THE MICROSCOPE IN DIAGNOSIS. 305 



deposits, derangements of quantity, and density in the 

 urine. 



SUGAR. 



Urine should be tested for sugar when diabetes is sus- 

 pected, or when the quantity is excessive, or the specific 

 gravity is high (above 1030). In some cases of cerebral 

 disease, also, sugar appears in the urine. The urine should 

 first be examined for albumen, since its presence is a serious 

 complication of diabetes, and it may interfere with the 

 reactions by the copper test. If present it should be re- 

 moved by boiling and filtration. Boiling albuminous urine 

 with crystals of sulphate of soda is said to render it suit- 

 able for the copper test, but the other way is best. 



Copper Test Trommer's Test. The urine is mixed with 

 a few drops of a solution of sulphate of copper in a test- 

 tube; excess of liquor potassee is then carefully added, 

 enough to just dissolve the precipitate it first throws 

 down ; the mixture is then boiled, and if sugar is present 

 a red precipitate of suboxide falls down. As errors occur 

 from not using the proper proportions, the following test 

 is preferred: 



Fehling's Test Solution. Sulphate of copper, 90 J grains ; 

 neutral tartrate of potash, 3tf4 grains; solution of caustic 

 soda (of specific gravity 1.12), 4 fluid ounces; add water 

 to make up 6 fluid ounces. (Or 40 grams of sulphate of 

 copper in crystals, 160 grams neutral tartrate or potash, 

 750 grams caustic soda, specific gravity 1.12; add water 

 up to 1154.5 cubic centimeters. Each 10 cubic centimeters 

 correspond to 0.05 gram of grape-sugar.) 



A little of the test fluid is first boiled in a test-tube to 

 see if it remains unchanged in color, since it is apt to alter 

 by age. If unaffected, add a drop or two of the suspected 

 urine. If sugar be present in quantity the color changes, 

 and a yellowish or reddish precipitate falls. If no reac- 

 tion occurs, add a little more urine, but less than the 



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