JUNE, 1906. New Forms oF CoNCRETIONS—NICHOLS. 45 
ANALYSIS OF THE CENTRE OF A NODULE FROM THE CHALLENGER 



BANK. 
EER ee we ee ek Se te ie ates 49.66 
ERIE ft PEI MEL Eas rN el ey as EE ete 42.92 
MS had Se ao Pe Rll te ed 2 due od we ee PAN Se v8 2.38 
OME Met tegen ei Ne nt Ao ee BN O34 
LET UN ese Esai 2 ee dar ae ee el a a ea ee 0.05 
ee I Se fe Net OO Wk ee en 0.12 
Ser ed es Oi Si Sieh G6 vale e so 8 0.58 
NON aT De oct eho rics, Se a re Rd as hw Dlg oa i 
ON ae se GS A era oa Ne ae ae O:55 
Me EE eerie Patty YS Mey ey dabatc @ siete x fie geet 0.02 
IN Si eR Stak a nd ge hie . ena eee ache ayer] 
SI AQT ara) My AC ay Mads neta ae Say Le Foe ake 2.93 
j 100.03 
ee a ears I ee. ie. atts ves ae aie 0.08 
99-95 
This corres ponds to: 
aL DONA Ly. Sok OK aN so oon beds tv's 88.61 
BECO LON ALC eine cee <n) desudhe oS C fw ie 425. oy 4.98 
Peet eG AL OOUALEC! crop. ten foes owls Shows de Fe te aes 3 eae 
Bae a ESS COL DONA LC Matias yes a. ciealvid ic nei aE ees 0.08 
DEBE HOOUBA Be UN giao ly ily cree. Xs hee ate 10 6.07 
99-95 
A magnesia determination was also made upon about two grams 
of the extreme outer portion of the nodule. 5.12% of magnesia was 
found, corresponding with 10.70% of carbonate of magnesia. Thus 
it appears that the exterior of the nodule is more magnesian than the 
interior. 
Inasmuch as the nodules occur isolated on a small bank in the 
midst of the Atlantic, away from any possibility of impregnation | 
or alteration by waters flowing from pre-existing mineral veins, the 
presence or absence of minute proportions of the heavy metals is of 
importance as it bears directly upon the much disputed question of 
the origin of ore deposits by lateral secretion or ascension. The 
isolation of the material removes wholly the serious doubt present in 
most determinations of this character as to whether any metals 
found may not have originated in mineral veins and later impregnated 
the surrounding rock. Consequently a search for traces of copper 
and lead in thirty-seven grams of the nodule material was carried out 
with great care. There was not a trace of either metal present. 
*LessCOz2. Chiefly organic matter and some water. The organic matter makes itself very 
evident upon igniting the specimen, both by its odor and by blackening. 
