MILK, BLOOD AND URINE 219 



rates, filter again. Dry the albumin and make the protein tests. 

 Test 10 c.c. of the filtrate from the albumin by the Biuret Test 

 (Experiment XVIII, 4, c) to prove the presence of a non-coagulable 

 protein (lactoglobulin). 



(4) Phosphates. Without separating the traces of lactoglobuhn 

 boil the albumin filtrate in an evaporating dish carefully until bump- 

 ing occurs. Filter through paper. The separated soHd is largely 

 calcium phosphate, Ca3(P04)2. Repeat the boiling with the filtrate 

 from the calcium phosphate and obtain a second crystallization of 

 phosphate. Repeat as many times as necessary until no more phos- 

 phate separates. Test the collected phosphate by dissolving in dilute 

 nitric acid and adding an equal volume of ammonium molybdate 

 solution. A yellow precipitate proves the presence of phosphates. 



(5) Milk Sugar. When no more separation of calcium phosphate 

 occurs, continue to evaporate the filtrate with a low flame so as to 

 prevent charring. When quite small in volume (about 100 c.c.) 

 transfer to a steam bath and continue the evaporation until the hquid 

 is of a sirupy consistency. Cool, and see if any crystals separate. 

 If not, evaporate further until crystallization does take place. Filter 

 or decant off the liquid, wash the crystals with a little water, dry them 

 on filter paper and examine by taste, etc. They are milk sugar 

 (lactose). Dissolve a few crystals in water and test with Fehling's 

 solution (Experiment XXIt, 2). 



THE BLOOD 



While the blood is the chief circulatory fluid of the animal 

 body, there is associated with it another known as lymph. In 

 discussing the metabolism of food we have stated that the ab- 

 sorbed food nutrients are carried to the cells by means of the 

 blood, where they come into intimate contact with the oxygen 

 brought from the lungs by means of the blood also. In bring- 

 ing about this contact between oxygen and food nutrients 

 within the cell, and thus effecting their final katabolism, the 

 lymph plays a very important part and also in removing from 

 the cells the waste products of katabolism. We shall not 

 attempt to discuss in detail the exact part which each of these 

 fluids takes in this utilization of food but present the general 



