MUSEUM OF COMPARATIVE ZOOLOGY. 53 



Suiphuric acid (S Ogj 2.74 



Fluorine 1.21 



Lime (Ca 0) 51.90 



Magnesia (Mg 0) 0.70 



Iron and Alumina. ....... 1.56 



Insoluble residue 0.21 



Loss on ignition 2.16 



99.70 

 Oxygen corresponding to Fluorine . . — 0.51 



99.19 



There were also traces of Silica and Chlorine. 



Atomic Ratios. 

 P2O5 1417 



1814. 



CO2 264 I 



s O3 69 r 



Fl 64 >' 



Ca 1853 



. ^ . 1888 



Mff 35 



■^o 



} 



At the same place and depth there was a concretion of a brown color 

 consisting of an aggregation of calcareous organisms cemented by a 

 brownish yellow matter, often showing concentric rings after the man- 

 ner of agate. This yellowish brown matter is isotropic, between crossed 

 nicols only the calcite and the shells of the Foraminifera brighten np ; 

 the calcite lies crystallized in the interior of the Foraminifera. In 

 treating the brown or yellow parts under the microscope with molyb- 

 date of ammonium and nitric acid, there is an abundant yellow precipi- 

 tate characteristic of phosphoric acid. 



At other stations small phosphatic concretions were also obtained by 

 the " Blake," all more or less resembling those described above. There 

 are difficulties in understanding how phosphate of lime and carbonate of 

 lime are deposited at the bottom of the sea, yet there is no doubt that 

 8uch a deposition does take place nnder some special circumstances. 

 Their solution is, however, an almost universal phenomenon in the 

 ocean. 



Specimen 60, Li>ie P'. — Lat. 24° 50' N. Lon^. 84° 50' 45" W. 15 May, 

 1875. Depth, 200S fathoms. A reddish brown Globigeriiia ooze dries into 

 slightly coherent lumps. 



