228 RALPH, ON THE EFFECTS OF 
gr. of cyanide of potassium, injected into the stomach. Three 
specimens of blood examined only showed a slaty-blue colour 
in one or two large flakes or patches. The blood-discs 
appeared to be dotted over with small oily looking dots. 
10th Exp.—A_ blow-fly was killed by exposure to the 
vapour of prussic acid. The muscles lining the thorax, in the 
vicinity of the principal nerve-centres, were examined. Several 
dark blue points were seen, and one large particle of a 
decidedly bright blue, equal to any seen in the experiments 
already quoted. 
llth Exp.—The same repeated, and with a bee, with 
similar results. 
Norr.—tThe bright blue particles are, I believe, really due 
to the action of the prussic acid, but I have also noticed in 
some flies not killed by prussic acid that there were present 
some indigo-blue coloured particles. These I refer to the 
natural pigment of the insect, serving, perhaps, to tinge the 
deep steel-blue coloured hairs; fragments of which will be 
met with in such examinations; hence this insect is not a fit 
subject for yielding positive results. With this in view I in- 
stituted the 
12th Exp.—The maggot of the blow-fly, which is very 
difficult to kill by prussic-acid vapour, was subjected to its 
influence in the fluid state. Two so treated exhibited the 
characteristic blue masses and particles. This experiment I 
consider to be very satisfactory, as all the organs appear to be 
free from pigmentary matters. 
13th Exp.—A rabbit six weeks old had four slides of blood 
taken from the ear; these exhibited no blue particles. It 
was then killed by inhalation of prussic-acid vapour, admi- 
nistered on two separate occasions ; it was intended to exa- 
mine the blood without killing the animal, but the second 
application of the vapour killed it very suddenly. The blood 
in one specimen exhibited a very large, brilliant, Prussian- 
blue concretion; some blue particles in the blood from the 
axillary vein, and also from several other sources. 
6. I will now, before proceeding, give a résumé of the ex- 
periments, and some observations on them. Eleven experi- 
ments in all gave evidence of the action of prussic acid, by 
the presence of blue-coloured particles, masses, or films, 
When I have used the term mass, J mean a solid substance 
occupying a space which twenty or thirty blood-dises would 
cover. 
The inhalation of the vapour of prussic acid goes to show 
that, in some of the experiments at any rate, but a very small 
quantity sufficed to kill, and its traces were detectable. 
