normal urine consists of phosphates; when they are in excess, the urine is generally of a light color. These salts are derived from the food and tissues, and are united with the organic, nitrogenized, proximate principles. Their quantity in the urine depends on the food eaten and the drain on the nervous system from study or sexual excesses.

Clinical Import.-When excreted in excess, there is danger of phosphatic calculus. Disease changes its proportions. Increased elimination occurs in inflammatory diseases of the nervous system, acute mania, delirium tremens, paralysis, diseases of the bones, and rickets. It is generally diminished in Bright's disease, gout, rheumatism and pneumonia.

TESTS.-Heat gives a cloudy precipitate, which nitric acid dissolves. The phosphates are deposited when the urine becomes alkaline and ferments. Under the microscope, phosphate of lime is amorphous. The triple phosphates occur in rhombic prisms, which readily dissolve in acetic acid, while oxalate of lime crystals do not.

Quantitative.—A rough estimation is made by making some urine alka. line with ammonia and adding an ammonio-magnesian solution to it. If the amount already in the urine is normal, a precipitate at once occurs; if the normal amount is lacking, this precipitate is delayed.

COMPOSITION OF URINE.

Water, about 940 parts in 1000; urea, about 30 parts in 1000; salts, about 6 to 10 parts in 1000; uric acid, about 1 part in 1000; extractives, about 23 to 26 parts in 1000.

CHEMICAL EXAMINATION OF URINE.

MICROSCOPICAL EXAMINATION OF URINE.

Hints. Shake the urine thoroughly, add a little salicylic acid to prevent decomposition, pour into a conical vessel, cover, and allow it to settle for half a day or longer. When about to examine it, prepare a clean glass slide, and upon this place a few drops of the urinary deposit by means of a pipette; cover the drops with a thin glass disc, and examine with a onequarter or one-fifth inch objective lens.

Search for the different crystals, amorphous urates and phosphates, epithelial cells, fat globules, mucus, pus and blood discs; and watch with extra care for tube casts, examining many specimens from the same deposit before any conclusion is reached, especially if the urine contains albumen, as these abnormal ingredients generally coexist.

Group of crystals of uric acid, often termed cayenne pepper grains, with cctahedra of oxal

Five classes of minute bodies are usually met with in sediment deposited from urine. These are: First, crystals; second, casts; third, mucus, blood and pus corpuscles; fourth, fungi, or minute vegetable organisms: fifth, accidental extraneous matters.

Appear.

CRYSTALS.-Normal urine should never contain a sediment. ance of crystals within twenty-four hours after the urine has been passed, may be accepted as indicating a non-healthy condition of the system, whether temporary or permanent. The crystals most frequently met with are, uric acid, ammonia, oxalate of lime and an amorphous deposit of the urates.

I. URIC ACID.-This is the product of a metamorphosis of tissue. A characteristic test for it is effected by the addition of a few drops of nitric acid to the suspected deposit, which has previously been placed in a capsule,

the mixture is then to be strongly agitated; a drop of ammonia is added, which instantly produces a rich purple tint. But both uric acid and the urates can be more easily and quickly determined by the microscope.

Crystals of uric acid, notwithstanding that they vary in size and form, are very readily distinguished. To obtain them rapidly, a portion of the suspected deposit is dissolved in a drop of liquor potassæ, and this alkaline solution is then treated with acetic acid, and in the lapse of a few hours the crystals of uric acid will be formed.

When we find the amount of acid diminished in the urine, we suspect the more advanced stages of Bright's disease, but an increase should lead

of soda. x 215. (After Beale.)

us to suspect a rheumatic diathesis, a tendency to acute inflammation, gastric or hepatic disorders or intemperance.

URATES. The pathological conditions in which the urates are found, are much the same as those in which uric acid occurs.

The urates consist principally of urate of soda and of ammonia, and of small quantities of urate of lime and magnesia, and the deposits formed on their precipitation are usually pink, brown or white. They are dissolved with great readiness on heating the urine. Acids decompose them. Under the microscope, the urates are seen to be either irregular amorphous particles, round globules or needle-like crystals. Urate of soda is shown. in the shape of round globules of various size, from some of which fine needles project. Urates of soda and of ammonia are usually globules

and crystals, while the irregular particles are supposed to represent urates of lime and soda.

Urine containing a sediment of urates is usually very acid, or not infrequently becomes so. In urine which has become cold, these deposits are thrown down much more abundantly than in that which is freshly passed.

TRIPLE PHOSPHATES.-These are generally beautiful microscopic objects, but their appearance varies greatly with the rapidity of their crystallization. Their color is produced by a combination of phosphoric acid with soda, lime and magnesia; and they are derived in part from food and in part from changes in albuminous substances-specially of the nervous

Crystals of triple phosphates. MgONH,O PO5 +12aq. In the form of triangular prisms, with obliquely truncated extremities, as they frequently occur in urine. In many cases the crystals are four-sided. Not unfrequently the shaft of the crystal is so short that the two triangular extremities are seen quite close together, and the crystal, without care, might be mistaken for an octahedron. × 45. (After Beale.)

These are kept in solution by the acidity of the urine, but as soon as this becomes alkaline, they become precipitated. They are often met with in heavy deposits containing purulent urine, resulting from chronic catarrh of the bladder, or in cases of temporary or permanent paralysis; and they are found also in many affections in which the vital powers have become seriously lowered and the acidity of the urine diminished.

Applicants laboring under great general debility and indigestion, associated with an impaired tone of the nervous system, usually present

this symptom, and it is very common in men depressed by mental toil or anxiety.

This is also found when an excess of animal food is taken into the system during very active exercises, and in the rheumatic diathesis. It is increased in all inflammatory diseases of the nervous system, in paralysis, in severe nerve lesion, in acute mania; and is diminished in Bright's disease and gout, in rheumatism and in most febrile and inflammatory affections.

OXALATE OF LIME.-The presence of crystals of this sort is noted in morbid conditions, and is generally found in persons who are weighed down by excessive anxiety, or who have given way to excessive indulgence or masturbation. Dyspeptic persons, or those who suffer from uneasiness after meals, or those troubled with frequent seminal emissions and irritation of the bladder, are apt to pass these crystals in quantity. These applicants are usually either very irritable or very dejected; frequently they complain of

loss of memory and of dull pain across the loins; they are very liable to boils and carbuncles, apt to be emaciated, and are generally out of health.

The urine containing this crystal is usually of high specific gravity, and shows an increase of urea, and ordinarily contains a cloudy deposit.

Persons in this condition are usually said to have oxaluria, although its existence as a separate affection has been denied.

Oxalate of lime may also be detected in the urine of persons after eating rhubarb plant; and may be also found in the urine of persons recovering from severe acute maladies, but it is only found in very small quantities in the urine of healthy persons, so that the presence of a few crystals cannot be looked upon as of the least practical importance. Under the microscope, it appears in well-defined octahedra, varying in size, and also dumb-bell shaped, the former being more common.

CASTS. These bodies are minute tubular masses of coagulated matter, which form in diseased renal tubules and are washed down into the bladder and voided in the urine. Their size corresponds to that of the tubes in