understood by the public. INSPECTION AND EXAMINATION OF MILK. 477 the milk to be examined are evaporated on the copper water bath to a condition of a thick paste in a thin Berlin porcelain dish of about 2-|- inches in diameter. As it is evaporating, move aside the scum that forms on the surface of the milk by means of a short glass rod, which may conveniently be allowed to remain in the dish. When it has evaporated so far as to become of a sticky pasty condition, remove the dish from the water bath. A funnel provided with a filter should be supported by a ring of a retort stand over a platinum dish of such a capacity that it will hold comfortably 100 c.c. Place a large Berlin dish containing some very hot water near at hand. Moisten the filter with a little methylated ether (10 c. c), allowing it to flow into the platinum dish. Pour this ether from the platinum dish into the Berlin dish containing the milk residue, and mix the same with the ether as thoroughly as possible by the aid of the glass rod. Place the Berlin dish on the surface of the hot water, so as to make the ether boil,'"' and then pour it on the filter. Pour a second 10 c. c. of ether into the Berlin dish on the milk residue, and by aid of the glass rod expose the whole of the sticky mass to the influence of the ether. Then float the dish again on the surface of the hot water in order that the ether may boil, and pour it on the filter. A washing should not be thrown on the filter, until the previous washing has passed through into the platinum dish. A third and a fourth 10 c. c. of ether are now poured into the Berlin dish, and dealt with in a similar manner. By the help of a clean finger, every portion of the sticky contents of the dish * It wiU be remembered that ether boils at a very low temperature. 478 INSPECTION AND EXAMINATION OF MILK. should be broken up and thoroughly exposed to the solvent action of the ether. Before removal the finger should be washed with a drop or two of pure ether. The Berlin dish is floated again in the hot water to make the ether boil. It should then be poured on the filter. A fifth washing with 10 c. c. by the aid of the finger should now be performed in the same manner as the last. When no fat globules are dis- cernible on the edge of the inside of the dish towards which they creep, and when the addition of a few drops of fresh ether does not raise any towards the edge, we know that the washing is complete, and vice versd. It will be seen that about 50 c. c. of ether are used up to the present time. Around the edges of the filter in the funnel will now be noticed some fat globules. To remove them, pour a little ether on to the edge of the filter, turning around the funnel whilst so doing. The ether will dissolve the fat, and the solution will run down be- tween the filter and the funnel into the platinum dish. A little fat will also be found on the outside of the tube of the funnel, that has crept up from the inside. Take it off with a clean finger, and wipe the finger on the edge of the platinum dish. Evaporate the solution of fat in ether to dryness on a water bath, guarding against the violent ebullition of the ether, which it should be remembered boils at about the temperature of the body. The evaporation of the ether may be conveniently accomplished during a temporary absence, by floating the platinum dish containing the ether on a large dish full of hot water. After evaporation, weigh. The difference between the weight of the dish and INSPECTION AND EXAMINATION OF MILK. 479 that of the dish and the fat should be multiplied by 20 to obtain the amount of fat, as grammes, contained in 100 c. c. of milk. If the percentage of fat is re- quu^ed, it is obtained by dividing the amount of fat by 1 • 2 9 . For example : — Fat and platinum dish . . 30' 349 Platinum dish . . .30-201 Weight of fat . . '148 gramme. •148 in 5 c. c. X 20 = 2"96 grammes of fat in 100 c. c. of milk, or 2'8 per cent of fat. Deduct the quantity of fat from the total milk solids, and the important datum " sohds not fat " is obtained. The amount of fat, and of " solids not fat," contained in good country and town milk are seen in the fore- going complete analyses. Casein. — The residue, after the removal of the fatty casem. matters by ether, consists of casein, lactin or milk-sugar, and ash. The lactin and the soluble portion of the ash, namely the chlorides, are separated from the casein by digesting the residue with very weak hot alcohol. On filtration the casein is left on the filter paper, from which it is washed into a little platinum dish. Keep the dish on the water bath to dry the casein until it ceases to lose weight. Weigh the dish containing the dried casein, ignite the casein, and subtract the weight of the dish and the adhering phosphate of lime. We then arrive at the weight of the casein in 5 c. c. of milk, which, if multiplied by 20, yields the quantity in 100 c. c. of milk. If a percentage statement is required, the result must be divided by 1'029. LoLctin or Milk-Sugar. — The process employed by Laetm or me in estimating the milk-sugar is that described in *^'^'^"sar. 480 rxsPECTiox and examination of ishlk. Partes' Hygiene by means of Fehling's solution. Take 10 c. c. of milk, add a few drops of acetic acid, and warm ; this coagulates the casein with the fat ; then make up 100 c. c. with distilled water, jBlter, and put the iiltered whey (which ought to be as clear as possible) into a burette. Take 10 c. c. of Fehling's standard copper solution,'" put it in a porcelain dish, and add 2 or 30 c. c. of distilled water; boil it; as soon as it is in brisk ebullition, drop in the whey from the burette ; take care that the liquid is boiling all the time ; con- tinue the process until the copper is all reduced to red suboxide, and no blue colour remains in the super- natant liquid, but stop before any yellow colour ap- pears. Read off the amount of whey used, and divide by 10 ; the result is the amount of milk which exactly decomposes 10 c. c. of the copper solution. The 10 c. c. of the copper solution are equal to "0667 grammes of lactin. The amount of lactin in the 10 c. c. of milk is then known by a simple rule of three ; and the amount in 100 c. c. of milk is at once obtained by shifting the decimal point one figure to the right. Example : — 15 c. c. of diluted whey were required to reduce the 10 c. c. of copper solution; if =1-5, the amount of original milk; 0*0667 -^ 1'5 = 0*0445 gramme of lactin in 1 c. c. ; there- fore 0-0445 X 100 = 4-45 per cent. Amount of To calculatc the Amount of vjater added to a milk. — Multiply the amount per cent of "solids not fat" found in the sample by 100, and divide by 9-3. For example : — * Recipe of Fehling's Copper Solution. Pure Sulphate of Copper . . . 34'64 grammes ) -p.. ■■ Distnied Water . . . . 200' c. c. ^-Dissolve. Tartrate of Soda and Potash . .173- grammes ) -p.. , Sol. of Caustic Soda or Caustic Potash . 480* c. e. ^ IJissoXve. Mix the two solutions slowlj'', and dilute with distilled water to one litre. 1 c. c. = -00667 gramme of lactin or milk-sugar. water added. INSPECTION AND EXAMINATION OF MILK. 481 8*4 solids not fat. 100 9-3)840-00(90-3 real milk. 837 300 279 The difference between result and 100 is added water, wliicli in this case is 100 90-3 9-7 Answer — 9 '7 per cent of water. To calculate the Amount of Fat removed. — Multiply Amount of the amount of " solids not fat " found in the sample of ^ '''^™°^® ■ milk by 3 "2, and divide by 9 '3. From the product deduct the amount of fat yielded by the milk. The difference is the fact abstracted. For example : — 9*04 solids not fat, found in sample. 3'2 qiiantity (roughly) of fat found in pure country milk. 1808 2712 " Solids not fat" in 9-3)28-928(3-ll fat equal to "solids not 100 grammes (not 279 fat" found in sample 100 c. c.) of pure (9-04). country milk. 102 93 98 93 3-11 5 1'22 fat found in sample. 1"89 quantity of fat abstracted from sample of milk. l-89x5 = 9-45 of cream removed. 2i Milks. 482 IXSPECTION AND EXAMINATION OF MILK. A great controversy has taken place for some time past as to the extent to which the components of milk may vary under the iniluence of feeding, age, time of year, distance of time from calving, etc. Certain cows Abnormal producc what are termed abnormal milks ; that is, milks that are exceptionally rich or exceptionally poor. The following analyses of rich and poor milk were made by Dr. Shea and Mr. John Pattinson. The rich milk was obtained from an animal fed on a sewage farm, chiefly on rye-grass, and the latter from a perfectly healthy Dm-ham shorthorn, fed on turnips, brewers' grains, peasmeal, and hay : — Sp. Gr. Total Solids. Fat. Solids not Fat. Ash. Eich milk 1035 14-8 5-6 9-20 -85 Poor milk 1023 9-94 S'O 6-94 -95 IMiLk taken at the commencement of a milking, which is called " fore milk," is poorer than that drawn afterwards, and that which is obtained at the termina- tion of a milking is generally rich with cream. The law pro^^.des that milk shall be taken to mean whole milk, that is, the mixed milk of an entire milking. Although the milk of individual cows may be found to vary, the milk of a dairy which consists of a mixture of the poor with the rich is pretty constant in compo- sition. Mr. J. Carter Bell has recently made analyses of the milk of 1 8 3 cows belonging to different dairies, the average of which (excluding that of two cows whose milk was in an abnormal state) is as follows : — '" Total SoUds . . .13-60 Solids not fat . . . 9-90 Fat . . . .. 3-70 Asli . . . . -76 * Analyst, December 1877, p. 155. INSPECTION AND EXAMINATION OF MILK. 483 Making every allowance for variations in composi- tion, the Society of Public Analysts have, after much standard of consideration, recommended that 9 per cent of " solids °°° ™ not fat," and 2'5 per cent of fat should be recognized as the minimum limits of these constituents of miLk. Dr. Yoelcker, who uses extinct and antiquated methods of analysis, and Dr. Campbell Brown, who obtains curious results, probably from operating on large quan- tities of milk, consider that this limit is too high. The latter writes :''" — "It is not safe to assert, on analytical grounds alone, that a sample of milk is adulterated with water, unless it contains below 11 per cent of total solids, as well as below 9 per cent of solids not fat ; nor even then, if it contains so much as 2*7 per cent of fat." The Inland Eevenue chemists at Somerset House hold views as to the variability of the composition of milk, which differ from the large majority of chemists. All this lamentable divergence of opinion has led to a result that might have been anticipated — namely, that magistrates will not convict in cases where the adul- teration with water does not exceed 10 per cent, so that milk-sellers may cheat to at least this extent without fear of punishment. Milk of Diseased Animals. Happily this secretion diminishes or disappears in many of the diseases of animals, notably in anthrax. Loiset states that at the public abattoir of Lille the employes of the cattle dealers and salesmen have con- sumed the milk of diseased cows for a great number of years without the slightest inconvenience. * Chemical News, July 1875. 484 INSPECTION AND EXAMINATION OE MILK, Cattle Plague or Rinderpest. Pleuro- pneumonia. Milk is not the diet of men and women, but of cML- dren, amongst whom the mortality under five years of age of affections resulting from improper food is fright- ful. The assertion of Loiset as to the harmlessness of the milk of diseased animals to men seems in no way to determine whether or not such milk is wholesome as the food for the sucking animal, for which it was alone designed by nature. The milk of diseased animals does not keep well. It is found, on microscopic examination, to contain pus, blood, and a larger quantity of epithelium than is pre- sent in good milk, casts of lacteal tubes, vibriones, cells, cTanules, etc. The milk of animals that have been driven fast, which is termed " heated milk," has been found to produce colic and diarrhoea amongst children. Cattle Plague. — There is no evidence to prove that the milk of animals suffering from cattle plague is hurtful. The changes that occur in it are, according to Dr. A. Gamgee, as follows : — 1. Eemarkable diminution of sugar of milk. 2. Enormous increase (except, perhaps, at the com- mencement) of butter. 3. Slight increase of salts. 4. The casein is generally increased. The milk of animals in a state of disease which ex- hibits such a derangement in the normal proportion of its ingredients cannot be wholesome as the staple food for infants and children. Contagious Fleuro-pneumonia.- — There is no evidence to prove that the milk of animals affected with this disease is hurtful to adults or middle-aged persons. Foot-and-mouth Disease. — Much discussion has taken INSPECTION AND EXAMINATION OF MILK. 485 Milk in Foot-and-Mouth Disease. Early Stage, place as to whether the milk of cows suffering from Foot-and- this disease is injurious or not to man, n^^se Pigs fed with the milk of animals thus affected are invariably seized with the disease in a few hours. It generally destroys sucking pigs and calves. Aphthous and herpetic patches, followed by sores, and sometimes diarrhoea, have been attributed to the use of such milk. These symptoms have naturally been observed most amongst children, because they are our great milk-con- sumers. The condition of the milk differs much, accord- ing as the udders are more or less affected. The milk is sometimes unaltered to the unaided eye ; at others it is red, or brown, or yellow, from the presence of blood and pus, or ropy, or re- sembling whey and curds, or foetid. Microscopically it is found to resemble the milk of cattle affected with rinderpest. In the first stage an aggregation of the milk corpuscles takes place. Subsequently pale, fine granules, spherical Pig. 93.— clustering of MUk corpuscles, x T ./ -^ _ T 200 diara. granular ceils a little larger than pus corpuscles, bacteria, vibriones, epithelial cells, yellow granular masses not unlike colostrum globules seen in the milk of cows newly calved, may be discerned. The milk from which the drawing, Fig. 94, was made, was taken from a cow which had been suffering from the disease for ten days. The fluid, after stand- 486 INSPECTION AND EXAMINATION OF MILK. Poot-and-Mouth Disease. Later Stage. 3.. ing for some time, separated into two parts — a curdy deposit and an amber- coloured whey. The same elements were found in both con- stituents, viz., large granular masses of a brownish-yellow col- our, numerous pus-like bodies, bacteria, vibri- ones, moving spherical bodies, and a few milk globules. These mor- bid elements were found in specimens of milk which, in their physical characters, presented no appreci- Fig. 94.— 1. Large gianular bodies ; 2. Milk cor- able peculiarity tO the puscles : 3. Pus-like bodies, x 1300 diam. • i i -55- unaided eye. Mr. Wynter Blyth has noticed, about the third day, some elongated, flattened, highly refractive bodies, "8 W ^° TWO ^^^^ ^^ length. On the fourth day they become few in number, and disappear during the later stages. As to the chemical composition of the milk, he has found that its constituents vary much in amount during the progress of the disease. During these fluctuations there is a deficiency of fat, of salts, and of milk solids not fat, the last named falling below nine per cent on one or two occasions.f * Lancet, October 23d, 1869. f Proceedings of the Society of Public Analysts, 1876, vol. i. p. 238. INSPECTION AND EXAMINATION OF MILK. 487 Continental veterinarians recognize foot-and-mouth disease millc by its easy coagulability on the appKcation of the least heat, with a separation into numerous little curds floating on the whey, the latter being of a pale- bluish colour. There is a strong impression afloat that milT^ drunk in a warm state, direct from a cow affected with the disease, is more likely to produce the foot-and-mouth disease than when cold, and that by boiling the milk all danger is removed. There appears to be no doubt but that the discharges from the vesicles and sores of cattle suffering from this exanthem will, if introduced into chaps or abrasions of the skin in man, create a diseased condition resembling the foot-and-mouth dis- ease of cattle, attended by violent constitutional dis- turbance, Negative evidence as to the injurious nature of foot- and-mouth disease milk is afforded by the investigations of the French Commune in 1839, by the epidemics of 1810, 1811, 1834, and 1835, in Paris, by Lawson Tait,""" and Dr. Thorne Thorne. Positive evidence is given by Poll, M'Bride,t Gooding,^ Hislop,§ Latham, || Briscoe,1[ and ISTauheimer. Cases where the foot was also involved have been re- corded by Spinola""" and Amyot.tt Stomatitis, with aphthous ulcerations in the mouth * Medical Times and Gazette^ October 1869. + British Medical Journal, November 13, 1869. + Medical Times and Gazette, January 1872. § Edinburgh Medical Journal, November 1869. II British Medical Journal, May 1872. IT British Medical Journal, October 1872. ** Eecueil de M6d. Viler., 1873, p. 577. tt Medical Times and Gazette, November 4, 1871. 488 DsrsPECTioN and exambtation of milk. of children, is known to be produced by milk wbicb contains pus from an abscess in the udder. " Sore mouths " were exceedingly prevalent amongst the chil- dren throughout the country during the extensive out- break of foot-and-mouth disease in 1869. The con- clusions arrived at by Dr. Thorne from an investiga- tion made by him on the "Effects produced on the human subject by consumption of milk from cows hav- ing foot-and-mouth disease" are as fallows : — ^ (1.) That a disease appears sometimes to have been produced in the human subject, when the milk of cows suffering from foot-and-mouth disease has been freely used with- out being boiled. There is no evidence to show whether this affection is of a specific nature or not ; but it seems to consist in a derangement of the alimentary canal, accompanied by febrile disturbance, the presence of vesicles on the mucous membrane of the mouth and tongue, which, having ruptured, leave superficial ulcera- tions, and at times a herpetic eruption about the ex- terior of the lips. (2.) That in a very large number of cases the milk of cows undoubtedly affected has been used without producing any noticeable morbid effects. This absence of result may, though only to an incon- siderable extent, have been due to the smallness of the consumption and the boiling of the milk. Outbreaks of illness from the employment of milk from foot-and-mouth disease cattle are recorded in British Medical Journal, November 30 and December 25, 1875, and in other periodicals. The knowledge that we at present possess as to the milk in this disease warrants us in prohibiting the employment of it in any shape for children, and in dis- * " Twelftli Eeport of Medical Officer of Privy Coimcil," 1869. INSPECTION AND EXAMINATION OF MILK. 489 suading adults from using it unless it is boiled and presents the physical characters of good milk. Anthracic Diseases. — The milk of animals affected Anthracie with these diseases is seldom consumed, partly because the secretion is very soon suspended, and partly because the physical appearance of the little milk that is sup- pKed prevents its employment. It is, so Fleming says,'"' of a dirty bluish colour, streaked with blood, and soon becomes putrid. Cases are recorded of diarrhoea and anthracic affec- tions having been produced in man by drinking the milk of diseased animals. Sucking pigs die in great numbers when sows are infected with " hog cholera." Tuherculosis amongst Dairy Cattle. — The most recent Tubercu- investigations show that the disease known as tuber- culosis in man, consisting as it does of the deposition of tubercles in various parts of the body, especially in the lungs and mesenteric glands, is a communicable disease. That the same disease, as it exists in cattle, can be conveyed to calves, rabbits, guinea pigs, etc., by the milk of an animal suffering from the disease, has been proved over and over again by Chauveau, Klebs, Ger- lach, Leisering, Ziirn, Bollinger, and others. Klebs asserts that, when milk has been deprived of its soKd particles, the tubercidous virus is found in the fluid portion, that it is not destroyed by cooking, and that it is all the more active as the disease has reached to an advanced stage. He is of opinion that the dis- ease may be developed in children through the medium of the milk. That such milk is liable to excite diar- rhoea and debility in children has been recognised. * A Manual of Veterinary Sanitary Science and Police, vol. ii. p. 200. 490 D^SPECTION A^^D EXAMniTATION OF MILK. Tuberculosis is a disease wMcIl is somewhat common amongst dairy cows that are shut up in towns in close, ill-ventilated, and foul cowhouses. The milk of such diseased animals is deficient in fat, sugar, and nitrogen- ous elements, whilst it possesses an increased proportion of earthy matters. In these days when the filthy feed- ing bottle, containing its imitation of mother's milk, in the shape of cow's milk, sugar, and water and a pinch of salt, is almost universally substituted for the supply afforded by natm-e, can it be wondered at that there should be such an . annual Herodian slaughter of inno- cents from diarrhcea, debility, atrophy, etc., when it is remembered that an immense quantity of the milk of animals thus diseased is sold throughout the country ? The milk of milch cows suffering from tuberculosis should not be employed by children. The milk of aU institutions occupied by the young, which are situated in his district, should be analysed by the medical of&cer of health, for he should be acquainted with the condi- tion of this " all in one " sort of nutriment, as supplied in large quantity for the food of children. If such milk should contain a deficiency of nitro- genous, fatty, and saccharine matters, as exhibited by very low milk solids, and if it is at the same time rich in mineral constituents, there is a suspicion, if unadul- terated, that the milk is derived from animals suffer- ing from tuberculosis. Parturition FartwitioTi ov Milk Fever. — A sample of the milk of Pever. a COW thus affcctcd was found by Mr. Smee* to contain an abnormally large proportion of phosphates. He states that during the progress of this disease the earthy phosphates leave the animals' bones, producing a * Op. cit. INSPECTION AND EXAMINATION OF MILK. 491 species of mollities ossium, wMch renders them exceed- ingly liable to fracture after recovery. In this disease there is happily, as a rule, a sup- pression of the lacteal secretion, otherwise we should have frequent instances of the injurious effects of milk of such altered composition on children. Changes take place in the proportion of the con- stituents of good milk in other diseases of cattle. The complaint known as the " grease " in cows is attended by a decrease of the alkaline salts, of the casein and the fat (Herheyer). In the vaccinia of cows the milk is strongly alkaline, and sugar is almost absent (Brewer). A complaint amongst children, known as milk-sick- ness, has prevailed in America, caused by the unboiled milk of cows that have fed on the JRhus toxicodendron, which produces in these animals a complaint termed " the trembles." The milk of goats that have fed on the (Ethusa cynapium,'''' and on euphorbiaceousf plants, has been found to be poisonous. * British Medical Journal, September 6, 1873. t Medical Times and Gazette, June 31, 1863. APPENDIX. DISTILLED WATER AND CHEMICALS. It is very important to be well supplied with an ample quantity of recently distilled water, free from ammonia, and to be Distuied enabled to oneself prepare it expeditiously and cheaply. The '^^ater. distilled water sold in chemists' shops is perfectly worthless for analytical purposes when it is necessary to estimate quantities of ammonia, for commercial distilled water is simply water freed from the greater part of its saline matters. It generally con- tains more or less ammonia. The analyst simply requires a large glass retort and a zinc vessel containing a worm to act as a condenser when full of water. The best water to use for distillation is the purest spring water. If such water is not conveniently obtainable in abundance, the purest water which contains the least amount of saline matter should be selected. Some analysts add a little carbonate of soda to the water which they distil. It is better to boil the water in a glass than in a metallic vessel, for the saline residue which lines its sides can be more readily removed by an acid from glass. The first * and last portions of the retort of water which we distil should be rejected. We should not begin to collect the distilled water vmtil it passes over quite free from ammonia, which can easily be ascertained by treating (say 50 c. c.) with 2 c. c. of ISTessler test. Distilled water will generally give off some little ammonia if re-distilled, so difficult is it to get rid of all traces of this body. If it is requisite to procure water of the greatest purity, it is necessary to distil twice-distilled water with alkaline permanganate of potash, taking care that this salt when dis- solved is perfectly free from ammonia. If this solution cannot * This impure distilled water will be found to be very useful for water-baths. 494 APPENDIX. Purity of chemicals. be guaranteed to be thus exempt it should be boiled for a short time previous to employment. All solutions and chemicals should be of the greatest purity. Chemicals adapted for analytical purposes are sold by Messrs. Hopkins and Williams of Cross Street, Hatton Garden, London. The medical oflficer of health should prepare his distilled water, and all his standard solutions, except the Nessler reagent. If he wishes to avoid the labour of making the standard solutions he can procure them of Sutton of Norwich. LIST OF APPARATUS REQUISITE. Apparatus. J^gtorts {2 Capacity rather more than 1^ litre, (about 48 ounces), one being for distilling sample, and the other for making distilled water. Liebitfs Condensers (3). — A large-sized one for ammonia process, a medium-sized one for Thorp's process for nitrates, and a small glass condenser for air analysis. Nessler Glasses (10). — Marked to measure 50 c. c. Bell Metal Clamps (3). — Expensive but indispensable. Burette. — Capacity 50 c. c, graduated to iVths, with an accu- rately ground tap at one end and a glass stopper at the other. Burette. — Capacity 5 c. c, the ^th divisions being widely apart. Burette. — 100 septems, graduated in 100 parts. Galvanized Iron Retort Stands (3). Gnielin's Wash Bottle. — Medium size. Measuring Flasks. — 1 litre, 500 c. c. = | litre, 250 c. c, 70 c. c, 50 c. c, 25 c. c. flask. Bunsen's Burners (3). — One large, one small, one small with chimney. Analytical Balance, in a glass-case, with weights. The balances of Becker of New York are good and cheap. The weights made by Oertling are unsurpassed- Flasks with welted mouths for corks. India-ruhier Corks. — Various sizes. Filter Papers, cut, German, which will not permit the pre- cipitate of sulphate of baryta to pass through them. and ^ c. c, 100 decigallon APPENDIX. 495 Platinum Dish, of a capacity of about 100 cub. cent. „ Crucible. „ Dishes (3) small, for milk. Berlin Evaporating Dishes (6), about 4 inches in diam. One small, like a large watch-glass. Wliite Porcelain Tiles (2), about 5 inches square. Pipette, with bulb in centre, and marked with file to indicate 2 c. c. for Nessler test. „ with bulb of capacity of 5 c, c. for milk. Pipettes (3) of the capacity of 5 c. c, and graduated to J^jths ; one for nitrate of silver sol, another for preparing ammonia standard, and the third necessary in the quantitative determination of nitrates and nitrites. Pipette (1) of the capacity of 10 c. c, and graduated to -^ihs for the standard soap solution. Pipettes (2 or 3). — Graduated in septems. Steam Condenser for preparing distilled water, made of zinc, con- taining worm. It is filled with cold water. A retort, in which the water is boiled, should be con- nected with it. Beahers. — A nest of difierent sizes. Adapters (2). Funnels. — One large and several small. Sample Bottles (36). — Stoppered. Made of stout glass. Tripods (2). Wire Gauze (2). — Pieces of coarse and fine, each about 4 inches square. Pipe Triangles (6). Copper Water Baths (2). Receiver for estimation of nitrates, which resembles a very large Nessler glass. A mark with file should indicate 50 c. c. and 100 c. c. Glass-rods of different sizes. Tongs for laboratory. 496 APPENDIX. EULES FOR CONVERSION OF DIFFERENT EXPRESSIONS OF RESULTS OF ANALYSIS. To convert parts, per 100,000, into grains per gaUon (= parts per 70,000), multiply by -7. To convert grains per gallon (= parts per 70,000) into parts per 100,000, divide by 7. To convert parts per million, or milligrammes per litre, into grains per gallon, multiply by '07 To convert gTains per gallon into parts per million, or milli- grammes per litre, divide by "07. To convert parts per 100,000 into parts per million, or milli- grammes per litre, multiply by 10. To convert parts of nitric acid into parts of ammonia, multiply by 17 and divide by 63. To convert parts of ammonia into parts of nitric acid, multiply by 63 and divide by 17. To convert grammes per litre into grains per gallon, multiply by 70. To convert parts of free ammonia, or ammonia from alb. am- monia, into parts of nitrogen, multiply by 14 and divide by 17. To convert " nitrogen as ammonia " into free ammonia, multi- ply by 17 and divide by 14. To convert "nitrogen as alb. ammonia" into alb. ammonia, multiply by 17 and divide by 14. To bring cubic inches into gallons, multiply by 40 and divide by 11,091, or multiply at once by -003607. METRICAL WEIGHTS AND MEASURES. Weight. 1 milligramme = "015432 grain. 1 centigramme = "15432 grain. 1 decigramme =1"5432 grains. 1 gramme = 15 "432 grains = weight of a cub. cent, of water at39"2°Fahr. 1 kilogramme = 15432"348 grains = 1000 gTammes = 2"2 lbs. avoir. APPENDIX. 497 Capacity. 1 culic centimetre = 15'432 grains = 16'9 minims = '06103 cubic inch. 1 litre = 15432-348 grains = 1 pint 15 ozs, 2 drs. and 11 minims = 61 '027 cubic incbes =: 1000 cubic centimetres = 35-3 ounces = '22 gallon = -035316 cubic foot = 1000 grammes = 1,000,000 milligrammes. 1 ounce = 28-35 cubic centimetres = 1-733 cubic inch. 1 ctibic inch = 16-4 cubic centimetres. 1 cubic foot =: 28-31 litres = 1728 cubic inches. 1 cubic metre = 1,000,000 cubic centimetres = 1,000,000 ■ grammes = 1,000,000,000 milligrammes = 1000 litres = 35-3 cubic feet. 1 pint = 34-59 cubic inches. Length, English Inches. 1 millimetre = -039. 1 centimetre = '39. 1 decimetre = 3-94. 1 metre = 39-37 — 3-28 feet. 1 kilometre = 1000 metres = 1094 yards = -62 mile = 3280 feet and 10 inches. Area, 1 square millimetre^ "0015 square inch. 1 square centimetre :^ "154 square inch. 1 square metre = 1542 square inches = 10-76 square feet. W.B. — The Latin prefix indicates division, and the Greek prefix indicates multiplication. 1 Septem = 7 grains = "decimillen." 1 Pound (Av.) = 7000 grains. 1 Gallon = 70,000 grains. 1 Decern =10 grains. -| Decigallon = 3500 grains. 2k 498 APPENDIX. TABLE FOE Reducing Baeombteic Observations to the Feeezing-Point (32° F). Temp. Fat. English Inches. Temp. Fah. 27 27-5 28 28-5 29 29^5 30 30^5 " 29 _• 001 —•001 — • 001 —•001 —•001 —•001 —•001 —•001 29 30 004 •004 004 •004 •004 •004 •004 •004 30 31 006 •006 006 •006 •007 •007 •007 •007 31 32 008 •009 009 •009 •009 •009 •009 •010 32 33 Oil •Oil Oil •012 •012 •012 •012 ■012 33 34 013 •014 014 •014 •014 •015 •015 •015 34 35 016 •016 016 •017 •017 •017 •018 •018 35 36 018 •019 019 •019 •020 •020 •020 •021 36 37 021 •021 021 •022 •022 •022 •023 •023 37 38 023 •023 024 •024 •025 •025 •026 •026 38 39 025 •026 026 •027 •027 •028 •028 •029 39 40 028 •028 029 •029 •030 •030 •031 •031 40 41 030 •031 031 •032 •033 •033 •034 •034 41 42 033 •033 034 •034 •035 •036 •036 •037 42 43 035 •086 036 •037 •038 •038 •039 •040 43 44 037 •038 039 •040 •040 •041 •042 •042 44 45 040 •041 041 •042 •043 •044 •044 •045 45 46 042 •043 044 •045 •045 •046 •047 •048 46 47 045 •046 046 •047 •048 •049 •050 •051 47 48 047 •048 049 •050 •051 •052 •052 •053 48 49 050 •050 051 •052 •053 •054 •055 •056 49 50 052 •053 054 •055 •056 •057 •058 •059 50 51 054 •055 056 •057 •058 •059 •060 •061 51 52 057 •058 059 •060 •061 •062 •063 •064 52 53 059 •060 061 •063 •064 •065 •066 •067 53 54 062 •063 064 •065 •066 •067 •068 •070 54 55 064 •065 066 •068 •069 •070 •on •072 55 56 066 •063 069 •070 •071 •073 •074 •075 56 57 069 •070 071 •073 •074 •075 •076 •078 57 58 071 •073 074 •075 •077 •078 •079 •081 58 59 074 •075 076 •078 •079 •080 •082 •083 59 60 076 •077 079 •080 •082 •083 •085 •086 60 61 078 •080 081 •083 •084 •086 •087 •089 61 62 081 •082 084 •085 •087 •088 •090 ■091 62 63 083 •085 086 •088 •089 •091 •093 •094 63 64 086 •087 089 •090 •092 •094 •095 •097 64 65 088 .•090 091 •093 •095 •096 •098 •100 65 66 090 •092 094 •096 •097 •099 •101 •102 66 67 093 •095 096 •098 •100 •102 •103 •105 67 68 095 •097 099 •101 •102 •104 •106 •108 68 69 098 •100 101 •103 •105 •107 •109 •110 69 70 100 ■102 104 •106 •108 •109 •111 •113 70 71 102 •104 106 •108 •110 •112 •114 •116 71 72 105 •107 109 •111 •113 •115 •117 •119 72 73 107 •109 111 •113 •115 •117 •119 •121 73 74 110 •112 114 •116 •118 •120 •122 •124 74 75 112 •114 116 •118 •120 •122 •125 •127 75 76 114 •117 119 •121 •123 •125 •127 •129 76 77 117 •119 121 •123 •126 •128 •130 •132 77 78 119 •122 124 •126 •128 •130 •133 •135 78 79 122 •124 •126 •128 •131 •133 •135 •137 79 80 124 •126 129 •131 •133 •136 •138 •140 80 81 126 ■129 •131 •134 •136 •138 •141 •143 81 82 •129 •131 •134 •136 •138 •141 •143 •146 82 83 131 •134 •136 •139 •141 •143 •146 •148 83 84 •134 •136 •139 •141 •144 •146 •149 •151 84 85 •136 •139 •141 •144 •146 •149 •151 •154 85 86 •138 •141 •144 •146 •149 •151 •154 •156 86 87 •141 •143 i 146 •149 •151 •154 •157 •159 87 88 •143 •146 •149 •151 •154 •157 •159 •162 88 89 •146 •148 •151 •154 •156 •159 162 •165 89 90 ■148 •151 •153 •156 •159 •162 •164 •167 90 APPENDIX. 499 TABLE FOE, Eeducing Baeometeic Obsekvations to the Level OF THE Sea ; and conveeselt, foe the Deteemination of Heights by the Baeometee. Mean Temperature of the Air. Differ- ences. KB 0° 10° 20° 30° 40° 50° 60° 70° 80° 90 Inch. Inch. Inch. Inch, Inch. Inch. Inch. Inch. Inch. Inch. Inch. 10 •012 ■012 •012 •Oil •Oil •Oil •Oil •Oil •010 •010 •000 20 •025 ■024 ■023 ■023 •022 •022 •022 •021 •021 •020 •001 30 •037 •036 •035 •034 •034 ■033 •032 •032 •031 •030 •001 40 •049 •048 •047 •046 ■045 •044 ■043 •042 ■041 •040 •001 50 •061 •060 •059 •057 •056 •055 •054 •053 ■052 •051 •002 60 •074 •072 •070 •069 •067 ■066 •065 •063 ■062 ■061 •002 70 •086 •084 •082 •080 •079 •077 •075 •074 ■072 ■071 •003 80 •098 •096 •094 •092 •090 •088 •086 ■084 ■083 ■081 •003 90 •110 •108 •106 •103 •101 •099 •097 •095 ■093 •091 ■003 100 •123 •120 ■117 •115 •112 •110 •108 •105 •103 ■101 •004 110 •135 •132 •129 •126 •124 •121 •118 •116 ■114 •111 •004 120 •148 ■144 •141 •138 •135 •132 •129 ■126 ■124 •121 •004 130 •160 •156 •153 •149 •146 •143 ■139 ■137 ■134 •131 •005 140 •172 ■168 •164 •160 •157 ■154 ■150 •147 ■144 •141 •005 150 •184 •179 •175 •171 '168 ■165 •160 •157 ■154 •151 •006 160 ■196 •191 •187 •183 •179 ■175 •171 •168 ■164 •161 •006 170 ■208 ■203 •198 •194 •190 ■186 •182 ■178 ■175 •171 •006 ISO •220 •215 •200 •206 ■201 ■197 ■192 •189 •185 ■181 •007 190 •232 ■227 •222 •217 •212 ■208 •203 ■199 ■195 ■191 •007 200 •244 •238 •233 •228 •223 ■218 ■213 ■209 •205 ■201 ■007 210 •256 •250 •245 •239 •234 ■229 •224 •219 •215 ■211 ■008 220 •268 •262 ■256 •250 •245 ■240 •235 •230 •225 ■221 ■008 230 •280 •273 ■268 •261 •255 ■250 •245 •240 •235 ■231 ■008 240 •292 •285 •279 ■272 •266 •261 •256 ■250 •245 •241 ■009 250 •305 •297 ■290 •284 ■278 •272 ■266 ■260 ■255 •250 ■009 260 •316 •309 •302 •295 •289 •283 ■277 ■271 ■265 •260 ■009 270 ■328 •320 •313 •306 •299 •293 •287 ■281 ■275 •270 ■010 280 •340 ■332 •325 •317 ■310 ■304 ■298 •291 •285 •280 ■010 290 •353 ■344 •336 ■329 •322 •315 •308 •302 •296 •290 ■010 300 •865 •356 •348 ■340 •333 ■326 •319 •312 ■306 •300 ■Oil 310 •377 •368 •360 •352 •344 ■337 •329 ■322 ■316 •310 ■Oil 320 •389 •380 •372 •363 •355 •348 ■340 ■333 ■326 •320 •012 330 •401 •391 •383 •374 •366 •358 ■350 ■343 ■336 •329 •012 340 •413 •403 •394 •385 •377 •369 ■361 ■354 ■346 •339 •012 350 •425 •415 •406 •397 •388 •380 •371 ■36i ■356 •349 •013 360 •438 •427 •417 •408 ■399 •390 •382 ■374 ■366 •359 •013 370 •450 •439 •429 •419 410 •401 •392 ■384 ■376 •369 ■013 380 •462 •451 •440 •430 •421 •412 •402 ■394 •386 ■378 ■014 390 •474 •463 •452 ■442 •432 •422 •413 ■405 •396 •388 ■014 400 •486 •475 •464 ■453 •443 •433 •424 ■415 •407 ■398 ■014 410 •498 ■487 ■475 ■464 •454 •444 •434 ■425 •417 ■408 ■015 420 •510 ■498 •486 •475 •465 •455 •444 •435 •427 ■418 •015 • 430 •522 ■509 •497 ■486 •476 •465 ■455 •446 ■437 ■427 •015 440 •534 •521 •509 •497 •487 •476 ■465 ■456 ■447 ■437 •016 450 •546 •532 •520 •508 •498 •487 •476 ■466 ■457 ■447 •016 400 •558 •544 •532 •520 •509 ■498 •486 ■477 ■467 ■457 •017 470 •570 •556 •543 •531 •520 •508 •497 •487 ■477 ■467 •017 480 •581 •568 •555 •542 •530 •519 ■507 •497 ■487 •477 •018 490 •593 •579 ■566 •553 •541 •529 ■518 •507 •497 •486 •018 500 ■605 •591 •577 •564 •551 ■639 •528 •517 •507 •496 ■018 N.B. — "When tlie barometric reading reduced to 32° and sea-level would be less tban 30 inches, the correction is too large ; and if greater, the correction is too small. To compensate for this error a column of ' differences ' is added to the table, giving the amounts to be added to or tal^en from the corrections for each inch which the pressure at sea-level faUs short of or exceeds 30 inches." — Buchan's Meteorology. 500 APPENDIX. TABLE— Continued. fcoS Mean Temperature of the Air. Diflfer- snces. w.a 0° 10° 20' 80° 40° 50° 60° 70° S0° 90° Inch. Inch. Inch. Inch. Inch. Inch. Inch. Inch. Inch. Inch. Inch. 510 •617 -602 •588 •575 ■562 •550 •588 •527 •516 506 •018 520 •629 ■614 •600 •586 •578 ■561 •549 •537 •526 •515 •019 530 •640 •625 •611 •597 •584 ■571 •559 •547 •536 •525 •019 540 •652 ■637 •622 •60S •594 ■581 •569 •557 •546 •535 ■019 550 •664 •648 •633 -619 •605 ■592 •579 •567 •556 •545 •020 560 ■676 •660 •644 -629 ■615 •602 •589 •577 •565 •554 ■020 570 •688 •672 •656 •641 •626 •613 •600 •587 •575 •564 ■020 5S0 ■699 ■683 •667 •652 •637 •623 •610 •597 •585 •573 •021 590 ■711 •694 -678 •663 ■648 •634 •620 •607 •595 •583 •021 600 •728 •706 •690 -674 •659 •644 •681 •617 •605 ■592 •021 610 •784 •717 •701 •685 ■670 •655 •641 •627 •514 •602 •022 620 •746 •729 •712 -696 •680 •665 •651 •687 •624 •611 •022 630 ■758 •740 •728 •707 •691 •676 •661 ■647 •634 •621 •028 640 •770 •752 •735 •718 •702 •686 -671 ■6.57 •644 ■631 •023 650 •7S2 •764 ■746 •729 •718 •697 •682 •667 •658 ■640 •028 660 •794 •775 •757 -740 •723 •707 •692 ■677 •668 •650 •024 670 ■806 •787 •768 •751 •734 •718 -702 •687 ■673 •659 •021 680 •818 •798 •779 •762 •744 •729 •712 •697 •683 -669 •024 690 •830 •810 •791 -773 •755 •789 •723 •708 •698 •679 •025 700 •842 •822 •803 •784 ■766 •749 •733 •718 •703 ■689 •025 710 •853 •833 •814 •795 •777 •760 •743 •728 ■713 ■698 •025 720 •865 ■844 •824 •805 •787 •770 •758 •788 •722 ■707 ■026 730 •876 •855 •835 •816 •798 •780 •763 •748 •732 ■717 •026 740 •888 •867 •846 •826 •80S •791 -774 ■758 •742 ■726 •026 750 •900 •878 •857 •837 ■818 ■801 •784 ■768 •752 ■736 ■027 760 •911 •889 ■868 -848 •229 •811 •794 •777 ■761, ■746 •027 770 •923 ■901 •879 •859 •840 •822 •804 •787 •771 ■755 •027 780 •935 ■913 •891 •870 •851 •832 -814 •797 •781 ■765 •028 790 •947 •924 •902 ■881 •862 •843 •825 •807 •791 •775 •028 800 •959 •936 •914 •893 •873 •853 •835 •817 •801 •785 •028 810 •970 •947 •925 ■904 •888 •864 •845 •827 •810 •794 •029 820 •982 •958 •985 ■914 •894 •874 •855 •837 •820 •804 •029 880 •994 •970 ■947 •925 •904 •884 •865 •S47 •830 •S13 •029 840 1^005 ■981 •958 ■986 •915 •895 -876 •857 •839 •822 •030 850 1^017 ■992 ■969 •947 •925 •905 -886 •867 •849 •831 •030 860 1-028 1^003 •979 ■957 ■936 ■915 -896 •876 •858 •840 •030 870 1-040 1^015 •991 •968 ■946 •925 -906 •886 •868 •850 •031 880 1-051 1^026 1-002 ■979 •957 •936 •916 •S96 •877 •859 •031 890 1-063 1-037 1-013 ■990 •968 ■946 •926 •906 •887 •869 •032 900 1-075 1-049 1-024 1^001 •979 •957 •986 •916 •897 •879 •032 910 1-086 1-060 1^035 1^012 •989 •967 •946 •926 •906 •888 •032 920 1-098 1-071 1^046 1-022 •999 ■977 -956 •935 •916 •897 •033 930 1-109 1-082 1-056 1-033 I^OIO •988 •966 •945 •925 •906 •033 940 1-120 1-093 1-067 1-043 1^020 •998 -976 •955 •935 ■916 •033 950 1-132 1-105 1-079 1-054 1-080 1-008 -986 •965 •945 •925 •084 960 1-144 1^116 1-090 1-065 1-041 1-018 -996 •975 ■954 •935 •034 970 1-155 1-128 1-101 1-076 1-052 1-029 1-006 •9S5 •964 •944 •034 980 1^167 1-139 1-112 1-087 1-068 1-040 1-017 ■995 ■974 •954 •035 990 1-178 1-150 1-123 1-098 1-073 1-050 1-027 1^005 ■983 •963 •085 1000 1-190 1-161 1-134 1-108 1-0S4 1-060 1-037 1^015 •993 •972 •035 APPENDIX. 501 TABLE OF THE Eelative Humidity given by the DIFFERENCE BETWEEN THE DbY AND WeT BuLB. 2 . 1 « Difference between the Dry and Wet Bulb. 1 2 3 4 1 5 6 1 7 8 I 9 10 11 12 13 14 16 Eelative HaiiiDiTY , Saturation = 100. 90 100 95 90 85 81 77 73 69 65 62 59 56 53 60 47 44 89 100 95 90 85 81 77 73 69 65 61 58 55 52 49 46 43 88 100 95 90 85 81 77 73 69 65 61 58 55 52 49 46 43 87 100 95 90 85 SI 77 73 69 65 61 58 65 52 49 46 43 86 100 95 90 85 SO 76 72 68 64 61 58 55 62 49 46 43 85 100 95 90 85 SO 76 72 68 64 61 68 55 52 49 46 43 84 100 95 90 85 80 76 72 68 64 60 57 54 61 48 45 43 83 100 95 90 85 80 76 72 68 64 60 57 54 61 48 45 42 82 100 95 90 85 80 76 72 6S 64 60 67 54 51 48 45 42 81 100 95 90 85 SO 76 72 68 64 60 56 53 50 47 44 41 SO 100 95 90 85 SO 75 71 67 63 59 56 63 50 47 44 41 79 100 95 90 85 80 75 71 67 63 59 56 53 50 47 44 41 78 100 94 89 84 79 75 71 67 63 59 56 53 50 47 44 41 77 100 94 89 84 79 75 71 67 63 59 56 53 50 47 44 41 76 100 94 89 84 79 75 71 67 63 59 55 52 49 46 43 40 75 100 94 89 84 79 74 70 66 62 58 55 52 49 46 43 40 74 100 94 89 84 79 74 70 66 62 58 55 62 48 45 43 40 73 100 94 89 84 79 74 70 66 62 5S 54 51 48 45 42 40 72 100 94 89 84 79 74 69 65 61 57 54 51 48 45 42 39 71 100 94 88 83 78 73 69 65 61 57 53 50 47 44 41 38 70 100 94 88 83 78 73 69 65 61 67 53 50 47 44 41 38 69 100 94 88 83 78 73 68 64 60 56 53 50 47 44 41 38 68 100 94 88 S3 78 73 68 64 60 56 52 49 46 43 40 37 67 100 94 88 83 78 73 68 64 60 56 52 49 46 43 40 37 66 100 94 88 S3 78 73 68 64 60 56 52 48 45 42 40 37 65 100 94 88 83 7S 73 68 63 59 65 51 48 45 42 39 36 64 100 94 88 82 77 72 67 63 59 55 51 48 46 42 39 36 63 100 94 88 82 77 72 67 63 59 55 61 47 44 41 38 35 62 100 94 88 82 77 72 67 62 58 55 50 47 44 41 38 36 61 100 94 88 82 77 72 67 62 58 54 50 47 44 41 38 35 60 100 94 88 82 76 71 66 62 58 54 60 46 43 40 37 34 59 100 94 88 82 76 71 66 61 57 53 49 46 43 40 37 34 58 100 93 87 81 76 71 66 61 57 53 49 46 43 40 37 34 57 100 93 87 81 75 70 65 61 57 53 49 45 42 39 36 33 56 100 93 87 81 75 70 65 60 56 52 48 44 41 38 35 32 55 100 93 87 81 75 70 65 60 56 52 48 44 41 38 35 32 54 100 93 86 80 74 69 64 59 55 51 47 43 40 37 34 31 53 100 93 86 80 74 69 64 59 55 61 47 43 39 36 33 30. 52 100 93 86 80 74 69 64 59 54 50 46 42 39 36 33 30 51 100 93 86 80 74 68 63 58 54 50 46 42 38 35 32 29 50 100 93 86 80 74 68 63 58 53 49 45 41 37 34 31 29 49 100 93 86 79 73 67 62 57 53 49 45 41 37 34 31 28 48 100 93 86 79 73 67 62 57 52 48 44 40 36 33 30 47 100 93 86 79 73 67 61 56 51 47 43 39 36 33 30 46 100 93 86 79 73 67 61 56 51 47 43 39 35 32 29 45 100 92 85 78 72 66 60 55 50 46 42 38 34 31 28 44 100 92 84 78 71 65 59 54 49 45 41 37 34 31 28 43 100 92 84 78 71 65 59 54 49 45 41 37 34 31 28 42 100 92 84 78 71 04 60 54 49 44 40 36 43 30 27 41 100 92 84 77 70 64 58 53 48 43 39 35 31 28 40 100 92 84 77 69 63 57 51 46 42 38 34 31 39 100 92 84 77 69 63 57 52 47 42 38 34 38 100 91 83 75 68 62 56 50 45 41 37 37 100 91 83 75 68 61 55 49 44 39 36 100 91 82 74 66 59 53 47 42 35 100 90 80 72 34 100 89 79 72 33 100 89 78 70 32 100 87 75 502 APPENDIX. REGISTER OF RAINFALL IN 18_. Ke2Jt at % Latitude Height of ( Above Ground Time of Observation... Eeceiver of-< Longitude ... Eain Gauge (_ Above Sea Level. Condensed Instructions. — Fix the gauge firmly, with its orifice level and 1 foot above the ground, quite clear of trees and ■walls, empty it daily at 9 a.m., and enter it against the preceding day. Snow should be melted slowly in a closed vessel, and the amount entered as rain, an "S" being prefixed. With a low temperature and high wind, it is sometimes blown out of the funnel ; then take one-twelfth of the average depth of snow, and enter that as the yield of water — e.g., 3 inches snow= '25 of rain. When there is no rain, a line should be drawn, rather than cyphers inserted. Date, 1-3 Si 1 ci p. <1 1-5 -^3 02 O > d 3 1=1 3 ^ c3 4 aj S fl "a 9 ^ a 10 i ^ 12 . 2 13 ;S O 14 tn 15 S 1° 16 ■C 'g 17 3 J IS d O 19 S 20 =2 -2 21 sis i ^ § .3 24 ^ - t i ^ a -^ 29 O 1 -g 30 * J 31 In. In. In. In. In. In. In. In. In. In. In. In. Totals Total from Jan. 1 INDEX. Agite and seasonal meteorology, 348. Air, chemical examination of, 272. churcliyard, 230. hygrometric state of the, and health, 324. marsh, 230. microscopic examination of, 264. of our houses, 231. organic matter in, 189. pressure of the, 330. purity of, 179. solid bodies in, 253. subsoil, 228. temperature of the, and health, 322. washings, 193. Ammonia, 66. albuminoid, estimation of, 40. free or saline, ,, 38. Animal impurities in air, 219. Animals, diseases of, 400. Anthracic diseases and meat, 414. ,, ,, and mUk, 489. Apparatus, chemical, requisite, 494. B Babometpjc pressure, its determination, 360. Braxy meat, 413. Bread, adulterations of, 457. alum in, 464, examination of, 455. ,, ,, chemical, 460. ,, ,, microscopic, 456. 504 INDEX. Broncldtis and seasonal meteorology, 350. Brucine test for nitiic acid, 92. c CaPvBONIC acid in air, 199. oxide „ 209. Cesspool filth, diagnosis of, in water, 168. Chlorine, determination of the, 104. Cholera and seasonal meteorology, 349, 350. Colour test, 17. Com, examination of, 435. D Data on which to form an opinion respecting a water, 157. Diarrhcea and dysentery, and seasonal meteorology, 348. Distilled water, preparation of, 493. Dust of the air, 264. E Electricitt, atmospheric, 388. Erysipelas and seasonal meteorology, 353. Excremental filth in air, 216. F Eevee and seasonal meteorology, 346. Fish, inspection of, 429. Eish-lihe odour of waters, 16. Eleck's test, 22. Flesh, condemned, destruction of, 481. Flour, examination of, 439. ,, ,, ,, chemical, 441. ,, ,, ,, microscopic, 445. Fluke in meat, 426. Food, the purity of, 397. Foot and mouth disease, and meat, 411. ,, ,, ,, milk, 485. Frankland and Armstrong process, 48. , , "Wanklyn processes compared, 64. Fruit and vegetahles, inspection of, 434. G Gases, poisonous, defiling air, 218. Gold, trichloride of, test, 20. INDEX, 505 H H^MOKEHAGES and seasonal meteorology, 352. Hardness, determination of the, 107. Height, corrections for, to barometric readings, 499. Heisch's test, 21. Horsley's test for Alum in bread, 466. ,, ,, Nitrates and Mtrites, 80. Humidity Tables, 501. Hydrophobia, 352. Hygrometry, 377. I Indigo process for estinaating nitrates, 84. Insanity and seasonal meteorology, 354. K " Keeping Powers " of a water, 17. M Magnesia, determination of the, 112. Measles and seasonal meteorology, 341. " Measly " meat, 421. Meat, characters of good and bad, 404. diseased, arguments for and against its employment, 416, 417. Memoranda for water analysts, 147. Metallic impmities in air, 221, 305. Metals, poisonous, determination of, 121! Meteorological observations, registration of, 393. Meteorology and health, 320. seasonal and disease, 337. Metrical weights and measures, 496. Microscopic examination of air, 264. ,, ,, of water, 124. Microzyme test, 12. Milk, diseased, 483. examinaltion of, 468. ,, ,, chemical, 473. ,, ,, microscopic, 470. • Mineral impurities in air, 219. Mistakes of water analysts, 139. Mortality at different ages and seasonal meteorology, 356. of the sexes, „ ,, „ 357. 506 INDEX. Nettralgia and seasonal meteorology, 852. Nitrates and Nitrites, qualitative examination for, 80. ,, ,, quantitative ,, ,, 83. ,, ,, utility of the estimation of the, 75. Nitrogen, as nitrates and nitrites, 70. Ordnance bench marks, 359. Old age and seasonal meteorology, 358. Opinion, formation of, as to a water, 160. Organic nitrogen and carbon, 52. matter in air, 189. ,, in water, 13. Ozonometry, 311. P Parturient apoplexy and meat, 414. Parturition or milk fever, and milk, 490. Peaty water, diagnosis of a, 164. Pericarditis and seasonal meteorology, 355. Permanganate of potash process, qualitative, 23. ,, ,, ,, quantitative, 29. ,, „ ,, ,, Drs. Letheby and Tidy's, 29. ,, ,, „ ,, Drs.WoodsandP.de Chaumont's, 32. Phosphates, determination of the, 118. Phthisis pulmonalis and seasonal meteorology, 351. Pleuro-pneumonia and meat, 408. Pneumonia and seasonal meteorology, 350. Pond water, 152. Poultry, game, etc., inspection of, 428. Previous sewage contamination, 53. Processes of water analysis compared, 57. Puerperal fever and seasonal meteorology, 353. Putrefactive processes, defiling air, 215. E Kain gauge, 378. Eainey's bodies in meat, 425. Kainfall register, 502. INDEX. 507 Record of analyses, 137. Eeport, preparation of, 170. Eheumatism and seasonal meteorology, 354. Einderpest and meat, 412. ,, „ milk, 484. S Samples of water, collection of, 131. Scarlatina and seasonal meteorology, 345. Sewage emanations, defiling air, 216. Sewage in water, 168. Sewer gas, pollution of water with, 106. Small-pox and seasonal meteorology, 340. Smell of a water, 14. Solid bodies in air, 253. Solid residue, determination of, 94. „ ,, ignition of, 97. Solids in water, 94. Solutions, standard for water analysis, 173. Spectroscope in hygrometry, 377. Splenic apoplexy and meat, 412. Standard of pure air, 247. ,, ,, water, 10. Starch tests for nitrous acid, 93. Sulphates, determination of the, 114. Surgical fever and meteorology, 337. TEMrEKATTTEE, Corrections for, to barometric readings, 498. its determination, 365. Thermometer stands, 367. Thermometers, solar max., 369. terrestrial min., 370. verification of, 372. Thorp's process for estimation of nitrates, 86. Time occupied in performing an analysis, 133. Trichina spiralis and meat, 423. Tubercular diseases and meat, 415. ,, ,, and milk, 489. u Urine in water, 167. 508 INDEX. V Vegetable impurities in air, 219. Ventilation, 248. Volatile matters, amount of, in a water residue, 102. w Wankltn, Chapman, and Smith process, 36. "Water, microscopic examination of a, 124. Waters, diiferent classes of, 54. Wholesomeness of a water, 9. Whooping cough and seasonal meteorology, 343. Wigner's, Mr., valuation table, 158. Wind, direction of the, and health, 336. ,, ,, and strength of, 384. Zymotic test, 22. Printed by R. & R. Clark, Edinhirgh. Illustrated ivitJi Wood Engravings, Litliographs, and Chromo- lithographs, Bivo, 12s. Qd. OZONE AND ANTOZONE. WHEN ) WHERE r IS OZONE OBSERVED IF ^W'HY f THE ATMOSPHERE ? HOW ; Bt COENELIUS B. fox, M.D., M.R.C.P. Lond. Medical Officer of Health of East, Central, and South Essex ; Fellow of the Chemical Society ; Fellow of the British Meteorological Society ; Fellow of the Obstetrical Society ; Member of the Scottish Meteorological Society ; Associate of the French Society of Hygiene, etc. ; Author of " Water Analysis as it should and should not be performed by the Medical Officer of Health," "The Disposal of the Slop Water of Villages," etc. The object of the Author of this Work is threefold : 1. To give a digest of the most important facts connected with Ozone and Antozone, including the interesting investigations recently made in France and Germany ; 2. To point out the circumstances and the manner in which, the localities where, and the reason why, Ozone has been and should be observed in the Atmosphere ; and, 3. To make known the results of his own investigations respecting these bodies. EXTRACTS FROM REVIEWS. " His work will be the standard authority on Ozone. ... A valuable scien- tific work, admirably complete." — Medical Times and Gazette. "An exhaustive work." — British Medical Journal. " Of great practical utility." — Lancet. " Well- written, important, and interesting work." — London Medical Record. " A very cleverly-executed work. . . . Most interesting." — Revue des Sciences Medicales. " An encyclopsedic work." — Meteorological Magazine. " The scientific world is deeply indebted to Dr. Pox for the volume which he has presented to it. . . . An indispensable vade mecum to. every health officer."— Public Health. " Interesting and instructive. . . . Exceedingly useful." — Athenaeum. " A veritable mine of wealth." — Popular Science Review. " The task — no light or trifling one — of analysing the detached literature of the subject, and of thoroughly investigating it for himself in a searching, a scientific, and a practical manner, has been ably accomplished by Dr. Fox." — Dublin Journal of Medical Science. " An elaborate monograph." — Chemical News. " The entire question is treated ably in this work." — Science Gossip. "A comprehensive vrorii."— Garden. " An elaborate and well-arranged digest of facts. . . . Most interesting and valuable." — Quarterly Journal of Science. " Independently of his own very valuable observations, the' author has given a critical review of the chief works on Ozone. . . . More particularly precious is the concluding chapter, entitled ' How should Ozone be observed ? ' " — Deutsche Klinilc. " We earnestly recommend it to the careful perusal of all persons interested in, or in any way connected with, the administration of the public health, as a work elucidating facts in regard to atmospheric influences of the utmost importance, and not to our knowledge elsewhere accessible." — Sanita/rian of the United Stages. " An excellent book, very suggestive, very compendious, well arranged, and as a guide, aid, and stimulus to new investigations, invaluable." — American Journal of Science and Arts. To he obtained direct from the Publishers, Messrs. J. & A. Churchill, New Burlington Street, London ; and from their American Agents, Messrs. Lindsay & Blakiston of Philadelphia, U.S. Also from MM. Galignani & Cie., 224 Eue de Rivoli, Paris ; or through any Country Bookseller. ((. COLUMBIA UNIVERSITY This book is due on the date indicated below, or at the expiration of a definite period after the date of borrowing, as provided by the rules of the Library or by special ar- rangement with the Librarian in charge. DATE BORROWED DATE DUE DATE BORROWED DATE DUE C2e(638)M50 RA430 Fox F83