726 



J Of. r rial of AgricuJiiiYal Research 



Vol. Xn, No. II 



in each. The reported boiling point of the ethyl ester of a number of 

 fatty acids that occur in butter fat, together with the range of the sev- 

 eral fractions as determined by analysis for a "high" side-tube 500-c. c. 

 distillation flask, may be noted in Table I. 



The apparent lack of agreement is probably due to the greater distance 

 the vapors have to rise in practical fractionation and to the influence of a 

 gradually increasing amount of ethyl oleate in the several fractions. 

 Analysis seemed to be the only method for accurately establishing the 

 required range. Hempel tubes or similar apparatus could not be em- 

 ployed to break up the distillate. 



As the preliminary work advanced, the results became more concord- 

 ant and indicated that it was possible to determine not only lauric and 

 myristic acids but also caproic, caprylic, and capric acids. A part of 

 the butyric acid was recovered, but the main portion was evidently lost 

 during the purification of the esters or distilled over with the ether, owing 

 to the greater solubility and volatility of this ester. 



Analysis of fractions. — Only the determinations of saponification 

 and of iodin numbers by the usual methods employed wth oils and fats 

 were required. 



Calculation of results. — Having determined the weight, saponifi- 

 cation and iodin numbers of the several fractions, the analyst must 

 ascertain whether the range of the fractions had been accurately estab- 

 lished. If correctly fractionated, the percentage of the different ethyl 

 esters in the several fractions can be calculated algebraically and their 

 weight computed, from which the percentage of the corresponding acids 

 in the butter fat can be determined. 



As a matter of convenience, the data necessary for these calculations 

 have been compiled in Table II. 



Table II. — Fatty acids and their ethyl esters 

 [C, 12.005; H, 1.008; 0, 16.000; K, 39.10; 1, 1^6.92] 



Add. 



Molecular 



weight of 



acid. 



Molecular 



•weight of 



ester. 



Saponifica- 

 tion No. 

 of ester. 



Iodin No. 

 of ester. 



Recipro- 

 cal. 



Conver- 

 sion fac- 

 tor, ester 

 to acid. 



Acetic ' 60. 042 



Butyric [ 8S. 084 



Valeric ; 102. 105 



Caproic 116. 126 



Caprylic 1 144- 168 



Capric . 



Lauric 



^lyristic 



Palmitic 



Stearic 



Arachic 



Oleic 



Erucic 



Linolic 



Linolenic 



Clupanodonic . . . 



Ricinoleic 



Dihydroxystearic . 



172. 210 

 200. 252 

 228. 294 

 256- 2,3^ 

 284. 378 

 312. 420 

 282. 362 

 338. 446 

 280. 346 

 278. 330 

 276.314 

 298. 362 

 316.378 



88.084 

 116. 126 

 130. 147 

 144. 168 

 172. 210 

 200. 252 

 228. 294 



256- z?,(> 



284. 378 

 312. 420 

 340. 462 

 310. 404 

 366. 488 

 308. 388 

 306. 372 

 304- 356 

 326. 404 

 344. 420 



Mgm. 

 636. 983 

 483. 165 



431- "3 

 589. 185 

 325.812 

 280. 187 

 245. 771 

 218. 885 

 197. 301 



179. 592 

 164. 800 



180. 758 

 153.096 



181. 940 



183. 137 



184. 350 

 171.897 

 162. 906 



0.81777 

 . 69263 

 I. 64624 

 2. 48561 

 3- 33609 

 • 77769 



I. 22284 



I- 44377 

 .60744 

 . 40232 



• 29975 

 I. 



68164 

 75852 

 78454 

 80540 

 83716 



85997 



87717 



, 89060 



90139 

 , 91024 

 , 91764 

 , 90966 

 , 92348 

 , 90907 

 ,90847 

 . 90786 

 ,91409 

 , 91858 



