41 .] APPEARANCES OF CARBON MONOXIDE BLOOD. 69 
4 times its volume of lead acetate remains red, but normal blood becomes 
brown. 1 
Solutions of platinum chloride or zinc chloride give a bright red 
colour with CO blood ; normal blood is coloured brown or very dark 
brown. 
Phospho-molybdic acid or 5 per cent, phenol gives a carmine-coloured 
precipitate with CO blood, but a reddish-brown precipitate with normal 
blood (sensitive to 16 per cent.). 
A mixture of 2 c.c. of dilute acetic acid and 15 c.c. of 20 per cent, 
potassic ferrocyanide solution added to 10 c.c. of CO blood produces an 
intense bright red ; normal blood becomes dark brown. 
Four parts of CO blood, diluted with 4 parts of water and shaken 
with 3 vols. of 1 per cent, tannin solution, become at first bright red 
with a bluish tinge, and remain so persistently. Normal blood, on the 
other hand, also strikes bright red at first, but with a yellowish tinge ; 
at the end of 1 hour it becomes brownish, and finally in 24 hours grey. 
This is stated to be delicate enough to detect 0'0023 per cent, in air. 
If blood be diluted with 40 times its volume of water, and 5 drops 
of phenylhydrazin solution be added, CO blood strikes rose-red ; normal 
blood grey-violet. 2 
Gustave Piotrowski 3 has experimented on the length of time blood 
retains CO. The blood of dogs poisoned by this agent was kept in 
flasks, and then the gas pumped out by means of a mercury-pump on 
the following dates :— 
Date. 
Jan. 
12, 
1892 
99 
20, 
99 
99 
28, 
99 
Feb. 
8, 
99 
99 
16, 
99 
99 
26, 
99 
March 
3, 
99 
99 
14, 
99 
99 
22, 
99 
Content of Gas 
in CO. 
24-7 
per cent. 
23-5 
99 
22-2 
99 
20-3 
99 
15-5 
99 
10-2 
99 
6-3 
99 
4-6 
99 
1-2 
99 
The same dog was buried on the 12th of January, and exhumed on 
March 28th, and the gas pumped out from some of the blood ; this gas 
gave 11 - 7 per cent, of CO; hence it is clear that burial preserves CO 
blood from change to a certain extent. 
N. Grehant 4 treated the poisoned blood of a dog with acetic acid, 
and found it evolved 14-4 c.c. CO from 100 c.c. of blood. 
Stevenson, in one of the cases detailed at p. 78, found the blood in 
the right auricle to contain 0-03 per cent, by weight of CO. 
1 M. Rubner, Arch. Hyg., x. 397. 
2 A. Welzel, Centr. med. Wiss., xxvii. 732-734. 
3 Compt. Rend. Soc. de Biol., v. 433. 
4 Compt. Rend., cvi. 289. 
