392 
THE VOYAGE OF H.M.S. CHALLENGER. 
material which, as will be presently pointed out, forms the principal mass of most of 
these little nodules. When examined on a fresh fracture, the greater part is seen to 
be formed of a brownish yellow, slightly shining, compact matter, in which are 
embedded black-brown granules of glauconite, that stand out on the broken surface, 
together with other mineral grains and remains of microscopic organisms. These 
concretions are hard and tenacious, the fundamental mass, in spite of its earthy aspect, 
being compact, and having a hardness that does not exceed 5. The fracture is plane 
or irregular and slightly granular. The matter forming the matrix presents the 
pyrognostic reactions of phosphate of lime ; it is fusible with difficulty on the edges of 
the splinters ; moistened with sulphuric acid it colours the blow-pipe flame with green ; 
it is soluble in h)"drochloric acid. It may be added that the concretions from the 
shallower depths were larger, contained much more glauconite, and presented a green- 
coloured external appearance, while those from 1900 fathoms were of a light brown 
colour. 
Chemical Composition . — The determination arrived at from the above-mentioned 
characters as to the phosphatic nature of the substance making up these nodules is 
confirmed by the following analyses : — 
Station* 142, 150 Fathoms, No. 72. 
Ratio of 
Equivalents. 
Station 143, 1900 Fathoms, No. 73. 
Ratio of 
Equivalents. 
PjOj, 
19-96 
0-422 1 
^2^5’ 
23-54 
0-498 
C 02 , 
12-05 
0-274 >0-713 
CO 2 , . . 
10-64 
0-242 
S 03 , . . 
1-37 
0-017 
SO 3 , . . 
1=39 
0-017 
SiO.^ 
1-36 
SiO.„ 
2-56 
C. 1 O, 
39-41 
0-704)0.721 
CaO‘, 
40-95 
0-731 
MgO, 
0-67 
0-017 / 
MgO, . . 
0-83 
0-021 
1 * G^Ojji 
2-54 
FC 203 , 
2-79 
AlA. • 
1-19 
AI 2 O 3 , 
1-43 
Loss,* 
Loss, 
3-65 
Insoluble residue. 
17-34 
Insoluble residue. 
11-93 
- 
95-89 
99-71 
AnahjinH of Imoluhle Residue, No. 72. 
Analysis of Insoluble Residue, No. 
SiOj, 
77-43 
SiOa, 
76-58 
A 1 ., 0 .„ . 
12-40 
AI 2 O 3 , 
13-85 
7-91 
FeaOa, 
7-93 
CaO, 
1-07 
CaO, 
1-27 
MgO, 
1-02 
MgO, 
1-18 
99-83 
100-81 
‘ An accident in the operation prevented the determination of the Loss. 
