144 METHODS OF ANALYSIS. 



15. Phytosterol and Cholesterol." Provisional. 



Boil 50 grams of fat or oil in a flask having a reflux condenser with 75 cc 

 of 95 per cent alcohol for five minutes and separate the alcoholic solution. 

 Repeat with another portion jp^ Alcohol and separate. Mix the alcoholic solu- 

 tion with 15 cc of 30 per cent sodium hydroxid and boil in a flask with a 

 condensation tube until one-fourth of the alcohol is s evaporated. Evaporate 

 nearly to dryness in a porcelain dish and shake the residue with ether. Evapo- 

 rate the ethereal solution to dryness, take up with a little ether, filter, again 

 evaporate, dissolve in hot 95 per cent alcohol, and allow to crystallize. 



Cholesterol can easily be distinguished from phytosterol by the form and 

 grouping of the crystals, also by the melting point, which is 14G C.,& while 

 that of phytosterol is from 130 to 137.5 C.c The crystals of phytosterol 

 separated from hot alcohol appear as tufts of needles. Cholesterol is char- 

 acteristic of animal fats ; it crystallizes in thin rhombic tables. 



16. Unsaponifiable Residue.** Provisional. 



Saponify 5 grams of oil or fat with alcoholic potassium hydroxid and remove 

 the alcohol by evaporation. Wash into separatory funnel with from 70 to 100 

 cc of water and extract with from 50 to 60 cc of ether. In case the two liquids 

 do not separate, a few cubic centimeters of alcohol may be added. Separate 

 the water solution and wash the ether with water containing a few drops of 

 sodium hydroxid. Again extract the soap solution and washings with ether 

 and evaporate the combined extracts to dryness. In most cases it is advisable 

 to add a little alcoholic potassium hydroxid to the residue and heat in order 

 to saponify any traces of fats left unsaponified and extract again with ether. 

 Transfer to a weighed dish and dry as quickly as possible in a water oven. 



Many of the hydrocarbon oils are volatile at 100 C., so that the drying should 

 not be carried any further than necessary. With resin oil, paraffin wax, and 

 the denser mineral oils there is little danger of loss at 100 C. 



On account of the solubility of soap in ether and petroleum ether it is well 

 to wash the residue with warm water containing a little phenolphthalein. If 

 the reaction is alkaline, soap is present and the residue must be further purified. 



17. Qualitative Tests, 

 (a) RESIN OIL. PROVISIONAL. 



Polarize the pure oil or a definite dilution with petroleum ether in a 200 mm 

 tube. Resin oil has a polarization in a 200 mm tube of from +30 to +40 on 

 the sugar scale (Schmidt and Haensch) while other oils read between +1 

 and 1. 



(b) HALPHEN REACTION FOB COTTON-SEED OIL. PROVISIONAL. 



Mix carbon disulphid, containing about 1 per cent of sulphur in solution 

 with an equal volume of amyl alcohol. Mix equal volumes of this reagent and 



Forster and Relchelmann, Analyst, 1897, 22 : 131 ; E. Salkowski, Zts. anal. Chem., 

 1887, 26: 557; E. Von Raumer, Zts. angew. Chem., 1898, 18: 555-556; J. Soc. Chem. 

 Ind., 1898, 17: 774; H. Kreis and O. Wolf, J. Soc. Chem. Ind., 1898, 17: 1075. 



E. Salkowski, Zts. anal. Chem., 1887, 26: 557. 



Bomer, Zts. Nahr. Genussm., 1898, 1: 81. 



"Allen, Commercial Organic Analysis, 3d ed., 2 (1): 112. 



J. Pharm. Chim., 1897, 6 : 390 ; Analyst, 1897, 22 : 326 ; Allen, Commercial Organic 

 Analysis, 3d ed., 2 (1): 143; Win ton, Conn. Agr. Exper. Stat. Kept., 1900, Part 2, p. 144. 



