1890 - 91 .] Mr J. Y. Buchanan on Sulphur in Marine Muds. 23 
thoroughly into contact at the moment of comminution with the 
sea water and the digestive secretions of the animal. The action of 
these secretions on the sulphates in the sea water is to produce 
sulphides, and the actions of the sulphides on the ochreous 
matter of the bottom is to produce sulphides of iron and 
manganese. Even if the bottom were covered with felspathic 
or augitic sand, the sulphides, acting on these silicates in the 
moment of partial decomposition, would convert the ochreous 
oxides by degrees into sulphides. That the volcanic material, lava, 
dust, scoriae, pumice, which forms the bulk of tbe unaltered material 
of tbe bottom of the ocean, is so dealt with by the animals, is 
evident from the specimen from the Pacific on the table, which is 
not a singular specimen, but ratber a typical one. 
Having extracted what nutriment they can from the mud, the 
animals reject it, containing a certain proportion of sulphides of 
iron and manganese. These sulphides, it is well known, are exceed- 
ingly 5 unstable in presence of water and oxygen, and if they come 
to lie on the surface of the mud, where they are exposed to the 
action of the sea water, which always contains dissolved oxygen, 
they must be quickly transformed into oxides. In the oxidation 
of ferrous sulphide by this process .there is always separation of 
free sulphur, which, however, is to a great extent further oxidised; 
but it is probable that some would persist. If then the process 
just described represents at all what takes place in nature, we 
should expect to find in the ochreous deposits (the hydrous oxides 
of iron and manganese) some relics of their connection with the 
organic world. These are not wanting. All the deep-sea muds and 
manganese concretions, of every diversity of form, gave without 
exception, when freshly collected and heated in a tube over the 
lamp, a large quantity of ammoniacal water. It was important to 
see if sulphur could be detected. And here it is well to bear in 
mind that in the case of a “blue mud,” which may contain unaltered 
sulphide, the sulphur found in the dried sample will come at least 
in part from that sulphide, and will be due to the oxidation by the 
atmosphere in the process of drying. In the case of an oceanic 
“ red clay ” or manganese nodule, where no blue matter is present, 
any sulphur which is found may be properly ascribed to oxidation 
on the bottom of the sea. 
