VII] FATS AND ALLIED SUBSTANCES 99 



choline. The same decomposition is effected by lipase. An enzyme, 

 glycerophosphatase, which decomposes glycero-phosphoric acid into 

 phosphoric acid and glycerol has been shown to be present in bran and 

 the seed of the Castor-oil Plant {Ricinus communis). Unlike lipase it is 

 soluble in water (Plimmer, 12). 



Expt. 98. Tests for lecithin. With commercial lecithin make the following tests : 

 (a) Test its solubility in ether, chloroform, benzene and carbon disulphide. It is 

 soluble in all these solvents. To the ether solution add acetone ; the lecithin is pre- 

 cipitated. 



{b) Boil a little lecithin with alcohol in a test-tube. It is soluble. 



(c) To the alcoholic solution from (6), add an alcoholic solution of cadmium 

 chloride. A white precipitate of a double salt of lecithin and cadmium chloride 

 separates out. Filter this oflf and test its solubilities in chloroform, benzene, etc. It 

 is soluble. The double cadmium salt has been employed in the preparation and 

 purification of lecithin. 



(d) Heat a little lecithin with some strong caustic soda solution in a test-tube. 

 Trimethylamine is evolved which can be detected by its smell. Acidify, and the 

 fatty acids will separate out. 



(e) Test for phosphoric acid in the following way. Weigh out 0*1 gm. of lecithin 

 a,nd mix it well with 1*4 gm. of potassium nitrate and 0*6 gm. of sodium carbonate. 

 Incinerate the mixture in a porcelain crucible until it is coloiu-less. Then dissolve 

 the residue in the minimum amount of hot water, neutralize with hydrochloric acid, 

 acidify with a few drops of concentrated nitric acid and pour the solution into an 

 equal volume of boiling 3 % ammonium molybdate solution. A yellow precipitate 

 of ammonium phosphomolybdate is produced, 



REFERENCES 



Books 



1. Abderhalden, E. Biochemisches Handlexikon, in. Berlin, 1911. 



2. Allen's Commercial Organic Analysis. Vol. 2. London, 1910. 



3. Leathes, J. B. The Fats. London, 1910. 



4. Le'wko'witsch, J. Chemical Technology and Analysis of Oils, Fats and 

 Waxes. 6th ed. London, 1921. 



5. Maclean, H. Lecithin and allied Substances. The Lipins. London, 1918. 



Papers 



6. Armstrong, H. B. Studies on Enzyme Action. Lipase. Froc. R. Soc, 

 1905, B Vol. 76, pp. 606-608. 



7. Armstrong, H. E., and Ormerod, B. Studies on Enzyme Action. Lipase. 

 II. Proc. R. Soc, 1906, B Vol. 78, pp. 376-385. 



8. Armstrong, H. B., and Gosney, H. W. Studies on Enzyme Action. 

 Lipase. III. Proc. R. Soc, 1913, B Vol. 86, pp. 586-600. 



9. Armstrong, H. E., and Gosney, H. W. Studies on Enzyme Action. 

 Lipase. IV. The Correlation of Synthetic and Hydrolytic Activity. Proc. R. Soc, 

 1915, B Vol. 88, pp. 176-189. 



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