VIII. On the reduction and oxidation of the colouring matter of the blood

Abstract

1. Some time ago my attention was called to a paper by Professor Hoppe, in which he has pointed out the remarkable spectrum produced the absorption of light by a very dilute solution of blood, and applied he observation to elucidate the chemical nature of the colouring matter. had no sooner looked at the spectrum, than the extreme sharpness and eauty of the absorption-bands of blood excited a lively interest in my ind, and I proceeded to try the effect of various reagents. The observation is perfectly simple, since nothing more is required than to place the solution to be tried, which may be contained in a test-tube, behind a slit, nd view it through a prism applied to the eye. In this way it is easy to erify Hoppe’s statement, that the colouring matter (as may be presumed at least from the retention of its peculiar spectrum) is unaffected by alkaline arbonates and caustic ammonia, but is almost immediately decomposed y acids, and also, but more slowly, by caustic fixed alkalies, the coloured product of decomposition being the haematin of Lecanu, which is easily dentified by its peculiar spectra. But it seemed to me to be a point of special interest to inquire whether we could imitate the change of colour of arterial into that of venous blood, on the supposition that it arises from reduction. 2. In my experiments I generally employed the blood of sheep or oxen obtained from a butcher; but Hoppe has shown that the blood of animals in general exhibits just the same bands. To obtain the colouring matter in true solution, and at the same time to get rid of a part of the associated matters, I generally allowed the blood to coagulate, cut the clot small, rinsed it well, and extracted it with water. This, however, is not essential, and blood merely diluted with a large quantity of water may be used; but in what follows it is to be understood that the watery extract is used unless the contrary be stated.