The most important of these inorganic salts are chlorid of sodium, phosphate of potassium, and the sulphates of calcium and magnesium. The inorganic constituents are chiefly urea, uric acid, and poisonous inorganic substances found in the body. The normal amount of urine voided by an adult weighing 160 pounds is from 40 to 70 ounces in twenty-four hours. The amount may be increased by drinking large quantities of fluid, especially water, and diminished by perspiration, emotion, and copious bowel movements. _Normal urine_ is aromatic. In health it may be faintly alkaline at certain times of the day. Urine passed in the morning has an acid reaction, a high specific gravity, and a dark color. After a hearty meal it may be turbid—perhaps alkaline, and of low specific gravity. Large quantities are pale, and vary with concentration. When just passed it is clear; then it collects a cloudy material made up of mucous corpuscles, which can be easily shaken up. Concentrated urine, when it cools, deposits a pinkish (brick-dust) precipitate. Gentle heat clears it up. When highly concentrated the crystals are red. When they collect and adhere together they become stones; if all precipitate on heating it is normal urine. _Alkaline urine_ throws down phosphates that are held in solution and clears up on addition of any acid; if urine is cold and acid in reaction, sediment, if present, may be urates, but is not phosphates; if urine is alkaline, they are normal phosphates. TO TEST REACTION. Litmus-paper is used. Acid changes the blue to red. Alkaline changes red to blue. When urine does not affect litmus-paper it is said to be neutral. _Pus in urine_ is turbid or milky in appearance; after standing a while it settles down. _Albumin in urine_ is held in solution, and therefore cannot be seen. A SIMPLE AND RAPID TEST FOR ALBUMIN. Fill an ordinary test-tube half full of urine, and add a half dram or more of potassium ferrocyanid solution (1 to 20). After thoroughly mingling the urine and the reagent, add a few drops of acetic acid (50 per cent.); then pause for a half minute and note the change. If albumin be present it will come plainly into view within half a minute to a minute, in the form of white, milk-like opacity, diffused throughout the whole contents of the tube. The above method precipitates all modifications of albumin. On the other hand, it gives no reaction with phosphates, peptones, mucin, the alkaloids, urates, or the pure acids. The reaction that sometimes occurs on long standing between the acid and potassium ferrocyanid should not be mistaken for albumin. The albuminous reaction appears within half a minute or so, while the other occurs only after ten minutes to half an hour, and is mingled with more or less blue coloration. TO OBTAIN A 24-HOUR SPECIMEN OF URINE.