Generation of Sulphur in 



decided to weigh it, the operation being, from an analytical 

 point of view, an advantageous one, as the sulphate of barium 

 weighed weighs seven times more than the sulphur to be 

 estimated. By far the largest amount of sulphur is contained 

 in the clay from the Sound of Jura, which, in its fresh state, 

 contained large quantities of sulphides, which were completely 

 oxidised on drying. The 0-197 grammes of residue may be 

 taken to be pure sulphur, which makes about 0-4 per cent. 

 By far the greater part, if not the whole, of this sulphur was 

 formed by oxidation during drying. Had it been possible 

 to collect and examine separately the reddish-brown surface 

 layer, we should, no doubt, have found very much less sulphur, 

 but it would have been mainly due to oxidation by the oxygen 

 of the bottom water. 



The "oil," which is extracted from all the muds along with 

 the sulphur, and which varies a good deal in quantity, is due 

 to the animal debris intimately mixed with the mud and with 

 the materials of the nodules, which are made up, for the most 

 part, of the materials of the bottom 1 . 



Nos. 2 and 3. The manganese nodules of the I2th July 

 1875, from the North Pacific, in lat. 37 52' N., long. 160 17' W., 

 came from a depth of 2740 fathoms, where they appear to have 

 been exceptionally abundant. Those of the i6th September 

 1875 came from a locality where they were equally abundant. 

 The water was a little shallower, being 2350 fathoms, in 

 lat. 13 28' S., long. 149 30' W. In both the samples of these 

 nodules examined, the weight of the residue is considerable, 

 but as there was a little oil in both cases it is not possible 

 to give the percentage of sulphur. 



No. 4. The mud from the Sound of Raasay, off the west 

 coast of Ross-shire, was dredged from 150 fathoms, and con- 

 sisted of very fine soft grey mud, which on washing left a 

 large residue of coprolitic pellets. 



No. 5 is a similar mud from Loch Duich, also in Ross-shire ; 

 it harboured many annelids. 



No. 6 is from the station in Loch Fyne, where, for the 

 first time, manganese nodules were obtained in comparatively 

 shallow water. It is a sandy clay with many dead shells. 

 1 For table of analytical results, see pp. 144, 145. 



