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det imellem 900 og 1100 Favne. I den Bugt af Havbunden,
der ligger Nord for Vesteraaleu. optråeder Biloculiuleret
først paa et Dyb af mere end 1200 Favne. Grændselinien
herfra og nordover indtil den 80de Breddegrad ligger
imellem 1000 og 1100 Favne. Paa det samme Dyb begynder
Biloculinleret i den sydligere Del af Nordhavet, hvor dette
grunder op mot! Færø—Islandsbanken.
Jeg har tænkt mig. at den ovenstaaende Betragtning
af Biloculinlerets Udbredelse maaske senere kan blive en
Støtte ved det fremadskridende Studium af Expeditionens
fysiske og zoologiske Materiale. Tildels med det samme
Hensyn for Øiet. har jeg anlagt mine kemiske
Undersøgelser af dette Sediment, til hvilke jeg nu vil gaa over.
Den kvalitative Undersøgelse af Biloculinleret viser,
at det foruden Jern; Lerjord. Kalk, Magnesia, Kiselsyre
og Spor af Fosforsyre indeholder smaa Mængder af
Manganoxyder. De sidste forekommer dog ikke som synlige
Bestanddele af Lermassen i Lighed med de smaa Korn
ell’*r Klumper, der saa ofte blev fundne ved
Challenger-expeditionen. men synes at maatte være meget fint fordelte
i Bundprøverne og udgjør i det Hele taget en saa ringe
Del af deres Bestanddele, at de vanskeliggjør en
kvantitativ Bestemmelse. Det .er muligt, at Manganoxyderne kan
bidrage til "at give Leret en stærkere brun Farve. Ved
Ophedning udvikler Biloculinleret en temmelig stærk
empy-reumatisk Lugt.
For den kemiske Undersøgelse af Biloculinleret har
jeg først og fremst udvalgt mig en Del Hovedstationer fra
forskjellige Punkter af Nordhavet og analyseret
Bundprøverne fra disse fuldstændig med Hensyn til alle Bestanddele.
T det følgende har jeg opstillet mine Analyser efter
Nurneret af de Stationer, hvor Bundprøverne er optagne.
Bestemmelserne er udført efter den paa Side 36 beskrevne
Methode.
Station 51.
N. B. 65° 53’. V. L. 7° 18’. 1163 Favne (2127
Meter). — 1.1°. Lysbruut Biloculinler.
Dekomponeret
af
Saltsyre
73.49 pCt.
Glødningstab . . 2.71
Jeruoxydul . . . 1.14
Jernoxyd.... 2.74
Lerjord .... 6.49
Magnesia.... 0.93
Kulsur Kalk . . 52.82
Fosforsyre . . . Spor
Kiselsyre.... 9.37
boundary for Biloculina clay follows a depth ranging
from 700 to 800 fathoms. Over the rapidly shelving
bottom off Lofoten and Vesteraalen. it extends between 900
and 1100 fathoms. In the bight of the sea-bed north of
Vesteraalen the first Biloculina clay occurs at a depth of
more than 1200 fathoms. The boundary-line extending
from this locality northwards to the 80th parallel of
latitude lies at a depth ranging from 1000 to 1100 fathoms.
This is the depth at which Biloculina clay first occurs iu
the southern part of the North Atlantic, where its bed
shoals up towards the Færoe-Iceland bank.
The above elucidative remarks on the distribution of
Biloculina clay, will, it is hoped, in some measure serve
to facilitate the progressive working- out of the large
amount of physical and zoological material collected on the
Norwegian Expedition. Moreover, my chemical
investigation of that deposit, to the results of which I shall now
pass on. has been modified with the same object in view.
A qualitative analysis shows that Biloculina clay, along
with iron, alumina, lime, magnesia, .silica, and traces of
phosphoric acid, also contains small quantities of oxide of
manganese. The last of these constituents does not
however occur in a visible form, as small granules or
concretions, so frequently met with on the "Challenger"
Expedition. but would appear to be most sparingly distributed
throughout the deposit, of which it constitutes so small a
proportion as hardly to admit of being quantitatively
determined. Possibly, this oxide of manganese gives a darker
colour to the deposit. On exposure to heat, Biloculina
clay emits a pimgent empyreumatic odour.
For my chemical examination of Biloculina clay I
selected samples brought up at some of the principal
ob-serving-stations in different parts of the North Atlantic,
submitting portions of the deposit to a rigorous general
analysis embracing all its constituents.
The analyses are arranged according to the numbers
of the Stations at which the samples of deposit were
collected. The method of determination was that described
on page 36.
Station 51.
Lat. 65° 53’ N., long. 7° 18’ W.; 1163 fathoms
(2127 metres); bottom-temperature —1.1°. Light-brown
Biloculina clay.
Decomposed
by
Hydrochloric acid
73.40 per cent.
Loss by ignition . 2.71
’Protoxide of iron . 1.14
Sesquioxide of iron 2.74
Alumina .... 6.49
Magnesia.... 0.93
Carbonate of lime. 52.82
Phosphoric acid Traces
Silica.....9.37
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