288 Proceedings of the Royal Society 
scraped to powder with a knife. They gradually get harder on 
exposure to the air. 
The powder, heated in a closed tube, gives out water which re- 
acts alkaline, and has an empyreumatic odour. Heated with strong 
hydrochloric acid, it liberates abundance of chlorine, and the 
residue which remains is white, consisting of silica, clay, and 
sand, the sand being the same as is found in the bottom mud from 
the same locality. Their composition varies greatly, different 
nodules containing different quantities of mechanically admixed 
mud, and the number of different elements found in them is very 
large. Copper, iron, cobalt, nickel, manganese, alumina, lime, 
magnesia, silica, and phosphoric acid have been detected in a 
large number ; but I have not as yet been able to make a com- 
pleted analysis of any of them. I have, however, made a few 
determinations of the most important component substances. For 
this purpose the outside and densest layers of the nodules were 
selected, and portions of them pulverised and dried for ten or 
twelve hours at 140° C. The amount of chlorine liberated on 
treatment with hydrochloric acid was determined by Bunsen’s 
method, and the iron was determined by titration with stannous 
chloride. The samples analysed were from four different localities. 
Nos. 2, 4, and 5 were from the same place, No. 2 being the 
matter collected round a shark’s tooth as nucleus ; Nos. 4 and 5 
being the outside rinds of ordinary nodules. 
The results are given in the following table, the numbers being 
in many cases the means of several observations : — 
Locality. 
A 
B 
C 
D 
E 
F 
G 
Lilt. 
Long. 
No. 
Insoluble 
Residue. 
0 
Mn0 2 
MnO 
Fe 2 0 3 
AI2O3 
H 2 0 
Na 2 0 
13° 52' S. 
149° 17' W. 
2 
1755 
6-13 
33-30 
2718 
... 
... 
• • • 
• • • 
... 
4 
15-30 
5-92 
32-23 
• •• 
23-86 
... 
• . • 
... 
... 
5 
15-30 
6-49 
35-28 
... 
24 85 
... 
10-2 
• •• 
37° 52' N. 
160° 17' W. 
6 
36-24 
6.49 
24 41 
... 
2016 
3-83 
7-70 
5-98 
42° 42' S. 
134° 10' E. 
7 
17-98 
7-54 
41-11 
33-53 
18-04 
2-55 
7-31 
... 
22° 21' S. 
150° 17' W. 
8 
21-74 
5.19 
28-20 
... 
24-52 
7-67 
8 54 
8.5 
A is the residue which remains undissolved after treating the 
mineral with strong hydrochloric acid, evaporating to dryness and 
redissolving. In No. 5 it contains 85T6 per cent, silica, and in 
No. 6, 82-27 per cent. 
B is the available oxygen determined by Bunsen’s method. 
