68 poisons: their effects and detection. [§41. 
diluted solution ; if the solution is shaken up with air, the spectrum 
changes into the one-banded alkaline hsematin (fig. 6), as seen in an 
alcoholic solution, but on standing the two-banded spectrum of hsemo- 
chromogen slowly comes back ; these changes can be traced with the 
naked eye, for the red solution, on shaking with air, takes a greenish 
tint, and then slowly returns back into purple-red. There is no dye 
which possesses similar properties, hence this naked-eye change is 
almost sufficient to identify a red organic substance as blood. Hsemato- 
porphyrin (figs. 8 and 9) is obtained by heating blood carefully for a 
short time with sulphuric acid of a certain concentration. 
Sulphsemoglobin (fig. 10) is obtained by treating diluted blood with 
sulphuretted hydrogen in the presence of air ; it gives a very definite 
band (619*8) ; at the same time the oxyhsemoglobin bands fade ; this 
is the appearance which may be seen in the blood of persons poisoned 
by hydric sulphide. 
The spectrum of carbon monoxide haemoglobin (fig. 11) is that 
of oxyhaemoglobin with the bands slightly displaced towards the 
violet end. 
Formanek, in researches on guinea-pigs, has shown that the maximum 
displacement only occurs when the blood has attained a certain amount 
of saturation with the gas. 
In four animals the blood was examined during life, when the 
convulsions began, and after death, with the following results :— 
In Convulsive Stage. 
After Death. 
Centre of 
Chief Band. 
Centre of 
Subsidiary 
Band. 
Centre of 
Chief Band. 
Centre of 
Subsidiary 
Band. 
1 . 
X 576 
X 540 
X 572-5 
X 538-3 
2. 
X 576 
X 540 
X 572-7 
X 538-5 
3. 
X 576 
X 540 
X 573-0 
X 538-7 
4. 
• • 
• • 
X 572-7 
X 538-5 
The blood in CO poisoning has also other characteristics. It is of a 
peculiar florid vermilion colour, a colour that is very persistent, lasting 
for days and even weeks. 
Normal blood mixed with 30 per cent, potash solution forms greenish 
streaky clots, while blood charged with CO forms red streaky clots. 
Normal blood diluted to 50 times its volume with water, and then 
treated successively with yellow ammonium sulphide in the proportion 
of 2 to 25 c.c. of blood, followed by 3 drops of acetic acid, gives a 
grey colour, while CO blood remains bright red. CO blood shaken with 
