896 Royal Society : — 



This difference of spectra shows that the colouring matter (hsema- 

 tine) obtained by acids is a product of the decomposition, or meta- 

 morphosis of some kind, of the original colouring matter. 



When hsematine is dissolved in alcohol containing acid, the spec- 

 trum nearly agrees with that represented in fig. 3. 



12. Hsematine is capable of reduction and oxidation likecruorine. 

 If it be dissolved in a solution of ammonia or of carbonate of soda, 

 and a little of the iron salt already- mentioned, or else of hydrosul- 

 phate of ammonia, be added, a pair of very intense bands of absorp- 

 tion is immediately developed (fig. 4). These bands are situated at 

 about the same distance apart as those of scarlet cruorine, and are 

 no less sharp and distinctive. They are a little more refrangible, a 

 clear though narrow interval intervening between the first of them 

 and the line D. They differ much from the bands of cruorine in 

 the relative strength of the first and second band. With cruorine 

 the second band appears almost as soon as the first, on increasing the 

 strength or thickness of the solution from zero onwards, and when 

 both bands are well developed, the second band is decidedly broader 

 than the first. With reduced hsematine, on the other hand, the first 

 band is already black and intense by the time the second begins to 

 appear ; then both bands increase, the first retaining its superiority 

 until the two are on the point of merging into one by the absorption 

 of the intervening bright band, when the two appear about equal. 



Like cruorine, reduced hsematine is oxidized by shaking up its 

 solution with air. I have not yet obtained hsematine in an acid 

 solution in more than one form, that which gives the spectrum fig. 3, 

 and which I have little doubt contains hsematine in its oxidized 

 form ; for when it is withdrawn from acid ether by an alkali, I have 

 not seen any traces of reduced hsematine, even on taking some precau- 

 tions against the absorption of oxygen. As the alkaline solution of 

 ordinary hsematine passes, with increase of thickness, through yellow, 

 green, and brown to red, while that of reduced hsematine is red 

 throughout, the two kinds may be conveniently distinguished as 

 brown hcematine and red hcp.matine respectively, the former or oxi- 

 dized substance being the hsematine of chemists. 



13. Although the spectrum of scarlet cruorine is not affected by the 

 addition to the solution of either ammonia or carbonate of soda, yet if 

 after such addition the solution be either heated or alcohol be added, 

 although there is no precipitation decomposition takes place. The 

 coloured product of decomposition is brown hsematine, as may be 

 inferred from its spectrum. Since, however, the spectrum of an alka- 

 line solution of brown hsematine is only moderately distinctive, and is 

 somewhat variable according to the nature of the solvent, it is well to 

 add hydrosulphate of ammonia, which immediately developes the 

 remarkable bands of red hsematine. This is the easiest way to obtain 

 them ; but the less refrangible edge of the first band as obtained in 

 this way is liable to be not quite clean, in consequence of the pre- 

 sence of a small quantity of cruorine which escaped decomposition. 



Some very curious reactions are produced in a solution of cruorine 

 by gallic acid combined with other reagents, but these require further 

 study. 



