68 CLINICAL MICROSCOPY AND DIAGNOSIS. 



the solid constituents, putrefactive changes, and the 

 like. The urine is variously colored by the presence of 

 such constituents as phosphates, urates, pus, blood and 

 bile. 



(c) Take the specific gravity. By this we get (par- 

 ticularly in a 24 hours specimen), a good indication of 

 the amount of solids in the urine. The usual formula 

 given is to multiply the last two figures by 2, and so 

 obtain the number of grammes of solids per litre. 



2. Chemical tests. 



(a) Take the reaction with litmus paper. The re- 

 action is important in carrying out certain albumin 

 tests. It may also indicate the nature of a sediment. 



(b) Examine the sample for albumin. 



If the urine be at all turbid, filter through several 

 sheets of filter paper, before the application of the tests. 



1. Use the heat and nitric acid test, 



2. Apply the nitric acid test. Simon advises an 

 excellent modification of the usual application of this 

 method. 20 cc. of urine are placed in a conical urine 

 glass, and 6 to 10 cc. of nitric acid are added through a 

 pipette, passed to bottom of glass. At point of junction 

 of the two fluids we have the formation of the usual 

 contact ring in the presence of albumin. This ring is 

 usually colored at bottom, rose to brick red, from the 

 normal urinary pigment. If indican be present in ex- 

 cess, we have a violet ring.. In biliary urine we have 

 the usual contact play of colors (acid must contain nit- 

 rous acid as well). On standing 5 to 10 minutes, high 



