Lecithin and Glucose. 



35 



cules in the alcoholic solution. Since this "lecithin " was prepared 

 by precipitation with acetone it probably contained considerable 

 kephalin and consequently had for a single molecule a lower 

 average weight than the 800 usually given (see Maclean 1 ). 



There was, as perhaps might be expected, a rise in the boiling 

 point when small amounts of glucose were added to a solution 

 of lecithin in alcohol. The present point of interest is that this 

 rise was only one half as much as it would have been had no 

 lecithin been present, provided that the sugar was added in such 

 quantities that there was considerable excess of lecithin molecules 

 over the sugar molecules present. 



The simplest interpretation that can be placed upon this is 

 that a portion of the lecithin disassociates and one molecule of 

 lecithin combines with one molecule of glucose. If the number of 

 moles of sugar added approach the number of moles of lecithin 

 present less than half of the sugar moles disappear. This may 

 mean either that there must be an excess of lecithin for the main- 

 tenance of equilibrium or that the sugar unites with only one of 

 the components of the "lecithin" which as indicated above is 

 confessedly a mixture. Again, when a comparatively large excess 

 of sugar is added there is apparently another compound found in 

 which more sugar is combined. This compound might be repre- 

 sented by L n G m in which m is greater than n. In the course of 

 this work a paper by Kornfeld 2 has come to my notice in which 

 the author has made use of the same method for the study of the 

 hydrates of pyridine. 



Again in two experiments in which a solution of the lecithin- 

 glucose preparation was dialyzed for several days through a 

 rubber membrane against chloroform, a reducing substance was 

 found outside the membrane. This passage of a reducing sub- 

 stance did not take place when either ether or benzene was used 

 as solvent. 



Although I feel that the results already obtained throw con- 

 siderable doubt upon the theory that this substance is an adsorp- 

 tion compound, work is being continued in which the samples 

 of lipins used are separated and purified by the best methods 

 available. 



1 Maclean, H., Biochem. Journ., IX, pp. 351-378, 1915. 



2 Kornfeld, G., Monalshefte f. Chemie, pp. 865-897, 1915. 



