XXIII] FATS AND OILS 315 



When thoroughly dry pulverize the glycerides and take their melting point in a 

 closed 1 mm. tube, using an apparatus similar to that indicated in 1 1 , Fig. 12. Heat 

 the water in the beaker rapidly to about 55°C. and maintain that temperature 

 until the thermometer carrying the melting-point tube registers 50°-55°C., then 

 heat again and carry the temperature of the outer bath somewhat rapidly to G7°C. 

 when the lamp is removed. The melting point of the crystals is regarded as that 

 point when the fused substance becomes perfectly clear and transparent. A dark 

 background placed about 4 inches from the apparatus will prove of advantage. 

 When the melting point of the glycerides obtained by this method is below 63.4°C. 

 the presence of beef fat should be suspected, while a melting point of 63°C., or below, 

 can be regarded as positive evidence that the sample is not pure lard. It is advis- 

 able to carry out this method with a control sample of pure lard in connection with 

 each batch of samples analyzed. 



FISH OIL AND MARINE ANIMAL OILS IN THE PRESENCE OF VEGETABLE OILS AND IN THE 

 ABSENCE OF METALLIC SALTS. 



41 Qualilative Tesl. — Tentative. 



Dissolve in a test tube about 6 grams of the oil in 12 cc. of a mixture of equal 

 parts of chloroform and glacial acetic acid. Add bromin, drop by drop, until a 

 slight excess is indicated by the color, keeping the solution at about 20°C. Allow 

 to stand 15 minutes or more and then place the test tube in boiling water. If vege- 

 table oils only are present, the solution will become perfectly clear, while fish oils 

 will remain cloudy or contain a precipitate due to the presence of insoluble bromids. 



42 COLORING MATTERS.-TENTATIVE. 

 Proceed as directed under XI, 3. 



BIBLIOGRAPHY. 



^ Allen. Commercial Organic Analysis. 4th ed., 1909-14, 2:50. 



2 Wiley. Principles and Practice of Agricultural Analysis. 2nd ed., 1906-14, 3: 

 414; Conn. Agr. Exp. Sta. Rept., 1900, (II), p. 142. 



3 Ber., 1882, 15: 1031; J. Am. Chem. Soc, 1899, 21: 991. 

 « J. Soc. Chem. Ind., 1898, 17: 1021. 



» U. S. Bur. Chem. Bull. 13 (IV), p. 448; Lewkowitsch. Chemical Technology 

 and Analysis of Oils, Fats and Waxes. 5th ed., 1913-15, 1 : 319; Wiley. Principles and 

 Practice of Agricultural Analvsis. 2nd ed., 1906-14, 3 : 390. 



« Arb. kais. Gesundh., 1903-04, 20: 545. 



' Lewkowitsch. Chemical Technology and Analvsis of Oils, Fats and Waxes. 

 5th ed., 1913-15, 2:425. 



8 Analyst, 1889, 14: 61; J. Am. Chem. Soc, 1893, 15: 110. 



9 J. Soc. 'Chem. Ind., 1897, 16:503; Benedikt. Analyse der Fette und Wachs- 

 arten. 5th ed., 1908, p. 143; Allen. Commercial Organic Analysis. 4th ed., 1909-14, 

 2: 33 



' 1" U. S. Bur. Animal Industry Circ. 212. 



" Chem. Ztg., 1913, 37: 1001. 



"Allen. Commercial Organic Analysis. 4th ed., 1909-14, 2: 79. 



" Lewkowitsch. Chemical Technology and Analysis of Oils, Fats and Waxes. 

 5th ed., 1913-15, 1:343. 



i« J. pharm. chim., 1897, 6th ser., 6: 390; Abs. Analyst, 1897, 22: 326; Allen. Com- 

 mercial Organic Analysis. 4th ed., 1909-14, 2: 135; Conn. Agr. Exp. Sta. Rept., 1900 

 (11), p. 143. 



"Allen. Commercial Organic Analj'sis. 4th ed., 1909-14, 2: 135. 



" Abs. J. Soc. Chem., Ind., 1899, 18: 711. 



" Compt. rend., 1871, 73: 1330; Lewkowitsch. Chemical Technology and Analy- 

 sis of Oils, Fats and Waxes. 5th ed., 1913-15, 2: 310. 



18 J. Am. Chem. Soc, 1893, 15: 110. 



i« J. Soc. Chem. Ind., 1893, 12: 67; 1894, 13: 69. 



" U. S. Bur. Animal Industry Circ. 132. 



