FATS AND OILS 



DETERMINATION. 



303 



XXIII] 

 13 



Saponify 75 grams of the sample in a metal dish with 60 cc. of 30% sodium hy- 

 droxid solution (36° Baum6) and 75 cc. of 95% alcohol by volume or 120 cc. of 

 water. Evaporate to dryness over a very low flame or on an iron or asbestos plate, 

 stirring constantly. Dissolve the dry soap in a liter of boiling water and, if alcohol 

 has been used, boil for 40 minutes to remove it, adding sufficient water to replace 

 that lost in boiling. Liberate the fatty acids by adding 100 cc. of 30% sulphuric 



FIG. 12. APPARATUS FOR THE MELTING POINT DETERMINATION. 



acid (25° Baum6) and boil until they form a clear, transparent layer. AVash with 

 boiling water until free from sulphuric acid, collect in a small beaker and 

 place on a steam bath until the water has settled and the fatty acids are clear; then 

 decant into a dry beaker, filter while hot and dry 20 minutes at 100°C. When 

 dried, cool the fatty acids to 15°-20°C. above the expected titer and transfer to the 

 titer tube, 25 by 100 mm. (1 by 4 inches) and made of glass about 1 mm. in thickness. 

 Place in a 16 ounce wide-mouthed bottle of clear glass, 70 by 150 mm. (2.8 by 6 



