WORKS BY THE SAME AUTHOR: Published by I). Appleton <& Company. The Physiology Of Man ; designed to represent the Existing State of Physiological Science as applied to the Functions of the Human Body. Volume 1., Introduction ; Blood; Circulation; Eespiration. 1 vol., Bvo, pp. 500. Cloth, $4.50, sheep, $5.50. The same, Vol. 11., Alimentation ; Digestion ; Absorption ; Lymph and Chyle. 1 vol., Bvo, pp. 550. Cloth, $4.50; sheep, $5.50. The same, Vol. 111., Secretion ; Excretion; Ductless Glands; Nutrition ; Animal Heat; Movements; Voice and Speech. 1 vol., Bvo, pp. 520. Cloth, $4.50; sheep, $5.50. The same, Vol. IV., The Nervous System. 1 vol., Bvo, pp. 470, Cloth, $5.50; sheep, $5 50. The same, Vol. V., Special Senses; Generation. 1 vol., Bvo, pp. 517. Cloth, $4.50; she.-p, $5.50. The same, complete in 5 vols. Cloth, $22.00; sheep, $27.00. A Text-Book of Human Physiology; designed for the use of Practitioners and Students of Medicine. Illustrated by three Lith- ographic Plates, and three hundred and thirteen Woodcuts. 1 vol., imperial Svo. Cloth, $6.00 ; sheep, $7.00. Kecherches experimentales sur une nouvelle fonction du foie, consistant dans la separation de la cholest6iine du sang et son elimination sous forme de stercorine (sordine de Boudet), Paris, Germer Bailifere ; and New York, D. Appleton & Company, 1868. 1 vol., Svo. pp. 122. Price $0,75. This work received an “Honorable Mention” with a “Recom- pense” of 1,500 francs from the Institute of France (Academic des Sciences), in 1869, Concours Montyon (Medecine et Chirwrgie). On the Physiological Effects of Severe and Protracted Mus- cular Exercise ; with special reference to its Influence upon the Excretion of Nitrogen. 1871. 1 vol., Svo, cloth, pp. 91. Price $l.OO. Manual of Chemical Examination of the Urine in Disease ; with brief Directions for the Examination of the most common Va- rieties of Urinary Calculi. Fifth edition, 1877. 1 vol., 16mo, cloth, pp. 76. Price $l.OO. MAN UAL OF CHEMICAL EXAMINATION OF THE HEINE IN DISEASE; WITH BRIEF DIRECTIONS FOR THE EXAMINATION OF THE MOST COMMON VARIETIES OF URINARY CALCULI, APPENDIX, CONTAINING A DIET-TABLE FOR DIABETICS. AKD AN BT AUSTIN FLINT, Jk., M. D., PROFESSOR OF PHYSIOLOGY IN THE BKLLEYUE HOSPITAL MEDICAL COLLEGE, NEW YORK; CONSULTING PHYSICIAN FOR THE CLASS OP NERVOUS DISEASES TO THE BUREAU OF MEDICAL AND SURGICAL RELIEF FOR OUT-DCOB POOR, BELLEVUE HOSPITAL; FELLOW OF THE NEW YORK ACADEMY OF MEDICINE; CORRESPONDENT OF THE ACADEMY OF NATU- RAL SCIENCES OF PHILADELPHIA; MEMBER CF THE AMERICAN PHILOSOPHICAL SOCIETY, ETC., ETC, SIXTH EDITION, REVISED AND CORRECTED. NEWYORK: AND COMPANY, o 5 BOND STEEET. 1884. Copyright, 1870, 18S4, By D. APPLETON AND COMPANY. PREFACE TO THE SIXTH EDITION. It is now fourteen years since this little work was published, the first edition having been issued in 1870. During this time not only has there been a constant and steady demand sufficient to exhaust five large editions, but several other little works of the same scope and on the same sub- ject have appeared. These facts have led me tp adhere to the original plan in revising the mat- ter for a sixth edition. It has seemed to me that the book would be less useful if it were more comprehensive. What I first supposed to be re- quired by the busy practitioner was a book giving clear and readily comprehensible directions for or- dinary examinations of urine, such as a physician must often have occasion to make, and which it is desirable that he should be able to make rapidly. 4 PREFACE I am now more than ever convinced of the cor- rectness of this view; and my effort has been, in revising the text, to make my descriptions of an- alytical processes as simple as possible. The pro- cess for analysis for phosphoric acid by uranic oxide is perhaps more accurate than the one I have given; hut this requires the use of heat, and the test-liquid is rather difficult to prepare. For these reasons I still recommend the solution of iron. The most important alteration in this edition is in the formulae for the preparation of the liquids to be used in making Fehling’s test for sugar. These liquids, as prepared recently by Dr. E. E. Squibb, of Brooklyn, E. Y., are now nearly perfect. I have also added, in this edition, an appendix con- taining a diet-table for diabetics. In conclusion, I venture to hope that my modest little book may continue to be kindly and favor- ably received by the profession. New York, 14 West Thirty-third Street, January, 18S4. PREFACE TO THE FIRST EDITION. Several months ago, I suggested to Messrs. Tiemann & Co., of this city, the desirability of ar- ranging a set of tests, etc., for such urinary exam- inations as are now constantly required by the medical practitioner; and I proposed to supervise the work and write a few simple directions for use, to accompany the apparatus ; but as I progressed, it became evident that the directions, to he complete and satisfactory, should be much more extended than I at first supposed, and they finally assumed the dimensions of this little volume. Microscopical examinations of the urinary de- posits form, often, an indispensable element in di- agnosis and prognosis; but, much more frequently, a very simple chemical examination of the urine, such as can and should be made by the physician, 6 PREFACE, will answer all practical purposes. I concluded, for tlie present at least, not to touch, upon urinary de- posits, a subject which can only be adequately con- sidered in extended treatises, but to confine myself to the chemical study of the urine in disease, with very brief directions for the examination of the most common forms of urinary calculi; and I have prefaced these practical points with a few introduc- tory remarks concerning the variations in the prop- erties and composition of the urine under normal conditions. My chief aim, in the preparation of this little work, has been to enable the busy practitioner to make for himself, rapidly and easily, all ordinary examinations of urine, and to give him the benefit of my own experience in eliminating little difficul- ties in the manipulations and in reducing processes of analysis to the utmost simplicity that is consist- ent with accuracy. Having for many years been daily in the habit of making chemical and micro- scopical examinations of the urine for physicians, I felt that I was able to appreciate pretty thoroughly what is required in ordinary practice. PREFACE, 7 My first object was to arrange a standard set of apparatus, simple, yet sufficient for all practical purposes. I have spared no time or pains in my endeavors to accomplish this end; and the makers have pledged themselves not to dispose of the set or any part of the set, which I have thoroughly tested, and which is to remain in their possession as a standard of accuracy. My next object was to remove as far as possible all of the difficulties which I had myself experienced in urinary examinations. lam fully aware of the fact that the processes suggested for the quantita- tive determination of the urea, chlorine, and sul- phuric acid in the urine, are not absolutely accurate; but I have no hesitation in recommending them as sufficiently exact to meet all the requirements of the practical physician, while their simplicity and the facility of their application put them within the reach of every one. I had hoped to be able to apply the volumetric method, which has proved so convenient in such analyses, to all of the examinations of the urine that are now recognized as important to the physician; PREFACE. but after a patient trial of the volumetric analysis for uric acid by a graduated solution of the per- manganate of potassa, I have become convinced that this process is so wanting in accuracy as to he unavailable, even for rough estimates. I am in- debted to my assistant, Mr. J. W. S. Arnold, for a simplification of the process for quantitative anal- ysis for this principle, which is sufficiently easy, though it occupies some time and requires the use of a tolerably delicate balance. There is at present no volumetric process for estimating uric acid, that is at all reliable. I have taken great care in the preparation of some new tables, by which the necessary calcula- tions are so simplified that the quantities of most of the important normal and abnormal ingredients of the urine may be ascertained almost instantly. I have also given a full table of the normal va- riations in the properties and composition of the urine. These tables are all printed upon a single sheet at the end of the volume; and, if this be cut out and posted in a conspicuous place for reference, after a little practice it will be seldom PREFACE. 9 necessary to consult the hook itself in the progress of an examination. If these objects be but in part accomplished, and if the attention of physicians can he directed more frequently to the condition of the urine in dis- ease, this little hook, with its modest pretensions and imperfect execution, will not be without value to the profession. New York, January 1, 1870. CONTENTS. INTKODUCTION. Recognition of abnormal matters in the urine—Mode of production of excrementitious principles in the system—Mode of elimina- tion of excrementitious principles by the kidneys—Variations in the general and physical properties of the normal urine—Normal variations in the elimination of urea and uric acid—Normal variations in the proportions of the inorganic constituents of the urine, Page 12 CHAPTER I. QUALITATIVE EXAMINATIONS OF THE URINE. Apparatus for urinary examinations—Method of obtaining a spe- cimen for examination—General appearance, color, and odor of the urine—Reaction—Specific gravity—Presence or absence of albumen—Presence or absence of sugar—Presence or absence of bile, . Page 24 CHAPTER 11. Analysis for albumen—Analysis for sugar—Differential-density method of analysis for sugar—Volumetric method for esti- mating sugar—Quantitative analysis for urea—Quantitative analysis for chlorine, sulphuric acid, phosphoric acid, and uric acid, ... , . Page 41 QUANTITATIVE ANALYSIS OF THE URINE. 12 CONTENTS, CHAPTER 111. URINARY CALCULI AND GRATEL CARE OF APPARATUS. Uric-acid calculi and gravel—Oxalate-of-lime calculi and gravel— Calculi of the mixed phosphates (fusible calculi)—Care of appa- ratus, Page 61 PACK A. Properties and composition of the normal urine 68 B. Table for reducing the indications of a glass urinometer TO THE STANDARD TEMPERATURE (60° Fahr.) WHEN THE SPE- CIFIC GRAVITY HAS BEEN TAKEN AT A HIGHER TEMPERATURE 69 C. Table showing the number of grains of solids in, and THE WEIGHT OF A FLUIDOUNCE OF URINE, OF EVERY DEN- SITY FROM 1001 TO 1042 70 D. Table showing the percentage of sugar in undiluted DIABETIC URINE, REPRESENTED by THE DEGREES OF THE SCALE ON THE BURETTE GRADUATED IN GRAINS 71 E. Table showing the quantity of urea per fluidounce of URINE, IN GRAINS, REPRESENTED BY THE DIVISIONS OF THE SCALE UPON THE TUBE GRADUATED IN CUBIC INCHES 72 F. Table showing the quantity, either of chlorine, sul- phuric ACID, OR PHOSPHORIC ACID, PER FLUIDOUNCE OF URINE, IN GRAINS, REPRESENTED BY THE DEGREES OF THE SCALE ON THE BURETTE GRADUATED IN GRAINS 73 Form for recording urinary examinations 74 TABLES. APPENDIX. DIET-TABLE FOE DIABETICS. LIST OF ILLUSTRATIONS. Fig. 1. Conical vessel for collecting urinary deposits 30 Fig. 2. Apparatus for taking the specific gravity of the urine 33 Fig. 3. Apparatus for determining the proportion of urea in THE URINE 49 Fig. 4. Sink for cleansing apparatus 65 CHEMICAL EXAMINATION OF THE DEIISTE DISEASE. INTRODUCTION. Recognition of abnormal matters in the urine—Mode of production of excrementitious principles in the system—Mode of elimina- tion of excrementitious principles by the kidneys—Variations in the general and physical properties of the normal urine—Normal variations in the elimination of urea and uric acid—Normal variations in the proportions of the inorganic constituents of the urine. The importance of urinary examinations, in their bearing upon diagnosis, treatment, and prog- nosis in disease, is now admitted by all who have kept pace with the progress of medical science dur- ing the last twenty-five or thirty years. Even if we except the examinations for sugar and for albu- men, there are many conditions of the urine, involv- ing either a modification in the proportion of its normal constituents or the presence of abnormal principles, which it is very important to recognize. 14 CHEMICAL EXAMINATION OF THE URINE, With regard to certain abnormal principles that may exist in the urine, it is essential to the prac- tical physician, not only to be able to recognize their presence by simple and reliable tests, but, in many instances, to estimate their quantity. In dia- betes mellitus, a knowledge of the fact that sugar exists in the urine is a necessary element in the diagnosis; and the influence of dietetic and other measures of treatment, in most cases, is speedily and certainly indicated by the modifications in the pro- portion of sugar in the urine. Indeed, it is impossible to treat this affection intelligently without estimat- ing from time to time the quantity of sugar dis- charged by the kidneys. Albuminuria, which is so prominent a symptom in certain diseases of the kid- neys that it is often spoken of as if it were in itself a disease, is a condition which must be recognized in the diagnosis of these disorders. It frequently hap- pens that the presence of albumen in the urine is the first positive indication of a pathological condition of the kidneys, and this single fact directs the atten- tion of the physician to an entire class of impor- tant diseases. Physiologists are constantly progressing in the knowledge of the phenomena that attend the gen- eral process of nutrition of the organism, and, with every development in this direction, additional im- PRODUCTION OF EXCREMENTITIOUS PRINCIPLES. 15 portance is attached to the examination of the urine in disease. The relations of physiology and pa- thology, as regards excretion, are to a considerable extent reciprocal. Pathologists cannot comprehend morbid changes in the process of disassimilation without a knowledge of the physiological conditions; and, on the other hand, modifications of the func- tion of excretion in disease frequently aid the phys- iologist in determining the relations of certain ex- crementitious principles to the healthy organism. There are few facts in physiology better estab- lished than that certain principles discharged from the body, called excrementitious, represent the physiological wear of the organism; and there is no avenue of discharge by which these effete mat- ters are so uniformly excreted as by the urinary apparatus. The faeces contain the debris of food in addition to the certain peculiar excrementitious principles; the skin discharges its excretions in such a form that they are with difficulty collected and studied; but the urine is the type of the ex- cretions ; its composition is constantly varying in health, and is almost of necessity modified in dis- ease ; and this fluid may be collected and analyzed so easily, that, certainly, the clinical student should only be restricted in the practical applications of the changes in this fluid in disease by the limits of 16 CHEMICAL EXAMINATION OF THE UHINE. physiological knowledge of the relations of the different excrementitious principles to the or- ganism. It may he useful, as an introduction to the clini- cal study of the urine, to sketch briefly the mode of production of certain of its constituents and their elimination by the kidneys. There is every rea- son to believe that all excrementitious matters are produced in the general system, are taken up by the blood in circulating through the tissues, and are separated from the blood and thrown off by the proper organs. The kidneys have nothing to do with the formation of the urinary principles; they simply purify the blood by separating from it cer- tain effete matters. Supposing, then, that the kid- neys be perfectly healthy, serious modifications in the urinary excretion may occur, depending upon diseases in the general system. It is not disease of the kidneys that gives rise to the presence of su- gar in the urine, or to an excess of urea, urates, uric acid, phosphates, etc.; but these changes are due to disturbances in nutrition and disassimila- tion. An excessive production of uric acid in the system may give rise to calculus, to certain general symptoms, and yet the kidneys be perfectly nor- mal ; and such examples as this might be multiplied. On the other hand, the general nutritive processes PRODUCTION OF EXCREMENTITIOUS PRINCIPLES. may be normal, except as they are secondarily influ- enced through the kidneys, and very grave disor- ders of the urinary excretion may be due exclu- sively to structural disease of the kidneys them- selves, by which they are rendered incapable of sep- arating the required quantity of excrementitions matter from the blood. The distinction between the two conditions just mentioned should be kept constantly in view in practice. In the great majority of instances, though not invariably, if there be serious structural disease of the kidneys, there will be albumen in the urine. The physician should fully appreciate the impor- tance of this symptom, albuminuria, as pointing to disease of the kidneys, it may be, of a transient char- acter, or it may be in the form of an irremediable structural lesion. Having the attention thus di- rected to the kidneys, it becomes an important ques- tion to decide how far these organs are capable of performing their function; and, in the great ma- jority of cases, the efficiency of their action may be measured by the daily discharge of urea, the most important of the solid constituents of the urine. I mention urea as the principle to be watched in these cases, because it is formed by the system in greater quantity, and accumulates in the blood, when its elimination by the kidneys is interrupted, 18 CHEMICAL EXAMINATION OF THE URINE. more rapidly than any other of the urinary con stituents. If it he impossible to determine the existence of structural disease of the kidneys by the presence of albumen in the urine or by microscopical exam- ination of the urinary sediment, it is generally, if not always, fair to assume that any changes in the composition in the urine, beyond its ordinary physiological variations, are due to conditions of nutrition involving the original production of the excrementitious principles in the general system. These conditions may affect the quantity of the urine, its color, odor, specific gravity, or reaction, and may modify the proportion of urea, of urates, chlorides, sulphates, phosphates, and perhaps other of its constituents, the physiological relations of which are as yet imperfectly understood. It is not contemplated, in this little work, to dis- cuss the significance of all the variations from the healthy standard, but, in the study of the urine in disease, it is absolutely necessary to keep in view the purely physiological conditions capable of mod- ifying this excretion. Physiologically, the variations in the quantity, color, and specific gravity of the urine bear a certain relation to each other. When the skin is acting very freely, and when the solid elements are increased by NORMAL VARIATIONS IN THE URINE. 19 exercise, the quantity of urine is apt to tend toward the minimum, the specific gravity being high and the color, though normal in character, of a deeper shade. This is most likely to occur when liquids are ingested in small quantity. On the other hand, when the skin is not active, as in very cold weather, the urine will probably approach the maximum in quantity, the specific gravity being low and the color light. The ingestion of large quantities of liquid will often induce, as a temporary condition, an abundant secretion of fluid of low density. In these conditions the real amount of solid excretion is not much affected, the difference being simply in the dilution of the urine. When the density is very low and the secretion scanty, showing an evi- dent deficiency in the activity of the kidneys, one is led to look for evidences of disease of these or- gans, the most prominent indication of which is albuminuria. When the specific gravity is very high and the quantity normal or increased, there may be reason to suspect the presence of some ab- normal solid matter in solution in the urine, and the principle most likely to be present is sugar. The normal conditions above enumerated, are, how- ever, capable of temporarily affecting the specific gravity to such an extent, that a specimen may pre- sent as low a density as 1005 or higher than 1030, 20 CHEMICAL EXAMINATION OF THE UHINE. without being, in itself, positive evidence of dis- ease. The odor of the urine varies, in the intensity of its “ urinous ” character, with the proportion of solid matter. Some albuminous urine of very low density is almost inodorous. Saccharine urine is apt to have a sweetish odor. Some phosphatic urine has an excessively fetid odor. It must be remembered, also, that peculiar odorous principles are sometimes developed in the urine after taking certain remedies, as turpentine, or particular ar- ticles of food, as asparagus. In clinical examina- tions it is frequently quite important to take ac- count of the odor of the urine in connection with the more elaborate processes of analysis. The reaction of the urine varies, in health, with digestion and other circumstances. Vegetable food diminishes the acidity and may render the urine alkaline, while animal food has the opposite effect. The rapid development of a free acid in the urine after it has been passed, may of itself decompose the urates, and be the sole cause of the deposition of uric acid; and a deposit of the triple phosphates may, on the other hand, be due entirely to an alka- line condition of the urine. It is sometimes an im- portant element in the treatment of disease to keep the urine alkaline, so that it is frequently very NORMAL VARIATIONS IN THE URINE. ' 21 desirable to take note of the reaction, as well as of the other general properties of the urine. In estimating the urea in the urine, which is so often recpiired in practice, it is a point of the greatest importance to keep in view the physiologi- cal variations in the proportion of this principle. Before the age of fifteen or eighteen years, the amount of urea and other solid matters excreted by the kidneys, in proportion to the weight of the body, is much greater than in the adult. In women the normal excretion of urea is generally less than in men; and when the amount of food taken is habit- ually small and the muscular system is very in- active, the amount of urea may be very much di- minished from these causes alone. In persons con fined to the bed with any disease and taking but little food, the urea may be small in quantity with- out indicating disease of the kidneys. Exercise increases the production of urea, and animal food has the same influence to a marked degree. It has been ascertained that a purely animal diet will in- crease the amount of urea fully two-fifths; a veg- etable diet will diminish it one-third; and a non- nitrogenized diet will reduce it more than one-half. It can be readily understood that these facts become exceedingly important in estimating the urea dis- charged in disease. In what is known as Bright’s 22 CHEMICAL EXAMINATION OF THE URINE. disease, it very often happens that the condition of the general nutrition of the body becomes such as to lead to a very great diminution in the actual production of urea, and the quantity in the urine may be small and yet the kidneys be separating from the blood all that is formed in the system. Inasmuch as the production of urea is pro- foundly affected by the quality of food, and as one of the great dangers to be feared in serious struc- tural disease of the kidneys is uraemia, it would seem as important to diminish the production of urea by a change in diet as to adopt measures to favor its elimination from the system. It is cer- tainly a reasonable supposition that the danger from uraemia would be diminished, if the production of urea be reduced by regulating the ingesta, particu- larly with reference to nitrogenized matters. Nearly the same remarks that have been made concerning the production of urea are applicable to uric acid. This principle always exists in health in the form of urates, the proportion of which is exceedingly variable under normal conditions. The pathological relations of uric acid, particularly in gout and in diseases accompanied with urinary concretions, cannot be adequately discussed within the limits of this work. In making quantitative examinations of the NORMAL VARIATIONS IN THE URINE. 23 arine for chlorides, sulphates, and phosphates, it must he remembered that the normal variations in these constituents are even greater than the fluc- tuations of urea and the urates, and that they are to a great extent dependent upon diet. It is not often, indeed, that much valuable information is to be derived from estimates of the proportions of the inorganic matters in the urine ; still, there are cer- tain pathological conditions in which the propor- tion of some of these principles is modified, par- ticularly the chlorides, for a consideration of which the reader is referred to elaborate works on the urine. In this brief introduction, I designed only to mention some of the most important of the physi- ological variations in the properties and composition of the urine, as a necessary preparation to the study of this excretion in disease. CHAPTER I. QUALITATIVE EXAMINATIONS OF THE HEINE. Apparatus for urinary examinations—Method of obtaining a spe. cimen for examination—General appearance, color, and odor of the urine—Reaction—Specific gravity—Presence or absence of albumen—Presence or absence of sugar—Presence or absence of bile. It is now so easy to make examinations of tlie urine extended and accurate enougli for ordinary clinical purposes, that there is no good reason why physicians, especially recent graduates, should not be able to ascertain for themselves most of the im- portant facts to be learned from a urinary analysis, and this without an undue expenditure of time and pains. A very simple examination, indeed, will suffice to exclude diseases of the kidneys and dis- orders of the general system that are attended with serious modifications in the composition of the urine; but it must frequently happen that a more extended analysis is required and should be made at once, and this many practitioners are not prepared to undertake. QUALITATIVE EXAMINATIONS. 25 Although many attempts have been made to de- vise a cheap, convenient, and sufficiently complete set of apparatus for ordinary examinations of the urine, few if any of them have been extensively used. It has seemed to me that this can be readily explained. A practitioner wants, in the first place, a convenient place and a quick and easy method for making his examinations, and his apparatus should be always ready for use; and none of the very cheap and compact sets of reagents will answer these requirements. An apparatus constructed on this principle is like a pocket microscope, convenient enough for transportation, but difficult and trying to the patience in actual use. A physician should be provided with a good, firm table, at least four feet by two, with drawers for stowing away odd articles, and a sufficiently complete chemical ap- paratus to enable him to do all his work conve- niently. He should see that his apparatus is al- ways clean and ready for use and that his solutions are kept in order. The table should be in a good light for microscopical as well as chemical work; and, in short, it should be so furnished that he is able to do his work with the least possible trouble. lie should have, in conspicuous places, tables and formulas for facilitating his calculations, and should be provided, in some way, with means 26 CHEMICAL EXAMINATION OF THE URINE. of recording tlie most important of the results of his examinations. A compact and scanty set of apparatus is always inconvenient, is usually in disorder, and will not answer for constant use. Having for some years been in the habit of making frequent examinations of the urine for phy- sicians, I have been led to arrange a set of appa- ratus that I have found by experience to be the most convenient for daily use. I have not, how- ever, been accustomed to subject the sediment to chemical tests, but have always used the micro- scope, as the simplest and most rapid method of ascertaining the character of urinary deposits. The microscopical characters of the urine in disease I shall not describe; for, although the application of the microscope in this way is not difficult, the sub- ject of urinary deposits is too extended to be ade- quately considered within the limits of this work, and reliable treatises on the subject are sufficiently accessible. Among the best, is a recent work by Dr. Roberts, which has been republished in this country.1 The following solutions are sufficient for ordi nary clinical examinations of the urine: 1 Roberts, A Practical Treatise on Urinary and Renal Diseases, ncludiny Urinary Deposits, Philadelphia, 18'72, APPARATUS FOR URINARY EXAMINATIONS. 27 List of Apparatus. Case of Eeagents, containing the following: 1. Nitric acid. 2. Hydrochloric acid. 3. Acetic acid. 4. Nitroso-nitric acid. 5. Nitrate of silver in solution (9*58 grains in a fluidoimce). 6. Sulphate of copper in solution (277 grains in 8|- fluidounces). 7. Solution of alkaline tartrates. 8. Liquor potasses. 9. Liquor am monies. 10. Ether. 11. Mercury. 12. Chloride of soda (concentrated). (Powers and Weightman.) 13. Solution of chloride of sodium (saturated). 14. Test-paper. 15. German yeast. A. Urinometer. B. Thermometer. C. Graduated glasses. (a.) Six ounce. (5.) One ounce graduated in drachms. (c.) One drachm. 28 CHEMICAL EXAMINATION OF THE URINE. D. 4 conical glasses with porcelain covers. E. Porcelain evaporating-dishes, and watch- glasses. F. Test-tube stands with test-tubes. Gr. 3 funnels, and filtering-paper. H. Shallow porcelain dish with a handle. I. Bunsen’s burner, rubber tubing, etc., or alco- hol-lamp. K. Burette, graduated in grains. L. 200 grain measure. M. Tube graduated in cubic inches, with vessel in which it can be inverted. H. Pings, and clamp for graduated tube. O. Stirring-rods and drop-tubes. P. Swabs and brushes for cleaning. P. Platinum spoon for calculi. S. Blow-pipe. T. A convenient sink for cleansing apparatus. {See page 65.) Extra Apparatus. A. Hydrometer of Baume, for liquids heavier than water. B. 1000 gr., 500 gr., and 100 gr. specific-gravity bottles. C. Water-bath. D. Water-oven and Swedish filters. APPARATUS FOR URINARY EXAMINATIONS. E. 2 wasli-bottles and 3 precipitating glasses. F. x\. balance, at least delicate enough to turn with of a grain. (r. Graduated solution of chloride of barium, (36‘6 grains in six fluidounces of water) for quantitative analysis for the sulphates. H. Three separate solutions for quantitative analysis for phosphoric acid. 1. Sesqui- chloride of iron; 9-J grains of iron by hydro- gen dissolved in hydochloric with a little ni- tric acid, evaporated to dryness, and dissolved in six fluidounces of water. 2. 400 grains of acetate of soda and 800 grains of acetic acid dissolved in six fluidounces of water. 3. 12 grains of ferrocyanide of potassium dissolved in six fluidounces of water. In ordinary examinations of the urine, a speci- men taken in the morning immediately after rising from bed will be found to represent, more nearly than any other, the general process of disassimilation. There are occasions in which it is desirable and in- dispensable to examine a specimen of the mixed urine of the twenty-four hours; but, in the great majority of cases, the morning urine will be suf- ficient, and this may be obtained without alarming the patient or friends or leading them to suppose that extraordinary attention is being directed to the 30 CHEMICAL EXAMINATION OF THE URINE. kidneys. I shall therefore indicate, first, the process for an ordinary examination, by which it may be desired simply to exclude the question of urinary dis- turbance, and afterward describe more minutely the processes involved in more important investigations. Method of obtaining a Specimen for Exam- ination.—A specimen of the morning urine should be collected a short time after it has been passed, in a perfectly clean bottle, holding from four to eight iiuidounces. This may be tested at once for reaction, specific gravity, the presence of albumen or sugar, and its color, general appearance, and odor may be noted. In most cases these points may be obtained with sufficient accuracy after twelve hours’ and, in the winter, even after twenty-four hours’ standing. The urine should then stand ten or twelve hours, to allow of the deposition of a sediment, the general appearance of 'which should also be noted. It may re- main in the original bottle, or the sediment may be allowed to de- posit in a conical vessel A, covered with a porcelain plate, on which the memoranda may be written in pencil. In specimens brought by patients, it is as well to have the urine stand in the original bottle. Fig. 1. 6. T/EMANN-CO. Vessel for collecting urinary deposits. GENERAL PROPERTIES OF THE URINE. 31 but the conical glasses are very convenient for spe- cimens freshly collected. In about twelve hours specimens of the sediment should be taken up with a pipette or drop-tube, to be examined micro- scopically. The points to be noted in ordinary chemical ex- aminations are the following: 1. The general appearance and color; the time of the day when the specimen was taken; the gen- eral appearance of the deposit, if any exist; the total quantity in the twenty-four hours; and the odor. 2. The reaction; whether acid, alkaline, or neutral. 3. The specific gravity. 4. The presence or absence of albumen. 5. The presence or absence of sugar. 6. The presence or absence of biliary matters, in case the color should lead to the suspicion of their existence. General Appearance, Color, and Odor.—A suf- ficiently definite record of the color and general appearance of the urine may be made by noting it as amber and normal, reddish, pale, tinged with 'bile, clear, turbid, etc., etc., as the case may be. The remarks under the head of color will readily suggest themselves in recording the appearances of 32 CHEMICAL EXAMINATION OF THE HEINE. different specimens under examination. With re- gard to the odor, it may be noted as normal, strong- ly or feebly nrinons, sweetish, ammoniacal, fetid, or by some term that will indicate any extraneous odorous principle. Reaction.—The most convenient method of de- termining the reaction of the urine, is by delicately- tinted blue litmus-paper for acid urine, and faintly- reddened litmus or turmeric paper for alkaline urine. Normal urine is usually acid, and con- sequently turns blue litmus red. If it be alkaline, it restores the blue color to reddened litmus, and changes yellow turmeric paper brown. It is not usually important to determine the amount of acid- ity of the urine, but this may be done by neutral- izing with alkaline solutions that have been gradu- ated to represent a known quantity of crystallized oxalic acid. It is frequently useful to determine whether the alkalinity of a specimen of urine be due to a fixed alkali (potash or soda), or to a volatile alkali, the result of ammoniacal decomposition. If the urine contain a fixed alkali, the blue color of the litmus will remain after the paper has been thoroughly dried; and if the reaction be due to a volatile alkali, the blue color will disappear from the paper as the moisture evaporates. In the treat- ment of certain diseases, one of the objects is to SPECIFIC GRAVITY. 33 keep the urine alkaline; and perhaps the most con- venient test to employ constantly, in these cases, is the turmeric paper. Specific Gravity.—The only absolutely accurate way of taking the specific gravity of anv liouid is by actual weight of a definite volume; but this requires a delicate balance, carefully adjusted, and the process must occupy considerable time. The most convenient method in ordinary examinations is by floating in the liquid a glass urinometer, when the number of degrees above 1000 may be read off from the scale. (See Fig. 2.) The urinometers in the set of ap- paratus I am describing may be com- pared with the standard in the posses- sion of Messrs. Tiemann & Co., which has been tested by actual weight throughout the entire scale. Of course, the specific gravity varies slightly with temperature. Corrections for temperature may be made from table B. The usual standard for the specific gravity of liquids is 60° Fahr. It may be useful sometimes to form an idea from the specific gravity, of the total amount of solids excreted; and it is a curious fact that between 1010 and 1030, the last two figures indicating the specific gravity Fio. 2. Apparatus for spe- cific gravity. CHEMICAL EXAMINATION OF THE HEINE. indicate also, with a very slight error, the number of grains of solids in the urine per fiuidounce. Table C gives the weight of a fiuidounce of urine, and also the proportion of solids when the specific gravity is between 1001 and 1042, except for diabetic urine. When the urine is too small in quantity to float the urinometer, add to a measured quantity four vol- umes of water and take the specific gravity of the mixture. Then multiply the excess of the specific gravity over 1000 by five and add 1000. Presence or Absence of Albumen.—There are two tests which, if used together, will easily and certainly determine the presence or absence of albu- men in urine, and these are heat and nitric acid. If a specimen of albuminous urine of a decidedly acid reaction be boiled, it will become more or less turbid or opaque in proportion to the quantity of albumen that is present. A method very generally recommended is to fill a test-tube about half-full of urine and apply the heat to the upper layer, which, if it be rendered turbid, will present a marked contrast with the clear fluid below. If the urine be neutral or alkaline, a few drops of acetic acid should be added before the heat is applied. In urine that is very feebly acid, neutral, or alkaline, turbidity may fol- low the application of heat when no albumen is present. This is due to a deposition of the earthy TESTS FOR ALBUMEN. 35 phosphates; and the character of this precipitate may be recognized by adding a drop or two of nitric acid, which immediately clears np the specimen. In urine containing a large quantity of albumen, opacity is produced at a comparatively low temperature; but if the proportion of albumen be small, cloudiness may not appear until the liquid has been brought to the boiling-point. In urine that is turbid from urates, heat will first dissolve the precipitate and render the liquid clear; and afterward, as the tempera- ture is raised, the albumen will be coagulated. In the test by nitric acid the reagent may be simply dropped in, or, as is recommended by some, it may be allowed to trickle along the side of the test-tube and fall to the bottom. In most speci- mens of albuminous urine, the nitric acid simply added to the urine will produce a well-marked coagulation. "When the acid is carefully passed to the bottom of the tube, there is a clear stratum be- low formed by the acid, a clear stratum of urine above, and an intermediate zone of coagulation, more or less opaque. When the urine contains a large excess of uric-acid compounds, the addition of nitric acid sometimes produces a precipitate of amor- phous urates; but this is dissipated by gentle heat. As a general proposition, it may be stated that urine in which there is an opacity produced by 36 CHEMICAL EXAMINATION OE THE URINE. heat that is not cleared up by nitric acid, or in which there is a precipitation by nitric acid that does not disappear with gentle heat, is sure to contain albumen. Presence or Absence of Sugar.—The ordinary methods for detecting sugar in clear solutions, par- ticularly the test with sulphate of copper and caustic potash, cannot be certainly and easily applied to the urine. If the test-liquids be added to the urine and the mixture be boiled, normal urine will decolorize the solution, and it is frequently difficult to form a negative opinion with regard to the presence of sugar. Almost all writers who have had practical experi- ence with these processes have recognized the diffi- culties in this mode of using the copper-tests; and the various other tests that have been proposed are neither very delicate nor convenient. In view of these facts, it has been suggested by Roberts and others, that the test-liquid be boiled and the urine added drop by drop ; and in this way the detection of sugar becomes as certain and easy as the test for albumen. Roberts uses the prepara- tion known as Fehling’s test-liquid, the formula for which, reduced to English grains, is as follows: Sulphate of copper, 94"73 grains (40 grammes); neutral tartrate of potash, 378’91 grains (160 gram- mes) ; solution of caustic soda, S23ecific gravity, IT2 TESTS FOR SUGAR. 37 (about of Baume’s hydrometer), fluidounces (750 grammes). Add water to make exactly 6 fluid- ounces (USAS cubic centimetres). If calculated by the English standard, exactly 200 grains of the test-liquid will correspond to one grain of sugar. If calculated by the French stand- ard, 10 cubic centimetres correspond to o’os of a gramme of sugar.1 For merely determining the presence or absence of sugar in any given specimen of urine, an ordi- nary test-tube is filled to the depth of about an inch with the test-liquid, which is boiled, and the urine is then added drop by drop. In ordinary dia- betic urine, the first few drops will produce a red- dish or yellowish opaque precipitate. If the urine be added to about the volume of the test-liquid and the mixture be again brought to the boiling-point and allowed to cool, without any precipitate, it is certain that no sugar is present. The only practical inconvenience in the use of 1 Dr. E. R. Squibb, No. 36 Doughty Street, Brooklyn, N. Y., pre- pares for sale Fehling’s test-liquid, which may be kept for a long time without deterioration. I procured a bottle of this test in March, 1878, and have used it from time to time, keeping it in an ordinary bottle with a rubber stopper. At the present time (Janu- ary, 1884) it shows no sign of alteration. Dr. Squibb states that his test is simply made of chemically-pure articles, according to the ordinary formula. It is better, however, to use the two liquids de- scribed on the next page. 38 CHEMICAL EXAMINATION OF THE URINE. this test is in the fact that the liquid is liable to alteration by keeping, and when it is thus altered it will precipitate by simple boiling, or by boiling after the addition of an equal volume of distilled water; but if care be taken to make a preliminary test of the liquid, there can be no error when the process is followed out with care. If the liquid be imper- fect from keeping, all that is necessary, in ordinary examinations, is to add a little more soda and filter; but in all accurate analyses, a fresh preparation should be made. To obviate this inconvenience, Dr. E. R. Squibb, of Brooklyn, hT. Y., has prepared two liquids, to be kept in separate bottles and mixed for use, as follows: For the Solution of Sulphate of Copper.—Weigh 227 grains (IT'32 grammes) of pure crystals of sul- phate of copper, dissolve in about 4 fluidounces (125 cubic centimetres) of distilled water, add 16 minims (i cubic centimetre) of pure sulphuric acid, and then add distilled water to make the whole measure 8J fluidounces (250 cubic centimetres). For the Solution of Alkaline Tartrates.—Weigh 2 ounces 391 grains (87-5 grammes) of recrystallized tartrate of potash and soda, or Rochelle salt, and dissolve it in about 6 fluidounces (175 cubic centi- metres) of distilled water. Filter the solution if necessary, add to it a clear solution of 386 grains TESTS FOR BILE. 39 (25 grammes) of caustic soda in about If fluidounce (50 cubic centimetres) of distilled water, and add distilled water to make the whole measure 8|- fluid- ounces (250 cubic centimetres). These two solutions, when mixed in equal vol- umes, make Fehling’s solution, of which 200 grains will correspond to 1 grain of sugar, or 10 cubic centimetres to 005 of a gramme of sugar. Presence or Absence of Bile.—The presence of the coloring matter of the bile is usually indicated by the characteristic tint, more or less strongly marked, in the urine. A simple and certain test is to spread a thin stratum of the urine upon a porce- lain surface, and add to it a drop of nitroso-nitric acid (a mixture of nitrous with nitric acid). If biliver- dine be present, the drop of acid will be fringed with a rapidly-varying play of colors, violet, green, and red, which speedily disappear. A drop of nitric acid will produce nearly the same appear- ance, though the colors are less strongly marked. It is stated that the biliary acids sometimes ap- pear in the urine, but it does not seem that their characteristic reaction is ever very distinct. The best mode of detecting these principles is by Petten- koffer’s test, which is applied in the following way: To the suspected fluid add a few drops of a strong solution of cane-sugar. Then add strong CHEMICAL EXAMINATION OF THE URINE. sulphuric acid, drop by drop, to about one-half or two-thirds the volume of the original liquid. If the biliary salts be present in large quantity, a red color shows itself almost immediately at the bottom of the test-tube, and soon extends through the entire liquid, rapidly deepening until it becomes of a dark lake or purple. These changes are very slow in the presence of a small quantity of the biliary salts, and may occupy from fifteen to twenty minutes. These are the phenomena observed in ordinary clear solutions of the biliary salts. In the urine the re- action is indefinite and unsatisfactory. CHAPTER IT. QUANTITATIVE ANALYSIS OF THE HEINE. Analysis for albumen—Analysis for sugar—Differential-density method of analysis for sugar—Volumetric method for esti- mating sugar—Quantitative analysis for urea—Quantitative analysis for chlorine, sulphuric acid, phosphoric acid, and uric acid. It is frequently very important, in the progress of a case, to be able to ascertain from time to time the amount of urea, urates, or sugar contained in the urine ; and these points may be determined very easily and rapidly by volumetric processes. It is also a very simple problem to determine the proportion of chlorine, sulphuric acid, and phos- phoric acid ; but, with regard to the last two, although a great many observations have been made on the urine in health and disease, it has not been ascertained that their variations are con- nected with any definite pathological conditions. I have omitted, in the list of reagents required in ordinary examinations, the liquids for quantitative 42 CHEMICAL EXAMINATION OF THE URINE. analysis for snlplmric acid, phosphoric acid, and uric acid. Of course, these acids actually exist in the urine only in combination with bases, but it is usually sufficient to ascertain their proportion, without calculating the amount of the salts. Quantitative Analysis for Albumen.—To ascer- tain the proportion of dry albumen, a small quan- tity of acetic acid is added to a weighed quantity of urine, and the specimen is boiled in a test-tube. The precipitate may then be collected on a filter, carefully dried and weighed, and its proportion cal- culated. This estimate, however, is seldom required. A rough but sufficiently accurate estimate may be made by adding acetic acid, boiling, and allow- ing the flaky precipitate to settle. Its proportion may then be expressed as one-eighth, one-fourth, etc., as the case may be. Quantitative Analysis for Sugar.—Roberts recommends an exceedingly easy process for quan- titative examinations of sugar, so rapid that it may be employed from day to day in ordinary cases of diabetes. This he calls the “differential density method.” 1 Professor Doremus has made repeated experiments with this process, and agrees with Dr. Roberts with regard to its accuracy. The estimate is made as follows: 1 Roberts, op. cit., Philadelphia, 1872, p. 198. ANALYSIS FOR SUGAR. 43 Two specimens of the urine are taken, about four ounces of each, one for comparison and the other for analysis. To one is added a lump of German yeast, about the size of a filbert, in a bottle with a nicked cork, to allow for the escape of gas; and the other is placed in a similar bottle tightly corked. The bottles are then set aside in a warm place, as the mantel-piece in winter or in the sun in summer. In twenty-four hours the fermentation will have been completed in the specimen to which yeast has been added. If the specific gravity of the two be now compared, the fermented specimen will be found much the lighter, from loss of sugar which has been decomposed into alcohol and carbonic acid. The difference in the density of the specimens, expressed in degrees of the urinometer, will represent the number of grains of sugar per fluidounce in the urine. For example, if the specific gravity of the fermented specimen be 1010, and the specific grav- ity of the unfermented specimen 1040, the urine contains 30 grains of sugar per fluidounce. In this process it is essential to compare the densities of the two specimens at the same temperature. The volumetric method is more troublesome, though it is also very simple. Fehling’s test-liquid is made up by the formulae already given (see pp. 37, 38), and 200 grains are measured off in a tube gradu- 44 CHEMICAL EXAMINATION OF THE URINE. ated for that purpose. The diabetic urine is then diluted with water, so that the proportion of urine shall be one in five or ten. The test-liquid is diluted with about twice its volume of water and placed in a shallow porcelain dish with a handle. A piece of caustic potash, about the size of a pea, added to the test-liquid, will facilitate the precipitation. A bu- rette graduated in grains is now filled with the diluted urine to 0. The test is then boiled, and the diluted urine is added from the burette in small quantities from time to time, producing each time a copious red precipitate and gradually discharging the blue color of the test-liquid. After each addi- tion of urine the mixture should be brought again to the boiling-point, and a few seconds allowed for the precipitate to fall. When the blue color of the test- liquid has entirely disappeared, as can be ascertained by tipping the vessel when the precipitate has sub- sided so that the color of the liquid is not obscured, and when no farther precipitate is formed by adding the urine, the analysis is complete. As the two hun- dred grains of the test used exactly correspond to one grain of sugar, by reading off the number of grains added from the burette, the calculation may be easi- ly made. For example, if the urine be diluted so that ten parts of the mixture represent one of urine, and if one hundred grains of the mixture be used from ANALYSIS FOR UREA. 45 the burette, ten grains of urine contain one grain of sugar. This gives the proportion of sugar per hundred or thousand. By reference to table C, which gives the weight of a fluidounce of urine of different specific gravities, the amount of sugar per fluidounce, and afterward the total quantity in the twenty-four hours, may be calculated, by multiplying the weight of a fluidounce by the percentage of sugar, and dividing by 100/ To facilitate these estimates, I have calculated table D, which gives the propor- tion of sugar in the undiluted urine represented by the graduations on the scale, supposing one part of urine to be diluted with nine of water. In urine diluted with four parts of water, the indications are to be doubled. Quantitative Analysis for Urea.—Several ac- curate, but at the same time complicated pro- cesses have been devised by chemists for determin- ing the proportion of urea in the urine ; but it becomes so often necessary for the physician to be able to measure the daily excretion of urea, particularly in organic diseases of the kidneys, that it is exceedingly desirable to fix upon some 1 Inasmuch as the grains of the diluted urine are represented in the burette by volume, and not by actual weight, there is neces- sarily a slight error in the calculation, depending upon differences in the specific gravity of the specimens ; but, in urine so much diluted, this error is unimportant and may practically be disregarded. 46 CHEMICAL EXAMINATION OF THE URINE. method, sufficiently accurate for practical purposes, but so rapid and easy that it may be employed con- stantly by the busy practitioner. Liebig’s volu- metric method is the one most frequently employed by chemists, but this is somewhat complicated and is liable to some sources of error. Bunsen’s method is perhaps more generally applicable to all condi- tions of the urine, but it is difficult. By far the simplest process is known as Davy’s method, with the hypochlorite of soda, or Labarraque’s solution. The only question is with regard to its accuracy. In describing this process, Dr. Davy states that he has repeatedly compared it with Liebig’s method, and has found it to correspond so nearly that the slight difference could be disregarded. I have ar- rived at this conclusion in the same way, using the solution of chloride of soda, prepared by Messrs. Powers and Weightman, of Philadelphia, or the liquor sodce chlorinates, prepared by Dr. Squibb, of Brooklyn. I have no hesitation in say- ing that, with either of these solutions, the method is all that could be desired by the medical prac- titioner. In describing this process, I cannot do better than to quote the directions given by Thudi- chum: 1 1 Thudichum, A Treatise on the Pathology of the Urine, London, 1858, p. 69. ANALYSIS FOR UREA. 47 A strong glass tube, about twelve or fourteen inches long, closed at one end, and its open ex- tremity ground smooth, and having the bore not larger than the thumb conveniently can cover, holding from two to three cubic inches, each divided into tenths and hundredths by graduation on the glass, is filled more than a third full of mercury, to which afterward a measured quantity of urine to be examined is poured, which may be from a quar- ter of a drachm to a drachm or upward, according to the capacity of the tube ; then holding the tube in one hand near its open extremity, and having the thumb in readiness to cover the aperture, the operator fills it completely full with a solution of the hypochlorite of soda (taking care not to overflow the tube), and then instantly covers the opening tightly with the thumb, and having rapidly invert- ed the tube once or twice, to mix the urine with the hypochlorite, he finally opens the tube under a saturated solution of common salt in water, con- tained in a steady cup or small mortar. The mercury then flows out, and the solution of salt takes its place, and the mixture of urine and hy- pochlorite being lighter than the solution of salt, will remain in the upper part of the tube, and will therefore be prevented from descending and mixing with the fluid in the cup. A rapid disengagement 48 CHEMICAL EXAMINATION OF THE HEINE. of minute globules of gas soon takes place in the mixture in the upper part of the tube, and the gas is there retained and collected. The tube is then left in the upright position till there is no farther appearance of minute globules of gas being formed, the time being dependent upon the strength of the hypochlorite and the quantity of urea present; but the decomposition is generally completed in from three to four hours ; it may, however, be left much longer, even for a day if convenient, and having set the experiment going, it requires no further atten- tion ; and when the decomposition is completed, it is only necessary to read the quantity of gas pro- duced off the scale on the tnbe. In cases where great accuracy is required, due attention must be paid to the temperature and atmospheric pressure, and certain corrections made if these deviate from the usual standards of comparison, at the time of reading off the volume of the gas; but in most cases sufficiently near approximations to accuracy may be obtained without reference to those par- ticulars.” I have lately been in the habit of modifying this process by adding to the solution of the solution of soda, just before using it, a drop or two of bromine (Knop, Hiifner, and others), which makes the disengagement of gas more rapid and remqves an element of inaccuracy dependent ANALYSIS FOR UREA. 49 upon the deterioration of the test-liquid by keep* ing. Using half a fluidrachm of urine, each cubic inch of gas represents 0645 of a grain of urea. To obtain the proportion, multiply the fractions of a cubic inch graduated on the tube by 0*645, and the result will be the amount of urea in half a fluidrachm, in grains. Multiply by sixteen to obtain the proportion per fluidounce (table E), or the entire quantity in the twenty-four hours may be calculated, if a specimen of the mixed urine of the twenty-four hours have been used. By reference to table C, the weight of a fluidounce with the specific gravity may be taken, and from this may be calculated the proportion of urea per 1,000 parts. Fig. 3. To farther facilitate the estimate of the proportion of urea, I have calculated table E, which gives the number of grains of urea per fluidounce represented by the divisions of the scale on the tube grad- uated in cubic inches. This is calculated, supposing that half a fluidrachm of urine has been used. Apparatus for determining the proportion of urea in the urine. 50 CHEMICAL EXAMINATION OF THE URINE. Quantitative Analysis for Chlorine, Sulphur ie Acid, and Phosphoric Acid.—lt is not so often im- portant to the physician to ascertain the propor- tions in the urine of the principles above enumer- ated, as to estimate the amount of urea or sugar; but by the volumetric method there is little diffi- culty in making quantitative estimates of chlorine, sulphuric acid, and phosphoric acid. Beyond this, however, in the present condition of medical sci- ence, there is little important information to be obtained from chemical examination of the urine, so imperfectly do we understand the physiological and pathological relations of the other normal and abnormal ingredients of this excretion. I am indebted to my colleague, Dr. R. O. Dore- mus, Professor of Chemistry in the Bellevue Hos- pital Medical College, and his assistant, Dr. A. W. Wilkinson, for valuable assistance in preparing the formulae of the following test-liquids, for chlorine, phosphoric and sulphuric acid, in solutions, gradu- ated so that each fluidounce will correspond to two grains of the principle to be estimated in the urine. Prof. Doremus appreciates fully the great impor- tance to the practical physician of simple and easy tests; and the want of absolute accuracy which some of these methods present is so slight that it may practically be disregarded, in view of the constant ANALYSIS FOR CHLORINE. 51 and unimportant variations in the urine in health and disease. Each one of these solutions represents in half a fluidounce one grain of the substance sought for, and half a fluidounce will fall a little short of filling the burette, graduated to two hundred and fifty grains. To make the tests still more delicate, without complicating the process, I propose to use the burette. Into this is poured a carefully-meas- ured half-ounce of the test-liquid, the burette be- ing then filled to 0 with distilled water. Every division of the burette into two grains will then repre- sent Trf-g- of a grain. Always using the same quantity of urine (two fluidrachms), I have calculated a table in which the proportion per fluidounce for either chlorine, sulphuric acid, or phosphoric acid, is given opposite the number of the divisions on the burette. Chlorine.—In a fluid so complex in its composi- tion as the urine, it is by no means a simple matter to estimate with absolute accuracy the proportion of chlorine; still, as far as any information valu- able to the practical physician is concerned, the pre- cipitation of chlorine from an acidulated solution by nitrate of silver is sufficiently exact. To prepare the test-liquid, make a solution of chemically pure fused nitrate of silver in distilled water, so that six fluidounces shall contain 57*47 52 CHEMICAL EXAMINATION OF THE URINE. grains of the salt. A fluidounce of this solution will correspond to two grains of chlorine. To estimate the amount of chlorine in a given specimen, measure out carefully two fluidrachms of urine, and add a few drops of nitric acid, to keep the phosphates in solution when the nitrate of silver is added. Measure out now half a fluidounce of the test-liquid, pour it into the burette, and careful- ly fill with distilled water to 0. The urine may now be diluted with water, if it be desired to make the estimate with great nicety, or the undiluted urine may be used. The solution is then gradually added to the urine from the burette, each addition being followed by a white precipitate. Each time, after adding the test- liquid, the mixture should be stirred with a glass rod, and the precipitate allowed to settle. At the moment when the addition of the test-liquid fails to produce a precipitate, the analysis is complete. This test will occupy from ten to fifteen minutes. Each division of the scale on the burette into two grains represents of a grain of chlorine. In table F, I have calculated the proportion per fluid- ounce of urine, supposing the quantity of urine used to have been two fluidrachms. If the urine be albuminous, two fluidrachms should be carefully measured, acidulated with a ANALYSIS FOR SULPHURIC ACID. 53 little acetic acid, and boiled. The coagulated albu- men may now be separated by filtration, the clear filtrate acidulated with nitric acid and then treated with the graduated solution of nitrate of silver. Sulphuric Acid.—The same remark made con- cerning the accuracy of the preceding test for chlo- rine is applicable to the process for estimating the sulphuric acid of the urine by a graduated solution of chloride of barium. For all ordinary purposes, however, the test I am about to describe is suffi- ciently exact. The test-liquid is simply a solution of chemically pure chloride of barium, six fluidounces of which contain 36'6 grains of the salt. A fluidounce of this solution represents exactly two grains of sul- phuric acid. To apply the test, two fluidrachms of urine are measured, as for the other tests, and acidulated with a few drops of nitric acid. If the urine be albumi- nous, it may be acidulated with acetic acid, boiled, filtered, and the filtrate treated with nitric acid. Half a fluidounce of the test-liquid is now poured into the burette, which is filled with distilled water to 0. The solution is then added from the burette little by little, stirring the mixture with a glass rod, and waiting for i?he deposit to subside, which takes place more rapidly than in the test for chlorine. CHEMICAL EXAMINATION OF THE URINE. When the addition of a fresh quantity of the solu- tion fails to produce a precipitate, the test is com- plete. The amount of the solution that has been added may then be read off from the burette, every division of which into two grains represents of a grain of sulphuric acid. Supposing the quantity of urine used to have been two fluidrachms, the proportion of sulphuric acid per fluidounce is given in table F. Phosphoric Acid.—The process for determining the proportion of phosphoric acid in the urine is not open to any serious objection on the score of want of accuracy, and, after the proper solutions have been prepared, the estimate may be made rapidly and presents no difficulty. I copy the following theory of this process from the excellent work of Neubauer and Yogel:1 “ A solution of phosphate of soda, which con- tains also both acetate of soda and free acetic acid, when treated with a dilute solution of perchloride (sesquichloride) of iron, yields a voluminous whit- ish-yellow precipitate of phosphate of iron, contain- ing one equivalent of oxide of iron to one equivalent of phosphoric acid. So that, if we add acetate of 1 Neubauer and Yogel, A Guide to the Qualitative and Quan- titative Analysis of the Urine, New Sydenham Society, London, 1863, p. 196. ANALYSIS FOR PHOSPHORIC ACID. 55 soda to a solution containing an unknown quantity of phosphoric acid, and then add a standard solution of perchloride of iron until the whole of the phos- phoric acid is thrown down, and a trace of the iron appears in the mixture, we can reckon the quantity of phosphoric acid, by taking the amount of iron- solution employed.” This process requires three solutions, viz.; a graduated solution of sesquichloride of iron, a solu- tion of acetate of soda containing free acetic acid, and a solution of ferrocyanide of potassium, the last being used to detect the first trace of an excess of iron. These solutions are prepared as follows: For the solution of sesquichloride of iron, take grains of pure iron (piano-forte wire has been recommended, hut iron by hydrogen is better) and dissolve in pure hydrochloric acid, adding a little nitric acid. Evaporate this carefully to dryness in a water-bath, in order to drive off the excess of hy- drochloric acid, and dissolve the residue in six fluid- ounces of distilled water. One fluidounce of this solution will correspond to two grains of phosphoric acid. For the second solution, dissolve 400 grains of acetate of soda in six fluidounces of water, and add 800 grains of ordinary acetic acid. Half of a flui- drachm of this solution is to be added to two flui 56 CHEMICAL EXAMINATION OF THE URINE. drachms of urine, before adding the solution of per- chloride of iron. The third solution is simply ferrocyanide of potassium in water, and the strength is not im- portant. I have prepared it in the proportion of twelve grains to six fluidounces. To estimate the entire amount of phosphoric acid in a given specimen, measure olf two fluidrachms of urine, and add half a fluidrachm of the solution of acetate of soda and acetic acid. Pour half a fluid- ounce of the solution of sesquichloride of iron into the burette, and dilute with distilled water to 0. The iron-solution is now to be gradually added to the mix- ture of urine, this producing a yellowish precipitate. During this process, the mixture is stirred with a glass rod, and a drop is taken from time to time, put upon a bit of filtering-paper, which is pressed with the fingers over a second piece of filtering- paper moistened with the solution of ferrocyanide of potassium. The faintest blue color appearing on the paper moistened with the solution of ferrocy- anide of potassium is an indication that an excess of iron is present in the mixture, and the analysis is then complete. The amount of iron-solution added may then be read off from the burette, and each division into two grains represents -g-f-g- of a grain of phosphoric acid. The proportion of phos- ANALYSIS FOR URIC ACID. 57 phoric acid per fluidounce may then be taken from table B. To estimate the relative proportions of phos- phoric acid combined with alkalies and that com- bined with earths, the following simple method may be employed: Measure off two fluidrachms of urine, as before, and add a few drops of ammonia. This will pre- cipitate the earthy phosphates, which after a few hours will deposit and may be separated by filtra- tion, The filtrate is collected, and the residue on the filter is washed with water, containing a little ammonia, which is also collected. The liquid, con- taining in solution the phosphoric acid combined with alkalies, is now carefully neutralized with acetic acid and treated with the acetate-of-soda solution and the iron-solution in the manner just described. By this means the amount of phosphoric acid com- bined with alkalies is estimated, and this, subtracted from the entire amount of phosphoric acid in the urine, will give the proportion of phosphoric acid combined with earths. Quantitative Analysis for Uric Acid.—After a thorough trial of the only volumetric method for the determination of the uric acid in the urine that has been recommended as at all accurate, it became evident that its process was so uncertain as to be en- 58 CHEMICAL EXAMINATION OF THE URINE. tirely unavailable in clinical examinations. I was compelled, therefore, to have recourse to the more tedious process of estimating the acid by weight. The process which I finally adopted is easy enough, but requires care and the use of a balance. Its theory is briefly as follows : Absolute alcohol, added to urine evaporated to a syrup, will dissolve urea, creatine, creatinine, and coloring matter, leaving the urates and the inorganic salts. By washing the residue of an alcoholic ex- tract with dilute hydrochloric acid, the inorganic salts are removed, leaving the uric acid set free from its combinations, which may be collected and weighed. The following are the manipulations to be employed in this analysis : Take one fiuidounce of urine, filtered, so as to remove any mucus that it may contain. The urine is then evaporated over a water-bath, to the con- sistence of a thick syrup, in a porcelain evaporat- ing-dish. To hasten the evaporation, the liquid is spread over the sides of the dish with a glass rod from time to time, as the evaporation is approach- ing completion. When it is so thick as to adhere to the vessel, add about half a fiuidounce of ab- solute alcohol, mixing the urine with the alcohol thoroughly, and pouring it upon a filter which has been previously weighed dry, and then moistened ANALYSIS FOR URIC ACID. 59 with alcohol. Extract in this way with alcohol two or three times, or until the alcohol no longer takes np any coloring matter. After pouring off the alcohol upon the filter, the residue left in the evaporating-dish should be extracted in the same way with a mixture of one part of hydrochloric acid to six of water, and the whole poured on the filter used to separate the al- coholic extract. In this part of the process, about a fluidounce of the acid solution should be used. The residue on the filter should then be washed with a wash-bottle, two or three times with the acid, and afterward with distilled water. After the liquid has separated, the filter is dried in a water-oven and carefully weighed. The in- crease in weight (the filter having been previously weighed), represents the amount of uric acid per fluidounce of urine. The process of evaporating will be much hastened by stirring the urine. A glass rod with a small piece of rubber-tubing attached to the end is very convenient for cleaning the residue from the evapo- rating-dish, but the rubber should be carefully washed, so that no particles can be lost. The lip of the evaporating dish may be smeared at its lower edge with a little grease, to prevent any loss of fluid in pouring. 60 CHEMICAL EXAMINATION OF THE URINE. If there be any crystals of uric acid in the spe- cimen, these may he collected on the filter before evaporating. For the minute details of this process, I am in dehted to my assistant, Mr.