SEA-FISHERIES LABORATORY. 129 
breaking. This extreme softness and pastiness does not 
proceed so far in the case of fish packed in oil. Oil oozes 
out from the fish into the watery media, and water comes 
out into the oil from fish that have been packed in an oil 
medium. In the latter case (with olive oil, at all events) the 
watery fluid that oozes out from the fish may form an 
apparently homogeneous mixture with the oil in the tin, so 
that the weight of the latter can be reduced on drying at 
100° C., even if the presence of water does not become 
apparent by the mechanical separation of the latter. 
The richness of the flavour may pass into something 
that (to the trained palate of the trade expert) suggests 
decomposition, just as game that has been “ hung” becomes 
> or as cheese may become too rich in taste. But 
“ gamey,’ 
nothing in the appearance, smell or taste of such over-matured 
tinned fish suggests putrefaction in the usual sense, and one 
has, of course, no reason to expect that this condition would 
be set up by well-packed hermetically-sealed fish, in oil, or 
other suitable media. 
The internal surface of the tin undergoes change. In 
marmaded goods, which may contain acid, or produce acid 
(at first) the tm may be etched. It is probable that no means 
of protecting the tin, such as by shellac varnish would be 
permanently effective. Both in oil and tomato sauce the tin- 
plate becomes slowly blackened, and this change is progressive 
with the length of maturation. The film of tin is apparently 
removed and the iron blackened, and it is easy to show that 
the black substance is a film of ferrous sulphide. The film 
of tin on the plate may be regarded as a solution of iron in tin 
and the iron is slowly attacked by sulphuretted hydrogen, 
or some sulphur compound liberated in extremely small 
quantity from the maturing fish. 
The decomposition is, apparently, not due to bacterial 
action. In the processes of cooking and sterilisation the contents 
