Apr. 17, 1916 Stearic Acid in Butter Fat 107 



the nature of shaking reduced the fragile crystals to a mass and ren- 

 dered filtration extremely difficult or impossible. 



EXPERIMENTAL METHOD IN DETAIL 



Five-tenths of a gram of melted insoluble acids are placed in an 8- 

 ounce sterilizer bottle and 150 c. c. of an alcohol-stearic-acid solution 

 (3 gm. to 1,000 c. c), accurately measured with a pipette at 30° C, 

 added. The bottle is sealed with a solid-rubber stopper, shaken at a 

 gradually increasing temperature until a clear solution is obtained, 

 placed immediately in a pocket of the ice tank, and allowed to stand 

 overnight. The following morning the solution is gently agitated by 

 inverting the bottle several times, and in the afternoon it is siphoned off 

 as thoroughly as possible by means of a small thistle tube and a per- 

 forated rubber stopper, using suction. The residue is dissolved in 

 ethyl ether, transferred to a tared 140 c. c. wide-mouth Erlenmeyer 

 flask, the ether carefully distilled off, the residue dried at 100° C, and 

 weighed. As saturation may vary somewhat mth the amount of 

 stearic acid present and as the quantity of solution retained by the 

 precipitate depends in a measure on the amount of precipitate, blanks 

 are run on a weight of stearic acid equivalent to that expected in the 

 test. By deducting the additional stearic acid taken from the weight 

 recovered the true blank for the alcohol-stearic-acid solution is obtained. 



NATURE OF THE PRECIPITATE 



To ascertain whether the crystalline substance obtained from butter 

 acids was stearic acid or a mixture, the residues from a number of tests 

 (one being insufficient for accurate work) were combined and the molec- 

 ular weight determined by saponification. Such a determination made 

 after securing satisfactory control of the stearic- acid method gave 284.64, 

 theoretically 284.288. The melting point was not determined, as it 

 was considered less reliable than the molecular weight. 



INFLUENCE OF DIFFERENT FATTY ACIDS ON PRECIPITATION OF 



STEARIC ACID 



Numerous tests were made in an effort to determine whether lauric, 

 myristic, palmitic, and oleic acids had any effect on the crystallization of 

 stearic acid and, if so, the nature and extent of such action. Table V 

 will serve to illustrate. 



According to molecular-weight determinations the lauric and palmitic 

 acids were of excellent quality and the myristic and oleic acids somewhat 

 inferior. 



Lauric, myristic, and oleic acids in relatively large amounts showed no 

 appreciable influence on the crystallization of stearic acid. Palmitic 

 acid, on the other hand, noticeably increased the solubility and affected 

 the crystalline structure of the precipitate. 



