200 AGRICULTURAL CHEMISTRY 



general properties are somewhat similar to those of 

 stearin. 



265. Olein (C 57 H 104 O 6 ) at moderate temperatures is a 

 liquid. It solidifies at 4 C. Olein predominates in the 

 oil of fish, as sperm oil and cod-liver oil. It is also present 

 to a great extent in many vegetable oils, as olive oil. 

 Whenever olein predominates, the fat is a liquid. 



266. Miscellaneous Fats. In addition to the three 

 fats mentioned, there are others, as butyrin, the charac- 

 teristic fat of butter, and linolein, the characteristic fat of 

 flaxseed . 



267. Saponification is a chemical change brought about 

 by the action of an alkali, as potash or soda, upon a fat. 

 An exchange takes place between the glycerol of the fat 

 and the metal of the alkali. Glycerine is a base, but 

 potash is a stronger base ; hence the potash replaces the 

 glycerol and forms salts, as potassium stearate or palmitate, 

 according to the fat used. 



Experiment 52. Saponification. Weigh about 20 grams of lard 

 into an evaporator. Melt the lard, but do not heat above 50 C. 

 Dissolve 10 grams NaOH in about 40 cc. water in a beaker. (Do 

 not let the NaOH come in contact with the scale pan.) Add this 

 solution to the evaporator, stirring constantly, and leave the evapo- 

 rator on the warm sand-bath, with a low flame underneath, for 

 40 to 50 minutes. Then place on the sand-bath in the desk until the 

 following day when a good soap should have formed. Dissolve a 

 little of the soap thus produced in a test-tube with 20 cc. water. 

 Divide the solution into two parts ; to one add a little salt, and to 

 the other a few drops of HC1. 



Questions. ( i ) Why was NaOH used in this experiment, and 

 what portion of the fat did it replace ? ( 2 ) What other materials 



