i88i.] The Poisonous Power of Metals. 719 
have been continued for forty years. A point of difference 
not to be forgotten is that Dr. Blake operated exclusively 
upon mammals and birds, for which M. Richet’s method 
would have been impracticable. The latter inquirer consi- 
ders that by his immersion method “ we escape the incon- 
veniences due to the variable weight of the animal, and to 
the disturbing chemical reactions which follow on a sudden 
injection into the blood.” We are by no means sure of such 
advantages. Without especial experiment — of which M. 
Richet makes no mention — it may be considered at least an 
open question whether a smaller subject might not succumb 
to a weaker poisonous solution than would a larger animal 
of the same species. It is also more than probable that the 
absorption of the various metallic salts into the circulatory 
system through the skin, and especially the gills, will vary 
quite apart from the poisonous power of each. 
In the cases of iron, strontium, and barium, the author 
tells us that the sulphates and phosphates present in the 
sea-water were previously eliminated by means of a suitable 
quantity of barium chloride. This operation, he maintains, 
did not appreciably affeCt the vital conditions of the fishes 
submitted to the experiment. On this point we must plead 
guilty to a slight degree of scepticism. 
The results obtained by M. Richet differ also from those 
obtained in general experience on the aCtion of poisons in- 
troduced into the animal system by the alimentary canal. 
Thus the soluble salts of barium are, when swallowed, very 
powerful poisons. In M. Richet’s scheme they rank as less 
formidable than the compounds of iron and potassium. 
Everyone knows that a method has been proposed for puri- 
fying “ plastered ” wines, by treating them with a quantity 
of barium tartrate proportionate to the sulphuric acid 
fraudulently introduced. The suggestion, theoretically very 
happy, has not come into any wide practical application, 
from the fear entertained by medical and chemical authorities 
that possibly from some oversight a little barium might re- 
main dissolved in the wine. But if M. Richet’s conclusions 
are of a general value we should find here little cause for 
alarm. In faCt, on the author’s scale, 5 grains of barium, 
in solution, would have only about the same injurious aCtion 
as 10 grains of magnesium ! 
In one very important point M. Richet agrees with Dr. 
Blake, with common experience, and, we venture to add, 
with common sense. He finds that the idea of poison is 
not qualitative, but quantitative. In contradiction to the 
rash dogma that whatever is poisonous in a large dose is, 
