508 



FOODS AND FOOD ADULTERANTS. 



He also gives the result of a comparison of tallow, lard, ami cotton 

 oil: 



Analyses were also made of cotton oil and cotton-oil acids, as indi- 

 cated in the following table : 



* Rising to 32.5. 



It is found that there is a marked difference in the specific gravity of 

 lard and cotton oil, and also in the iodine absorption of the two. Lard 

 and beef fat have substantially the same specific gravity. The difference 

 is important, since it would enable one to distinguish a mixture of beef 

 stearine and cotton oil, having an iodine absorption of about GO from 

 genuine lard. Thus, with a proportion of the adulterant in a mixed com- 

 position of lard, the cotton oil only can be ascertained with considerable 

 accuracy by determining the iodine absorption ; the estimation will be 

 below the truth if beef stearine be present. On the other hand, tin- 

 presence of beef steariue does not interfere with the deduction to be 

 drawn from the increased specific gravity of the melted sample. 



Mr. Allen finds Milliau's nitrate of silver test to be valuable, and pic 

 fers it to the original one proposed by Bechi. In his opinion the in- 

 dications obtained from the melting point or solidifying point of the 

 glycerides of the fatty acids are of no value. Samples of lard oil were 

 found to have an iodine absorption of 73 and 71, while one several years 

 old gave only 41. It is recommended that the iodine absorption be de- 

 termined on the fatty acids instead of the original glycerides, thus avoid- 

 ing the use of chloroform, which has a marked disturbing influence on 

 the strength of the iodine solution employed. 



