120 MASS. EXPERIMENT STATION BULLETIN 166. 



From the above formulas factors were deduced for the insoluble acids 

 enumerated below, by means of which the percentage of triglycerides and 

 of glycerol may be readily calculated from the percentage of fatty acids: — 



Acid. 



Factor for Per 



Cent, of 

 Triglycerides. 



Factor for 



Per Cent, of 



Glycerol. 



Laurie, 



Myristic, 



Palmitic, 



Stearic, 



Arachic, 



Oleic, . 



Erucic, 



Linolic, 



Linolenic, . 



Clupanodonic, 



Ricinoleic, . 



Dihydroxystearic, 



1.06330 

 1.05552 

 1.04945 

 1.04457 

 1.04057 

 1.04489 

 1.03745 

 1.04522 

 1.04554 

 1.04588 

 1.04248 

 1.04006 



.15329 

 .13446 

 .11976 

 .10795 

 .09826 

 .10872 

 .09070 

 .10950 

 .11029 

 .11110 

 .10289 

 .09703 



Lactones and Anhydrides. 



The amount of lactones and anhydrides present in the separated insolu- 

 ble acids of oils and fats can be measured in terms of milligrams of potas- 

 sium hydroxide by the difference in the amount of alkali required to titer 

 (neutralize) the acids in cold alcohol and that absorbed on saponifying 

 with alcohohc potash. Lactones and anhydrides are unable to combine 

 with alkah until transformed into acids. They are not hydrolyzed to any 

 considerable extent in cold alcohol, but are readily hydrolyzed by boil- 

 ing alcoholic potash. 



Reagents. — Same as for "Acid'' and "Saponification" numbers. 



Method. — Five grams of insoluble fatty acids are brought into a 300 

 cubic centimeter Erlenmeyer flask, together with 100 cubic centimeters of 

 alcohol, and titrated in the cold with N/2 potassium hydroxide, using 1 

 cubic centimeter of phenolphthalein or cotton blue as indicator. An 

 additional 5 grams of insoluble acid are brought into a flask and treated 

 exactly as described for saponification number. The difference between 

 the two determinations, in terms of milligrams of potassium hydroxide to 

 the gram of insoluble acids, measures the aYnount of lactones and anhy- 

 drides present. The same weight of fat may serve for both determina- 

 tions if desired. 



Limit of error, same as in the determinations of acid and saponification 

 numbers. 



Synopsis of Reaction. — Solution in alcohol. 



