DE. A. GAMGEE ON THE ACTION OE NITEITES ON BLOOD. 
595 
in a hollow glass prism, which permitted me to examine definite and varying thicknesses 
of fluid. The prism had a capacity of 200 cub. centims. 
With a layer of solution 2 centimetres thick, the following observations were made : — 
Extent of spectrum visible . . . 30-110 
Absorption-band in yellow (a) . 60-65 
Absorption-band in green (/3) . . 71-76 
Five drops of nitrite of amyl were now added ; after ten minutes a slight fading of 
the band in the green and a brown tinge in the colour of the fluid was noticed. After 
fifteen minutes the two absorption-bands a and /3 had become so exceedingly faint and 
ill-defined as not to be capable of accurate measurement. There was also a faint 
absorption-band in the red, having its centre at 49. A stratum of the fluid 3-8 centi- 
metres broad was now examined with the following results : — 
Extent of spectrum visible . . . 35-110 
Absorption-band a 60-65 (very faint) 
Absorption-band /3 71-76 (very faint) 
Absorption-band l (in red) . . . 48-51 
The fluid was now made faintly ammoniacal. The band in the red instantly disap- 
peared ; the haemoglobin bands became much darker ; the orange was, however, shaded 
partly by a faint absorption-band which appeared to run into the band a. The following 
observations were made : — 
Length of visible spectrum . . . 30-110 
Absorption-band a 60-65 
Absorption-band a' 56-59 
Absorption-band (3 72-78 
The observation just detailed is merely taken as an example of what always occurs 
when a nitrite acts upon blood, and when the latter is afterwards treated with ammonia. 
Obs. II. If after the action of a nitrite upon blood and the subsequent addition of 
ammonia, a solution of sulphide of ammonium or a reducing iron-solution be added, 
there is a very rapid and extraordinary change, viz. the spectrum of the original blood 
is first re-established, and thereafter gives place to that of reduced haemoglobin. 
The reduced blood then differs in no respect from blood that has been reduced 
without the previous addition of nitrites; it yields, when shaken with air, the spec- 
trum of the oxidized colouring-matter, and instead of a brown chocolate-colour-, it 
possesses again the colour of blood. The action of the reducing-solution in first of all 
changing the nitrite spectrum to that of oxidized haemoglobin takes place quite inde- 
pendently of the external air. If, for example, the blood-solution in which a nitrite 
had induced its characteristic action be placed in the prism bottle, and then a long- 
pipette full of sulphide of ammonium be plunged to the bottom of it, the two sharply- 
defined absorption-bands of O-Hb at once appear at the point where the fluids have 
