FATS, OILS, AND WAXES 



upon. For example, Sudan III not only stains oils red but 

 also resins, latex, wax, and cuticle ; chloroplasts are stained 

 a pale red ; cellulose, lignified walls, gelatinized membranes, 

 starch, and tannin are unstained. 



The staining tests mentioned above may be employed after 

 extracting the oil with ether or other solvent. 



QUANTITATIVE ESTIMATION OF FATS. 



I. By Means of Soxhlefs Extraction Apparatus. The 

 fact that oils and fats are readily dissolved by ether, 

 chloroform, and light petroleum, is made use of in their esti- 

 mation ; but it must be borne in mind that the method only 

 yields correct results provided other substances, which would 

 be extracted by the solvent employed, are absent from the 

 material under examination. 



The general arrangement of the apparatus required is given 

 in Fig. i . The flask F, which is half-filled 

 with the solvent to be employed, is con- 

 nected to the extractor by a closely fitting 

 cork. The material to be extracted is put 

 into a thimble made of special quality filter 

 paper and placed in the extractor, which is 

 connected to a reflux condenser (C). 



The method may be conveniently em- 

 ployed for determining roughly the propor- 

 tion of oil in the reserve food of the castor- 

 oil seed, for example. 



A number of seeds, freed from their 

 testas, are carefully weighed and one by one 

 are broken up in a perfectly clean glass 

 basin with the well-rounded end of a glass 

 rod. The material is then dropped into 

 the thimble ; any particles adhering to the 

 basin or rod must be carefully removed by 

 means of a platinum wire and also placed 

 FIG. i. in t h e thimble. 



The basin and glass rod should then be carefully washed 

 with a few drops of ether to remove the last traces of fat, and 

 the resulting solution should be added to the broken-up seeds 

 in the thimble, care being taken not to employ enough ether 

 for the solution to trickle through the thimble. 



