EXAMINATION OF FATS. 1427 



for from twelve to fifteen hours. Then attach to the bulb of a delicate 

 thermometer graduated to one-fifth degree, immerse in a beaker of 

 water, and warm up very slowly. The point where the acid becomes 

 transparent is taken as the melting point. 



DETERMINATION OF MAUMENE NUMBER. a 



A beaker, 5 inches by 1 inches, is placed inside of another, 6 inches 

 by 3 inches, and a wet mixture of asbestus and plaster of paris tightly 

 packed around the inner beaker. b This, when dried, makes a hard, 

 solid packing, which radiates heat very slowly. 



Remove the inner beaker, weigh into it 50 grams of fat, and note 

 the temperature carefully. Then, from a pipette which will deliver 

 it in approximately one minute, add 10 cc of the strongest sulphuric 

 acid, which is at the same temperature as the oil. 



While the acid is being introduced, stir the .oil and acid with the 

 bulb of an accurate thermometer. Then hold the thermometer care- 

 fully in the center of mixture, and when the mercuiy reaches the high- 

 est point, note the reading. It is easy to determine this point, as the 

 column of mercury remains stationary for some time. It is necessary 

 to take care not to read the temperature too soon, as some oils take 

 considerable time to reach their maximum point. 



The difference between the initial reading and the final reading, 

 expressed in degrees centigrade, give the Maumene number. 



Great care must be taken to have the acid of the highest strength. 

 It is always best to test the apparatus and acid by use of water and 

 oils of known purity. With 50 grams of water and 10 cc of 99 per 

 cent sulphuric acid, Thomson and Ballantyne c obtained a rise of 

 46.5. Working with acid of specific gravity of 1.844 the average of 

 a number of determinations in this laboratory was 45, but this will 

 vary with the apparatus and manipulator. 



The acid which is used in testing the apparatus should be used in all 

 the determinations and care taken that it does not lose its strength. 

 When this test is conducted with care, it is one of the most valuable 

 in detection of adulteration in fats and oils. 



In reporting results obtained, the rise of temperature with water 

 should be stated, otherwise no comparative value can be attached to 

 the results. 



DETERMINATION OF RESIN OIL. 



Take the pure oil or a definite dilution with petroleum ether and 

 polarize in a 200 mm tube. 



ft Allen, Com. Org. Anal., 3d ed., vol. 2, pt. 1, p. 76. 



b The apparatus described is one used by the writer in working with a large num- 

 ber of oils and fats, and was found to give very satisfactory results. 

 c Jour. Soc. Chem. Ind., 1891, 10, 234. 



