454 



Mr. H. C. -Sorby on 



[June 19, 



band in the middle of the blue ; the whole of the blue is absorbed, and 

 not, as in the case of blue chlorophyll, a considerable portion transmitted. 

 The general colour is therefore such a yellow-green that the term yellow 

 chlorophyll seems very appropriate. When dissolved in alcohol the prin- 

 cipal band in the red is made about twice as broad, and half as dark, as 

 when in benzole or bisulphide of carbon, and can no longer be seen quite 

 detached and separate from that due to blue chlorophyll, especially i£ the re- 

 lative amount of the latter be considerable, and merely causes an unsymme- 

 trical shading on the side towards the orange. It is to this circumstance 

 in great measure that must be attributed the fact of the compound nature 

 of chlorophyll having been overlooked, alcohol having been so generally 

 used as the solvent. 



Chlorofucine. 



It is some time since I was first led ' to believe that a third kind of 

 colouring-matter belonging to the chlorophyll group existed in some 

 freshwater Algce. I first obtained it separate from blue chlorophyll in 

 examining a complicated mixture of that and other substances obtained 

 by Mr. Charles Horner from an Actinia, viz. Anthea cereus, var. smarag- 

 clina. The special bands due to this other substance had attracted his 

 attention, and led him to think that the chlorophyll, as a whole, was 

 different to that in plants. I have since found that this third member 

 of the group is one of the fundamental constituents of Focus and other 

 olive Algce, and have therefore named it chlorofucine. In order to obtain 

 it approximately pure, the fresh fronds should be crushed in a mortar 

 and slightly dried, so that on adding ordinary spirit of wine too much 

 water may not be present. For the same reason the solution should be 

 kept covered up at a gentle heat, and not boiled. On agitating with 

 repeated quantities of bisulphide of carbon, the whole of the blue chlo- 

 rophyll may be removed, and the alcoholic solution then contains much 

 f ucoxanthine and the chlorofucine, shoving two well-marked absorption- 

 bands, one between the red and the orange and the other in the yellow. 

 On adding water and agitating with more bisulphide, both these sub- 

 stances are carried down; and on evaporating the mixed solution, the 

 chlorofucine is often partially lost by decomposition in some unknown 

 way. To prepare it free from fucoxanthine, the above-named alcoholic 

 solution, should be diluted with an equal bulk of water, a drop or two of 

 ammonia added, and agitated over and over again with fresh bisulphide, 

 until it subsides to the bottom almost colourless. By thus adding' am- 

 monia the chlorofucine is retained in solution, and the whole of the 

 fucoxanthine is carried down in the bisulphide. The dilute alcoholic 

 solution is then of a pale green colour, and contains chlorofucine mixed 

 with a yellow substance soluble in water. On evaporating to small bulk 

 at a gentle heat, the loss of alcohol causes impure chlorofucine to be 

 deposited ; and after transferring to a narrow tube, allowing it to sub- 

 side, and removing the yellow aqueous solution, almost pure chlorofucine 



