1895- ''CHALLENGER'' CHEMISTRY AND PHYSICS, iir 



the surface-water of the Pacific than it is in the surface-water of the 

 Atlantic Ocean. 



The sea being dependent on the atmosphere for its supphes of 

 oxygen and nitrogen, the absolute quantity of these gases present in 

 a sample will depend on the temperature and barometric pressure at 

 the time of absorption. Thus, at 760 mm. and 2° C. (35'6° F.) one 

 cubic foot of sea-water will absorb 1 3 -42 cubic inches of oxygen and 

 25*67 cubic inches of nitrogen, while at 27° C. (8o-6° F.) it will only 

 absorb 8-15 cubic inches of oxygen and 16-13 of nitrogen. The 

 normal proportion of oxygen in sea-water air is thus from 34^ to 33I- 

 per cent., but while the inert nitrogen remains unaltered, the oxygen 

 ever tends to diminish. 



In surface-waters the total quantity of gas in solution was found 

 to decrease as one went from the poles to the equator, as also did the 

 proportion of oxygen. In high latitudes the proportion of oxygen is 

 sometimes so high as to amount to supersaturation, 35*01 per cent, 

 being found near the Antarctic Circle. A similar phenomenon was 

 observed by Tornoe in Arctic waters, wherein he found as 

 much as 36*7 per cent, of oxygen. The lowest percentage of oxygen 

 was found in warm regions where oxidation processes are rapid, and 

 fell as low as 32-2 per cent, towards the south-east of the Philippine 

 Islands. This contrast between the percentages of oxygen in warm 

 and cold waters was most pronounced in the water strata from loa 

 to 300 fathoms in depth. Bottom waters were almost always poorer 

 in oxygen than intermediate waters from great depths. No water 

 was found to be absolutely devoid of oxygen, although in waters from 

 great depths the quantity was often very small. Thus, from a station 

 on the 30th parallel, to the north of the Sandwich Islands, the dis- 

 solved air contained only 3-84 per cent, of oxygen, amounting to 

 about one cubic inch per cubic foot of water. From the amount of 

 nitrogen present there must have been originally fourteen cubic 

 inches of oxygen present. 



The discussion of Deep-Sea Deposits involved a considerable 

 amount of chemical work, consisting chiefly of analyses of samples of 

 deposits, minerals, corals, manganese concretions, and organic 

 remains, 161 analyses altogether being recorded in the Report on 

 Deep-Sea Deposits. The majority of the analyses were executed by 

 the late Professor Brazier, of Aberdeen ; the remainder by Anderson, 

 Church, Dittmar, Giimbel, Hornung, Klement, Renard, Ross, and 

 Sipocz. 



This Report also includes a remarkable analysis of manganese 

 nodules, with special reference to the presence or absence of the rarer 

 elements, carried out with all the resources of modern analysis by 

 Professor Gibson, of Edinburgh. Space will not permit us to quote 

 it in full, but we may mention that he detected and estimated 

 the amount present of sodium, potassium, ammonium, magnesium, 

 calcium, strontium, barium, manganese, cobalt, nickel, zinc, thallium,. 



