340 Dr. A Gam gee. Relations of Turacin and [Mar. 19, 



It occurred to me that it would be extremely interesting to de- 

 termine whether turacin, which, as Professor Church first showed in 

 1869,* presents two absorption bands in the visible spectrum, which 

 have a remarkable resemblance to those of oxy-hsemoglobin, would 

 exhibit in the extreme violet or the ultra- violet, an absorption band 

 similar to that of the compounds and certain of the derivatives of the 

 blood colouring matter. To my surprise, I discovered that solutions 

 of turacin in caustic soda or ammonia, so dilute as to be almost 

 colourless, and to exhibit, when a stratum 10 mm. thick was examined, 

 only a faint shading in the position of the stronger of the two turacin 

 bands in the green, absorbed the extreme violet and ultra-violet rays 

 of the spectrum precisely as highly diluted solutions of the acid 

 compounds of hasmatin (e.g., hsematin hydrochloride dissolved in 

 glacial acetic acid). My first observations were made by allowing 

 the spectrum of a beam of sunlight reflected into the dark room from 

 the mirror of the heliostat, and which had passed through the solution 

 of turacin, to fall upon a fluorescent screen of the double cyanide of 

 platinum and barium, when an intense absorption band at the com- 

 mencement of the ultra-violet was visible to the naked eye. I sub- 

 sequently confirmed this observation by taking a series of photographs 

 of the spectrum, employing solutions of turacin of various degrees of 



G HK L M N OP OR 



Absorption Spectrum oe Turacin (violet and ultra-violet) . 

 Highly diluted solution in NaOH exhibiting, when a stratum 10 mm. thick was 

 examined, only a faint shadow in the position of the stronger of the two 

 turacin bands in the green.f 



* A. H. Church, " Researches on Turacin, an Animal Pigment containing 

 Copper," ' Roy. Soc. Proc.,' vol. 17 (1869), p. 436 ; ' Phil. Trans.,' vol. 159 (1869), 

 pp. 627—636. 



f This solution contained not more than 1 part of turacin in 200,000 parts. 

 March 22, 1896. 



