THE ALUMNI JOURNAL, 39 



tin fnmi an alcoholic solution and leaves the xanthophyll in the 

 alcohol. 



Two general methods can be used for the separation of chlorophyll 

 from its yellow companions. 



Fremy's Process: Shalce one volume of alcoholic solution of chlo- 

 rophyll with a mixture of two volumes of ether and one volume of 

 concentrated HCl. Upon separation, the upper layer contains the 

 golden yellow xanthophyll, the lower acid layer is colored blnish- 

 green and contains a decomposition product, ])h\llocyanin. 



2. Kraiis' Method: A 65% alcoholic solution of chlorophyll is 

 shaken with twice its volume of benzine (.714). The upper layer is 

 green due to chlorophyll, the lower one is yellow due to xanthophyll. 



Very little, indeed, was known of the chemistry of these coloring 

 matters until Willstatter and his assistants took up the work. To- 

 day we know many interesting facts regarding their chemistry and, 

 thanks to this genial research chemist, a large amount of work has 

 been and is now being done on chlorophyll. Judging by his past most 

 successful work, we can confidently expect that the chemistry of these 

 interesting substances will be completely cleared up within reasonable 

 time. 



I will give a summary of his work of the last six or seven years 

 and, in order not to tire you, I will omit all purely chemical dis- 

 cussions and theories and present facts and how they were found. 



Hoppe-Seylor, von Tschirch, Schenck, Marchkowski and many 

 others had experimented with chlorophyll and came to divergent con- 

 clusions in many cases. 



To obtain chlorophyll in comparatively pure form, Kraus' method 

 was used and improved considerably by the substitution of wood 

 alcohol for ethyl alcohol. Grass, spinach, and many other chloro- 

 phylls were used. It was observed that chlorophyll forms a colloidal 

 solution with water. This colloidal solution was used for purposes of 

 further purification. Ether does not extract chlorophyll from it, but 

 its impurities, especially the carotin. The colloidal solution is pale 

 green, turbid, not fluorescent. The chlorophyll can be recovered from 

 it either by salting out and extracting with ether, or by adding an acid, 

 when the chlorophyll is changed to its insoluble form, deeply colorec;!, 

 when it can be extracted with ether. The chlorophyll, thus purified, 

 was subjected to acid and alkali of dififcrent strength and under dif- 



