METHODS OF ANALYSTS. 18 



or more to product- it, nlthou<r|i I .-liaise up my I'ruil at I cents a IMMIIK!, which 

 is \\hal \ve paid when we \\ere niniiiiiir tin- I'll M.mtecito Maniil'actin in- Com- 

 pany. l>ut they are quote.! n,,\ v at just hall is|i) a ton), \\liirli is just t \\i.v\vhat 

 I lia\c to pay fur picking ( 1 cent a pound). \Ve have spent a small fortune, I 

 think fully sf>0,()00, in trying to introduce /</// <>!',<; nil, and faile(l, closin^the mill 

 indelinitely. I think in our mill the oil cost us $1. 17 a bottle, and much of it had to 

 be sold at 40 cents. 



Respectfully, yours, I'i:\ KKII, MEIOS. 



METHODS OF ANALYSIS AND INTERPRETATION OF RESULTS. 



The methods used in this work arc not given j M this bulletin if they 

 tire to he found in Bulletin 65" of this I>ureau or arc modifications of 

 methods already published. More attention will he given to the dis- 

 cussion of the application of these methods and their limitations in the 

 detection of various adulterants. In many control laboratories it is 

 customary to make a few of the simpler determinations and qualita 

 tive tests, and to judge the state of purity of the oil from the results 

 obtained by these determinations. While in many cases this is suffi- 

 cient, especially if gross adulteration has been practiced, it is entirely 

 inadequate in case the amount of foreign oil added is small. In such 

 an instance a thorough examination is essential to properly judge an 

 oil. The condition of an oil may frequently be such as to give abnor- 

 mal values, even though it is absolutely pure. For example, an oil 

 having a high acidity would give too low results for specific gravity, 

 index of refraction, and possibly too low a Hubl value, especially if 

 the free fatty acids had become oxidized. If the determination of 

 acidity were made, it would explain at once the abnormal results. 

 Frequently an oil that may be pronounced adulterated upon super- 

 ficial examination will upon more careful analysis be found to be 

 unadulterated. 



The qualitative tests, while in many cases conclusive, must be u-<-d 

 with caution. Halpheirs test, if positive. i> satisfactory proof of cot 

 ton-seed oil, but, as will be shown later, the heated oil does not respond 

 with this reagent. The tests of Baudouin and of Villivecchia for 

 sesame oil are conclusive if used with proper precaution s. but >oiue 

 oils from Tunis give a color with this reagent that may easily be mis- 

 taken. The Bechi test for cotton-seed oil and the Kenard tc-st for pea- 

 nut oil must be used with extreme care or misleading results will be 

 obtained. 



SPECIFIC GRAVITY. 



The specific gravity was determined by the u-e of a hydrometer 

 graduated from 0.9100 to O.i'.'jnn ; ,t 15.5 C. and reading to O.IMMH*. 



"Provisional methods for the analysis of foods, adopted by the Association of Offi- 

 cial Agricultural Chemists. November 14, 15, If}, 1901. 



