dole: chlorine content of rain water 3 



In the southwestern portion of the basins of the Pacific, At- 

 lantic and Indian oceans the abyssal water slowly rises and, 

 flowing southward, takes the place in the circumpolar antarctic 

 circulation of the water lost thru the Humboldt, Benguela and 

 Australian currents. 



In the central portion of the oceanic basins the general motion 

 of the water is from east to west, the water lost from the currents 

 flowing northward across the basins and being picked up by the 

 southerly currents on the other side. This circulation is rapid in 

 the high southern latitudes, diminishing in intensity northward. 



The water of the circumpolar west wind drift of low southern 

 latitudes, north of the true antarctic current, is mainly surface 

 water from the north caught up and driven forward by the strong 

 wind. This west wind drift forms a band dividing the abyssal 

 antarctic circulation from the superficial circulation further north. 



By this drift many organisms, pelagic at some stage of their 

 existence, or capable of transportation by floating objects, are 

 distributed thniout the southern latitudes, tho they are unable 

 to withstand truly antarctic conditions; and to this is largely 

 due the similarity of the faunas of southern Africa, southern 

 South America, southern Australia and New Zealand, a simi- 

 larity which is in no way indicated by the crinoids of these 

 localities. 



GEOCHEMISTRY. — Note on the chlorine content of rain water 

 at Tortugas, Fla. R. B. Dole, Geological Surve}'. Com- 

 municated by F. W. Clarke. 



The appreciable quantity of salt carried by normal rainfall 

 off the seacoast is well shown by test of a sample collected by 

 the writer on Loggerhead Key, Tortugas, Fla. After heavy all- 

 night rains and morning showers had thoroly washed the roof of 

 the Marine Biological Laboratory a large sample of rain was col- 

 lected during the afternoon of June 13, 1913, in a galvanized 

 bucket under one of the gutters. This sample was immediately 

 bottled and later tested at Washington, D. C, by E. C. Bain. A 

 250 cc. portion concentrated to 25 cc. and titrated with a solu- 

 tion of silver nitrate, 1 cc. of which was equivalent to 0.5 mgm. 



