42 VETERINAEY STATE BOARD 



Describe the process of determining the per cent, of butter fat in a 

 specimen of milk. 

 Take 20 e.c. of milk and add to it a small amount of a sodium 

 hydrate solution. Extract the fat by adding 80 c.c. of ether which 

 has been saturated with water. This is done by shaking in a tightly 

 closed bottle. After the ethereal extract has entirely separated, 

 60 c.c. are placed in a weighed beaker, and the ether allowed to 

 evaporate ; the residue is dried and weighed. The result is calculated 

 out for 80 c.e. of the ethereal extract, corresponding to 20 c.c. of 

 milk. 



Describe briefly the cause of the souring of milk and the changes 

 thereby produced. 

 The lactic acid bacteria act upon the lactose, forming lactic acid 

 which renders the milk sour and coagulates the easeinogen, the curd. 

 The milk becomes acid in reaction, the curd settles as a thick, jelly- 

 like mass, leaving a watery fluid, the whey, above. 



Give the requirements of the State of New York in regard to milk 

 composition. 

 Milk must contain twelve per cent, solids, of which three per cent, 

 must be butter fat. 



Give the Pennsylvania State requirements for milk composition. 



Milk must contain not less than 12.5 per cent, solids, of which 

 3 per cent, must be fat. 



URINE 



Describe a test for sugar in the urine. 



Place some Fehling's solution in a test tube and boil it. If no 

 discoloration takes place, it is suitable for the test. Add a few 

 drops of the suspected urine and boil. If the mixture suddenly 

 turns to an opaque yellow or red color, the presence of sugar is 

 indicated. 



Give a test for albumin in the urine. 



To a small amount of nitric acid in a test tube, gently pour upon 

 the surface some of the suspected urine. If albumin is present, 

 a ring of white coagulum occurs at the junction of the two fluids. 



Describe a method of detecting the presence of bile in the urine. 



Agitate a few drops of chloroform with the suspected urine 

 in a test tube. If bile be present, the chloroform becomes turbid 



Digitized by Microsoft® 



