894 



APPENDIX. 



sulphuric acid ; this solution if exposed to the air in an open dish turns blue, 

 green, and finally yellow ; the sulphuric acid under the chloroform has a green 



[FiG. 234. 



Cholesterin Crystals and Fatty Aggregations and Molecules Spontaneously 

 Deposited in the Urine.] 



fluorescence. After evaporation to dryness with nitric acid, the residue turns red 

 on treating with ammonia. 



This body is described here rather for the sake of convenience than from its possessing any 

 close relationship to the substances immediately preceding. 



COMPLEX NITROGENOUS FATS. 

 Lecithin. C 44 H 90 NP0 9 . 



Occurs widely spread throughout the body. Blood, bile, and serous fluid con- 

 tain it in small quantities, while it is a conspicuous component of the brain, nerves, 

 yolk of egg, semen, pus, white blood-corpuscles, and the electrical organs of the ray. 



When pure it is a colorless, slightly crystalline substance, which can be kneaded, 

 but often crumbles during the process. It is readily soluble in cold, exceedingly so 

 in hot alcohol ; ether dissolves it freely though in less quantities, as also do chloro- 

 form, fats, benzol, carbon disulphide, etc. It is often obtained from its alcoholic 

 solution by evaporation, in the form of oily drops. It swells up in water and in 

 this state yields a flocculent precipitate with sodium chloride. 



Lecithin is easily decomposed ; not only does this decomposition set in at 70 C., 

 but the solutions, if merely allowed to stand at the ordinary temperature, acquire 

 an acid reaction, and the substance is decomposed. Acids and alkalies, of course, 

 effect this much more rapidly. If heated with baryta water it is completely decom- 

 posed, the products being neurin, glycerin-phosphoric acid, and baric stearate. This 

 may be thus represented : 



Lecithin. 



Stearicacid. 



Glycerin^phosphoric 



C 3 H 9 P0 6 + 



Neurin> 



C 5 H 15 N0 2 . 



When treated in an ethereal solution with dilute sulphuric acid, it is merely split 

 up into neurin and distearyl-glycerin-phosphoric acid. Hence, Diakonow 1 regards 

 lecithin as the distearyl-glycerin-phosphate of neurin, two atoms of hydrogen in the 



1 Hoppe-Seyler's Med.-Chem. Untersuch., Heft ii. (1867), S. 221 ; Heft iii. 

 f. d. med. Wiss. (1868), Nr. 1, 7, u. 28. 



S. 405. Centralbl. 



