the two fluids mixed by inclining the tube several times. Care must be taken not to agitate the tube violently, else some of the flakes

.......

R

of albumin will be included in the froth. The tube is now allowed to stand for twenty-four hours, and the height of the sediment on the graduations of the tube read off. These correspond to parts of dried albumin in 1000 parts of urine. If the urine be found to contain more than 0.7 per cent., it should be diluted with an equal volume of water, and the result obtained multiplied by 2.

The method is not satisfactory from a scientific point of view, for the specific gravity of the urine and the temperature exercise a considerable influence on the volume of the precipitate. As a comparative method, which can be easily carried out in the physician's office, it answers very well.

-

Peptonuria. The qualitative examination of the urine for peptones and albumoses is often of importance, for, like indican, the substances are found in the urine in cases in which large quantities of pus are being formed in the system and simultaneous disintegration is taking place. Peptones are never present in

FIG. 29.-Esbach's albuminometer.

large amounts in the urine, and therefore a fairly large volume of the urine must be taken for examination.

Hofmeister's modification of Salkowski's method may be used. Fifty c.c. of the urine are precipitated with a solution of phosphotungstic acid, after being acidulated with 5 c.c. of concentrated hydrochloric acid. The precipitation is brought about by boiling the solution and adding the phosphotungstic acid in sufficient quantity to produce a flaky brown precipitate. On continued boiling the precipitate becomes adherent to the sides of the beaker, and the solution may be poured away. The brown precipitate is washed with a little water, and dissolved in a dilute solution of caustic potash. The potassium hydroxid solution is heated till the color, which at first is blue, changes to a light yellow. The solution which contains the peptones is transferred to a small test-tube, and a drop of a dilute solution of cupric sulfate added. A beautiful reddish-violet color is produced if peptone be present.

The solution of phosphotungstic acid is made by dissolving 20 grams of pure sodium tungstate in 100 c. c. of water. Enough syrupy phosphoric acid is added to give the solution a strongly acid reaction. The mixture is filtered and allowed to stand, and the solution poured off from any insoluble residue.

Albumoses are also precipitated with phosphotungstic acid, and also give the biuret-test. As they are identical for clinical purposes, no attempt is made to distinguish them. The albumoses may, how

ever, be tested for by removing all the coagulable proteids with acetic acid and heat, as was detailed in the quantitative estimation of albumin, and treating the filtrate with potassium ferrocyanid solution. This gives a white cloud if traces of albumoses be present.

Hematuria and Hemoglobinuria.-The presence of one or more of the constituents of blood in the urine may be taken to indicate a pathological condition in some part of the urinary tract; it is, therefore, important to be able to recognize it with as great surety as possible. Urine containing blood may be recognized by its color, which will vary from a slightly smoky yellow to deep red or black. Two pathological states may be distinguished :

1. Hemoglobinuria.—In this state only the coloring-matter of the blood is present, while the organized elements are absent.

2. Hematuria.-All the elements which go to make up the blood-corpuscles, red and white, and blood-coloring matter-are present. Hematuria thus implies hemoglobinuria, while the reverse is not the case.

The tests for hemoglobin are in most respects the same as those given in the section on the Blood. The changes which have been made are to adapt them for the urine.

1. To a sample of urine add a dilute solution of potassium hydroxid, and boil. A precipitate of earthy phosphates is thrown down, which differs from that in a specimen of normal urine in being colored brown by the blood-pigment. The phos

phates are filtered off, and transferred to a microscopic slide. A drop of glacial acetic acid is added, and a tiny crystal of sodium chlorid. Heat gently after covering with a cover-slip. The characteristic crystals of hemin will appear.

2. The guaiacum-test is performed, using 10 C.C. of urine. The details of the test are the same as

those given on page 46. This test is particularly valuable in urinalysis, as the blood will often be indicated in the nephritis following scarlet fever

FIG. 30.-Blood-corpuscles: a, normal; b, abnormal (Ogden).

before any other symptoms of the process will be apparent.

Hemoglobin will also be detected in the urine by means of the spectroscope. The form which appears in the urine is either oxyhemoglobin or hemoglobin. The spectroscopic appearance of these two forms has been described on page 46. In cases of poisoning from potassium chlorate the spectrum of methemoglobin has been recognized in the urine.

Hematuria. In this condition the corpuscles will be recognized. The form which these elements take on is largely dependent on the state of the urine in which they are present. Should the urine be high in specific gravity, the corpuscles will be

found to be crenated, and will have the normal biconcave appearance exaggerated (Fig. 31) on account of the diffusion of the contents of the corpuscle into the urine. With a dilute urine the corpuscles swell up and become almost spheroidal in shape. They also become paler and almost colorless from the passing out of the hemoglobin into the urine.

Glycosuria. In testing for sugar in the urine,

× 350.

the tests given in the section on monosaccharids are used. Some of the tests, notably the a-naphtol test, are so delicate that they detect other reducing agents in the urine, and so complicate the reaction. As with albumin, so with sugar, it is a question if in normal urine there is not a small amount of glucose