246 



PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



MECHANICAL AND CHEMICAL ANALYSES. 



The following tables show the results of mechanical analyses of the 



Murray Island bottom samples and chemical analyses of the bottom samples, 



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



areas, and of calcareous alga: 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. 



Si0 2 



Fe 2 3 +A1A . . . 



CaO 



MgO 



PA 



S0 3 



Na+K 



Total . 

 C0 2 needed.. 



No. I. 



44 



23 



3S 

 80 

 69 

 00 



Trace. 



Trace. 



98.96 

 42.87 



No. 2. 



44 51 

 ■31 



.30 



51-54 



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 

 °7 



5i 



41 

 68 

 00 



Trace. 



Trace. 



99.22 

 43-33 



No. 5. 



45-24 

 22 

 26 

 80 



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). 



Si0 2 



(Al, Fe)A 

 MgC0 3 .... 

 CaCO,.... 

 Ca s PA... 

 CaSO,.... 



Total . 



0.24 

 .36 



83 

 57 

 00 

 Trace. 



0.32 



■31 



5-52 



93 -85 



.00 



Trace. 



100.00 



0.09 

 .22 



95 



74 

 00 

 Trace. 



100.00 



0.07 



. 10 



5.76 



94.07 



.00 



Trace. 



i 00 . 00 



0.23 

 27 



57 

 93 

 00 

 Trace. 



100.00 



0.16 



■27 

 .60 

 98.97 

 .00 

 .00 



No. 1, 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, 12 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. 



