532 THE SECRETIONS. 



Collect 200 cubic centimetres of perfectly fresh urine in a 

 vessel which has been carefully washed with dilute sulphuric 

 acid, and afterwards with distilled water. Examine the reac- 

 tion of the fluid, which will be found acid, then divide it in four 

 equal parts: 1st. Pour fifty cubic centimetres into a clean 

 beaker, and set it aside to serve as a standard with which to 

 compare the other portions. 



2d. Place fifty cubic centimetres in a clean beaker, and add 

 to it a few drops of urine which has been allowed to become 

 foetid. After twenty-four hours compare this sample with the 

 first, determining the following points : a, smell, which will 

 have become ammoniacal in the second, unchanged in the first ; 

 6, clt'ann\*a. The second sample will have become opalescent, 

 or a considerable deposit will have fallen ; c, reaction will be 

 strongly alkaline in the second, and still acid in the first. The 

 alkaline reaction m&y be shown to be due to the presence of a 

 volatile alkali by heating the test-paper which lias been used, 

 and observing that the reaction which indicated alkalinity dis- 

 appears on the application of heat ; thus the blue color pro- 

 duced when reddened litmus paper was plunged into the fluid, 

 will disappear, and again give place to red when the paper is 

 heated. 



I 3d. A third quantity of fifty cubic centimetres is placed in 



a Florence flask and boiled briskly for some time, then a plug 

 of clean cotton wool is inserted into the neck of the flask 

 whose contents are still boiling, and is thrust down by means of 

 a glass rod. The urine is allowed to boil for some minutes 

 after the insertion of the plug, the flask is then allowed to 

 cool, set aside for many weeks and then examined. 



The flask containing boiled urine and protected by the plug 

 / of cotton wool, will, if the operator have been sufficiently 

 expert, retain its transparency and its acidity, and when 

 examined with the microscope will present no animal or vege- 

 table forms. On, however, exposing the contents of the flask 

 to the air, the alkaline fermentation will soon occur. 



182. Enumeration of the normal constituents of 

 the Urine. The normal urine of man consists <// ///?/ of a 

 watery solution of urea and common salt, mixed with smaller 

 though important quantities of other substances, viz., hippuric 

 acid. (Toatinim 1 , uric acid, coloring matters yet not accurately 

 invcsti.uati'd, indican, traces of fat, besides ammonium and 

 potassium chlorides, sulphates of potassium and sodium, phos- 

 phates of calcium and magnesium, acid phosphate of sodium, 

 hi lick- acid and iron. To the list of organic substances pres- 

 ent in urine, we may add unknown substances which contain 

 sulphur and phosphorus in an unoxidized condition, besides 

 well-known bodies which are certainly present in the urine in 



