CHAPTER XIII. 

 THE QUANTITATIVE ANALYSIS OF URINE. 



To determine the nature of the metabolic processes 

 in the body a sample of the measured 24 hours' urine 

 must be analysed. In taking the 24 hours' urine it is 

 best to finish with that voided after the night's rest. 

 The total collected during the 24 hours is mixed and 

 carefully measured. The analyses should be performed 

 as soon as possible, owing to the risk of bacterial decom- 

 position of certain of the constituents. Should it be 

 necessary to postpone the analyses an antiseptic should 

 be added. Toluol is the best to use. Chloroform must 

 not be used in any case, since it is decomposed by alkalies 

 and has a marked effect on certain processes. 



The analyses performed will vary with the nature 

 of the case that is being investigated, and the time and 

 apparatus at the disposal of the analyst. It is of the 

 utmost importance for the student to acquire skill in the 

 conduction of a complete analysis, and it is to be hoped 

 that the specially selected methods described below will be 

 practised until satisfactory results can be obtained in the 

 minimum of time. By careful organisation in a well- 

 equipped laboratory it is possible to estimate total nitrogen, 

 urea, ammonia, acidity, uric acid and creatinine in three 

 hours. 



The remarks on pages 380 to 382 on the use of pipettes, 

 etc., should be carefully studied before undertaking any 

 analytical work. For the method of returning the results 

 of analyses see the form on page 374. 



A. Total Nitrogen by KjeldahPs method. 



Principle. The nitrogenous compounds in a given volume of urine are 

 converted into ammonium sulphate by boiling with sulphuric acid, copper 

 sulphate being added to aid the oxidation, and potassium sulphate to raise 



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