DE. A. GAMGEE ON THE ACTION OE NITEITES ON BLOOD, 
621 
On the Nature of the Action which Nitrites exert on the Colouring-matter of Blood. 
Whatever might be the nature of the change induced by nitrites in haemoglobin, 
it resulted from my experiments that it could not be one which deeply altered the con- 
stitution of the substance, seeing that the addition of certain reagents at once caused 
all the effects of the action to disappear and revealed the continued existence of oxidized 
haemoglobin in the blood. Nitrites had, by my experiments, been shown to resemble in 
no way those agents which thrust oxygen out of the blood ; on the other hand, it had 
been proved that the action of nitrites resulted in the locking up of the oxygen of the blood 
so as to render it irremoveable by CO or by a vacuum. A consideration of all the facts 
which I had observed led me to believe that probably nitrites might actually link them- 
selves to oxidized haemoglobin — a supposition which has been verified in the most ample 
manner. 
In the experiments now to be described I have always made use of haemoglobin pre- 
pared from the blood of the Dog, in the following manner. The dog whose blood was 
to be used for the preparation of haemoglobin was kept for a considerable time under 
the influence of chloroform, and then bled to death. 
The blood was allowed to coagulate, and the serum separated as completely as pos- 
sible. 
After twenty-four hours the blood-clot was broken up and firmly squeezed in linen or 
calico. The red fluid thus expressed was mixed with one and a half times its volume 
of distilled water, and set aside for three or four hours. At the end of that time the 
fluid was filtered through Swedish paper and mixed with one-fourth of its volume of 
eighty per cent, spirit. It was then placed in a vessel surrounded by ice and salt, and 
set aside until the following morning. The fluid was usually found to have become semi- 
solid from the separation of magnificent microscopic crystals of haemoglobin. These 
were collected on a filter, washed with distilled water, and then dissolved in water at 
about 38° C. The clear red solution was filtered, treated with one-fourth of its volume 
of alcohol (eighty per cent.), and frozen. The haemoglobin had at the end of twenty- 
four hours again crystallized out. 
1. Action of Nitrite of Potassium on Hcemoglobin. 
When solutions of haemoglobin are treated with solutions of nitrite of potassium, the 
colour changes, as in the case of blood similarly acted upon, to a dark brown. Simul- 
taneously the spectrum assumes the characters observed when nitrites act upon blood. 
If a saturated solution of haemoglobin be treated with a solution of nitrite of potassium 
until its colour is thoroughly changed, and if one-fourth of its volume of alcohol be 
then added, and the fluid set aside in a freezing-mixture, a brown deposit separates 
after some hours, having very much the colour of chocolate. This deposit consists of 
magnificent microscopic crystals, quite undistinguishable in form from those of oxidized 
haemoglobin, but differing from these in appearing much less coloured, under the micro- 
scope, than the crystals of O-Hb, and in possessing only a faint yellow, but no red colour. 
