824 



THE ATLANTIC. 



[chap. v. 



No. 18.— Station XXI. March 13tli. Lat. 18° 54' N., Long. 61° 28' 

 W. Depth, 3025 fathoms. Bottom temperature, 1°"3 C. Chemical 

 composition : 



Loss on ignition after drying at 230° F 5-92 



' Alumina 704 



Ferric oxide 12'25 



Portion soluble in Calcium phosphate Small traces 



hydrochloric acid -J Calcium sulphate 0-51 



Calcium carbonate 2'44 



Magnesium carbonate 3"48 



Silica 24-'70 



' Alumina 5'51 



Ferric oxide 6"73 



Lime 0-81 



Magnesia 0'41 



Sihca 30-20 



= 50-42. 



Portion insoluble 

 in hydrochloric 

 acid = 43-66. 



lOO-OO 



A red clay, containing much amorphous clayey matter, with iron per- 

 oxide ; many fragments of sanidine, augite, olivine, hornblende, and 

 magnetite ; many of the mineral particles much larger than those at 

 Station XX. A few fragments of the tests of Globigerina. 



No. 19.— Station XXII. March 14th. Lat. 18° 40' N., Long. 62° 56' 

 W. Depth, 1420 fathoms. Bottom temperature, 3°"0 C. Chemical 

 composition : 



Loss on ignition after drying at 230° F 3-80 



' Alumina } 



Ferric oxide \ 



Portion soluble in Calcium phosphate 2-41 



hydrochloric acid -l Calcium sulphate 0-41 



= 92-'7o. Calcium carbonate 80-69 



Magnesium carbonate 0-68 



Silica 4-14 



Portion insoluble "] 



in hydrochloric J- 



acid = 3-45. j 



Insoluble residue, principally alumina and ferric oxide, 



with silica 3-45 



100-00 



A globigerina ooze, containing many pelagic foraminifera of the gen- 

 era Globif/eriua, Orbulina, Fulvimdina, Pullenia, and Sphceroidina ; 

 many shells of pteropods and heteropods ; a few coccoliths and rhabdo- 

 liths ; otolites of fishes, and spines of echini ; a few siliceous spicules. 

 Amorphous mineral matter and particles of quartz, feldspar, horn- 

 blende, and magnetite. 



