556 THE SECRETIONS. 



* 202. Determination of the Amount of Albumin in 

 Urine. A known volume of the urine, say 50 or 100 cubic 

 centimetres, is boiled ; if the reaction is alkaline or neutral, a 

 trace of acetic acid being previously added, the albumin sepa- 

 rates freely and is collected on a weighed filter. The substance 

 on the filter is repeatedly washed with boiling water, and 

 after being allowed to drain, it is dried, first in a water oven at 

 100 C.. and afterwards in an air oven at 120 C. The weight 

 of the filter and albumin, minus the weight of the filter, fur- 

 nMies us with the quantity of albumin (with adhering salts) 

 Mt in the quantity of urine taken for analysis. 



When a large number of determinations of nlbumin in urine 

 have to be made, it is advisable to make use of the polariscope. 

 The extent to which the plane of polarized light is rotated to 

 the left bears a strict relation to theqnantity of albumin present 

 in a thud, providing the depth of fluid examined be the same, 

 and that no other substance (>\ r/., sugar) be present, exerting 

 an opposite action on polarized light. 



** 203. Detection of Bile-coloring Matter in Urine. 

 When a large quantity of bilirubin is present in urine it may 

 be separated from it by agitating the fluid with chloroform, 

 decanting, evaporating the chloroform solution, dissolving the 

 residue in pure chloroform, and allowing the fluid to evaporate 

 spontaneously. In this way red rhombic prisms of bilirubin 

 may be obtained. 



In all cases where bile-coloring matter is present, we can de- 

 tect it by the well known reaction with nitric acid (Gmelin's 

 reaction). If strong nitric acid, containing nitrous acid, be 

 added t<> a thin stratum of urine containing bile, in a flat por- 

 celain di>h. a s!ieee*sim of beautiful tints is perceived. The 

 fluid is seen at first to be green, then blue and violet ; it then 

 assumes a rather dirty claret, and ultimately a dirty yellow 

 color (see $ 1.35). 



In cases where a very satisfactory search for traces of bili- 

 rubin is to be made, it is advisable to separate it from the urine, 

 by means of chloroform, and then to test the evaporated residue 

 with nitric acid. A property which is very characteristic of 

 urine or other animal fluids colored by bile pigment, is that of 

 staining, of a yellow color, linen which is moistened with it. 



** 204. Separation and Detection of Bile Acids in 

 Urine. Four or five hundred cubic centimetres of urine 

 are treated with acetate of lead until a precipitate ceases to fall, 

 and then solution of ammonia is added. The precipitate is 

 collected on a filter, washed with water, and allowed to drain. 

 The filter paper, with the very bulky precipitate which it con- 

 tain-, is then boiled in a flask, with alcohol, and the solution is 

 filtered whilst hot. A few drops of solution of sodium carbot 

 nate being added, the fluid is evaporated to dry ness on the 



