1881J The Ptomaines and the Snake Poisons . 735 
death of the person in question might be wrongfully con- 
victed. 
Fortunately a method of distinguishing the two classes of 
poisons has been discovered. The ptomaines have a most 
intense reducing power. If a small trace of one of them is 
brought in contact with a trace of potassium ferricyanide — 
commonly called the red prussiate of potash — the latter is 
instantly converted into potassium ferrocyanide, the yellow 
prussiate. This change is at once known by the faCt that 
the mixture after the reduction gives an immediate blue 
colour with a small quantity of a ferric salt (persalt of iron), 
the liquid being of course neutral or very slightly acid. 
Certain of the vegetable alkaloids — such as hyoscyamine, 
emetine, igasurine, veratrine, colchicine, nicotine, and apo- 
morphine— reduce, indeed, the ferricyanide, but less rapidly 
than the ptomaines. So far, then, we are freed from the 
terrible risk of being led by deceptive reactions to condemn 
an innocent person. At the same time it must be admitted 
that certain highly poisonous artificial bases — phenylic, pyr- 
ridic, hydro-pyrridic, allylic, &c. — behave with potassium 
ferricyanide, and with a subsequent addition of a persalt of 
iron, exactly like the ptomaines. Certain authorities, indeed, 
console themselves and the public with the reflection that 
these artificial bases have not yet found a place among the 
stock-in-trade of the criminal classes. We fear this is but 
a broken reed to lean upon, and it is therefore highly im- 
portant that the properties of the ptomaines should be more 
thoroughly examined, so as to find some absolute method of 
detection. 
It appears in the meantime that Dr. Gautier was engaged 
in the investigation of these carcase-poisons almost simul- 
taneously with Selmi, and he has since greatly extended our 
knowledge of the subject. He finds that the ptomaines are 
formed not indifferently from any and every portion of the 
dead body, but solely from its albumenoid portions. What 
is much more important, he has proved that these poisons 
are not essentially and solely generated after death and 
during putrefaction, but occur in the normal excretions of 
man and of other animals, and in small quantities in most 
of our tissues. They are, in his opinion, necessary products 
of the process of dis-assimilation which is constantly going 
on in the tissues, — a residue, so to speak, of their life. The 
signification of this idea, theoretical and practical, can 
scarcely be over-rated. 
In urine — not in any diseased condition, but in its normal 
state— two highly poisonous bodies have "been not merely 
