Mar. 1 8, 1918 



Faity Acids in Butter Fat 



725 



All the agitation necessary can be obtained by reversing the separatory 

 funnel several times, which gives a clear separation much quicker than a 

 more violent shaking. The resulting esters contain ether and probably 

 some alcohol, but do not require neutralizing or drying. 



Fractionation (fig. 2). — Fractionation of the esters in vacuo by means 

 of a Bruehl or other type apparatus was found impracticable as a quanti- 

 tative process for the reason that a constant level of the liquid in the dis- 

 tilling flask and a constant pressure were prime requisites for a definite 

 fraction, neither of which co^ld be successfully maintained with the 

 facilities at hand. Furthermore, the use of such apparatus necessitates 

 a certain aptitude or technic not possessed by all analysts. 



Fractionation at atmospheric pressure required a high temperature, 

 but proved feasible. Gas could not be used as a direct source of heat 

 owing to fluctuations in pressure, influence of air currents, tendency to 

 decompose the esters, etc., but when applied to a bath of superheated 

 valve oil proved entirely satisfactory. This oil is a cheap commercial 

 product that will safely withstand a temperature of OA^er 400° C. when 

 covered and may be used three times, possibly more, without appreci- 

 able loss of efficiency. All the exposed surface of the side-neck flask 

 should be wound with asbestos paper to prevent chilling the vapors and 

 breakage of the flask. 



For some reason fractionation of the purified esters proved imprac- 

 ticable, possibly due to the influence of a relatively large amount of the 

 higher esters particularly oleic, but was readily accomplished after a pre- 

 liminary distillation. Accurate results are dependent in large measure 

 on a slow, steady rise in temperature during the first distillation and 

 subsequent fractionation. Glass beads were found helpful in boiling. 



T.'^BLE I. — Boilinq point and range of fractions {uncorrected) of esters of butter fat 



The range of the several fractions is more or less arbitrary, being de- 

 pendent on the speed of distillation and the distance the vapors have to 

 rise. The object was to secure fractions that did not contain more than 

 two esters in addition to oleic ester, and, furthermore, adjacent fractions 

 should contain approximately one-half of the saturated ester appearing 



