246 



PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



MECHANICAL AND CHEMICAL ANALYSES. 



The following tables show the results of mechanical analyses of the 

 Murra}^ Island bottom samples and chemical analj'ses of the bottom samples, 

 of certain foraminifera important as contributors to deposits in coral-reef 

 areas, and of calcareous algae from Murray Island and Cocos-Keeling Islands. 



Mechanical analyses of samples from Murray Island. 



(By U. S. Bureau of Soils.) 

 [The results of these analyses are graphically shown on plate 94.] 



Chemical analyses of Murray Island bottom samples. 

 (By .Alfred .A. Chambers.^ 



Chemical analyses of bottom samples. 



Loss on ignition. 



SiO, 



FesOj+AUO, . . . 



CaO 



MgO 



PjO. 



SO, 



Na+K 



Total . 

 COi needed. . 



No. I. 



44. b9 

 .23 



■35 



50.80 



2.69 



.00 

 Trace. 

 Trace. 



98.96 



42.87 



No. 2. 



44-51 

 •3" 



.30 



SIS4 



2.58 



.00 



Trace. 



Trace. 



99.24 

 44 34 



No. 3. 



44.87 

 .09 

 .21 



50.86 



2-75 



.00 



Trace. 



Trace. 



98.78 

 42-98 



No. 4. 



44.96 



-07 

 .10 



51.41 



2.68 



.00 



Trace. 



Trace. 



99.22 

 43-33 



No. 5. 



45.24 

 .22 

 .26 



49.80 



3-49 



.00 



Trace. 



Trace. 



99.01 

 42.87 



No. 6. 



43-86 

 .16 

 -27 



55-35 



.28 



.00 



.00 



(?) 



99-92 

 43-72 



Reduced analyses (hypothetical combinations). 



SiO, 



(.\1, Fe),Oj . 



MgCO, 



CaCO, 



Ca,PA... 

 CaSO. 



Total . 



0.24 



.36 



5.83 



93-57 



.00 



Trace. 



100.00 



0.32 



-31 



5-52 



93-85 



.00 



Trace. 



100.00 



0.09 



2** 



5-95 



93-74 



.00 



Trace. 



100.00 



0.07 



. 10 



5-76 



94.07 



.00 



Trace. 



100.00 



0.23 

 -27 



57 

 93 

 00 

 Trace. 



100.00 



0.16 

 -27 

 .60 



98-97 

 .00 

 .00 



100.00 



No. I, Murray Island, line I, southeast reef, 1,600 feet from shore. Water, 10 inches deep; low tide, 



October 2, 1913. 

 No. 2, Murray Island, line I, southeast reef, 200 feet from shore. Water, 4 inches deep. 

 No. 3, Murray Island, line I, southeast reef, 600 feet from shore. Water, 7 inches deep at low tide. 

 No. 4, Murray Island, line I, southeast reef, 1,200 feet from shore. Water, i; to 16 inches deep at low tide. 

 No. 5, Murray Island, line III, north end, 1,700 feet from shore, washed up on reef above low-tide level. 

 No. 6, Murray Island, limestone from 500 to 700 feet above sea-level. 



