916 
THE VOYAGE OF H.M.S. CHALLENGER. 
“ carbonate of calcium ” indicates the percentage of CaC0 3 ; the general designations of 
the principal calcareous organisms in the deposit are then given. 
The part insoluble in the hydrochloric acid, after the determination of the carbonic 
acid, is designated “ residue.” The number placed after this word indicates its percentage 
in the deposit ; then follow the colour and principal physical properties. This residue is 
washed and submitted to decantations, which separate the several constituents according 
to their density into three groups — (1) Minerals, (2) Siliceous Organisms, (3) Fine 
Washings. 
1 . Minerals. — The number within brackets indicates the percentage of particular 
minerals and fragments of rocks, and is the result of an approximate evaluation. As 
it is important to know the dimensions of the grains of minerals which constitute 
the deposit, their mean diameter in millimetres is given after the contraction m. di.\ 
then the species of minerals and rocks are enumerated. In this enumeration the minerals 
are placed in the order of the importance of the role which they play in the deposit. The 
specific determinations have been made with the mineralogical microscope in parallel or 
convergent polarised light. 
2. Siliceous Organisms. — The number between brackets indicates the percentage of 
siliceous organic remains which, as in the case of the minerals, is an approximate evaluation. 
Under this heading the glauconitic casts of the Foraminifera and other calcareous 
organisms are also placed. 
3. Fine Washings. — The particles which, resting in suspension, pass with the first 
decantation, are thus designated. The number within brackets which follows the words 
“ fine washings ” is obtained in the same manner as those placed after “ minerals ” and 
“ siliceous organisms.” The “ fine washings ” are fully described above (see pp. 913, 914). 
The various kinds of deposits referred to in the descriptions of the deposits throughout 
this volume have been arranged as follows by Messrs. Murray and Fenard : — 
Terrigenous deposits. 
Shore formations, 
Blue mud, 
Green mud and sand, 
Red mud, 
Volcanic mud and sand, 
Coral mud and sand, 
Coralline mud and sand, 
Globigerina ooze, 
Pteropod ooze, 
Abysmal deposits. f Diatom ooze, 
Radiolarian ooze, 
Red clay, 
Found in inland seas and along the shores of 
C continents. 
Found around oceanic islands and along the shores 
of continents. 
- Found in the abysmal regions of the ocean basins. 
The shore formations which are being laid down on the coast or in very shallow water 
need not be here referred to, as they were somewhat carefully described prior to the 
