MKTHODS OK ANALYSIS. 



15 



high as o.iil'.Hi. /aiiniiit " called attention to the fact that the presence 

 of free ac'nl> in olive oils minces the >perifi<- gr:i\ it\ . :ind the following 

 table taken from his results shows the ell'ect of excessive amounts: 

 TAMI.K I II. Effect of excessive amount* of free <n-i<l* in olive oils on their sped fir 



Table I\' gives the range of specific gravity of all the oils considered 

 in this bulletin. Oils having an excessive amount of free aci<U. and 

 cmiMMjuentlv abnormal specific gravity, have been excluded from the 

 ranges given in the column of '"Results obtained in Bureau of Chem- 

 istry." This explains in many cases the lack of agreement between 

 the results from the two sources. An example of this is one sample 

 of peanut oil having 13.51 per cent of free acids and a specific gravity 

 of O.D155. The other three samples of peanut oil have specitic gravities 

 of 0.9186 and above, which are considered about normal for this oil. 



TABLE IV. Specific gravity of nils. 



INDEX OF REFRACTION. 



This determination was made with a Zeiss butyro-ref ractometer, the 

 readings being made as nearly at 15.5 C. as possible. As it is not 

 alwa} T s convenient to make the readings at this temperature, the factor 

 to be used for the correction for temperature was determined on oils 

 likely to be used as substitutes for olive oil. b The butyro-ref ractometer, 

 on account of its ease of manipulation, is \ cry widely used, but its 

 empirical scale, with divisions of varying value in refractive indices, 

 requires for an accurate correction for temperature that the scale read- 

 ings be calculated to indices of refraction and the temperature correction 

 applied thereto. The reason for this can be seen from Table V. 



Rev. Int. Fals. Alim., 1899, 12: 84. 



&Tolman and Munson, Jour. Amer. Chem. Soc., 1902, 24: 754. 



