1896.] Contributions to the Chemistry of Chlorophyll. 233 



meter, a, of the sensitive surface was about in., while A was 2 ft., 

 so that a/A = 1/480; hence we have (q.p.) — 



I]i = 516 x 10 24 , 



that is, Procyon is equivalent to about 516 billions of billions of 

 standard candles. 



We cannot help being struck by the enormous power of Betelgeuse 

 as indicated in the table. The deflection observed was the mean of 

 jive, all very fairly close. Now the only parallax recorded for this 

 star, so far as I can ascertain, is a negative one ! The star is, there- 

 fore, immeasurably distant, and yet the E.M.F. of its light is very 

 great; hence it must be possessed of tremendous energy. 



We hope that our next observations will be taken with still better 

 appliances, as Mr. Wilson has suggested a great improvement in the 

 call-carrying apparatus, which will enable us to see simply and with 

 certainty when the light of the star is falling exactly on the sensitive 

 selenium surface. 



III. " Contributions to the Chemistry of Chlorophyll. No. VII. 

 Phylloporphyrin and Hseniatoporphyrin : a Comparison." 

 By Edward Schunck, F.R.S., and Leon Marchlewski, 

 Ph.D. Received January 23, 1896. 



In the memoir on the Chemistry of Chlorophyll immediately pre- 

 ceding this one, we described a derivative of chlorophyll, the analysis 

 of which, confirmed by that of its zinc salt, led to the formula 

 C 32 H3i]N"402. This substance being probably in the main identical 

 with tbe phylloporphyrin of previous observers, we saw no reason to 

 give it another name. 



Recent investigations of the colouring matter of blood, more espe- 

 cially that of JSTencki and Sieber, have shown that to the anhydride 

 of hasmatoporphyrin, a derivative of haemoglobin, the formula 

 C 3 >H34N" 4 05 is to be ascribed. This formula differs from that of 

 phylloporphyrin simply by three atoms more of 0. Bat the resem- 

 blance between the two substances is not confined to the approxima- 

 tion of their formulas ; it extends also to several of their physical 

 properties, such as the colour of their solutions, but more especially 

 the appearance of these solutions before the spectroscope, which is 

 so nearly alike, so far as the absorption spectra are concerned, that not 

 knowing their wide difference in other respects we might be inclined 

 to consider them as identical. That the two series of derivatives, that 

 of chlorophyll and that of haemoglobin, each playing an important 

 part in the vegetable and animal organism respectively, should so 

 nearly touch at one point is certainly a remarkable circumstance. In 



VOL. LIX. E 



