954 
THE VOYAGE OF H.M.S. CHALLENGER. 
the cruise was that, however much the proportion of total salts to water might vary, the 
composition of the saline mixture was very constant. From his analyses he has 
calculated the following numbers for the average composition of ocean water salts. 
Table IV . — Average Composition of Ocean Water Salts. 
Per 100 parts 
of Total Salts. 
Per 100 of Halo- 
gen calculated 
as Chlorine. 
Chlorine, . 
55-292 | 
99-848 
Bromine, ........ 
0-1884) 
0-3402 
Sulphuric acid (S0 3 ), . . 
6-410 
11-576 
Carbonic acid (C0 2 ), . . . . 
0-152 
0-2742 
Lime (CaO), . . . . 
1-676 
3-026 
Magnesia (MgO), ....... 
6-209 
11-212 
Potash (K 2 0), ....... 
1-332 
2-405 
Soda (Na 2 0), . . . . . . 
41-234 
74-462 
Oxygen equivalent of halogen, ..... 
-12-493 
-22-559 
Total Salts, . . 
100-000 
- 180-584 
“ Combining acids and bases, we have the following average composition of sea salt : — 
Chloride of sodium, . . . . . . . 77 -758 
Chloride of magnesium, . . . . . 10 ‘878 
Sulphate of magnesium, . . . . . 4'737 
Sulphate of lime, ........ 3 - 600 
Sulphate of potash, . . . . . . .2-465 
Bromide of magnesium, ....... 0'217 
Carbonate of lime, ........ 0-345 
100-000 ” 
With these tables the results of observations of density can be interpreted so as to 
give a very accurate indication of the chemical composition of the water . 2 
1 Equal conjointly to 55-376 parts of chlorine, -which accordingly is the percentage of “halogen reckoned as 
chlorine ” in the real total solids. 
2 Prof. Dittmar says : — “From my experiments, hitherto unpublished, on the dissociation of sea water carbonates 
I conclude that, supposing at a certain time all oceanic carbonates had been of the general formula R"0.1|C0 2 , it could 
not have sunk below this state of saturation anywhere, i.e., it could not, even in the tropics, have arrived at the 
composition R"0 .nC0 2 where n < l- 2 -; and supposing, secondly, all oceanic carbonates had been of the formula R"0. If C0 2 , 
it would not probably have lost carbonic acid, even if the temperature were 32° C. All this rests on the tacit 
