1910.] PUBLIC DOCUMENT — No. 31. 133 



the sealed bottles was guarded from light ^ and from moisture, 

 and served as a cheek. Two sets of both closed and open bottles 

 had 1 cubic centimeter of water added, one set of each being- 

 exposed to north and east light (not sun) and one set protected 

 from light. ^ Another set of both closed and open bottles was 

 exposed to the light. From these various combinations it was 

 thought deductions might be drawn as to the relative action of 

 air, light and moisture upon butter fat. 



The fat was of fair average composition, as shown by the 

 analytical results : — 



Saponification number, .... 



Acid numbei", ...... 



Reichert-Meissl number, .... 



]\Iean molecular Aveight of volatile acids, . 

 Insoluble acids (per cent.), 

 Mean molecular weight of insoluble acids, . 

 Iodine number, ...... 



Melting point (Wiley method), . 

 Refractive index, 40° C, .... 



Valenta test, ...... 



232.47 

 1.48 



29.84 



96.90 



88.21 

 253.08 



28.40 



32.95° C. 

 1.4525 



28.50° C. 



One or two samples were drawn from every series in June 

 and December, 1908, and March and October, 1909, melted, 

 filtered and analyzed. The testing in June, 1908, was more or 

 less unsatisfactory, especially the iodine number, because of the 

 high temperature prevailing, and what deductions may be offered 

 will be based largely upon the remaining data, which represents 

 periods of six, twelve and eighteen months. 



Physical Changes. 



The original fat, when melted, gave a transparent oil of a 

 pronounced yellow color and a slight but characteristic odor. 

 On standing, the color gradually faded. This, however, was far 

 from uniform, even with members of the same series. The 

 cheeks were very irregular, varying at the end of the test from 

 yellow to almost white ; with moisture the color was less intense, 

 with light similar, and with moisture and light rather better 



• In providing for the circulation of air, a little diffused light reached the samples. 



