43 

 XI 



142. Prepare four test tubes as follows, labeling them in 

 order 1, 2, 3, 4, and adding- a bit of fibrin to each tube. To 

 No. 1 add 30 drops of the pancreatic extract from the pig, 

 and some distilled water ; to No. 2, the same amount of the 

 pig's pancreatic extract and excess of 0.2% hydrochloric acid ; 

 to No. 3, some 1 % sodium carbonate alone ; for No. 4, put 30 

 drops of the pancreatic extract into a separate test tube, add 

 a little of the 1% sodium carbonate and boil, and then add 

 the fibrin. Put all of the test tubes in the water-bath at 40°C. 

 After a few hours examine them and explain the result. 



143. Emulsion Experiment, Shake up a few drops of 

 olive oil in a test-tube with 2 cc. artificial pancreatic juice 

 and 2 cc. 1 % sodium carbonate. Place the mixture for a few 

 minutes in the bath at 40°C., and shake again, compare the 

 results before and after warming. If the oil is neutral, there 

 may be no emulsion or only a poor one. The addition of a 

 few drops of oleic acid will improve it. Why ? 



144. In another tube with a little olive oil add 2 cc. bile 

 and 2 cc. 1% sodium carbonate, shake and place in water-bath 

 at 40°C. and compare the emulsive effect with 143. Note 

 whether the oil is neutral or not. 



145. Action on Fat. For this experiment it is necessary 

 that the fat should be perfectly neutral. Commercial oils, 

 usually contain free fatty acids. 



The following method has been recommended for neutralization by Kruken- 

 berg : Place the oil in a porcelain capsule and mix it with not too much baryta 

 solution, (baryta mixture is prepared by mixing one volume of a solution of 

 barium nitrate and two volumes of barium hydrate, both saturated in the cold), 

 and boil for some time. Allow it to cool. The unsaponified oil is extracted 

 with ether. The ethereal extract is separated from the insoluble portion and the 

 ether evaporated over warm water. (The flame must not be brought near the 

 ether. Let the water come to a boil, put out the flame and then put the dish 

 containing the ether upon the hot water). The oil should now be neutralized. 



The cream from milk is usually of a neutral reaction and 

 serves very well in the following experiments. 



146. Take two test tubes and place in each 2 cc, of cream 

 — neutral fat. Add 1 cc. blue litmus to color. In the first 

 tube place a small piece of fresh pancreas. Put both tubes 

 in the water bath and observe at intervals. Note if any 



