1890 - 91 .] Mr J. Y. Buchanan on Sulphur in Marine Muds. 29 
No. 25 is a very remarkable white clay from the bottom of 
Loch Ness, and therefore a fresh-water formation. It occurs in a 
small area opposite Urquhart Castle, and in various depths, often 
covered by a thin layer of peaty substance ; but in some places, in 
depths of about 30 fathoms, the sounding-tube brings up the white 
clay alone. It was observed also in Loch Oich. It is chemically 
quite distinct from the marine clays, being much more acid. The 
amount of matter extracted by chloroform is enormous, being 374 
milligrms. per 100 grms., most of which is oil or wax, but con- 
taining 4 milligrms. of oxidisable sulphur. It is not impossible 
that in this case the sulphur may exist as an organic compound ; 
and the amount of oily matter in the clay is interesting in the 
indication which it gives of the possible mode of formation of our 
oil-bearing shales. 
No. 26 is from the anchorage of Isle Oronsay in the Sound of 
Sleat. 
No. 27 is from a depth of 87 fathoms off Garroch Head, in the 
Firth of Clyde. Both in this case and in that of No. 26 the 
amounts of residue and of sulphur are insignificant. 
Sulphur was thus detected in all these samples and determined 
in the greater number of them. Putting aside shallow water coast 
muds, the largest amounts of sulphur are found in the Celebes Sea 
(No. 16), in the Diatomaceous ooze of the Antarctic (No. 18), and 
in the Badiolarian ooze of the Pacific (No. 20). -So far, therefore, 
as it goes, we have the evidence of the sulphur in favour of former 
organic agency. It is worthy of remark that the property of giving 
off alkaline water on heating has in the course of years disappeared, 
and in its place the nodules on being heated give off acid vapours, 
which, it is true, contain some ammonia, but along with an 
excess of nitric acid, which is without doubt due to the gradual 
oxidation of the nitrogenous matter. It is possible that the finely 
divided sulphur may diminish and finally disappear in the same way. 
But in 1881, there was still enough to be easily determined. Let 
us consider the chemical reactions more closely. 
When a mud containing ferrous sulphide is treated with dilute 
hydrochloric acid, the sulphide dissolves with evolution of sulphur- 
etted hydrogen, so long as there is no substance present which has 
a decomposing action on the sulphuretted hydrogen. If there be 
