URINE AND ITS CONSTITUENTS. 729 



ozonized oil of turpentine to flow down the side of a test-tube in 

 such a manner as to form a distinct layer above the urine. A white 

 ring, gradually turning blue, will appear at the surface of contact. 

 (Ozonized oil of turpentine is oil which has been exposed to air for 

 some time ; in place of it may be used peroxide of hydrogen or a 

 mixture of this compound with ether.) 



3. Add a little of a solution of egg-albumin to 100 c.c. of urine, 

 heat to boiling, and filter off the coagulum, which has taken up the 

 hsematin. Mix the precipitate in a mortar with 20 c.c. of absolute 

 alcohol and a few drops of sulphuric acid, transfer to a flask, heat 

 to boiling, and filter. After cooling, render alkaline with sodium 

 hydroxide, reduce with ammonium sulphide, and examine spectro- 

 scopically for reduced ha3matin. (Fig. 72.) 



The direct spectroscopic examination of urine is generally unsatisfactory > 

 because it often contains a number of substances giving absorption spectra. 



Carbohydrates in urine. Dextrose (glucose) in urine is normally 

 present in minute amount. When the amount is sufficient to give 

 the customary reduction tests, the condition is spoken of as glyco- 

 suria. If dextrose be eaten in large amount the body is unable to 

 burn all of it, and a temporary glycosuria results. This is called ali- 

 mentary glycosuria and is not a serious condition. The amount of 

 sugar, the " assimilation limit," which can be ingested without the 

 appearance of the sugar in the urine, differs for the different sugars 

 and differs in different individuals. A more serious condition, per- 

 sistent glycosuria, exists in diabetes when the body is unable to carry 

 on the normal sugar metabolism. In this disease the amount of dex- 

 trose in the urine may be very large, and frequently dextrose is 

 present, even when the patient is on a carbohydrate-free diet. In 

 both of these conditions the glycosuria is secondary to an increase 

 in the dextrose content of the blood, while in experimental " phlorid- 

 zin diabetes " the change is in the kidneys, and there is no increase 

 in the dextrose of the blood. 



There are many tests by which dextrose can be detected. They 

 depend chiefly on the following properties of dextrose, viz. : 1, to act 

 as a deoxidizing or reducing agent upon certain metallic oxides (cop- 

 per, bismuth, silver, mercury) in the presence of alkalies ; 2, to pro- 

 duce a yellow or brown color when in contact with alkalies, slowly 

 in the cold, rapidly on heating ; 3, to ferment with yeast ; 4, to unite 

 with phenyl-hydrazine to a crystalline compound; 5, to have the 

 power of rotating the plane of polarization to the right. 



