I'KAM T niL SKSAMK nil,. 8, r ) 



in case of very gross adulteration. Sample !!:>. Table XXX 1 1 1, a cold 

 pressed oil prepared in this laboratory. is an example of this. It \\;^ 

 a specific gravity of n.JMS<J. a Ili'ibl number of sT.S and <>.!<> per cent 

 of free acid. Such an oil could be mixed in alnmM any proportion 

 with an olive oil of low iodin number and not give even a hint from 

 the physical and chemical values of its presence. Practicallv thennlv 

 lest that i> positive is tin- isolation of arachidic acid, which is present 

 in peanut oil to the extent of from :\ to .'> pel 1 cent. In four sample- of 

 peanut oil examined in this laboratory from .'I. -11 t.> -I.-_M per cent of 

 the acid was found, having a melting point <>f from 7 L' to 73. Allen" 

 gives an average of 5 per cent. In Table XXXIII results are given 

 on two samples of peanut oil. Nos. \:\^:\4 and 1;^>5.'. which were exam- 

 ined to determine the effect of age. Both had been kept in stoppered 

 bottles for eight years; No. 13l!o;> was a heated oil. Both were exceed- 

 ingly rancid to taste and smell, but No. 1323-4- had only 2.93 percent of 

 free acid, showing that acidity is not an index of rancidity. No. I:-'.!': 1 ..". 

 show> that great changes have been brought about in the oil in the 

 process of heating. 



RenardV' test is as satisfactory as any of the methods for detecting 

 arachidic acid. Twenty grams of the oil to be tested should be taken 

 so that enough of the arachidic acid can be separated to make the melt- 

 ing point which should be determined in every case, as some oils, such 

 as cotton-seed and lard, will give a precipitate which resembles ara- 

 chidic acid except that it has a lower melting point. 



SESAME OIL. 



Like peanut oil, sesame oil has a pleasant flavor and is well adapted 

 to the adulteration of olive oil. However, it is not extensively used 

 in this country, as the analyses of commercial samples show. Table 

 XXV gives the results compiled from published data on ^esame oil. 



Com <>r:. Anal., :!<l c<l., vol. L>, pt. 1, ].. i:}4. 



& Coinp. Rend. 1871, 73: l.'WO. T.S. Dcpt. A-r., nmvam.f ( 'lu-i nisi ry. lliil.j;,, p.88. 



