ABNORMAL CONSTITUENTS OF THE URINE. 107 



one of urine, but drop the latter from a height. The mix- 

 ture becomes more or less garnet red if indican be present. 



(d.) Add acetate of lead = a precipitate of chloride, sul- 

 phate, and phosphate of lead. Filter, the nitrate is an 

 almost colourless solution. This substance is used to de- 

 colourise urine for the saccharimeter. 



(e.) Filter urine through animal charcoal, the urine will 

 be decolourised. 



If possible, obtain a dark-yellow coloured urine, and perform 

 the following test : 



(/) Take 40 drops of urine + 3 to 4 cc. of strong HC1 

 and 2 to 3 drops of HNO 3 ; on heating, a violet red colour 

 with the formation of true rhombic crystals of indigo-blue, 

 indicates the presence of indican. 



The pathological pigments bile, blood, &c. occurring in urine 

 will be referred to later. 



13. Mucus. A trace of mucus occurs normally in urine. Col- 

 lect fresh urine in a tall vessel, and allow it to stand for some 

 time, when fine clouds ("mucous clouds ") like delicate cotton- 

 wool appear. These consist of mucus entangling a few epithelial 

 scales. 



(a.) If urine contain an excess of mucus, on adding a 

 saturated solution of citric acid to form a layer at the bottom 

 of the test-tube, a haziness at the line of junction of the 

 urine and acid indicates mucus. There is no deposit with 

 healthy, freshly-passed urine. Citric acid is used because it 

 is heavier than acetic. 





LESSON XVIII. 



ABNORMAL CONSTITUENTS OF 

 THE URINE. 



Some of the substances referred to in the subsequent lessons 

 are present in excessively minute traces in normal urine e.g,, 



