No. 8. [From Nature, Oct. 10, 1878, Vol. xvni. p. 628.) 



MANGANESE NODULES IN LOCH FYNE 1 



ON September 21, 1878, I anchored the steam yacht 

 "Mallard" near the mouth of Loch Fyne, in 104 fathoms, for 

 the purpose of making physical and chemical observations on 

 the water of this, the deepest part of the Firth of Clyde. When 

 the anchor was got up a large mass of clay and shells was 

 found sticking to one of the flukes. It was gently dried, and 

 on examining it I observed a number of nodular concretions, 

 which, on being freed from the surrounding clay, presented a 

 finely mammillated black surface, were easily cut with a knife, 

 giving a brownish-black powder, which liberated chlorine from 

 strong hydrochloric acid, and possessed all the properties of 

 peroxide of manganese; in short, they were identical with 

 the manganese nodules which we found in the "Challenger" 

 to form so important a constituent of the sea-bottom in the 

 greatest depths. 



One half of the dried mud was carefully broken up and 

 searched through, the nodules being collected by themselves 

 and also the shells. It was thus separated into three portions, 

 which were weighed, with the following results: 



Manganese nodules . . . . 142-7 grammes 30 per cent. 



Shells 35-0 7-5 



Sandy clay . . . . . . 289-0 62-5 



Total . . 466-7 ,, i oo-o 



The manganese nodules, therefore, made up thirty per cent, 

 of the weight of the mud. Compared with those frequently 

 met with on board the "Challenger," the nodules were small. 

 In the sample examined there were eighty-three nodules 

 weighing 142-7 grammes, hence the average weight was 1-7 

 1 See Contents, p. xxviii. 



