DR. A. GrAMGrEE ON THE ACTION OE NITRITES ON BLOOD. 
597 
The two observations which I have adduced suffice to show the action which the solu- 
tion of any nitrite exerts upon the colouring-matter. In my observations I have most 
frequently treated blood with solutions of nitrite of potassium and sodium. The action 
of a solution of nitrite of silver is, however, similar. The latter solution should be 
freshly prepared, and should not be much exposed to light. The observations should 
also, in this case, be made within a short time after the addition of the nitrite to the 
blood-solution, as otherwise the solution often becomes turbid. 
The fact that ammonia altered the colour of blood which had been treated with 
nitrites from a chocolate-colour to red, might be explained on the supposition that some 
change had occurred in the constitution of the body formed under their influence, although 
it was quite possible that the spectrum of the body in a decidedly alkaline fluid might be 
different from that of the same substance in a nearly neutral solution. In order to deter- 
mine whether the difference induced in the colour and spectrum was merely due to the 
alkalinity of the fluid, or to the presence of free ammonia, I prepared a dilute solution 
of ammonia. This solution contained 10 grms. of ammonia in 1 litre. I then made 
an exactly equivalent solution of phosphoric acid. The solutions were so exactly made 
that when equal quantities were mixed the fluid had no action on litmus. A weak 
solution of haemoglobin was made, and a solution of nitrite of sodium added to it. As 
soon as the bands a and j3 had almost disappeared and the band in the red had ap- 
peared, I added 1 cub. centim. of the solution of ammonia. Immediately thereafter 
the absorption-band in the red disappeared, and the spectrum previously described as 
developed by the action of ammonia was seen, i. e. the orange was shaded over, and the 
bands ct and j3 became more distinct. 
One cub. centim. of the dilute solution of phosphoric acid was now added. Instantly 
the spectrum returned to the condition in which it had been before the addition of am- 
monia. On again adding another cub. centim. of ammonia, the band in the red disap- 
peared and the orange became shaded over. By repeated observations I found that if 
care were taken to measure out exactly the same volume of the dilute acid and ammonia, 
the change from one spectrum to the other might be almost indefinitely repeated. 
Without wishing at this stage to enter into a discussion concerning the cause of the 
changes which nitrites induce, I shall confine myself to remarking that the observations 
which I have described appeared to me to show — 
First, that nitrites exert a marked influence both on the colour and the spectrum of 
blood, due obviously to a chemical change exerted on the colouring-matter. 
Secondly, that, whatever the nature of the change, it is obviously not one which mate- 
rially alters the composition of the colouring-matter, as by mere action of reducing-agents 
all effects of the change disappear ; and 
Thirdly, that the fact of reducing-agents developing, without the intervention of the 
atmospheric oxygen, the spectrum of oxidized haemoglobin before exerting their reducing- 
action, proves that by the action of nitrites the loose oxygen of the blood is neither 
expelled nor removed. 
