AN ANIMAL PIGMENT CONTAINING COPPER. 
517 
that its spectrum bears a very close resemblance to that of alkaline haematoporphyrin. 
It has four well-marked absorption-bands (shown in fig. A), the wave-lengths of 
which, in millionths of a millimetre, are—1st band, X 619 to 601 ; 2nd band, 577 to 
550'5 ; 3rd band, 545 to 526 ; 4tli band, 512*5 to 488. These bands differ in position 
Fig. A 
Fig. XB 
and relative intensity and breadth from those of a similar solution of turacin (compare 
figs. 6 and 7). The resemblance of this new derivative of turacin to haematoporphyrin 
is strongly accentuated by the further observation, that the acid filtrate from the 
precipitate above described possesses a spectrum which Dr. MacMunn says has “ a most 
remarkable resemblance to that of acid haematoporphyrin.” It has a purple rather 
than a crimson hue ; and, though its spectrum has four bands (shown in fig. B), they 
differ in position and in relative intensity from those of the alkaline solution just 
described, and from those of an alkaline solution of turacin. Their wave-lengths are— 
1st band, 601 to 587 ; 2nd band, 579 to 569 ; 3rd band, 562 to 535 ; 4th band, 523 
to 499 ; the 2nd band is faint, the 4th a slight shading only. This acid solution, 
when very nearly neutralised with ammonia, becomes colourless, depositing a floccu- 
lent precipitate, which proves to be identical with that previously separated on pouring 
the oil of vitriol solution into cold water. It is, in fact, soluble in some dilute acids, 
but not in pure water nor in solutions of neutral salts. 
From the analyses which will be presently given, it seemed likely that the atomic 
ratio of metal to nitrogen in turacin might prove to be 1 : 4, as in hae matin ; and it was, 
indeed, the resemblance between these two pigments which induced me to try and 
ascertain whether turacin would yield, by solution in oil of vitriol, a coloured metal- 
free derivative similar to that which hsematin produces under the same circumstances. 
My expectation has, it will be seen, been partially realised ; but the new coloured 
derivative of turacin still retains much copper. Its solubility in dilute sulphuric acid 
and the spectra of its alkaline and acid solutions afford, however, strong corroborative 
evidence in favour of the view that the new derivative of turacin is nearly related to 
haematoporphyrin, and that turacin itself, though nearly related to haematin, has a 
somewhat more complex constitution. 
