1869.] 



on the Scientific Exploration of the Deep Sea. 



485 



It will be seen from this that while the quantity of Nitrogen is only 

 1*97 per cent, less than in surface-water, the quantity of Oxygen is dimi- 

 nished by 4'48 per cent., and the quantity of Carbonic acid increased by 

 6*45 per cent. This difference is greater if Bottom- waters only are com- 

 pared with Surface-waters. 





30 Surface. 



24 Intermediate. 



35 Bottom. 



Per cent. 



Proportion. 



Per cent. 



Proportion. 



Per cent. 



Proportion. 





2 5-05 



ICO 



22*03 



IOO 



J 9*53 



ICO 





54-21 



216 



51-82 



2 35 



52-60 



261 





2074 





26-15 



119 



27-87 



143 





ioo-oo 





ICO'CO 





IOO'OO 





The two Series of analyses, before referred to, performed duringthe Second 

 cruise upon Intermediate waters at successive depths over the same spot 

 both show a regular increase of the Carbonic acid, and diminution of the Oxy- 

 gen, as the depth increases, the percentage of Nitrogen varying but slightly. 



These general results appear to show that the Oxygen diminishes and 

 the Carbonic acid increases with the depth until the bottom is reached ; 

 but that at the bottom, whatever the depth from the surface, the propor- 

 tions of Carbonic acid and of Oxygen do not conform to this law, Bottom- 

 water at a comparatively small depth often containing as much carbonic 

 acid and as little oxygen as Intermediate water at a greater depth. No 

 instance occurred during the first two Cruises in which (where samples of 

 surface and intermediate or bottom-waters were taken at the same place) 

 the quantity of Carbonic acid was less and of Oxygen greater than at the 

 surface ; the only exception occurred in the Third cruise, at a place where, 

 it is believed, currents of water were meeting. 



It was frequently noticed that a large percentage of Carbonic acid in 

 Bottom-water was accompanied by an abundance of Animal life, as shown 

 by the dredge ; and that where the dredge-results were barren, the quantity 

 of Carbonic acid was much smaller. The greatest percentage of Carbonic 

 acid ever found was accompanied by an abundance of life ; while at a short 

 distance (62 fathoms) above the bottom, the proportion of Carbonic acid 

 was conformable to the law of variation with depth before referred to : 



Bottom, 862 fras. 800 fms. 7o0fras. 



Oxygen 17*22 



Nitrogen 34*50 



Carbonic acid 48*28 



100*00 



17*79 

 48*46 

 33-75 

 100*00 



18-76 

 49*32 

 31*92 

 100-00 



The lowest percentage of Carbonic acid (7*93) ever found in Bottom- 

 water, occurring at a depth of 362 fathoms, was accompanied by a "very 

 bad haul." 



