Researches on the blood.—On the action of nitrites on the blood

The paper commences with a statement of the facts with which we are at present acquainted, relating to the nature and character of the blood-colouring-matter, and its relation to gases. I. The action of nitrites in modifying the colour and spectrum of blood is then described. Under the influence of nitrites, arterial blood assumes a chocolate coloration. Coincidently the bands of scarlet cruorine (oi oxidized hæmoglobin) become very faint, and an additional absorption band, occupying the same position as that of acid hæmatin, appears. The addition of ammonia to blood in which nitrites have induced the characteristic change of colour and spectrum, causes the red colour to return and gives rise to a new spectrum in which the normal blood-bands are again better defined, but accompanied by a faint and rather undefined absorption band in the orange. It appears from the experiments of the author that the change in optical properties induced by ammonia is not due to any decomposing action exerted upon the body formed under the influence of nitrites; for on neutralizing the solution to which ammonia has been added, the original spectrum is reproduced. When sulphide of ammonium, oi a reducing-solution of iron is added to a blood solution which has been acted upon by nitrites, all effects of their action disappear, and the solution again possesses the spectrum of oxidized blood-colouring-matter, although precautions have been taken to exclude atmospheric air. The continued action of the reducing-solution then leads to the reduction of the blood-colouring, matter, which when shaken with air again yields the perfectly normal spectrum of blood. It would therefore appear that when nitrites act upon the blood-colouring-matter they do not decompose it, nor thrust out oi remove the loose oxygen with which it is combined.