THE MONTHLY 
JOURNAL OF SCIENCE. 
MARCH, 1879. 
I. THE KEYS OF DEATH. 
t S strychnin, or prussic acid, or arsenic a poison ? The 
answer is ready. What is a poison ? The oracles 
are dumb. We have in these days almost ceased 
playing at the game of definitions. We no longer ask what 
is gravitation, or motion, or light, feeling that our answers 
to such questions can only bewilder. Definitions of life are 
still gravely asked for, and as gravely propounded. But 
they, too, will soon be given up, and neither Science nor 
daily life will find cause to regret them. As concerns a 
satisfactory definition of poison the case is very similar. 
Two attempts have, however, been lately made to supply 
this deficiency. Certain physiologists, speaking in the in- 
terest of a certain philanthropic movement, contend that 
the idea of poison is purely qualitative, and that whatever 
is poisonous in large doses is poisonous also in the very 
smallest proportions, the only difference being that the 
injury done may escape observation unless the dose is often 
repeated. We cannot for a moment accept this view. We 
maintain that it is perfectly unchemical to ignore the ideas 
of quantity and concentration. It would be easy to give 
numerous instances where — if the reagents employed are 
less in proportion, or weaker than the required standard — 
we obtain not a smaller quantity of the product sought for, 
but a substance totally different, or, in certain cases, no 
aCtion at all. Or if we, coming at once to the mark, fix our 
attention upon the higher animals, we find that for them all 
oxygen is the first necessary of life. If deprived of it for 
but a few minutes they inevitably perish. Yet Davy proved 
VOL. ix. (n.s.) p 
