144 Supposed Identity of Biliverdin with Chlorophyll^ ^c. [Feb. 25, 



The paper concludes "with a brief deduction of the observed laws of 

 Conjugate and Secondary Joints from known mechanical principles. 



II. " On the supposed Identity of Biliverdin with Chlorophyll, with 

 remarks on the Constitution of Chlorophyll." By G. G. Stokes, 

 M.A., Sec.R.S. Received February 25, 1864. 



I have lately been enabled to examine a specimen, prepared by Professor 

 Harley, of the green substance obtained from the bile, which has been 

 named biliverdin, and which was supposed by Berzelius to be identical 

 with chlorophyll. The latter substance yields with alcohol, ether, chloro- 

 form, &c., solutions which are characterized by a peculiar and highly di- 

 stinctive system of bands of absorption, and by a strong fluorescence of a 

 blood-red colour. In solutions of biliverdin these characters are wholly 

 wanting. There is, indeed, a vague minimum of transparency in the red ; 

 but it is totally unlike the intensely sharp absorption-band of chlorophyll, 

 nor are the other bands of chlorophyll seen in biliverdin. In fact, no one 

 who is in the habit of using a prism could suppose for a moment that the 

 two were identical ; for an observation which can be made in a few seconds, 

 which requires no apparatus beyond a small prism, to be used with the naked 

 eye, and which as a matter of course would be made by any chemist work- 

 ing at the subject, had the use of the prism made its way into the chemical 

 world, is sufficient to show that chlorophyll and biliverdin are quite distinct. 



I may take this opportunity of mentioning that I have been for a good 

 while engaged at intervals with an optico-chemical examination of chloro- 

 phyll. I find the chlorophyll of land-plants to be a mixture of four sub- 

 stances, two green and two yellow, all possessing highly distinctive optical 

 properties. The green substances yield solutions exhibiting a strong red 

 fluorescence ; the yellow substances do not. The four substances are soluble 

 in the same solvents, and three of them are extremely easily decomposed by 

 acids or even acid salts, such as binoxalate of potash ; but by proper treat- 

 ment each may be obtained in a state of very approximate isolation, so far 

 at least as coloured substances are concerned. The phyllocyanine of Fremy* 

 is mainly the product of decomposition by acids of one of the green bodies, 

 and is naturally a substance of a nearly neutral tint, showing however ex- 

 tremely sharp bands of absorption in its neutral solutions, but dissolves in 

 certam acids and acid solutions with a green or blue colour. Fremy's 

 phylloxanthine differs according to the mode of preparation. "When pre- 

 pared by removing the green bodies by hydrate of alumina and a little 

 water, it is mainly one of the yellow bodies ; but when prepared by hydro- 

 chloric acid and ether, it is mainly a mixture of the same yellow body 

 (partly, it may be, decomposed) with the product of decomposition by acids 

 of the second green body. As the mode of preparation of phylloxantheine 



* Comptes Rendus, lorn. 1. p. 406. 



