208 
THE VOYAGE Of H.M.S. CHALLENGER. 
ciilcium, and magnesium ; indeed the presence of these silicates was revealed by the 
microscopic examination of the mineral particles. 
The following analysis of a Radiolarian Ooze was made by Dr. Sipocz : — 
Station. | 
c «* 
5 § 
No. 
Lo.ss on 
Ignition. 
SiOj 
AI3O3 
Fe„Os 
MnO 
CaO 
MgO 
P2O5 
CuO 
Co 
K2O 
Na^O 
Total. 
‘266 
2750 
30 
16-62 
52-85 
8-22 
6-94 
1-74 
6-61 
4-84 
3-99 
0-16 
tr. 
tr. 
tr. 
100-87 
Tliis analysis likewise shows a high percentage of silicic acid, and from the large quantity 
of water shown by the loss on ignition, the major part of this silica, as well as of the iron 
and alumina, must be in the form of hydrate. The phosphoric acid, and a part of the 
calcium, are due to the presence of phosphate of lime in the organic remains. The 
rather high percentage of magnesia is probably explained by the presence in the deposit 
of fragments of rocks, containing magnesia and lime, such as the numerous fragments 
of altered volcanic minerals and glass noticed in the microscopic examination. The 
foregoing analyses then corroborate the results obtained by the macroscopic and micro- 
scopic examination of the Radiolarian Ooze ; that is to say, we find the deposit com- 
posed of a mass of mineral matters analogous to those met with in the Red Clays, but 
this deposit is distinguished from the Red Clay by a greater abundance of hydrated 
silica due to the presence of the organisms which give their name to the deposit. 
In addition to the samples of Radiolarian Ooze obtained by the Challenger, other 
areas of this deposit were discovered by the U.S. ship “Tuscarora” in the Pacific, and 
by H.M.S. “Egeria”in the Indian Ocean. No specimens of this deposit have as yet 
been met with in the Atlantic Ocean, and for a variety of reasons it is, indeed, unlikely 
that a Radiolarian Ooze vdll be discovered in the Atlantic. By reference to Chart 1 it 
will be seen that the patches of Radiolarian Ooze in the Pacific are confined to the 
central and western regions of that ocean, the seven patches shown on the map covering 
about 1,161,000 square miles. In the Indian Ocean there is a great patch of this deposit, 
in the deep water of the central eastern region surrounding the Cocos and Christmas 
Lslands, the area of w'hich Is estimated at about 1,129,000 square miles. 
Diatom Ooze. 
Just as the name Radiolarian Ooze was introduced by Mr. Murray to distinguish those 
deposits in which Radiolarian remains })layed a prominent part, so the name Diatom 
Ooze Wits applied during the Challenger Expedition to distinguish those deposits in which 
Diatom frustules were excej)tionally abundant. Dr. Joseph Hooker,^ during Sir James 
• BoUnjr of the Antarctic Voyage of H.M.SS. “ Erebna” and “ Terror,” I. “ Flora Antarctica,” p. 503, London, 1847; 
Kejrf'rt of British Amociation for 1847, pp. 83-95, London, 1848. 
