REPORT ON THE DEEP-SEA DEPOSITS. 
371 
The two analyses, Nos. 106 and. 136, which could not well be tabulated with the 
rest, are given apart : — 
Station 252, 2740 fathoms (No. 106). 
extract- 
Total water, 
Total carbonic acid, 
Total phosphoric acid 
able by HCl, 
a. In Acetic Acidf 
Extract. 
h. In Hydrochlo- 
ric Acid Ex- 
tract from - 
Acetic Acid 
Kesidue. 
Magnesia, 
vSoda, . 
Silica, 
Lead, 
Copper, 
Cobalt, 
Mckel, 
Manganous oxide 
Loose oxygen. 
Lime, 
Magnesia, . 
Alkalies, 
Alumina, . 
L Ferric oxide. 
0-01 
0-272 1 
0-25 f 
0-40 J 
24-90 
0-38 
0-07 
0-45 
0-36 
0-60 
7-47 
0-93 
19-39 
3-95 
1-33 
1-42 
0-34 
3-03 
16-20 
c. In Sulphuric^ 
Acid ^tract j ferric oxide, 
from Hydro- . . . 
chloric Acid j 
Residue. j 
d. Ultimate Eesi- 1 ^ 
due. 
Station 276, 2350 fathoms (No, 136). 
Water, 
Silica, 
Lime, ...... 
Alumina, ..... 
Ferric oxide, .... 
Magnesia, 
Manganous oxide. 
Nickel oxide, .... 
Oxygen, 
1-62 
0-83 
14-91 
98-18 
9-51 
19-34 
3-19 
6-36 
26-70 
1-79 
26-46 
1-82 
6-31 
101-48 
The analyses Nos. 106 and 136 were undertaken with the view of determining the 
degree of oxidation of the manganese in the nodules. The results of Dittmar’s experi- 
ments show that the quantity of peroxide-oxygen in the samples examined by him is 
slightly greater than what would be required by the assumption that the manganese exists 
in the state of binoxide.^ Buchanan arrived at similar results from his analyses of some 
nodules,^ We obtained the same result in analysing a nodule from Station 276, 2350 
fathoms.® In this case we have been able to determine that the oxidation and hydration 
of the manganese answers approximately to Mn 02 + 2 H 2 O, and that this hydrated oxide 
is united with limonite (2Fe203-l- 3 H 2 O), 26’7 per cent. The estimation of peroxide- 
oxygen was also made by Dr (xibson in nodules from Station 285, 2375 fathoms ; the 
quantity found by him showed that barely all the manganese might exist as peroxide, and 
he points out that the cobalt, nickel, and thallium, present in the nodules, may also exist 
as peroxides, and thus account for the excess of oxygen.'* 
We thus arrive at the conclusion that these nodules of iron and manganese must be 
classed along with the impure variety of manganese known as wad or bog manganese ore. 
Under this name are included the manganese ores occurring in amorphous and reniform 
masses, made up, in addition to manganese, largely of a mixture of limonite and sandy 
materials, together with small percentages of cobalt, nickel, copper, and other substances. 
They are related to psilomelane under the formula ROMn 02 + H 2 O, but are mixtures of 
different oxides and cannot be considered distinct mineral species. In continental rocks 
wad or bog manganese occurs often as a deposit formed under water, and has originated 
from the decomposition of other manganese ores, principally manganese carbonates. 
1 See Analysis No. 106, App. III. 
^ See Analysis No. 136, App. III. 
2 Proc. Roy. Soe. Edin., vol. ix. p. 287, 1877. 
■* See Appendix II. 
