LECITHINE. 139 



3. Lactic acid forms numerous crystalline salts 

 which are mostly but sparingly soluble in water ; they 

 are prepared by boiling the acid with a carbonate. 



4. E.g. Boil lactic acid with zinc carbonate, filter 

 hot ; the solution will on cooling deposit crystals of 

 zinc lactate. 



5. Similarly boil lactic acid with calcium carbonate, 

 when calcium lactate will be formed. 



6. Heat the syrupy acid : it will give off water, and 

 be converted into the anhydride, which fuses below 

 100 C. ; when further heated to 260 C. it is converted 

 into lactide, which sublimates in white crystalline 

 plates. 



Lecithine, C 42 H 84 NP0 9 . 1. Preparation of Lecithine 

 (from egg-yelk). Extract the yelk with a mixture of 

 ether and alcohol, distil off part of the ether from the 

 extract, add alcohol as long as turbidity ensues from 

 the separation of a fatty oil, and mix the clear yellow 

 solution with platinic chloride acidified with hydro- 

 chloric acid. A copious yellow flocculent precipitate 

 of a double salt will be formed, differing greatly from 

 choline-platinic chloride, insoluble in water, easily 

 soluble in ether, carbon disulphide, chloroform, and 

 benzol, precipitated from these solutions by alcohol in 

 yellow flakes agglutinating on agitation. To free it 

 from fat, it must be dissolved five or six times in ether 

 and precipitated each time by alcohol. In vacuo over 

 sulphuric acid it dries without losing its solubility in 

 ether, but at 100 C. it blackens, melts, and loses 



