140 Generation of Sulphur in 



are exceedingly 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 repre- 

 sents 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. 



Acting on these considerations, in the winter of 1880-81, 

 a number of muds and nodules were examined with a view 

 to the detection, and if possible the estimation, of free sulphur. 



Estimation of Sulphur in Muds. 



A certain quantity of the clay, dried at about 80 C., was 

 put into a bottle with a known weight of chloroform. The 

 stopper was tied down, and it was then put into a water-bath 

 for about an hour at about the temperature of boiling chloro- 

 form (61 C.). It was then allowed to cool, filtered into a 

 weighed fractionating flask, and washed twice with a little 

 more chloroform. The chloroform was then distilled off, 

 and the residue heated slightly and weighed. 



The residue was treated with hot nitric and hydrochloric 



