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Generally the quantity of sodium is much less than the estimated 
average of Murray. On nearer consideration of the results of analyses 
of some river waters this fact is still more clearly brought to evidence. 
Especially this appears in the cases of the Meuse and the Elbe. In 
both cases the stated values are not only of especial value on account 
of the large number of reliable analyses on which they are based, so 
that we may admit them as indicating the true average composition 
during a year, but also because the local circumstances are somewhat 
better known. Considered together they moreover have a particular 
importance from the fact that in the drainage area of the Elbe crystalline 
rocks predominate, whereas in that ot the Meuse the soil is composed 
of clastic rocks belonging to the most different formations. 
In both cases a part of the sodium and a still more considerable 
part of the chlorine is surely not to be accounted for as resulting from 
chemical denudation, but as derived from the sea and carried back to it 
by the rivers. SPRING and Prost calculated that the principal manu- 
factories of chemical products between Namur and Liege use so much 
sea salt, that they bring yearly 17.5 million kilograms of chlorine, i.e. 
about 45 pCt of the whole amount stated in the analyses, into the Meuse, 
Certainly 40 pCt of it is not combined with sodium. Instead of the 
small surplus of 0.60 mgrm chlorine (above the quantity which could 
combine with all the sodium) we should, without this pollution of the 
water of the Meuse, undoubtedly have a considerable deficit, of about 
1.75 mgrm of chlorine per liter. Moreover great quantities of sodium and 
chlorine were supplied to the river in consequence of the physiolo- 
gical consumption of salt by the population of the basin of the 
Meuse up to Liege, at that time at least 3.000.000. Stating this 
supply of chlorine with’ Sprine at about 7 mgrm per head and 
per day we find more then 7.6 million kilograms of chlorine per 
annum. According to the statistics for the German empire the 
annual consumption of salt for the preparation of food was 7.6 
kilograms per head, i.e. 4.6 kilograms of chlorine and 3 kilograms of 
sodium. Supposing an equal consumption in the basin of the Meuse, 
we would have from this source an annual contribution to the river 
of 13.8 million kilograms of chlorine and 9 million kilograms of sodium. 
No insignificant quantities of chloride of sodium in the rivers 
are, moreover, supplied by the rain water and therefore simply 
return to the ocean, whence they were derived by the wind. For 
Great-Britain this quantity is so important, that JoLy admits that 
rivers, free from pollution, may owe their amount of salt to that 
source. In fact the water of the Dee near Aberdeen contains 9.6 
mgrm, that of the Don 18.9 mgrm of chlorides, whereas the average 
