NARRATIVE OF THE CRUISE. 
915 
the finest matter. The second contained the smaller and the third the larger Fora- 
minifera. This difference in the quantity of carbonate of lime in the decantations shows 
how two samples of the same ooze may vary when it is allowed to settle after being 
shaken by carriage in bottles or by the action of the dredge or trawl during collection. 
For these reasons an average sample of the deposit was generally carefully selected 
for analysis, and this has usually been taken from the specimen obtained in the sounding 
tube, where this sorting is much less likely to have taken place. 
The following analysis by Professor Brazier is from an average sample from the 
dredge : — 
Acid = 97T1, 
Acid = l - 49, 
at 230° F., . 
. 1-40 
[ Alumina, .... 
. 0-65 
Ferric Oxide, 
. 0-60 
Calcium Phosphate, 
. 0-90 
j Manganese Oxide, 
. trace 
Calcium Sulphate, 
. 0-19 
Calcium Carbonate, 
. 92-54 
Magnesium Carbonate, . 
. 0-87 
Silica, .... 
. 1-36 
\ Consisting of . Alumina and [ 
[ Ferric Oxide, with Silica, j 
. 1-49 
100-00 
It will be seen that this deposit has a high percentage of carbonate of calcium, 
and a small residue. The slightly higher percentage of the carbonate of lime in tins 
analysis than that given above (90'38) may be owing partly to the sorting of the 
materials of the ooze, and partly to the prolonged action of the hydrochloric acid in 
the complete analysis. 
On Deep-Sea Deposits in General . — The foregoing example will serve to show the 
method adopted by Messrs. Murray and Renard in the examination of the deep-sea 
deposits. The description commences by indicating the kind of deposit (red clay, blue 
mud, Globigerina ooze, &c.), with the macroscopic characters when wet or dry. When a 
complete chemical analysis has not been made the amount of carbonate of calcium has 
always been determined. 
This determination was generally made by estimating the carbonic acid ; a gramme 
of a mean sample of the substance was taken for this purpose, using dilute and cold 
hydrochloric acid. However, as the deposits often contain carbonates of magnesia and 
iron as well, the results calculated by associating the carbonic acid with the lime are not 
perfectly exact, but these carbonates of magnesia and iron are almost always in very small 
proportion, and the process is sufficiently accurate, for, owing to the sorting of the 
elements which goes on during collection and carriage, no two samples from the same 
Station give exactly the same percentage. The number which follows the words 
