*204 
THE VOYAGE OF H.M.S. CHALLENGER. 
Combining Acids and Bases in the ( arbitrary ) mode * shown, we have from 
my Numbers — 
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 
Total Salts, 
100-000 
As a general result of Forchhammer’s and my own analyses, the above numbers 
mat/ be taken as holding approximately for any sample of ocean-ivater. Of the degree 
of approximation we can form an idea by comparing my numbers for the percentages 
of chlorine, sulphuric acid, magnesia, and potash, with the corresponding entries in the 
77 reports tabulated on pages 23 to 25, and the numbers for the lime there with 
one another. The percentages of soda being too largely affected by the cumulative 
error of the other determinations, had better be left out of consideration. But even if we 
do so, we often meet with fluctuations which are too great to be taken as arising from 
analytical errors, and consequently must correspond to differences in the actual 
composition. I have taken great pains in trying to explain these differences by natural 
causes, but have not been very successful. The final results of my inquiries may be 
summed up as follows : — 
From my analyses (which I do not pretend exhaust the subject), it would appear 
that the comp<».-it i« m of >.-n-watrr salt is independent of the latitude and longitude 
whence the sample is taken. Nor can we trace any influence of the depth from 
which the sample comes, if we confine ourselves to the ratio to one another of 
chlorine, sulphuric acid, magnesia, potash, and bromine. I emphasise the bromine 
b. i-ausi*, while present in very small proportion, it is taken up preferably by sea- 
plants, and consequently must be presumed to be more liable than any of the major 
• 'om]»oncnts to at least temporary local diminution. And yet my analyses of the three 
mixtures ..f Challenger waters, and <>f the Arran water referred to, gave identical values 
f-r tin- bromine present per 100 of chlorine. But the determinations of the lime in the 
• inie -'-t of waters make it most highly probable that the proportion of this component 
it ■ r* f - with the depth. Referring to 100 parts of halogen calculated as chlorine, we 
find for the quantity of lime : — 
• Tho ro«lr here eho*>n differ* •omcwluit from tin- one I adopted on page 138, which represents the carbonic acid aa 
f ; .T, > > Neither*. in claim to I *• the tru>- mode ; hut I now thiuk the one chosen here is the more accurate. 
