222 Mr. A.W.E. O’Shaughnessy on Green Oysters. 
had been subjected to about six months sojourn in the company 
of their French brethren. Coming, after this prefatory informa- 
tion, to the case in point, he related how a certain tradesman, 
actuated by the lawless desire of premature aggrandizement, 
had been guilty of selling, in the market of Rochefort, oysters 
from Falmouth which had remained only three weeks in the 
French beds. By a prompt analysis of the remaining indivi- 
duals belonging to this poisonous batch of oysters, made by 
M. Cuzent, it was found that an average of “23 centigrammes 
(about 34 grains) of salt of copper was yielded by a dozen of 
these oysters”—a dose which, as M. Crosse remarks, in the 
‘ Journal de Conchyliologie,’ is more than sufficient to account 
for the evil effects which are said to have manifested themselves. 
The presence of so extraordinary a product as copper in these 
oysters was soon accounted for by the discovery that the part of 
the Bay of Falmouth whence they were brought was in the im- 
mediate vicinity of a mine of copper then in process of working. 
The waters which continually washed the bank, being strongly 
impregnated with salts of copper, communicated a similar sea- 
soning to the oysters, which, thanks to their obtuseness of or- 
ganization, seem to have been very little affected by it them- 
selves, and to have become in some sort acclimatized. 
Very different, however, was the effect produced on the un- 
suspecting dupes of the Rochefort merchant. According to all 
accounts, it would appear to have been a veritable case of poi- 
soning, although, we believe, fatal consequences were averted ; 
and, in spite of the assurances of M. Bourricaud, that a “ com- 
plete poisoning” by means of these oysters would be impossible, 
we agree with the editor of the ‘ Journal de Conchyliologie’ that 
an incomplete one is a sufficiently disagreeable affair. 
In order to ascertain the presence of copper in the oyster, 
M. Cuzent recommends that a sufficient quantity of pure am- 
monia be poured upon the flesh, which will soon declare its 
poisonous qualities by assuming the dark-blue tint which dis- 
tinguishes ammoniacal salts of copper. Another method is to 
plunge a sewing-needle into the green parts of the oyster, and 
immerse it so transfixed in vinegar. In a few seconds the parts 
of the needle in contact with the flesh will become covered with 
a coating of red copper reduced to the metallic state. It appears 
that an oyster in which the green tint is peculiarly clear is 
especially to be avoided, while those which are of a bluish green 
colour are not only fit to eat, but are considered very choice. 
Now the green tint frequently observable in the oyster has 
attracted the attention of scientific men from time to time, long 
before the serious occurrences just mentioned, which took place 
in the spring of 1862; and it would seem that, in nearly all the 
