134 EXPERIMENT STATION. [Jan. 



than the checks. Light, in the absence of air, did not accelerate 

 loss of color. 



Air induced the most uniform destruction of color. As the 

 air always carried more or less moisture, it was impossible to 

 differentiate as to the effect of light and added moisture. The 

 most notable change was obtained from the combined action of 

 all three factors. 



The sealed samples were porous, and developed a slight odor, 

 imlike that of tlie original fat. The open samples were more 

 like tallow, both in appearance and odor. Old sam})les contain- 

 ing added water were turbid on melting, and required consider- 

 able time to settle clear. 



Chemical Changes. 



As decomposition of fats and oil seems to progress along two 

 fairly well-defined lines, that of hydrolysis and that of oxidation, 

 only such determinations were planned as would readily serve 

 to measure these changes ; acid and saponification numbers for 

 the former, and iodine number for the latter. Too much must 

 not be expected of these determinations for so complex a re- 

 action, but they are at least indicative. If the decomposition 

 became extensive, other tests would be warranted. 



As shown by Table 1, added moisture, in the absence of air, 

 had no appreciable hydrolytic action in excess of the check. 

 Light alone, and with moisture present, preserved the original 

 fat practically unchanged for eighteen months while the check 

 manifested a noticeable breaking down. ]\Ioist air increased 

 hydrolysis, both light and added water intensified the reaction. 

 Lewkowitsch states that dry air without light has no action on 

 oils and fats, and his explanation will be presented later. 



Aldehydes were produced in lx)th open and closed sam]>les, 

 as shown by the brown color of the saponification test (October, 

 1900), except in the sealed samples exposed to light. 



