Diagnosis by the urine; or, The practical examination of urine with special reference to diagnosis

Front matter

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•ECOfin i;0 py,

Preface To Second Edition

The exhaustion of the first edition, together with the advance in science and knowledge gained by the author since the .publication of his work, rendered a thorough review of what was before written necessary. This has been carefully done, and the work now goes forth with many additions and radical changes which the later experience of the writer has found necessary so as to give more accurate results in diagnosis.

A few remarks have been made as to the different kinds of tube-casts and the significance of their presence, but the main addition to the work has been in the chapter on the Differential Diagnosis of Chronic Bright' s Disease as Based on a Classification of the Normal Absolute, the Absolute, and the Relative Absolute of Solids and Urea.

This chapter represents the views of the vi PREFACE TO SECOND EDITION.

author, and it is sincerely hoped that the matter therein contained, and which has been gathered from a long and painstaking observation of several years, will be of value to others, and likewise substantiated by those w r ho work in this field of science. Trusting, then, this edition will meet with as much favor from the profession as did the last, and that the views expressed, although possibly a little ultra to what is generally taught as to the significance of tube-casts, will yet be confirmed by future investigations, he has the pleasure of submitting to his critics what he has written.

The Author.

69 George Street, Charleston, South Carolina. February ^ i8gg.

Introduction

The urine is the secretion of the kidneys, and, normally considered, is a solution of tissue which has undergone retrograde metamorphosis. The process by which this is brought about is a double one : filtration, which occurs chiefly in the Malpighian capsules of the kidney, and excretion, which is brought about by means of the epithelial lining of the tubules of the kidney. Although this is true for all practical purposes, still the lines are not so accurately defined as this, a certain though small proportion of the excretion taking place through the Malpighian tufts, and, conversely, a certain percentage of water being excreted along with the solids by means of the epithelium of the tubules. The average composition of this fluid is as follows :

Total solids, 60 to 65 gm.

io DIAGNOSIS BY THE URINE.

Uric acid, 0.5 to 0.8 gm

Chlorids, 10 " 12

Phosphoric acid, 2.5 " 3

Earthy phosphates, . . . . 1 "1.3

Sulphuric acid, 1.5 " 2.5

Hippuric acid, °- 2 5" o-5

Creatinin, 0.5 " 1

In disease the urine, besides showing deviations in the normal constituents and physical characteristics, contains albumin, sugar, biliary coloring-matter, acids and fats, uroerythrin (red coloring-matter), ammonium sulphid, blood, leucin and tyrosin, carbonate and oxalate of calcium, carbonate of ammonium, cystin, xanthin, pus, epithelium, spermatozoa, and fungi.

Diagnosis by the Urine.

Chapter I. Physical Characteristics Of Urine In Health

AMOUNT.

The quantity of urine passed in twenty-four hours by one in health is dependent upon so many circumstances, at times controlled by mental, emotional, and physical causes, that it is hard to give an accurate norm. After most careful observations, however, extending over years, the author has arrived at the following estimate of quantities as fairly representing, in a vast number of cases, a condition of health in the adult :

1. A winter average of 1500 c.c.

2. A winter occasional average of 2000 c.c, depending almost entirely on sudden cold changes, accompanied frequently by moist, easterly winds.

3. A winter minimum of 1200 c.c.

4. A summer average of 1 100 c.c.

5. A summer occasional average of 1500 c.c, depending much upon the same conditions as in winter.

9. A summer minimum of 900 c.c.

The average quantity, then, of urine passed by one in health in the twenty-four hours in winter is 1500 c.c, or 50 fluidounces. Most is passed in the afternoon, less in the morning, and least at night. Of course, the amount passed will be much influenced by the causes already mentioned, as also by the quantity of fluid taken into the system ; but the above is the general average for winter in health, and a variation of 500 c.c less than the maximum, or 500 c.c more than the minimum, must be allowed, not constituting in this variation a condition of disease.

SPECIFIC GRAVITY.

The specific gravity of normal urine for the twenty-four hours has quite an extensive range ; and, as in the case of quantity, so have our

PHYSICAL CHARACTERISTICS IN HEALTH. 13

observations shown us that quite a different range is to be observed between the specific gravity of urine passed in winter and that passed in hot weather.

Winter urine has a general average of 1.018, and varies, according to the quantity of water passed, from 1.013 to 1.022.

Summer urine has a general average of 1.023, and varies, according to the quantity of water passed, from 1.017 to 1.030.

The urine, too, of children shows very different specific gravities in health and disease from that of the adult ; and, in the experience of the writer, has a normal specific gravity in winter varying from 1.008 to 1.012, and in summer, from 1.012 to 1.017.

The water solids and urea will be found one-third less than in the adult ; therefore calculations made as to the normal and relative absolutes of solids and urea, as indicating a state of health or disease, must be made with this understanding.

In my experience, also, the urine of old men and old women shows a corresponding similarity to that of very young persons.

DIAGNOSIS BY THE URINE.

The specific gravity is most easily obtained by means of the urinometer, as follows :

Fill a small standing glass cylinder four-fifths full of the urine, remove all froth by means of

Fig. i. — Urinometer.

filter-paper, and place in cylinder the urine float (hydrometer), — do not allow the float to touch sides, — and read depth to w 7 hich hydrometer sinks ; the number so found, if urine has

PHYSICAL CHARACTERISTICS IN HEALTH. 15

temperature of 6o° to 62 F., represents the specific gravity. If the temperature is above or below, wait until it becomes 6o° or 62 , and then make your observations.*

From the specific gravity we can approximately, and for all usual clinical purposes, calculate the solids excreted in the twenty-four hours. The rule is as follows : Multiply the decimal of the specific gravity by 2.33 and the result will represent the weight of solids contained in 1000 c.c. of urine ; hence we can, if we have the quantity of urine passed in twenty-four hours, estimate the weight of solids contained in the whole. For example, patient passed 3000 c.c. of urine of specific gravity 1.015 ; therefore 15 X 2.33 = 34.95 grams of solids contained in 1000 c.c. Consequently, to arrive at amount in 3000 c.c. we say :

If a more accurate determination of the solid matter is desired, the same is readily attained by evaporating a definite quantity of urine on

* Hydrometers carrying temperature-chart on them can be procured of Messrs. Eimer & Amend, of New York.

the water-bath, drying at 21 2° F. the residue thus obtained, and then, by means of the chemic balance, ascertaining its weight.

CONSISTENCE.

Normal urine is a thin and easily dropping fluid, and only becomes viscid w r hen it has undergone or is undergoing some pathologic change. It foams on being shaken, but the same subsides and vanishes very soon after ; if, however, it contains sugar or albumin, the foam remains for a long time.

COLOR.

The color of normal urine is a bright amber or sherry-wine yellow if the entire quantity for the twenty-four hours (1500 c.c.) is taken ; if not, the color varies in consequence to the time of day taken — on rising in the morning it is darker, and during the day, and particularly after dinner, the tint is less strong.

PHYSICAL CHARACTERISTICS IN HEALTH. 17

TRANSPARENCY AND ODOR.

Normal urine is always clear and transparent, and shows, on standing, a cloud of mucus ; this mucus is only mechanically suspended in the urine, and not in any wise dissolved ; the odor is sharp and slightly aromatic, and its cause is at present unknown.

REACTION.

The reaction of normal urine for the twenty-four hours is slightly acid, the same being caused by the presence of acid phosphates of the alkalies. To determine whether or not urine is acid, moisten a slip of blue litmus-paper with the secretion, and if it changes from blue to red, the urine is acid ; should the urine show an excessive degree of acidity, it is a sign that the urine is passing from a normal state to an abnormal one. Having now considered the general physical characteristics of normal urine, let us pass on to consider a deviation from these, and note those points which mark the beginning of disease in the urinary organs.

Chapter II. Deviations In The Physical Characteristics Of Urine In Disease

AMOUNT.

As has been previously said, the amount of urine passed in health in the twenty-four hours is about 1500 c.c.,or say 50 fluidounces. If the quantity is much increased, and habitually so, we have a condition of things known as polyuria ; if, on the other hand, it is much diminished, a condition known as oliguria ; and if entirely suppressed, anuria.

Polyuria may be either physiologic or pathologic ; in the first instance it is called urina potus (from excessive taking-in of fluids), and in the second hydruria or diabetes. To make a differential diagnosis in these cases, the total quantity of solids passed in the twenty-four hours is requisite, so this brings me at once to the consideration of the deviations in

specific gravity which constitute disease.

PHYSICAL CHARACTERISTICS IN DISEASE. 19

SPECIFIC GRAVITY.

The specific gravity of normal urine, as has been said, varies much, being in winter at times 1. 01 3, and again 1.022, but averaging about 1. 01 8. As in the case, however, of the total quantity of urine passed in the twenty-four hours it was shown that an allowance, excessive or the reverse, to the amount of 500 c.c. must be made, so in the specific gravity a variation of a few degrees either way by itself indicates nothing ; when, however, a urine habitually falls below the winter minimum, or goes above its maximum, it is an evidence in the first instance of a pathologic hydruria, and in the second of a condition known as polyuria.

This latter condition is commonly called diabetes, and is of two kinds : Diabetes insipidus, where the solids are all increased, but no sugar is present; when sugar is. found it is called diabetes mellitus. As examples of these different kinds of- urine, I will say that in the first class of urines — the true pathologic hydrurias — we have a urine of low specific gravity, 1.002 or so, and large quantities of water, 4000 to 6000 c.c. On calculating the total solids, it will be found that they are much diminished, whereas the water is in a corresponding degree increased above the normal. In the second class of urines the hydrometer shows a specific gravity of 1.025 to 1.030, and the quantity of water is also considerably increased, being 1500 c.c. to 2500 c.c. in the twenty-four hours. In these urines, if no sugar is found, the increase in solids is most surely due to excessive quantity of urea or else to phosphoric acid. If the increase of solids is due to an increase of phosphates, it is called phosphaturia ; when, however, sugar is the cause of the increased specific gravity, it is called diabetes mellitus.*

COLOR.

Deviations in color mark the beginning of pathologic changes going on in the urinary organs. Colorless urines of low specific gravity

* A condition known as chyluria, and simulating phosphatic diabetes, sometimes occurs ; the urine here is thick and heavy, and appears as a milky white liquid. It coagulates readily on being heated, as it contains much fibrin, and the coagulum does not dissolve on the addition of acetic acid, as would the phosphates ; this reaction, therefore, together with the presence of fat, renders the differential diagnosis in these cases easy.

PHYSICAL CHARACTERISTICS IN DISEASE. 21

and excessive increase of water — 4000 c.c. to 6000 c.c. — evidence a neurotic affection. Colorless urines, again, with habitual low specific gravity, — 1.010 to 1.005, — but not necessarily an increase of water, point to atrophy of the kidney as the probable cause ; as the disease advances, however, the water increases beyond the normal. Urines also appear dark yellow-red, bright garnet-red, dark brown, and greenish-yellow. The color in dark yellow-red urines is due either to blood or else to a coloring-matter called uroerythrin. As the consideration of the morbid constituents found in urine is taken up separately, together with the consideration of the other colors named, I will defer this until later on, and will consider urines colored garnet-red, as this color is generally due to foreign vegetable coloring-matters. Take three drams of clear urine (filter, if not clear) ; add to the same in a test-tube ten drops of nitric acid (strong), and boil for a minute ; if the red is not due to pathologic changes in the urine the color will disappear, and on the addition of an alkali it will return, to be again dissolved when the urine is once more acidified by nitric acid and heated.

TRANSPARENCY AND ODOR.

Normal urine being clear and transparent, with only floating particles of mucus, a urine deviating much from this is an indication of disease in the urinary organs. To determine this, take a portion of the twenty-four hours' urine, place in a glass cylinder, and stand same on piece of white paper ; by this we can determine not only the amount of floating matter in the urine, but also, from the same specimen, the color, specific gravity, odor, and reaction. If the urine by this procedure appears thick and cloudy, it may be due simply to an insufficiency of water, or else to morbid changes. To differentiate these conditions, heat the urine in a test-tube, and if all dissolves, the turbidity was due to urates ; if, on heating, instead of clearing up it becomes more turbid, add a few drops of acetic acid, and if it now clears up, it is an evidence that the urine was too concentrated, and therefore the solids precipitated out.

If, finally, the urine appears with the addition of acid and heat as it does without them, the turbidity is surely due to bladder or kidney detritus, and may therefrom be taken as an indication of disease.

PHYSICAL CHARACTERISTICS IN DISEASE. 23

REACTION.

Normal human urine shows in the twenty-four hours' urine a slightly acid reaction ; if, however, the urine is taken at different periods of the day, it will be found that the acidity varies. Shortly after a meal the urine is slightly alkaline, but after a while it again rights itself. If the urine shows too decided an acid reaction it is abnormal, and marks either an excessive quantity of uric acid present or else an acid condition of the urine caused by free acid. This latter condition is easily determined by taking three drams of the twenty-four hours' urine (clear ; and, if not, filtered so as to make it so), placing it in a test-tube, and pouring into it one-half the quantity of a strong solution of the hyposulphite of sodium. If free acid be present, a turbidity immediately forms whose density is in proportion to the quantity of acid present. This reaction is caused by the precipitation of sulphur, the free acid having united with the sodium of the salt.

The reaction, again, of urine may deviate in the opposite direction, constituting an alkaline urine, and therefore indicating disease. There are two ways in which the urine may become alkaline, and it is very important, from a clinical standpoint, to name and understand them. The first is from fixed alkali and the second from volatile (carbonate of ammonia).

Both forms of alkaline urine change red litmus-paper to blue on being moistened ; but in the case of fixed alkali, litmus-paper, on being dried, does not regain its red color, whereas in the case of urine rendered alkaline from volatile alkali, the red litmus-paper regains its color on being dried. Urine showing the presence of volatile alkali is always an evidence of disease (inflammation) of some part of the genito-urinary apparatus.

If there be both fixed and volatile alkali present in the urine, the above test will give a negative result ; so important, however, is it for us to know whether or not volatile alkali is present, and therefore if inflammation is to be excluded, that we proceed as follows : Place ioo c.c. of the urine in a glass flask, to which is fitted a cork; on inserting the cork, allow a slip of moistened red litmus-paper to be placed against its side and extending down into the

PHYSICAL CHARACTERISTICS IN DISEASE. 25

flask, but not reaching into the urine ; heat the flask gently (do not boil), and if any carbonate of ammonia is present, the red litmus-paper will immediately turn blue. I suppose it is needless for me to caution that this test must always be applied to fresh urine.

Urines alkaline from fixed alkali generally effervesce on the addition of an acid, and though not indicating any particular derangement of the kidneys, are usually met with in enfeebled conditions of the body in which the respiratory act is performed with difficulty, and thus carbonic acid is allowed to accumulate in the system ; also whenever the bile is diminished, or when there is a tendency to fermentative changes in the stomach or intestines. The dyspepsia which accompanies this kind of urine is attended with great depression of spirits ; flatulence is marked, the bowels confined, and the skin dark and sallow, showing evident derangement of the liver.

Chapter III. Deviations In The Normal Chemic Com- Position Of Urine In Disease

UREA.

From a clinical standpoint, of all the normal constituents found in human urine we need only consider urea, uric acid, chlorids, and phosphates of the alkalies and alkaline earths. Urea is the main solid which is passed in the urine, and averages from thirty to thirty-five grams (460 to 540 grs.) in the twenty-four hours. It is a diureid, and has the formula CON 2 H 4 .

The quantity of urea excreted from the body in the twenty-four hours is much influenced by : (1) The amount of nitrogenous food supplied the system ; (2) amount of active exercise taken during the day ; and (3) the quantity of water drunk. If the three indications are all met, then urea increases very much in the urine. If, however, the amount increases and the three

conditions mentioned are not given, why then

NORMAL CIIEMIC COMPOSITION IN DISEASE. 27

the increase is an approximate evidence of the waste of the system. This takes place in all fevers and wasting diseases, and as long as the liver and kidneys remain intact, the former to manufacture and the latter to convey away retrograde tissue products, why then the estimate from day to day of the urea in the urine will be a pretty fair approximate estimate of the wearing away of tissue, and consequently of the loss of vital force. When urea, instead of being increased, is found to have decreased, it is then an evidence of either a diseased condition of the liver or kidneys. It is surprising to see, however, how low the urea finally runs in some cases before the fatal hour arrives. I have notes of a case treated for two months, and on no occasion during this time was there more passed than 13.52 grams in the twenty-four hours. We can safely say, therefore, that when urea in the urine of the twenty-four hours habitually falls below twenty grams in the case of an adult of active pursuits and well-nourished body, we should suspect disease of the liver or else of the kidneys.

ESTIMATION OF UREA.

The manner in which the estimation of urea is made is very simple and sufficiently accurate for clinical purposes. It is founded on the decomposition of urea by the action of such an agent as the hypobromite of soda :

H 4 CON 2 + 3NaBrO = N 2 + C0 2 + 2H 2 + 3NaBr.

The results would be a little low if urine contained urea alone, but since we find in it also uric acid, urates, and kreatinin, these, in giving up their nitrogen, make up for the loss, and thus nicely counterbalance this source of error. The manipulation of the process is as follows : We advise for use the most excellent ureometer designed by Dr. Charles Doremus, of New York, to whom, allow me to say, the profession owes a debt of gratitude for making so simple a process which has heretofore been so the reverse. These ureometers are graduated according to the French and English systems, respectively ; the manipulation with either is the same, but the calculations being different, I deem it best to describe the procedure with each.

1. Make a solution of sodium hydrate, ioo grams to 250 c.c. of distilled water. Keep this in bottle with rubber stopper.

2. Make solution of hypobromite by adding one c.c. of bromin to ten c.c. of sodium hydrate

Fig. 2. — Ureometer of Dr. Doremus.

solution and diluting with ten c.c. of distilled water.

It is convenient, instead of making this solution previously (which does not keep long), to pour directly into the ureometer the sodium hydrate solution until the liquid rises to the mark " = ", which is on each ureometer; by means, now, of a little nipple pipette, which goes with each set, measure out one c.c. of bromin, add this to the hydrate solution, and, after the bromin has all gone into solution, dilute by pouring in water so as to fill the long arm and bend of the ureometer ; see, now, that the instrument is full, and thoroughly luted at the bend in the arm, — which is easily attained by tilting and then raising again until all air has been expelled, — and you have a thorough and complete mixture.

The instrument is now in condition for your test, and the remarks made are true for the English as well as for the French instrument I am describing.

Draw up by means of the pipette one c.c. of urine to be tested ; if the urine contains much albumin, free it of the same by heating, but not boiling ; if the quantity, however, is small, disregard it, and pass the pipette into the ureometer as far as the bend, and compress the rubber on end of pipette, thereby causing urine to ascend in hypobromite slow T ly; on so doing, there is great disengagement of gas (carbonic acid and nitrogen), and after the disturbance is over and several minutes are allowed to elapse, the volume of nitrogen may be read, as the column of liquid in the ureometer will be depressed just in proportion to the quantity of evolved gas, the carbonic acid gas being all absorbed by the hydrate of sodium. Each division mark on the ureometer indicates o.ooi gram of urea in one c.c. of urine. The quantity, therefore, of urea voided in the tw r enty-four hours is ascertained by multiplying the result of the test by the number of cubic centimeters of urine passed during that period. When the English ureometer is used, — divided, as it is, into grains, — the solutions are prepared and calculations made as follows :

1. Make a solution of sodium hydrate, six ounces to the pint of distilled water ; keep this in bottle with rubber stopper.

2. Make solution of hypobromite of sodium as previously described, and proceed exactly in the same way with the urine, etc.

Each division on this ureometer indicates one grain of urea in one fluidounce of urine ; the quantity, therefore, of urea voided in the twenty-four hours is ascertained by multiplying the result of the test by the number of ounces of urine passed during that period.

URIC ACID.

Uric acid is found only in small quantity in human urine, and when occurring in excessive amounts, its great insolubility in water causes it at once to crystallize out. This, unfortunately, frequently takes place in the kidneys, and thus concretions are lodged there which form foci of irritation, and finally, if allowed to continue, eventuate in one or other of the chronic forms of nephritis.

Uric acid, also in union with sodium, potassium, and calcium, is often found in large quantities in urine, principally, we may say, in the beginning 1 Q f fevers and in all conditions in which the system is subjected either to a higher temperature for a short time, or else to a lower temperature for a longer period. Along with these urates is precipitated a coloring-matter, called uroerythrin ; this coloring-matter is red, and gives to uric acid and urate deposits a rosyred tint — the so-called brick-dust deposit, so often observed in the pot de chambre in the

NORMAL CHEMIC COMPOSITION IN DISEASE.

morning. If this deposit habitually occurs in the urine of persons not suffering from fever, it is a sign that the liver is at fault, and that the gouty or rheumatic gout diathesis is being established.

Fig. 3. — Forms of Uric-acid Crystals. 1. Rhombic plates. 2. Whetstone forms. 3. Quadrate forms. 4, 5. Prolonged into points. 6, 8. Rosettes. 7. Pointed bundles. 9. Barrel forms precipitated by added hydrochloric acid to urine.

The presence of uroerythrin, uric acid, and urates is most easily ascertained.

If these are present, the urine will be turbid, the urates will clear up on being heated, and the uric acid will be dissolved if to the sediment is added an alkali. To determine the presence of uroerythrin, take three drams of urine, place in a test-tube, add one to three drops of a solution of the acetate of lead, and if it is present, a precipitate of a rosy pink (flesh colored) will immediately fall. When uric acid occurs in abnormal amounts, it will be found, if the case is one of true lithemia, that all the other solids are diminished ; this state of things points strongly to grave diseases of the liver, acute yellow atrophy, cirrhosis, and cancer. If the urine for the twenty-four hours is near the normal amount, and uric acid crystallizes out a short time after standing, it is in abnormal quantity. Its detection is readily made in the following manner : Filter, if the urine is not clear, 100 c.c. ; acidify with ten c.c. of strong hydrochloric acid, allow it to stand, and after twelve hours uric acid will be found crystallized, and can be verified by either the microscope or else by the murexid test, which is performed as follows : Take a few of the crystals ; place on a watch-glass, add a few drops of nitric acid, and apply heat gently ; after thus attaining solution of the uric acid, dry carefully over the flame, and to the dry and cool mass add a few drops of ammonia ; if the crystals be uric acid, a most magnificent purple color will rapidly spread over the touched mass.

CHLORIDS.

In the urine of adults the chlorids consist almost entirely of chlorid of sodium, and the average quantity passed in twenty-four hours is between twelve and thirteen grams ; consequently it ranks next to urea as the principal constituent in urine. The quantity of chlorids present is subject, as with the other constituents, to fluctuations ; when, however, the average falls much below the figures just given, it is a sign of disease of the kidneys, or else of the final stage of some lung trouble or continued fever. Whenever, in pneumonia, the chlorids leave the urine, the case must be regarded as very serious. In cases of chronic nephritis the regular and habitual falling-off of chlorid of sodium in the urine gives to the case a serious and grave aspect. The chlorids are not increased in pathologic urines, but are sometimes found in larger quantities than usual when a salt diet is instituted.

To determine whether they are in normal or diminished quantity, take two ounces of urine, filter if not perfectly clear, and if albumin is present heat with nitric acid and filter. Take the filtrate in this case, or, if albumin is not present, the clear urine, and acidify with nitric acid ; add to it four drops of a solution of nitrate of silver, — strength one part AgN0 3 to eight parts H 2 0, — and if chlorids are in normal quantity {y 2 of one to one per cent.) thick curdy masses of chlorid of silver (AgCl) immediately fall to the bottom of the test-glass. If, on the other hand, the urine contains a small quantity of chlorid, — say \ to -^ of one per cent., — the solution (urine, etc.), after the addition of the silver nitrate, shows only a cloud, and instead of the thick masses falling to the bottom, which do not mix readily with the urine, we have a solution of milky and turbid appearance.

PHOSPHORIC ACID.

The amount of phosphoric acid passing from the system in the course of twenty-four hours is, as we have said, 2.5 to 3.0 grams, and is distributed among the bases — lime, magnesia, soda, and potassa. Two- thirds are in combination with the oxids of the alkalies, and the remaining one-third in union with the oxids of the alkaline earths. The alkaline phosphates are extremely soluble and are never deposited from the urine ; on the other hand, the earthy phosphates are only held in solution by the acid of the urine, and so soon as this is changed to a neutral or alkaline state a deposition takes place. To approximately determine the quantity of phosphoric acid in the urine : estimate, by rule already given, the total quantity of solids in the urine, expressed in grams ; then by the hypobromite method the total quantity of urea, expressed also in grams ; to this add eighteen grams, and subtract the same from the total solids, and the quotient divided by four will give the approximate quantity of phosphoric acid (P 2 O s ) passing from the body. Thus, for example, the total quantity of solids found in a certain specimen of urine was 89 grams, the quantity of urea was found to be 32 grams, hence, 32 + 18 = 50, therefore, 89 — 50 = 39, which divided by 4 gives 9.75 grams as the daily elimination of phosphoric acid in this case. This condition is known as phosphaturia or phosphatic diabetes, and as much as 8, 10, or 12 grams of phosphoric acid pass away in the twenty-four hours. Urines of this class resemble closely the urine of diabetes mellitus — high specific gravity ; usually a normal quantity of water ; acid reaction, and an excessive or normal quantity of urea. Should, then, a urine show these characteristics, and the approximate quantitative test for phosphates, as just explained, show their excessive amount, an accurate gravimetric determination of the phosphoric acid should be made. To this end measure out 50 c.c. of clear urine ; if albumin is present, precipitate out by nitric acid and take filtrate. Supposing, therefore, we have 50 c.c. of clear urine : add to it 50 c.c. of strong sulphuric acid and 100 c.c. of water, boil in a beaker for a few minutes and then add a teaspoonful of the nitrate of ammonia (in crystals) ; while still hot add a nitric-acid solution of molybdate of ammonia, adding this in excess ; stir well, boil a few minutes, and cast on a tarred (weighed) filter paper. Wash yellow precipitate two or three times with molybdate of ammonia solution; dry at 21 2° F. in a steam oven, and weigh precipitate and paper ; deduct weight of latter from former (precipitate and paper), and the result will give the weight of the precipitate of the phosphomolybdate of ammonia; this multiplied by 3.142 gives the equivalent quantity of phosphoric acid, which in our case represents the quantity in 50 c.c. of urine. To find, therefore, the quantity passed in the twenty-four hours is but a simple calculation ; for example :